`crate`-only several BOLT12 methods that require unbounded generics

[rust-lightning] / lightning / src / offers / invoice.rs

// This file is Copyright its original authors, visible in version control
// history.
//
// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// You may not use this file except in accordance with one or both of these
// licenses.

//! Data structures and encoding for `invoice` messages.
//!
//! A [`Bolt12Invoice`] can be built from a parsed [`InvoiceRequest`] for the "offer to be paid"
//! flow or from a [`Refund`] as an "offer for money" flow. The expected recipient of the payment
//! then sends the invoice to the intended payer, who will then pay it.
//!
//! The payment recipient must include a [`PaymentHash`], so as to reveal the preimage upon payment
//! receipt, and one or more [`BlindedPath`]s for the payer to use when sending the payment.
//!
//! ```
//! extern crate bitcoin;
//! extern crate lightning;
//!
//! use bitcoin::hashes::Hash;
//! use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
//! use core::convert::{Infallible, TryFrom};
//! use lightning::offers::invoice_request::InvoiceRequest;
//! use lightning::offers::refund::Refund;
//! use lightning::util::ser::Writeable;
//!
//! # use lightning::ln::PaymentHash;
//! # use lightning::offers::invoice::BlindedPayInfo;
//! # use lightning::blinded_path::BlindedPath;
//! #
//! # fn create_payment_paths() -> Vec<(BlindedPayInfo, BlindedPath)> { unimplemented!() }
//! # fn create_payment_hash() -> PaymentHash { unimplemented!() }
//! #
//! # fn parse_invoice_request(bytes: Vec<u8>) -> Result<(), lightning::offers::parse::Bolt12ParseError> {
//! let payment_paths = create_payment_paths();
//! let payment_hash = create_payment_hash();
//! let secp_ctx = Secp256k1::new();
//! let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32])?);
//! let pubkey = PublicKey::from(keys);
//! let wpubkey_hash = bitcoin::util::key::PublicKey::new(pubkey).wpubkey_hash().unwrap();
//! let mut buffer = Vec::new();
//!
//! // Invoice for the "offer to be paid" flow.
//! InvoiceRequest::try_from(bytes)?
#![cfg_attr(feature = "std", doc = "
    .respond_with(payment_paths, payment_hash)?
")]
#![cfg_attr(not(feature = "std"), doc = "
    .respond_with_no_std(payment_paths, payment_hash, core::time::Duration::from_secs(0))?
")]
//!     .relative_expiry(3600)
//!     .allow_mpp()
//!     .fallback_v0_p2wpkh(&wpubkey_hash)
//!     .build()?
//!     .sign::<_, Infallible>(
//!         |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
//!     )
//!     .expect("failed verifying signature")
//!     .write(&mut buffer)
//!     .unwrap();
//! # Ok(())
//! # }
//!
//! # fn parse_refund(bytes: Vec<u8>) -> Result<(), lightning::offers::parse::Bolt12ParseError> {
//! # let payment_paths = create_payment_paths();
//! # let payment_hash = create_payment_hash();
//! # let secp_ctx = Secp256k1::new();
//! # let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32])?);
//! # let pubkey = PublicKey::from(keys);
//! # let wpubkey_hash = bitcoin::util::key::PublicKey::new(pubkey).wpubkey_hash().unwrap();
//! # let mut buffer = Vec::new();
//!
//! // Invoice for the "offer for money" flow.
//! "lnr1qcp4256ypq"
//!     .parse::<Refund>()?
#![cfg_attr(feature = "std", doc = "
    .respond_with(payment_paths, payment_hash, pubkey)?
")]
#![cfg_attr(not(feature = "std"), doc = "
    .respond_with_no_std(payment_paths, payment_hash, pubkey, core::time::Duration::from_secs(0))?
")]
//!     .relative_expiry(3600)
//!     .allow_mpp()
//!     .fallback_v0_p2wpkh(&wpubkey_hash)
//!     .build()?
//!     .sign::<_, Infallible>(
//!         |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
//!     )
//!     .expect("failed verifying signature")
//!     .write(&mut buffer)
//!     .unwrap();
//! # Ok(())
//! # }
//!
//! ```

use bitcoin::blockdata::constants::ChainHash;
use bitcoin::hash_types::{WPubkeyHash, WScriptHash};
use bitcoin::hashes::Hash;
use bitcoin::network::constants::Network;
use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, self};
use bitcoin::secp256k1::schnorr::Signature;
use bitcoin::util::address::{Address, Payload, WitnessVersion};
use bitcoin::util::schnorr::TweakedPublicKey;
use core::convert::{AsRef, Infallible, TryFrom};
use core::time::Duration;
use crate::io;
use crate::blinded_path::BlindedPath;
use crate::ln::PaymentHash;
use crate::ln::channelmanager::PaymentId;
use crate::ln::features::{BlindedHopFeatures, Bolt12InvoiceFeatures, InvoiceRequestFeatures, OfferFeatures};
use crate::ln::inbound_payment::ExpandedKey;
use crate::ln::msgs::DecodeError;
use crate::offers::invoice_request::{INVOICE_REQUEST_PAYER_ID_TYPE, INVOICE_REQUEST_TYPES, IV_BYTES as INVOICE_REQUEST_IV_BYTES, InvoiceRequest, InvoiceRequestContents, InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef};
use crate::offers::merkle::{SignError, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, TlvStream, WithoutSignatures, self};
use crate::offers::offer::{Amount, OFFER_TYPES, OfferTlvStream, OfferTlvStreamRef, Quantity};
use crate::offers::parse::{Bolt12ParseError, Bolt12SemanticError, ParsedMessage};
use crate::offers::payer::{PAYER_METADATA_TYPE, PayerTlvStream, PayerTlvStreamRef};
use crate::offers::refund::{IV_BYTES as REFUND_IV_BYTES, Refund, RefundContents};
use crate::offers::signer;
use crate::util::ser::{HighZeroBytesDroppedBigSize, Iterable, SeekReadable, WithoutLength, Writeable, Writer};
use crate::util::string::PrintableString;

use crate::prelude::*;

#[cfg(feature = "std")]
use std::time::SystemTime;

pub(crate) const DEFAULT_RELATIVE_EXPIRY: Duration = Duration::from_secs(7200);

/// Tag for the hash function used when signing a [`Bolt12Invoice`]'s merkle root.
pub const SIGNATURE_TAG: &'static str = concat!("lightning", "invoice", "signature");

/// Builds a [`Bolt12Invoice`] from either:
/// - an [`InvoiceRequest`] for the "offer to be paid" flow or
/// - a [`Refund`] for the "offer for money" flow.
///
/// See [module-level documentation] for usage.
///
/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
///
/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
/// [`Refund`]: crate::offers::refund::Refund
/// [module-level documentation]: self
pub struct InvoiceBuilder<'a, S: SigningPubkeyStrategy> {
        invreq_bytes: &'a Vec<u8>,
        invoice: InvoiceContents,
        signing_pubkey_strategy: S,
}

/// Indicates how [`Bolt12Invoice::signing_pubkey`] was set.
///
/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
pub trait SigningPubkeyStrategy {}

/// [`Bolt12Invoice::signing_pubkey`] was explicitly set.
///
/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
pub struct ExplicitSigningPubkey {}

/// [`Bolt12Invoice::signing_pubkey`] was derived.
///
/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
pub struct DerivedSigningPubkey(KeyPair);

impl SigningPubkeyStrategy for ExplicitSigningPubkey {}
impl SigningPubkeyStrategy for DerivedSigningPubkey {}

impl<'a> InvoiceBuilder<'a, ExplicitSigningPubkey> {
        pub(super) fn for_offer(
                invoice_request: &'a InvoiceRequest, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>,
                created_at: Duration, payment_hash: PaymentHash
        ) -> Result<Self, Bolt12SemanticError> {
                let amount_msats = Self::check_amount_msats(invoice_request)?;
                let signing_pubkey = invoice_request.contents.inner.offer.signing_pubkey();
                let contents = InvoiceContents::ForOffer {
                        invoice_request: invoice_request.contents.clone(),
                        fields: Self::fields(
                                payment_paths, created_at, payment_hash, amount_msats, signing_pubkey
                        ),
                };

                Self::new(&invoice_request.bytes, contents, ExplicitSigningPubkey {})
        }

        pub(super) fn for_refund(
                refund: &'a Refund, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, created_at: Duration,
                payment_hash: PaymentHash, signing_pubkey: PublicKey
        ) -> Result<Self, Bolt12SemanticError> {
                let amount_msats = refund.amount_msats();
                let contents = InvoiceContents::ForRefund {
                        refund: refund.contents.clone(),
                        fields: Self::fields(
                                payment_paths, created_at, payment_hash, amount_msats, signing_pubkey
                        ),
                };

                Self::new(&refund.bytes, contents, ExplicitSigningPubkey {})
        }
}

impl<'a> InvoiceBuilder<'a, DerivedSigningPubkey> {
        pub(super) fn for_offer_using_keys(
                invoice_request: &'a InvoiceRequest, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>,
                created_at: Duration, payment_hash: PaymentHash, keys: KeyPair
        ) -> Result<Self, Bolt12SemanticError> {
                let amount_msats = Self::check_amount_msats(invoice_request)?;
                let signing_pubkey = invoice_request.contents.inner.offer.signing_pubkey();
                let contents = InvoiceContents::ForOffer {
                        invoice_request: invoice_request.contents.clone(),
                        fields: Self::fields(
                                payment_paths, created_at, payment_hash, amount_msats, signing_pubkey
                        ),
                };

                Self::new(&invoice_request.bytes, contents, DerivedSigningPubkey(keys))
        }

        pub(super) fn for_refund_using_keys(
                refund: &'a Refund, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, created_at: Duration,
                payment_hash: PaymentHash, keys: KeyPair,
        ) -> Result<Self, Bolt12SemanticError> {
                let amount_msats = refund.amount_msats();
                let signing_pubkey = keys.public_key();
                let contents = InvoiceContents::ForRefund {
                        refund: refund.contents.clone(),
                        fields: Self::fields(
                                payment_paths, created_at, payment_hash, amount_msats, signing_pubkey
                        ),
                };

                Self::new(&refund.bytes, contents, DerivedSigningPubkey(keys))
        }
}

impl<'a, S: SigningPubkeyStrategy> InvoiceBuilder<'a, S> {
        fn check_amount_msats(invoice_request: &InvoiceRequest) -> Result<u64, Bolt12SemanticError> {
                match invoice_request.amount_msats() {
                        Some(amount_msats) => Ok(amount_msats),
                        None => match invoice_request.contents.inner.offer.amount() {
                                Some(Amount::Bitcoin { amount_msats }) => {
                                        amount_msats.checked_mul(invoice_request.quantity().unwrap_or(1))
                                                .ok_or(Bolt12SemanticError::InvalidAmount)
                                },
                                Some(Amount::Currency { .. }) => Err(Bolt12SemanticError::UnsupportedCurrency),
                                None => Err(Bolt12SemanticError::MissingAmount),
                        },
                }
        }

        fn fields(
                payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, created_at: Duration,
                payment_hash: PaymentHash, amount_msats: u64, signing_pubkey: PublicKey
        ) -> InvoiceFields {
                InvoiceFields {
                        payment_paths, created_at, relative_expiry: None, payment_hash, amount_msats,
                        fallbacks: None, features: Bolt12InvoiceFeatures::empty(), signing_pubkey,
                }
        }

        fn new(
                invreq_bytes: &'a Vec<u8>, contents: InvoiceContents, signing_pubkey_strategy: S
        ) -> Result<Self, Bolt12SemanticError> {
                if contents.fields().payment_paths.is_empty() {
                        return Err(Bolt12SemanticError::MissingPaths);
                }

                Ok(Self { invreq_bytes, invoice: contents, signing_pubkey_strategy })
        }

        /// Sets the [`Bolt12Invoice::relative_expiry`] as seconds since [`Bolt12Invoice::created_at`].
        /// Any expiry that has already passed is valid and can be checked for using
        /// [`Bolt12Invoice::is_expired`].
        ///
        /// Successive calls to this method will override the previous setting.
        pub fn relative_expiry(mut self, relative_expiry_secs: u32) -> Self {
                let relative_expiry = Duration::from_secs(relative_expiry_secs as u64);
                self.invoice.fields_mut().relative_expiry = Some(relative_expiry);
                self
        }

        /// Adds a P2WSH address to [`Bolt12Invoice::fallbacks`].
        ///
        /// Successive calls to this method will add another address. Caller is responsible for not
        /// adding duplicate addresses and only calling if capable of receiving to P2WSH addresses.
        pub fn fallback_v0_p2wsh(mut self, script_hash: &WScriptHash) -> Self {
                let address = FallbackAddress {
                        version: WitnessVersion::V0.to_num(),
                        program: Vec::from(&script_hash.into_inner()[..]),
                };
                self.invoice.fields_mut().fallbacks.get_or_insert_with(Vec::new).push(address);
                self
        }

        /// Adds a P2WPKH address to [`Bolt12Invoice::fallbacks`].
        ///
        /// Successive calls to this method will add another address. Caller is responsible for not
        /// adding duplicate addresses and only calling if capable of receiving to P2WPKH addresses.
        pub fn fallback_v0_p2wpkh(mut self, pubkey_hash: &WPubkeyHash) -> Self {
                let address = FallbackAddress {
                        version: WitnessVersion::V0.to_num(),
                        program: Vec::from(&pubkey_hash.into_inner()[..]),
                };
                self.invoice.fields_mut().fallbacks.get_or_insert_with(Vec::new).push(address);
                self
        }

        /// Adds a P2TR address to [`Bolt12Invoice::fallbacks`].
        ///
        /// Successive calls to this method will add another address. Caller is responsible for not
        /// adding duplicate addresses and only calling if capable of receiving to P2TR addresses.
        ///
        /// This is not exported to bindings users as TweakedPublicKey isn't yet mapped.
        pub fn fallback_v1_p2tr_tweaked(mut self, output_key: &TweakedPublicKey) -> Self {
                let address = FallbackAddress {
                        version: WitnessVersion::V1.to_num(),
                        program: Vec::from(&output_key.serialize()[..]),
                };
                self.invoice.fields_mut().fallbacks.get_or_insert_with(Vec::new).push(address);
                self
        }

        /// Sets [`Bolt12Invoice::invoice_features`] to indicate MPP may be used. Otherwise, MPP is
        /// disallowed.
        pub fn allow_mpp(mut self) -> Self {
                self.invoice.fields_mut().features.set_basic_mpp_optional();
                self
        }
}

impl<'a> InvoiceBuilder<'a, ExplicitSigningPubkey> {
        /// Builds an unsigned [`Bolt12Invoice`] after checking for valid semantics. It can be signed by
        /// [`UnsignedBolt12Invoice::sign`].
        pub fn build(self) -> Result<UnsignedBolt12Invoice, Bolt12SemanticError> {
                #[cfg(feature = "std")] {
                        if self.invoice.is_offer_or_refund_expired() {
                                return Err(Bolt12SemanticError::AlreadyExpired);
                        }
                }

                let InvoiceBuilder { invreq_bytes, invoice, .. } = self;
                Ok(UnsignedBolt12Invoice::new(invreq_bytes, invoice))
        }
}

impl<'a> InvoiceBuilder<'a, DerivedSigningPubkey> {
        /// Builds a signed [`Bolt12Invoice`] after checking for valid semantics.
        pub fn build_and_sign<T: secp256k1::Signing>(
                self, secp_ctx: &Secp256k1<T>
        ) -> Result<Bolt12Invoice, Bolt12SemanticError> {
                #[cfg(feature = "std")] {
                        if self.invoice.is_offer_or_refund_expired() {
                                return Err(Bolt12SemanticError::AlreadyExpired);
                        }
                }

                let InvoiceBuilder {
                        invreq_bytes, invoice, signing_pubkey_strategy: DerivedSigningPubkey(keys)
                } = self;
                let unsigned_invoice = UnsignedBolt12Invoice::new(invreq_bytes, invoice);

                let invoice = unsigned_invoice
                        .sign::<_, Infallible>(
                                |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
                        )
                        .unwrap();
                Ok(invoice)
        }
}

/// A semantically valid [`Bolt12Invoice`] that hasn't been signed.
///
/// # Serialization
///
/// This is serialized as a TLV stream, which includes TLV records from the originating message. As
/// such, it may include unknown, odd TLV records.
pub struct UnsignedBolt12Invoice {
        bytes: Vec<u8>,
        contents: InvoiceContents,
        tagged_hash: TaggedHash,
}

impl UnsignedBolt12Invoice {
        fn new(invreq_bytes: &[u8], contents: InvoiceContents) -> Self {
                // Use the invoice_request bytes instead of the invoice_request TLV stream as the latter may
                // have contained unknown TLV records, which are not stored in `InvoiceRequestContents` or
                // `RefundContents`.
                let (_, _, _, invoice_tlv_stream) = contents.as_tlv_stream();
                let invoice_request_bytes = WithoutSignatures(invreq_bytes);
                let unsigned_tlv_stream = (invoice_request_bytes, invoice_tlv_stream);

                let mut bytes = Vec::new();
                unsigned_tlv_stream.write(&mut bytes).unwrap();

                let tagged_hash = TaggedHash::new(SIGNATURE_TAG, &bytes);

                Self { bytes, contents, tagged_hash }
        }

        /// Returns the [`TaggedHash`] of the invoice to sign.
        pub fn tagged_hash(&self) -> &TaggedHash {
                &self.tagged_hash
        }

        /// Signs the [`TaggedHash`] of the invoice using the given function.
        ///
        /// Note: The hash computation may have included unknown, odd TLV records.
        ///
        /// This is not exported to bindings users as functions aren't currently mapped.
        pub(crate) fn sign<F, E>(mut self, sign: F) -> Result<Bolt12Invoice, SignError<E>>
        where
                F: FnOnce(&Self) -> Result<Signature, E>
        {
                let pubkey = self.contents.fields().signing_pubkey;
                let signature = merkle::sign_message(sign, &self, pubkey)?;

                // Append the signature TLV record to the bytes.
                let signature_tlv_stream = SignatureTlvStreamRef {
                        signature: Some(&signature),
                };
                signature_tlv_stream.write(&mut self.bytes).unwrap();

                Ok(Bolt12Invoice {
                        bytes: self.bytes,
                        contents: self.contents,
                        signature,
                })
        }
}

impl AsRef<TaggedHash> for UnsignedBolt12Invoice {
        fn as_ref(&self) -> &TaggedHash {
                &self.tagged_hash
        }
}

/// A `Bolt12Invoice` is a payment request, typically corresponding to an [`Offer`] or a [`Refund`].
///
/// An invoice may be sent in response to an [`InvoiceRequest`] in the case of an offer or sent
/// directly after scanning a refund. It includes all the information needed to pay a recipient.
///
/// [`Offer`]: crate::offers::offer::Offer
/// [`Refund`]: crate::offers::refund::Refund
/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
#[derive(Clone, Debug)]
#[cfg_attr(test, derive(PartialEq))]
pub struct Bolt12Invoice {
        bytes: Vec<u8>,
        contents: InvoiceContents,
        signature: Signature,
}

/// The contents of an [`Bolt12Invoice`] for responding to either an [`Offer`] or a [`Refund`].
///
/// [`Offer`]: crate::offers::offer::Offer
/// [`Refund`]: crate::offers::refund::Refund
#[derive(Clone, Debug)]
#[cfg_attr(test, derive(PartialEq))]
enum InvoiceContents {
        /// Contents for an [`Bolt12Invoice`] corresponding to an [`Offer`].
        ///
        /// [`Offer`]: crate::offers::offer::Offer
        ForOffer {
                invoice_request: InvoiceRequestContents,
                fields: InvoiceFields,
        },
        /// Contents for an [`Bolt12Invoice`] corresponding to a [`Refund`].
        ///
        /// [`Refund`]: crate::offers::refund::Refund
        ForRefund {
                refund: RefundContents,
                fields: InvoiceFields,
        },
}

/// Invoice-specific fields for an `invoice` message.
#[derive(Clone, Debug, PartialEq)]
struct InvoiceFields {
        payment_paths: Vec<(BlindedPayInfo, BlindedPath)>,
        created_at: Duration,
        relative_expiry: Option<Duration>,
        payment_hash: PaymentHash,
        amount_msats: u64,
        fallbacks: Option<Vec<FallbackAddress>>,
        features: Bolt12InvoiceFeatures,
        signing_pubkey: PublicKey,
}

macro_rules! invoice_accessors { ($self: ident, $contents: expr) => {
        /// The chains that may be used when paying a requested invoice.
        ///
        /// From [`Offer::chains`]; `None` if the invoice was created in response to a [`Refund`].
        ///
        /// [`Offer::chains`]: crate::offers::offer::Offer::chains
        pub fn offer_chains(&$self) -> Option<Vec<ChainHash>> {
                $contents.offer_chains()
        }

        /// The chain that must be used when paying the invoice; selected from [`offer_chains`] if the
        /// invoice originated from an offer.
        ///
        /// From [`InvoiceRequest::chain`] or [`Refund::chain`].
        ///
        /// [`offer_chains`]: Self::offer_chains
        /// [`InvoiceRequest::chain`]: crate::offers::invoice_request::InvoiceRequest::chain
        pub fn chain(&$self) -> ChainHash {
                $contents.chain()
        }

        /// Opaque bytes set by the originating [`Offer`].
        ///
        /// From [`Offer::metadata`]; `None` if the invoice was created in response to a [`Refund`] or
        /// if the [`Offer`] did not set it.
        ///
        /// [`Offer`]: crate::offers::offer::Offer
        /// [`Offer::metadata`]: crate::offers::offer::Offer::metadata
        pub fn metadata(&$self) -> Option<&Vec<u8>> {
                $contents.metadata()
        }

        /// The minimum amount required for a successful payment of a single item.
        ///
        /// From [`Offer::amount`]; `None` if the invoice was created in response to a [`Refund`] or if
        /// the [`Offer`] did not set it.
        ///
        /// [`Offer`]: crate::offers::offer::Offer
        /// [`Offer::amount`]: crate::offers::offer::Offer::amount
        pub fn amount(&$self) -> Option<&Amount> {
                $contents.amount()
        }

        /// Features pertaining to the originating [`Offer`].
        ///
        /// From [`Offer::offer_features`]; `None` if the invoice was created in response to a
        /// [`Refund`].
        ///
        /// [`Offer`]: crate::offers::offer::Offer
        /// [`Offer::offer_features`]: crate::offers::offer::Offer::offer_features
        pub fn offer_features(&$self) -> Option<&OfferFeatures> {
                $contents.offer_features()
        }

        /// A complete description of the purpose of the originating offer or refund.
        ///
        /// From [`Offer::description`] or [`Refund::description`].
        ///
        /// [`Offer::description`]: crate::offers::offer::Offer::description
        pub fn description(&$self) -> PrintableString {
                $contents.description()
        }

        /// Duration since the Unix epoch when an invoice should no longer be requested.
        ///
        /// From [`Offer::absolute_expiry`] or [`Refund::absolute_expiry`].
        ///
        /// [`Offer::absolute_expiry`]: crate::offers::offer::Offer::absolute_expiry
        pub fn absolute_expiry(&$self) -> Option<Duration> {
                $contents.absolute_expiry()
        }

        /// The issuer of the offer or refund.
        ///
        /// From [`Offer::issuer`] or [`Refund::issuer`].
        ///
        /// [`Offer::issuer`]: crate::offers::offer::Offer::issuer
        pub fn issuer(&$self) -> Option<PrintableString> {
                $contents.issuer()
        }

        /// Paths to the recipient originating from publicly reachable nodes.
        ///
        /// From [`Offer::paths`] or [`Refund::paths`].
        ///
        /// [`Offer::paths`]: crate::offers::offer::Offer::paths
        pub fn message_paths(&$self) -> &[BlindedPath] {
                $contents.message_paths()
        }

        /// The quantity of items supported.
        ///
        /// From [`Offer::supported_quantity`]; `None` if the invoice was created in response to a
        /// [`Refund`].
        ///
        /// [`Offer::supported_quantity`]: crate::offers::offer::Offer::supported_quantity
        pub fn supported_quantity(&$self) -> Option<Quantity> {
                $contents.supported_quantity()
        }

        /// An unpredictable series of bytes from the payer.
        ///
        /// From [`InvoiceRequest::payer_metadata`] or [`Refund::payer_metadata`].
        pub fn payer_metadata(&$self) -> &[u8] {
                $contents.payer_metadata()
        }

        /// Features pertaining to requesting an invoice.
        ///
        /// From [`InvoiceRequest::invoice_request_features`] or [`Refund::features`].
        pub fn invoice_request_features(&$self) -> &InvoiceRequestFeatures {
                &$contents.invoice_request_features()
        }

        /// The quantity of items requested or refunded for.
        ///
        /// From [`InvoiceRequest::quantity`] or [`Refund::quantity`].
        pub fn quantity(&$self) -> Option<u64> {
                $contents.quantity()
        }

        /// A possibly transient pubkey used to sign the invoice request or to send an invoice for a
        /// refund in case there are no [`message_paths`].
        ///
        /// [`message_paths`]: Self::message_paths
        pub fn payer_id(&$self) -> PublicKey {
                $contents.payer_id()
        }

        /// A payer-provided note reflected back in the invoice.
        ///
        /// From [`InvoiceRequest::payer_note`] or [`Refund::payer_note`].
        pub fn payer_note(&$self) -> Option<PrintableString> {
                $contents.payer_note()
        }

        /// Paths to the recipient originating from publicly reachable nodes, including information
        /// needed for routing payments across them.
        ///
        /// Blinded paths provide recipient privacy by obfuscating its node id. Note, however, that this
        /// privacy is lost if a public node id is used for [`Bolt12Invoice::signing_pubkey`].
        ///
        /// This is not exported to bindings users as slices with non-reference types cannot be ABI
        /// matched in another language.
        pub fn payment_paths(&$self) -> &[(BlindedPayInfo, BlindedPath)] {
                $contents.payment_paths()
        }

        /// Duration since the Unix epoch when the invoice was created.
        pub fn created_at(&$self) -> Duration {
                $contents.created_at()
        }

        /// Duration since [`Bolt12Invoice::created_at`] when the invoice has expired and therefore
        /// should no longer be paid.
        pub fn relative_expiry(&$self) -> Duration {
                $contents.relative_expiry()
        }

        /// Whether the invoice has expired.
        #[cfg(feature = "std")]
        pub fn is_expired(&$self) -> bool {
                $contents.is_expired()
        }

        /// SHA256 hash of the payment preimage that will be given in return for paying the invoice.
        pub fn payment_hash(&$self) -> PaymentHash {
                $contents.payment_hash()
        }

        /// The minimum amount required for a successful payment of the invoice.
        pub fn amount_msats(&$self) -> u64 {
                $contents.amount_msats()
        }

        /// Fallback addresses for paying the invoice on-chain, in order of most-preferred to
        /// least-preferred.
        ///
        /// This is not exported to bindings users as Address is not yet mapped
        pub fn fallbacks(&$self) -> Vec<Address> {
                $contents.fallbacks()
        }

        /// Features pertaining to paying an invoice.
        pub fn invoice_features(&$self) -> &Bolt12InvoiceFeatures {
                $contents.features()
        }

        /// The public key corresponding to the key used to sign the invoice.
        pub fn signing_pubkey(&$self) -> PublicKey {
                $contents.signing_pubkey()
        }
} }

impl UnsignedBolt12Invoice {
        invoice_accessors!(self, self.contents);
}

impl Bolt12Invoice {
        invoice_accessors!(self, self.contents);

        /// Signature of the invoice verified using [`Bolt12Invoice::signing_pubkey`].
        pub fn signature(&self) -> Signature {
                self.signature
        }

        /// Hash that was used for signing the invoice.
        pub fn signable_hash(&self) -> [u8; 32] {
                merkle::message_digest(SIGNATURE_TAG, &self.bytes).as_ref().clone()
        }

        /// Verifies that the invoice was for a request or refund created using the given key. Returns
        /// the associated [`PaymentId`] to use when sending the payment.
        pub fn verify<T: secp256k1::Signing>(
                &self, key: &ExpandedKey, secp_ctx: &Secp256k1<T>
        ) -> Result<PaymentId, ()> {
                self.contents.verify(TlvStream::new(&self.bytes), key, secp_ctx)
        }

        #[cfg(test)]
        pub(super) fn as_tlv_stream(&self) -> FullInvoiceTlvStreamRef {
                let (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream) =
                        self.contents.as_tlv_stream();
                let signature_tlv_stream = SignatureTlvStreamRef {
                        signature: Some(&self.signature),
                };
                (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream,
                 signature_tlv_stream)
        }
}

impl InvoiceContents {
        /// Whether the original offer or refund has expired.
        #[cfg(feature = "std")]
        fn is_offer_or_refund_expired(&self) -> bool {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } =>
                                invoice_request.inner.offer.is_expired(),
                        InvoiceContents::ForRefund { refund, .. } => refund.is_expired(),
                }
        }

        fn offer_chains(&self) -> Option<Vec<ChainHash>> {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } =>
                                Some(invoice_request.inner.offer.chains()),
                        InvoiceContents::ForRefund { .. } => None,
                }
        }

        fn chain(&self) -> ChainHash {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => invoice_request.chain(),
                        InvoiceContents::ForRefund { refund, .. } => refund.chain(),
                }
        }

        fn metadata(&self) -> Option<&Vec<u8>> {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } =>
                                invoice_request.inner.offer.metadata(),
                        InvoiceContents::ForRefund { .. } => None,
                }
        }

        fn amount(&self) -> Option<&Amount> {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } =>
                                invoice_request.inner.offer.amount(),
                        InvoiceContents::ForRefund { .. } => None,
                }
        }

        fn description(&self) -> PrintableString {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => {
                                invoice_request.inner.offer.description()
                        },
                        InvoiceContents::ForRefund { refund, .. } => refund.description(),
                }
        }

        fn offer_features(&self) -> Option<&OfferFeatures> {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => {
                                Some(invoice_request.inner.offer.features())
                        },
                        InvoiceContents::ForRefund { .. } => None,
                }
        }

        fn absolute_expiry(&self) -> Option<Duration> {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => {
                                invoice_request.inner.offer.absolute_expiry()
                        },
                        InvoiceContents::ForRefund { refund, .. } => refund.absolute_expiry(),
                }
        }

        fn issuer(&self) -> Option<PrintableString> {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => {
                                invoice_request.inner.offer.issuer()
                        },
                        InvoiceContents::ForRefund { refund, .. } => refund.issuer(),
                }
        }

        fn message_paths(&self) -> &[BlindedPath] {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => {
                                invoice_request.inner.offer.paths()
                        },
                        InvoiceContents::ForRefund { refund, .. } => refund.paths(),
                }
        }

        fn supported_quantity(&self) -> Option<Quantity> {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => {
                                Some(invoice_request.inner.offer.supported_quantity())
                        },
                        InvoiceContents::ForRefund { .. } => None,
                }
        }

        fn payer_metadata(&self) -> &[u8] {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => invoice_request.metadata(),
                        InvoiceContents::ForRefund { refund, .. } => refund.metadata(),
                }
        }

        fn invoice_request_features(&self) -> &InvoiceRequestFeatures {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => invoice_request.features(),
                        InvoiceContents::ForRefund { refund, .. } => refund.features(),
                }
        }

        fn quantity(&self) -> Option<u64> {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => invoice_request.quantity(),
                        InvoiceContents::ForRefund { refund, .. } => refund.quantity(),
                }
        }

        fn payer_id(&self) -> PublicKey {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => invoice_request.payer_id(),
                        InvoiceContents::ForRefund { refund, .. } => refund.payer_id(),
                }
        }

        fn payer_note(&self) -> Option<PrintableString> {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => invoice_request.payer_note(),
                        InvoiceContents::ForRefund { refund, .. } => refund.payer_note(),
                }
        }

        fn payment_paths(&self) -> &[(BlindedPayInfo, BlindedPath)] {
                &self.fields().payment_paths[..]
        }

        fn created_at(&self) -> Duration {
                self.fields().created_at
        }

        fn relative_expiry(&self) -> Duration {
                self.fields().relative_expiry.unwrap_or(DEFAULT_RELATIVE_EXPIRY)
        }

        #[cfg(feature = "std")]
        fn is_expired(&self) -> bool {
                let absolute_expiry = self.created_at().checked_add(self.relative_expiry());
                match absolute_expiry {
                        Some(seconds_from_epoch) => match SystemTime::UNIX_EPOCH.elapsed() {
                                Ok(elapsed) => elapsed > seconds_from_epoch,
                                Err(_) => false,
                        },
                        None => false,
                }
        }

        fn payment_hash(&self) -> PaymentHash {
                self.fields().payment_hash
        }

        fn amount_msats(&self) -> u64 {
                self.fields().amount_msats
        }

        fn fallbacks(&self) -> Vec<Address> {
                let chain = self.chain();
                let network = if chain == ChainHash::using_genesis_block(Network::Bitcoin) {
                        Network::Bitcoin
                } else if chain == ChainHash::using_genesis_block(Network::Testnet) {
                        Network::Testnet
                } else if chain == ChainHash::using_genesis_block(Network::Signet) {
                        Network::Signet
                } else if chain == ChainHash::using_genesis_block(Network::Regtest) {
                        Network::Regtest
                } else {
                        return Vec::new()
                };

                let to_valid_address = |address: &FallbackAddress| {
                        let version = match WitnessVersion::try_from(address.version) {
                                Ok(version) => version,
                                Err(_) => return None,
                        };

                        let program = &address.program;
                        if program.len() < 2 || program.len() > 40 {
                                return None;
                        }

                        let address = Address {
                                payload: Payload::WitnessProgram {
                                        version,
                                        program: program.clone(),
                                },
                                network,
                        };

                        if !address.is_standard() && version == WitnessVersion::V0 {
                                return None;
                        }

                        Some(address)
                };

                self.fields().fallbacks
                        .as_ref()
                        .map(|fallbacks| fallbacks.iter().filter_map(to_valid_address).collect())
                        .unwrap_or_else(Vec::new)
        }

        fn features(&self) -> &Bolt12InvoiceFeatures {
                &self.fields().features
        }

        fn signing_pubkey(&self) -> PublicKey {
                self.fields().signing_pubkey
        }

        fn fields(&self) -> &InvoiceFields {
                match self {
                        InvoiceContents::ForOffer { fields, .. } => fields,
                        InvoiceContents::ForRefund { fields, .. } => fields,
                }
        }

        fn fields_mut(&mut self) -> &mut InvoiceFields {
                match self {
                        InvoiceContents::ForOffer { fields, .. } => fields,
                        InvoiceContents::ForRefund { fields, .. } => fields,
                }
        }

        fn verify<T: secp256k1::Signing>(
                &self, tlv_stream: TlvStream<'_>, key: &ExpandedKey, secp_ctx: &Secp256k1<T>
        ) -> Result<PaymentId, ()> {
                let offer_records = tlv_stream.clone().range(OFFER_TYPES);
                let invreq_records = tlv_stream.range(INVOICE_REQUEST_TYPES).filter(|record| {
                        match record.r#type {
                                PAYER_METADATA_TYPE => false, // Should be outside range
                                INVOICE_REQUEST_PAYER_ID_TYPE => !self.derives_keys(),
                                _ => true,
                        }
                });
                let tlv_stream = offer_records.chain(invreq_records);

                let (metadata, payer_id, iv_bytes) = match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => {
                                (invoice_request.metadata(), invoice_request.payer_id(), INVOICE_REQUEST_IV_BYTES)
                        },
                        InvoiceContents::ForRefund { refund, .. } => {
                                (refund.metadata(), refund.payer_id(), REFUND_IV_BYTES)
                        },
                };

                signer::verify_payer_metadata(metadata, key, iv_bytes, payer_id, tlv_stream, secp_ctx)
        }

        fn derives_keys(&self) -> bool {
                match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => invoice_request.derives_keys(),
                        InvoiceContents::ForRefund { refund, .. } => refund.derives_keys(),
                }
        }

        fn as_tlv_stream(&self) -> PartialInvoiceTlvStreamRef {
                let (payer, offer, invoice_request) = match self {
                        InvoiceContents::ForOffer { invoice_request, .. } => invoice_request.as_tlv_stream(),
                        InvoiceContents::ForRefund { refund, .. } => refund.as_tlv_stream(),
                };
                let invoice = self.fields().as_tlv_stream();

                (payer, offer, invoice_request, invoice)
        }
}

impl InvoiceFields {
        fn as_tlv_stream(&self) -> InvoiceTlvStreamRef {
                let features = {
                        if self.features == Bolt12InvoiceFeatures::empty() { None }
                        else { Some(&self.features) }
                };

                InvoiceTlvStreamRef {
                        paths: Some(Iterable(self.payment_paths.iter().map(|(_, path)| path))),
                        blindedpay: Some(Iterable(self.payment_paths.iter().map(|(payinfo, _)| payinfo))),
                        created_at: Some(self.created_at.as_secs()),
                        relative_expiry: self.relative_expiry.map(|duration| duration.as_secs() as u32),
                        payment_hash: Some(&self.payment_hash),
                        amount: Some(self.amount_msats),
                        fallbacks: self.fallbacks.as_ref(),
                        features,
                        node_id: Some(&self.signing_pubkey),
                }
        }
}

impl Writeable for UnsignedBolt12Invoice {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                WithoutLength(&self.bytes).write(writer)
        }
}

impl Writeable for Bolt12Invoice {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                WithoutLength(&self.bytes).write(writer)
        }
}

impl Writeable for InvoiceContents {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
                self.as_tlv_stream().write(writer)
        }
}

impl TryFrom<Vec<u8>> for UnsignedBolt12Invoice {
        type Error = Bolt12ParseError;

        fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
                let invoice = ParsedMessage::<PartialInvoiceTlvStream>::try_from(bytes)?;
                let ParsedMessage { bytes, tlv_stream } = invoice;
                let (
                        payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream,
                ) = tlv_stream;
                let contents = InvoiceContents::try_from(
                        (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream)
                )?;

                let tagged_hash = TaggedHash::new(SIGNATURE_TAG, &bytes);

                Ok(UnsignedBolt12Invoice { bytes, contents, tagged_hash })
        }
}

impl TryFrom<Vec<u8>> for Bolt12Invoice {
        type Error = Bolt12ParseError;

        fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
                let parsed_invoice = ParsedMessage::<FullInvoiceTlvStream>::try_from(bytes)?;
                Bolt12Invoice::try_from(parsed_invoice)
        }
}

tlv_stream!(InvoiceTlvStream, InvoiceTlvStreamRef, 160..240, {
        (160, paths: (Vec<BlindedPath>, WithoutLength, Iterable<'a, BlindedPathIter<'a>, BlindedPath>)),
        (162, blindedpay: (Vec<BlindedPayInfo>, WithoutLength, Iterable<'a, BlindedPayInfoIter<'a>, BlindedPayInfo>)),
        (164, created_at: (u64, HighZeroBytesDroppedBigSize)),
        (166, relative_expiry: (u32, HighZeroBytesDroppedBigSize)),
        (168, payment_hash: PaymentHash),
        (170, amount: (u64, HighZeroBytesDroppedBigSize)),
        (172, fallbacks: (Vec<FallbackAddress>, WithoutLength)),
        (174, features: (Bolt12InvoiceFeatures, WithoutLength)),
        (176, node_id: PublicKey),
});

type BlindedPathIter<'a> = core::iter::Map<
        core::slice::Iter<'a, (BlindedPayInfo, BlindedPath)>,
        for<'r> fn(&'r (BlindedPayInfo, BlindedPath)) -> &'r BlindedPath,
>;

type BlindedPayInfoIter<'a> = core::iter::Map<
        core::slice::Iter<'a, (BlindedPayInfo, BlindedPath)>,
        for<'r> fn(&'r (BlindedPayInfo, BlindedPath)) -> &'r BlindedPayInfo,
>;

/// Information needed to route a payment across a [`BlindedPath`].
#[derive(Clone, Debug, Hash, Eq, PartialEq)]
pub struct BlindedPayInfo {
        /// Base fee charged (in millisatoshi) for the entire blinded path.
        pub fee_base_msat: u32,

        /// Liquidity fee charged (in millionths of the amount transferred) for the entire blinded path
        /// (i.e., 10,000 is 1%).
        pub fee_proportional_millionths: u32,

        /// Number of blocks subtracted from an incoming HTLC's `cltv_expiry` for the entire blinded
        /// path.
        pub cltv_expiry_delta: u16,

        /// The minimum HTLC value (in millisatoshi) that is acceptable to all channel peers on the
        /// blinded path from the introduction node to the recipient, accounting for any fees, i.e., as
        /// seen by the recipient.
        pub htlc_minimum_msat: u64,

        /// The maximum HTLC value (in millisatoshi) that is acceptable to all channel peers on the
        /// blinded path from the introduction node to the recipient, accounting for any fees, i.e., as
        /// seen by the recipient.
        pub htlc_maximum_msat: u64,

        /// Features set in `encrypted_data_tlv` for the `encrypted_recipient_data` TLV record in an
        /// onion payload.
        pub features: BlindedHopFeatures,
}

impl_writeable!(BlindedPayInfo, {
        fee_base_msat,
        fee_proportional_millionths,
        cltv_expiry_delta,
        htlc_minimum_msat,
        htlc_maximum_msat,
        features
});

/// Wire representation for an on-chain fallback address.
#[derive(Clone, Debug, PartialEq)]
pub(super) struct FallbackAddress {
        version: u8,
        program: Vec<u8>,
}

impl_writeable!(FallbackAddress, { version, program });

type FullInvoiceTlvStream =
        (PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream, InvoiceTlvStream, SignatureTlvStream);

#[cfg(test)]
type FullInvoiceTlvStreamRef<'a> = (
        PayerTlvStreamRef<'a>,
        OfferTlvStreamRef<'a>,
        InvoiceRequestTlvStreamRef<'a>,
        InvoiceTlvStreamRef<'a>,
        SignatureTlvStreamRef<'a>,
);

impl SeekReadable for FullInvoiceTlvStream {
        fn read<R: io::Read + io::Seek>(r: &mut R) -> Result<Self, DecodeError> {
                let payer = SeekReadable::read(r)?;
                let offer = SeekReadable::read(r)?;
                let invoice_request = SeekReadable::read(r)?;
                let invoice = SeekReadable::read(r)?;
                let signature = SeekReadable::read(r)?;

                Ok((payer, offer, invoice_request, invoice, signature))
        }
}

type PartialInvoiceTlvStream =
        (PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream, InvoiceTlvStream);

type PartialInvoiceTlvStreamRef<'a> = (
        PayerTlvStreamRef<'a>,
        OfferTlvStreamRef<'a>,
        InvoiceRequestTlvStreamRef<'a>,
        InvoiceTlvStreamRef<'a>,
);

impl SeekReadable for PartialInvoiceTlvStream {
        fn read<R: io::Read + io::Seek>(r: &mut R) -> Result<Self, DecodeError> {
                let payer = SeekReadable::read(r)?;
                let offer = SeekReadable::read(r)?;
                let invoice_request = SeekReadable::read(r)?;
                let invoice = SeekReadable::read(r)?;

                Ok((payer, offer, invoice_request, invoice))
        }
}

impl TryFrom<ParsedMessage<FullInvoiceTlvStream>> for Bolt12Invoice {
        type Error = Bolt12ParseError;

        fn try_from(invoice: ParsedMessage<FullInvoiceTlvStream>) -> Result<Self, Self::Error> {
                let ParsedMessage { bytes, tlv_stream } = invoice;
                let (
                        payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream,
                        SignatureTlvStream { signature },
                ) = tlv_stream;
                let contents = InvoiceContents::try_from(
                        (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream)
                )?;

                let signature = match signature {
                        None => return Err(Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingSignature)),
                        Some(signature) => signature,
                };
                let message = TaggedHash::new(SIGNATURE_TAG, &bytes);
                let pubkey = contents.fields().signing_pubkey;
                merkle::verify_signature(&signature, message, pubkey)?;

                Ok(Bolt12Invoice { bytes, contents, signature })
        }
}

impl TryFrom<PartialInvoiceTlvStream> for InvoiceContents {
        type Error = Bolt12SemanticError;

        fn try_from(tlv_stream: PartialInvoiceTlvStream) -> Result<Self, Self::Error> {
                let (
                        payer_tlv_stream,
                        offer_tlv_stream,
                        invoice_request_tlv_stream,
                        InvoiceTlvStream {
                                paths, blindedpay, created_at, relative_expiry, payment_hash, amount, fallbacks,
                                features, node_id,
                        },
                ) = tlv_stream;

                let payment_paths = match (blindedpay, paths) {
                        (_, None) => return Err(Bolt12SemanticError::MissingPaths),
                        (None, _) => return Err(Bolt12SemanticError::InvalidPayInfo),
                        (_, Some(paths)) if paths.is_empty() => return Err(Bolt12SemanticError::MissingPaths),
                        (Some(blindedpay), Some(paths)) if paths.len() != blindedpay.len() => {
                                return Err(Bolt12SemanticError::InvalidPayInfo);
                        },
                        (Some(blindedpay), Some(paths)) => {
                                blindedpay.into_iter().zip(paths.into_iter()).collect::<Vec<_>>()
                        },
                };

                let created_at = match created_at {
                        None => return Err(Bolt12SemanticError::MissingCreationTime),
                        Some(timestamp) => Duration::from_secs(timestamp),
                };

                let relative_expiry = relative_expiry
                        .map(Into::<u64>::into)
                        .map(Duration::from_secs);

                let payment_hash = match payment_hash {
                        None => return Err(Bolt12SemanticError::MissingPaymentHash),
                        Some(payment_hash) => payment_hash,
                };

                let amount_msats = match amount {
                        None => return Err(Bolt12SemanticError::MissingAmount),
                        Some(amount) => amount,
                };

                let features = features.unwrap_or_else(Bolt12InvoiceFeatures::empty);

                let signing_pubkey = match node_id {
                        None => return Err(Bolt12SemanticError::MissingSigningPubkey),
                        Some(node_id) => node_id,
                };

                let fields = InvoiceFields {
                        payment_paths, created_at, relative_expiry, payment_hash, amount_msats, fallbacks,
                        features, signing_pubkey,
                };

                match offer_tlv_stream.node_id {
                        Some(expected_signing_pubkey) => {
                                if fields.signing_pubkey != expected_signing_pubkey {
                                        return Err(Bolt12SemanticError::InvalidSigningPubkey);
                                }

                                let invoice_request = InvoiceRequestContents::try_from(
                                        (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream)
                                )?;
                                Ok(InvoiceContents::ForOffer { invoice_request, fields })
                        },
                        None => {
                                let refund = RefundContents::try_from(
                                        (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream)
                                )?;
                                Ok(InvoiceContents::ForRefund { refund, fields })
                        },
                }
        }
}

#[cfg(test)]
mod tests {
        use super::{Bolt12Invoice, DEFAULT_RELATIVE_EXPIRY, FallbackAddress, FullInvoiceTlvStreamRef, InvoiceTlvStreamRef, SIGNATURE_TAG, UnsignedBolt12Invoice};

        use bitcoin::blockdata::constants::ChainHash;
        use bitcoin::blockdata::script::Script;
        use bitcoin::hashes::Hash;
        use bitcoin::network::constants::Network;
        use bitcoin::secp256k1::{Message, Secp256k1, XOnlyPublicKey, self};
        use bitcoin::util::address::{Address, Payload, WitnessVersion};
        use bitcoin::util::schnorr::TweakedPublicKey;
        use core::convert::TryFrom;
        use core::time::Duration;
        use crate::blinded_path::{BlindedHop, BlindedPath};
        use crate::sign::KeyMaterial;
        use crate::ln::features::{Bolt12InvoiceFeatures, InvoiceRequestFeatures, OfferFeatures};
        use crate::ln::inbound_payment::ExpandedKey;
        use crate::ln::msgs::DecodeError;
        use crate::offers::invoice_request::InvoiceRequestTlvStreamRef;
        use crate::offers::merkle::{SignError, SignatureTlvStreamRef, TaggedHash, self};
        use crate::offers::offer::{Amount, OfferBuilder, OfferTlvStreamRef, Quantity};
        use crate::offers::parse::{Bolt12ParseError, Bolt12SemanticError};
        use crate::offers::payer::PayerTlvStreamRef;
        use crate::offers::refund::RefundBuilder;
        use crate::offers::test_utils::*;
        use crate::util::ser::{BigSize, Iterable, Writeable};
        use crate::util::string::PrintableString;

        trait ToBytes {
                fn to_bytes(&self) -> Vec<u8>;
        }

        impl<'a> ToBytes for FullInvoiceTlvStreamRef<'a> {
                fn to_bytes(&self) -> Vec<u8> {
                        let mut buffer = Vec::new();
                        self.0.write(&mut buffer).unwrap();
                        self.1.write(&mut buffer).unwrap();
                        self.2.write(&mut buffer).unwrap();
                        self.3.write(&mut buffer).unwrap();
                        self.4.write(&mut buffer).unwrap();
                        buffer
                }
        }

        #[test]
        fn builds_invoice_for_offer_with_defaults() {
                let payment_paths = payment_paths();
                let payment_hash = payment_hash();
                let now = now();
                let unsigned_invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths.clone(), payment_hash, now).unwrap()
                        .build().unwrap();

                let mut buffer = Vec::new();
                unsigned_invoice.write(&mut buffer).unwrap();

                assert_eq!(unsigned_invoice.bytes, buffer.as_slice());
                assert_eq!(unsigned_invoice.payer_metadata(), &[1; 32]);
                assert_eq!(unsigned_invoice.offer_chains(), Some(vec![ChainHash::using_genesis_block(Network::Bitcoin)]));
                assert_eq!(unsigned_invoice.metadata(), None);
                assert_eq!(unsigned_invoice.amount(), Some(&Amount::Bitcoin { amount_msats: 1000 }));
                assert_eq!(unsigned_invoice.description(), PrintableString("foo"));
                assert_eq!(unsigned_invoice.offer_features(), Some(&OfferFeatures::empty()));
                assert_eq!(unsigned_invoice.absolute_expiry(), None);
                assert_eq!(unsigned_invoice.message_paths(), &[]);
                assert_eq!(unsigned_invoice.issuer(), None);
                assert_eq!(unsigned_invoice.supported_quantity(), Some(Quantity::One));
                assert_eq!(unsigned_invoice.signing_pubkey(), recipient_pubkey());
                assert_eq!(unsigned_invoice.chain(), ChainHash::using_genesis_block(Network::Bitcoin));
                assert_eq!(unsigned_invoice.amount_msats(), 1000);
                assert_eq!(unsigned_invoice.invoice_request_features(), &InvoiceRequestFeatures::empty());
                assert_eq!(unsigned_invoice.quantity(), None);
                assert_eq!(unsigned_invoice.payer_id(), payer_pubkey());
                assert_eq!(unsigned_invoice.payer_note(), None);
                assert_eq!(unsigned_invoice.payment_paths(), payment_paths.as_slice());
                assert_eq!(unsigned_invoice.created_at(), now);
                assert_eq!(unsigned_invoice.relative_expiry(), DEFAULT_RELATIVE_EXPIRY);
                #[cfg(feature = "std")]
                assert!(!unsigned_invoice.is_expired());
                assert_eq!(unsigned_invoice.payment_hash(), payment_hash);
                assert_eq!(unsigned_invoice.amount_msats(), 1000);
                assert_eq!(unsigned_invoice.fallbacks(), vec![]);
                assert_eq!(unsigned_invoice.invoice_features(), &Bolt12InvoiceFeatures::empty());
                assert_eq!(unsigned_invoice.signing_pubkey(), recipient_pubkey());

                match UnsignedBolt12Invoice::try_from(buffer) {
                        Err(e) => panic!("error parsing unsigned invoice: {:?}", e),
                        Ok(parsed) => {
                                assert_eq!(parsed.bytes, unsigned_invoice.bytes);
                                assert_eq!(parsed.tagged_hash, unsigned_invoice.tagged_hash);
                        },
                }

                let invoice = unsigned_invoice.sign(recipient_sign).unwrap();

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                assert_eq!(invoice.bytes, buffer.as_slice());
                assert_eq!(invoice.payer_metadata(), &[1; 32]);
                assert_eq!(invoice.offer_chains(), Some(vec![ChainHash::using_genesis_block(Network::Bitcoin)]));
                assert_eq!(invoice.metadata(), None);
                assert_eq!(invoice.amount(), Some(&Amount::Bitcoin { amount_msats: 1000 }));
                assert_eq!(invoice.description(), PrintableString("foo"));
                assert_eq!(invoice.offer_features(), Some(&OfferFeatures::empty()));
                assert_eq!(invoice.absolute_expiry(), None);
                assert_eq!(invoice.message_paths(), &[]);
                assert_eq!(invoice.issuer(), None);
                assert_eq!(invoice.supported_quantity(), Some(Quantity::One));
                assert_eq!(invoice.signing_pubkey(), recipient_pubkey());
                assert_eq!(invoice.chain(), ChainHash::using_genesis_block(Network::Bitcoin));
                assert_eq!(invoice.amount_msats(), 1000);
                assert_eq!(invoice.invoice_request_features(), &InvoiceRequestFeatures::empty());
                assert_eq!(invoice.quantity(), None);
                assert_eq!(invoice.payer_id(), payer_pubkey());
                assert_eq!(invoice.payer_note(), None);
                assert_eq!(invoice.payment_paths(), payment_paths.as_slice());
                assert_eq!(invoice.created_at(), now);
                assert_eq!(invoice.relative_expiry(), DEFAULT_RELATIVE_EXPIRY);
                #[cfg(feature = "std")]
                assert!(!invoice.is_expired());
                assert_eq!(invoice.payment_hash(), payment_hash);
                assert_eq!(invoice.amount_msats(), 1000);
                assert_eq!(invoice.fallbacks(), vec![]);
                assert_eq!(invoice.invoice_features(), &Bolt12InvoiceFeatures::empty());
                assert_eq!(invoice.signing_pubkey(), recipient_pubkey());

                let message = TaggedHash::new(SIGNATURE_TAG, &invoice.bytes);
                assert!(merkle::verify_signature(&invoice.signature, message, recipient_pubkey()).is_ok());

                let digest = Message::from_slice(&invoice.signable_hash()).unwrap();
                let pubkey = recipient_pubkey().into();
                let secp_ctx = Secp256k1::verification_only();
                assert!(secp_ctx.verify_schnorr(&invoice.signature, &digest, &pubkey).is_ok());

                assert_eq!(
                        invoice.as_tlv_stream(),
                        (
                                PayerTlvStreamRef { metadata: Some(&vec![1; 32]) },
                                OfferTlvStreamRef {
                                        chains: None,
                                        metadata: None,
                                        currency: None,
                                        amount: Some(1000),
                                        description: Some(&String::from("foo")),
                                        features: None,
                                        absolute_expiry: None,
                                        paths: None,
                                        issuer: None,
                                        quantity_max: None,
                                        node_id: Some(&recipient_pubkey()),
                                },
                                InvoiceRequestTlvStreamRef {
                                        chain: None,
                                        amount: None,
                                        features: None,
                                        quantity: None,
                                        payer_id: Some(&payer_pubkey()),
                                        payer_note: None,
                                },
                                InvoiceTlvStreamRef {
                                        paths: Some(Iterable(payment_paths.iter().map(|(_, path)| path))),
                                        blindedpay: Some(Iterable(payment_paths.iter().map(|(payinfo, _)| payinfo))),
                                        created_at: Some(now.as_secs()),
                                        relative_expiry: None,
                                        payment_hash: Some(&payment_hash),
                                        amount: Some(1000),
                                        fallbacks: None,
                                        features: None,
                                        node_id: Some(&recipient_pubkey()),
                                },
                                SignatureTlvStreamRef { signature: Some(&invoice.signature()) },
                        ),
                );

                if let Err(e) = Bolt12Invoice::try_from(buffer) {
                        panic!("error parsing invoice: {:?}", e);
                }
        }

        #[test]
        fn builds_invoice_for_refund_with_defaults() {
                let payment_paths = payment_paths();
                let payment_hash = payment_hash();
                let now = now();
                let invoice = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
                        .build().unwrap()
                        .respond_with_no_std(payment_paths.clone(), payment_hash, recipient_pubkey(), now)
                        .unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                assert_eq!(invoice.bytes, buffer.as_slice());
                assert_eq!(invoice.payer_metadata(), &[1; 32]);
                assert_eq!(invoice.offer_chains(), None);
                assert_eq!(invoice.metadata(), None);
                assert_eq!(invoice.amount(), None);
                assert_eq!(invoice.description(), PrintableString("foo"));
                assert_eq!(invoice.offer_features(), None);
                assert_eq!(invoice.absolute_expiry(), None);
                assert_eq!(invoice.message_paths(), &[]);
                assert_eq!(invoice.issuer(), None);
                assert_eq!(invoice.supported_quantity(), None);
                assert_eq!(invoice.signing_pubkey(), recipient_pubkey());
                assert_eq!(invoice.chain(), ChainHash::using_genesis_block(Network::Bitcoin));
                assert_eq!(invoice.amount_msats(), 1000);
                assert_eq!(invoice.invoice_request_features(), &InvoiceRequestFeatures::empty());
                assert_eq!(invoice.quantity(), None);
                assert_eq!(invoice.payer_id(), payer_pubkey());
                assert_eq!(invoice.payer_note(), None);
                assert_eq!(invoice.payment_paths(), payment_paths.as_slice());
                assert_eq!(invoice.created_at(), now);
                assert_eq!(invoice.relative_expiry(), DEFAULT_RELATIVE_EXPIRY);
                #[cfg(feature = "std")]
                assert!(!invoice.is_expired());
                assert_eq!(invoice.payment_hash(), payment_hash);
                assert_eq!(invoice.amount_msats(), 1000);
                assert_eq!(invoice.fallbacks(), vec![]);
                assert_eq!(invoice.invoice_features(), &Bolt12InvoiceFeatures::empty());
                assert_eq!(invoice.signing_pubkey(), recipient_pubkey());

                let message = TaggedHash::new(SIGNATURE_TAG, &invoice.bytes);
                assert!(merkle::verify_signature(&invoice.signature, message, recipient_pubkey()).is_ok());

                assert_eq!(
                        invoice.as_tlv_stream(),
                        (
                                PayerTlvStreamRef { metadata: Some(&vec![1; 32]) },
                                OfferTlvStreamRef {
                                        chains: None,
                                        metadata: None,
                                        currency: None,
                                        amount: None,
                                        description: Some(&String::from("foo")),
                                        features: None,
                                        absolute_expiry: None,
                                        paths: None,
                                        issuer: None,
                                        quantity_max: None,
                                        node_id: None,
                                },
                                InvoiceRequestTlvStreamRef {
                                        chain: None,
                                        amount: Some(1000),
                                        features: None,
                                        quantity: None,
                                        payer_id: Some(&payer_pubkey()),
                                        payer_note: None,
                                },
                                InvoiceTlvStreamRef {
                                        paths: Some(Iterable(payment_paths.iter().map(|(_, path)| path))),
                                        blindedpay: Some(Iterable(payment_paths.iter().map(|(payinfo, _)| payinfo))),
                                        created_at: Some(now.as_secs()),
                                        relative_expiry: None,
                                        payment_hash: Some(&payment_hash),
                                        amount: Some(1000),
                                        fallbacks: None,
                                        features: None,
                                        node_id: Some(&recipient_pubkey()),
                                },
                                SignatureTlvStreamRef { signature: Some(&invoice.signature()) },
                        ),
                );

                if let Err(e) = Bolt12Invoice::try_from(buffer) {
                        panic!("error parsing invoice: {:?}", e);
                }
        }

        #[cfg(feature = "std")]
        #[test]
        fn builds_invoice_from_offer_with_expiration() {
                let future_expiry = Duration::from_secs(u64::max_value());
                let past_expiry = Duration::from_secs(0);

                if let Err(e) = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .absolute_expiry(future_expiry)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with(payment_paths(), payment_hash())
                        .unwrap()
                        .build()
                {
                        panic!("error building invoice: {:?}", e);
                }

                match OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .absolute_expiry(past_expiry)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build_unchecked()
                        .sign(payer_sign).unwrap()
                        .respond_with(payment_paths(), payment_hash())
                        .unwrap()
                        .build()
                {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12SemanticError::AlreadyExpired),
                }
        }

        #[cfg(feature = "std")]
        #[test]
        fn builds_invoice_from_refund_with_expiration() {
                let future_expiry = Duration::from_secs(u64::max_value());
                let past_expiry = Duration::from_secs(0);

                if let Err(e) = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
                        .absolute_expiry(future_expiry)
                        .build().unwrap()
                        .respond_with(payment_paths(), payment_hash(), recipient_pubkey())
                        .unwrap()
                        .build()
                {
                        panic!("error building invoice: {:?}", e);
                }

                match RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
                        .absolute_expiry(past_expiry)
                        .build().unwrap()
                        .respond_with(payment_paths(), payment_hash(), recipient_pubkey())
                        .unwrap()
                        .build()
                {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12SemanticError::AlreadyExpired),
                }
        }

        #[test]
        fn builds_invoice_from_offer_using_derived_keys() {
                let desc = "foo".to_string();
                let node_id = recipient_pubkey();
                let expanded_key = ExpandedKey::new(&KeyMaterial([42; 32]));
                let entropy = FixedEntropy {};
                let secp_ctx = Secp256k1::new();

                let blinded_path = BlindedPath {
                        introduction_node_id: pubkey(40),
                        blinding_point: pubkey(41),
                        blinded_hops: vec![
                                BlindedHop { blinded_node_id: pubkey(42), encrypted_payload: vec![0; 43] },
                                BlindedHop { blinded_node_id: node_id, encrypted_payload: vec![0; 44] },
                        ],
                };

                let offer = OfferBuilder
                        ::deriving_signing_pubkey(desc, node_id, &expanded_key, &entropy, &secp_ctx)
                        .amount_msats(1000)
                        .path(blinded_path)
                        .build().unwrap();
                let invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap();

                if let Err(e) = invoice_request.clone()
                        .verify(&expanded_key, &secp_ctx).unwrap()
                        .respond_using_derived_keys_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build_and_sign(&secp_ctx)
                {
                        panic!("error building invoice: {:?}", e);
                }

                let expanded_key = ExpandedKey::new(&KeyMaterial([41; 32]));
                assert!(invoice_request.verify(&expanded_key, &secp_ctx).is_err());

                let desc = "foo".to_string();
                let offer = OfferBuilder
                        ::deriving_signing_pubkey(desc, node_id, &expanded_key, &entropy, &secp_ctx)
                        .amount_msats(1000)
                        // Omit the path so that node_id is used for the signing pubkey instead of deriving
                        .build().unwrap();
                let invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap();

                match invoice_request
                        .verify(&expanded_key, &secp_ctx).unwrap()
                        .respond_using_derived_keys_no_std(payment_paths(), payment_hash(), now())
                {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12SemanticError::InvalidMetadata),
                }
        }

        #[test]
        fn builds_invoice_from_refund_using_derived_keys() {
                let expanded_key = ExpandedKey::new(&KeyMaterial([42; 32]));
                let entropy = FixedEntropy {};
                let secp_ctx = Secp256k1::new();

                let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
                        .build().unwrap();

                if let Err(e) = refund
                        .respond_using_derived_keys_no_std(
                                payment_paths(), payment_hash(), now(), &expanded_key, &entropy
                        )
                        .unwrap()
                        .build_and_sign(&secp_ctx)
                {
                        panic!("error building invoice: {:?}", e);
                }
        }

        #[test]
        fn builds_invoice_with_relative_expiry() {
                let now = now();
                let one_hour = Duration::from_secs(3600);

                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now).unwrap()
                        .relative_expiry(one_hour.as_secs() as u32)
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();
                let (_, _, _, tlv_stream, _) = invoice.as_tlv_stream();
                #[cfg(feature = "std")]
                assert!(!invoice.is_expired());
                assert_eq!(invoice.relative_expiry(), one_hour);
                assert_eq!(tlv_stream.relative_expiry, Some(one_hour.as_secs() as u32));

                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now - one_hour).unwrap()
                        .relative_expiry(one_hour.as_secs() as u32 - 1)
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();
                let (_, _, _, tlv_stream, _) = invoice.as_tlv_stream();
                #[cfg(feature = "std")]
                assert!(invoice.is_expired());
                assert_eq!(invoice.relative_expiry(), one_hour - Duration::from_secs(1));
                assert_eq!(tlv_stream.relative_expiry, Some(one_hour.as_secs() as u32 - 1));
        }

        #[test]
        fn builds_invoice_with_amount_from_request() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .amount_msats(1001).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();
                let (_, _, _, tlv_stream, _) = invoice.as_tlv_stream();
                assert_eq!(invoice.amount_msats(), 1001);
                assert_eq!(tlv_stream.amount, Some(1001));
        }

        #[test]
        fn builds_invoice_with_quantity_from_request() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .quantity(2).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();
                let (_, _, _, tlv_stream, _) = invoice.as_tlv_stream();
                assert_eq!(invoice.amount_msats(), 2000);
                assert_eq!(tlv_stream.amount, Some(2000));

                match OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .quantity(u64::max_value()).unwrap()
                        .build_unchecked()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now())
                {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12SemanticError::InvalidAmount),
                }
        }

        #[test]
        fn builds_invoice_with_fallback_address() {
                let script = Script::new();
                let pubkey = bitcoin::util::key::PublicKey::new(recipient_pubkey());
                let x_only_pubkey = XOnlyPublicKey::from_keypair(&recipient_keys()).0;
                let tweaked_pubkey = TweakedPublicKey::dangerous_assume_tweaked(x_only_pubkey);

                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .fallback_v0_p2wsh(&script.wscript_hash())
                        .fallback_v0_p2wpkh(&pubkey.wpubkey_hash().unwrap())
                        .fallback_v1_p2tr_tweaked(&tweaked_pubkey)
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();
                let (_, _, _, tlv_stream, _) = invoice.as_tlv_stream();
                assert_eq!(
                        invoice.fallbacks(),
                        vec![
                                Address::p2wsh(&script, Network::Bitcoin),
                                Address::p2wpkh(&pubkey, Network::Bitcoin).unwrap(),
                                Address::p2tr_tweaked(tweaked_pubkey, Network::Bitcoin),
                        ],
                );
                assert_eq!(
                        tlv_stream.fallbacks,
                        Some(&vec![
                                FallbackAddress {
                                        version: WitnessVersion::V0.to_num(),
                                        program: Vec::from(&script.wscript_hash().into_inner()[..]),
                                },
                                FallbackAddress {
                                        version: WitnessVersion::V0.to_num(),
                                        program: Vec::from(&pubkey.wpubkey_hash().unwrap().into_inner()[..]),
                                },
                                FallbackAddress {
                                        version: WitnessVersion::V1.to_num(),
                                        program: Vec::from(&tweaked_pubkey.serialize()[..]),
                                },
                        ])
                );
        }

        #[test]
        fn builds_invoice_with_allow_mpp() {
                let mut features = Bolt12InvoiceFeatures::empty();
                features.set_basic_mpp_optional();

                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .allow_mpp()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();
                let (_, _, _, tlv_stream, _) = invoice.as_tlv_stream();
                assert_eq!(invoice.invoice_features(), &features);
                assert_eq!(tlv_stream.features, Some(&features));
        }

        #[test]
        fn fails_signing_invoice() {
                match OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(|_| Err(()))
                {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, SignError::Signing(())),
                }

                match OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign)
                {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, SignError::Verification(secp256k1::Error::InvalidSignature)),
                }
        }

        #[test]
        fn parses_invoice_with_payment_paths() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                if let Err(e) = Bolt12Invoice::try_from(buffer) {
                        panic!("error parsing invoice: {:?}", e);
                }

                let mut tlv_stream = invoice.as_tlv_stream();
                tlv_stream.3.paths = None;

                match Bolt12Invoice::try_from(tlv_stream.to_bytes()) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingPaths)),
                }

                let mut tlv_stream = invoice.as_tlv_stream();
                tlv_stream.3.blindedpay = None;

                match Bolt12Invoice::try_from(tlv_stream.to_bytes()) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InvalidPayInfo)),
                }

                let empty_payment_paths = vec![];
                let mut tlv_stream = invoice.as_tlv_stream();
                tlv_stream.3.paths = Some(Iterable(empty_payment_paths.iter().map(|(_, path)| path)));

                match Bolt12Invoice::try_from(tlv_stream.to_bytes()) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingPaths)),
                }

                let mut payment_paths = payment_paths();
                payment_paths.pop();
                let mut tlv_stream = invoice.as_tlv_stream();
                tlv_stream.3.blindedpay = Some(Iterable(payment_paths.iter().map(|(payinfo, _)| payinfo)));

                match Bolt12Invoice::try_from(tlv_stream.to_bytes()) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InvalidPayInfo)),
                }
        }

        #[test]
        fn parses_invoice_with_created_at() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                if let Err(e) = Bolt12Invoice::try_from(buffer) {
                        panic!("error parsing invoice: {:?}", e);
                }

                let mut tlv_stream = invoice.as_tlv_stream();
                tlv_stream.3.created_at = None;

                match Bolt12Invoice::try_from(tlv_stream.to_bytes()) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => {
                                assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingCreationTime));
                        },
                }
        }

        #[test]
        fn parses_invoice_with_relative_expiry() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .relative_expiry(3600)
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                match Bolt12Invoice::try_from(buffer) {
                        Ok(invoice) => assert_eq!(invoice.relative_expiry(), Duration::from_secs(3600)),
                        Err(e) => panic!("error parsing invoice: {:?}", e),
                }
        }

        #[test]
        fn parses_invoice_with_payment_hash() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                if let Err(e) = Bolt12Invoice::try_from(buffer) {
                        panic!("error parsing invoice: {:?}", e);
                }

                let mut tlv_stream = invoice.as_tlv_stream();
                tlv_stream.3.payment_hash = None;

                match Bolt12Invoice::try_from(tlv_stream.to_bytes()) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => {
                                assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingPaymentHash));
                        },
                }
        }

        #[test]
        fn parses_invoice_with_amount() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                if let Err(e) = Bolt12Invoice::try_from(buffer) {
                        panic!("error parsing invoice: {:?}", e);
                }

                let mut tlv_stream = invoice.as_tlv_stream();
                tlv_stream.3.amount = None;

                match Bolt12Invoice::try_from(tlv_stream.to_bytes()) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingAmount)),
                }
        }

        #[test]
        fn parses_invoice_with_allow_mpp() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .allow_mpp()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                match Bolt12Invoice::try_from(buffer) {
                        Ok(invoice) => {
                                let mut features = Bolt12InvoiceFeatures::empty();
                                features.set_basic_mpp_optional();
                                assert_eq!(invoice.invoice_features(), &features);
                        },
                        Err(e) => panic!("error parsing invoice: {:?}", e),
                }
        }

        #[test]
        fn parses_invoice_with_fallback_address() {
                let script = Script::new();
                let pubkey = bitcoin::util::key::PublicKey::new(recipient_pubkey());
                let x_only_pubkey = XOnlyPublicKey::from_keypair(&recipient_keys()).0;
                let tweaked_pubkey = TweakedPublicKey::dangerous_assume_tweaked(x_only_pubkey);

                let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap();
                let invoice_request = offer
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap();
                let mut invoice_builder = invoice_request
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .fallback_v0_p2wsh(&script.wscript_hash())
                        .fallback_v0_p2wpkh(&pubkey.wpubkey_hash().unwrap())
                        .fallback_v1_p2tr_tweaked(&tweaked_pubkey);

                // Only standard addresses will be included.
                let fallbacks = invoice_builder.invoice.fields_mut().fallbacks.as_mut().unwrap();
                // Non-standard addresses
                fallbacks.push(FallbackAddress { version: 1, program: vec![0u8; 41] });
                fallbacks.push(FallbackAddress { version: 2, program: vec![0u8; 1] });
                fallbacks.push(FallbackAddress { version: 17, program: vec![0u8; 40] });
                // Standard address
                fallbacks.push(FallbackAddress { version: 1, program: vec![0u8; 33] });
                fallbacks.push(FallbackAddress { version: 2, program: vec![0u8; 40] });

                let invoice = invoice_builder.build().unwrap().sign(recipient_sign).unwrap();
                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                match Bolt12Invoice::try_from(buffer) {
                        Ok(invoice) => {
                                assert_eq!(
                                        invoice.fallbacks(),
                                        vec![
                                                Address::p2wsh(&script, Network::Bitcoin),
                                                Address::p2wpkh(&pubkey, Network::Bitcoin).unwrap(),
                                                Address::p2tr_tweaked(tweaked_pubkey, Network::Bitcoin),
                                                Address {
                                                        payload: Payload::WitnessProgram {
                                                                version: WitnessVersion::V1,
                                                                program: vec![0u8; 33],
                                                        },
                                                        network: Network::Bitcoin,
                                                },
                                                Address {
                                                        payload: Payload::WitnessProgram {
                                                                version: WitnessVersion::V2,
                                                                program: vec![0u8; 40],
                                                        },
                                                        network: Network::Bitcoin,
                                                },
                                        ],
                                );
                        },
                        Err(e) => panic!("error parsing invoice: {:?}", e),
                }
        }

        #[test]
        fn parses_invoice_with_node_id() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                if let Err(e) = Bolt12Invoice::try_from(buffer) {
                        panic!("error parsing invoice: {:?}", e);
                }

                let mut tlv_stream = invoice.as_tlv_stream();
                tlv_stream.3.node_id = None;

                match Bolt12Invoice::try_from(tlv_stream.to_bytes()) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => {
                                assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingSigningPubkey));
                        },
                }

                let invalid_pubkey = payer_pubkey();
                let mut tlv_stream = invoice.as_tlv_stream();
                tlv_stream.3.node_id = Some(&invalid_pubkey);

                match Bolt12Invoice::try_from(tlv_stream.to_bytes()) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => {
                                assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InvalidSigningPubkey));
                        },
                }
        }

        #[test]
        fn fails_parsing_invoice_without_signature() {
                let mut buffer = Vec::new();
                OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .contents
                        .write(&mut buffer).unwrap();

                match Bolt12Invoice::try_from(buffer) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingSignature)),
                }
        }

        #[test]
        fn fails_parsing_invoice_with_invalid_signature() {
                let mut invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();
                let last_signature_byte = invoice.bytes.last_mut().unwrap();
                *last_signature_byte = last_signature_byte.wrapping_add(1);

                let mut buffer = Vec::new();
                invoice.write(&mut buffer).unwrap();

                match Bolt12Invoice::try_from(buffer) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => {
                                assert_eq!(e, Bolt12ParseError::InvalidSignature(secp256k1::Error::InvalidSignature));
                        },
                }
        }

        #[test]
        fn fails_parsing_invoice_with_extra_tlv_records() {
                let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
                        .sign(recipient_sign).unwrap();

                let mut encoded_invoice = Vec::new();
                invoice.write(&mut encoded_invoice).unwrap();
                BigSize(1002).write(&mut encoded_invoice).unwrap();
                BigSize(32).write(&mut encoded_invoice).unwrap();
                [42u8; 32].write(&mut encoded_invoice).unwrap();

                match Bolt12Invoice::try_from(encoded_invoice) {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, Bolt12ParseError::Decode(DecodeError::InvalidValue)),
                }
        }
}