lightning/ln/

invoice_utils.rs

//! Convenient utilities to create an invoice.

use lightning_invoice::{
	Bolt11Invoice, CreationError, Currency, InvoiceBuilder, SignOrCreationError,
};
use lightning_invoice::{Bolt11InvoiceDescription, Description, Sha256};

use crate::prelude::*;

use crate::ln::channel_state::ChannelDetails;
use crate::ln::channelmanager::{
	PhantomRouteHints, MIN_CLTV_EXPIRY_DELTA, MIN_FINAL_CLTV_EXPIRY_DELTA,
};
use crate::ln::inbound_payment::{create, create_from_hash};
use crate::routing::gossip::RoutingFees;
use crate::routing::router::{RouteHint, RouteHintHop};
use crate::sign::{EntropySource, NodeSigner, Recipient};
use crate::types::payment::PaymentHash;
use crate::util::logger::{Logger, Record};
use alloc::collections::{btree_map, BTreeMap};
use bitcoin::hashes::Hash;
use bitcoin::secp256k1::PublicKey;
#[cfg(not(feature = "std"))]
use core::iter::Iterator;
use core::ops::Deref;
use core::time::Duration;

/// Utility to create an invoice that can be paid to one of multiple nodes, or a "phantom invoice."
/// See [`PhantomKeysManager`] for more information on phantom node payments.
///
/// `phantom_route_hints` parameter:
/// * Contains channel info for all nodes participating in the phantom invoice
/// * Entries are retrieved from a call to [`ChannelManager::get_phantom_route_hints`] on each
///   participating node
/// * It is fine to cache `phantom_route_hints` and reuse it across invoices, as long as the data is
///   updated when a channel becomes disabled or closes
/// * Note that if too many channels are included in [`PhantomRouteHints::channels`], the invoice
///   may be too long for QR code scanning. To fix this, `PhantomRouteHints::channels` may be pared
///   down
///
/// `payment_hash` can be specified if you have a specific need for a custom payment hash (see the difference
/// between [`ChannelManager::create_inbound_payment`] and [`ChannelManager::create_inbound_payment_for_hash`]).
/// If `None` is provided for `payment_hash`, then one will be created.
///
/// `invoice_expiry_delta_secs` describes the number of seconds that the invoice is valid for
/// in excess of the current time.
///
/// `duration_since_epoch` is the current time since epoch in seconds.
///
/// You can specify a custom `min_final_cltv_expiry_delta`, or let LDK default it to
/// [`MIN_FINAL_CLTV_EXPIRY_DELTA`]. The provided expiry must be at least [`MIN_FINAL_CLTV_EXPIRY_DELTA`] - 3.
/// Note that LDK will add a buffer of 3 blocks to the delta to allow for up to a few new block
/// confirmations during routing.
///
/// Note that the provided `keys_manager`'s `NodeSigner` implementation must support phantom
/// invoices in its `sign_invoice` implementation ([`PhantomKeysManager`] satisfies this
/// requirement).
///
/// [`PhantomKeysManager`]: crate::sign::PhantomKeysManager
/// [`ChannelManager::get_phantom_route_hints`]: crate::ln::channelmanager::ChannelManager::get_phantom_route_hints
/// [`ChannelManager::create_inbound_payment`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment
/// [`ChannelManager::create_inbound_payment_for_hash`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment_for_hash
/// [`PhantomRouteHints::channels`]: crate::ln::channelmanager::PhantomRouteHints::channels
/// [`MIN_FINAL_CLTV_EXPIRY_DETLA`]: crate::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA
#[cfg_attr(feature = "std", doc = "")]
#[cfg_attr(
	feature = "std",
	doc = "This can be used in a `no_std` environment, where [`std::time::SystemTime`] is not available and the current time is supplied by the caller."
)]
pub fn create_phantom_invoice<ES: Deref, NS: Deref, L: Deref>(
	amt_msat: Option<u64>, payment_hash: Option<PaymentHash>, description: String,
	invoice_expiry_delta_secs: u32, phantom_route_hints: Vec<PhantomRouteHints>,
	entropy_source: ES, node_signer: NS, logger: L, network: Currency,
	min_final_cltv_expiry_delta: Option<u16>, duration_since_epoch: Duration,
) -> Result<Bolt11Invoice, SignOrCreationError<()>>
where
	ES::Target: EntropySource,
	NS::Target: NodeSigner,
	L::Target: Logger,
{
	let description = Description::new(description).map_err(SignOrCreationError::CreationError)?;
	let description = Bolt11InvoiceDescription::Direct(description);
	_create_phantom_invoice::<ES, NS, L>(
		amt_msat,
		payment_hash,
		description,
		invoice_expiry_delta_secs,
		phantom_route_hints,
		entropy_source,
		node_signer,
		logger,
		network,
		min_final_cltv_expiry_delta,
		duration_since_epoch,
	)
}

/// Utility to create an invoice that can be paid to one of multiple nodes, or a "phantom invoice."
/// See [`PhantomKeysManager`] for more information on phantom node payments.
///
/// `phantom_route_hints` parameter:
/// * Contains channel info for all nodes participating in the phantom invoice
/// * Entries are retrieved from a call to [`ChannelManager::get_phantom_route_hints`] on each
///   participating node
/// * It is fine to cache `phantom_route_hints` and reuse it across invoices, as long as the data is
///   updated when a channel becomes disabled or closes
/// * Note that the route hints generated from `phantom_route_hints` will be limited to a maximum
///   of 3 hints to ensure that the invoice can be scanned in a QR code. These hints are selected
///   in the order that the nodes in `PhantomRouteHints` are specified, selecting one hint per node
///   until the maximum is hit. Callers may provide as many `PhantomRouteHints::channels` as
///   desired, but note that some nodes will be trimmed if more than 3 nodes are provided.
///
/// `description_hash` is a SHA-256 hash of the description text
///
/// `payment_hash` can be specified if you have a specific need for a custom payment hash (see the difference
/// between [`ChannelManager::create_inbound_payment`] and [`ChannelManager::create_inbound_payment_for_hash`]).
/// If `None` is provided for `payment_hash`, then one will be created.
///
/// `invoice_expiry_delta_secs` describes the number of seconds that the invoice is valid for
/// in excess of the current time.
///
/// `duration_since_epoch` is the current time since epoch in seconds.
///
/// Note that the provided `keys_manager`'s `NodeSigner` implementation must support phantom
/// invoices in its `sign_invoice` implementation ([`PhantomKeysManager`] satisfies this
/// requirement).
///
/// [`PhantomKeysManager`]: crate::sign::PhantomKeysManager
/// [`ChannelManager::get_phantom_route_hints`]: crate::ln::channelmanager::ChannelManager::get_phantom_route_hints
/// [`ChannelManager::create_inbound_payment`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment
/// [`ChannelManager::create_inbound_payment_for_hash`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment_for_hash
/// [`PhantomRouteHints::channels`]: crate::ln::channelmanager::PhantomRouteHints::channels
#[cfg_attr(feature = "std", doc = "")]
#[cfg_attr(
	feature = "std",
	doc = "This version can be used in a `no_std` environment, where [`std::time::SystemTime`] is not available and the current time is supplied by the caller."
)]
pub fn create_phantom_invoice_with_description_hash<ES: Deref, NS: Deref, L: Deref>(
	amt_msat: Option<u64>, payment_hash: Option<PaymentHash>, invoice_expiry_delta_secs: u32,
	description_hash: Sha256, phantom_route_hints: Vec<PhantomRouteHints>, entropy_source: ES,
	node_signer: NS, logger: L, network: Currency, min_final_cltv_expiry_delta: Option<u16>,
	duration_since_epoch: Duration,
) -> Result<Bolt11Invoice, SignOrCreationError<()>>
where
	ES::Target: EntropySource,
	NS::Target: NodeSigner,
	L::Target: Logger,
{
	_create_phantom_invoice::<ES, NS, L>(
		amt_msat,
		payment_hash,
		Bolt11InvoiceDescription::Hash(description_hash),
		invoice_expiry_delta_secs,
		phantom_route_hints,
		entropy_source,
		node_signer,
		logger,
		network,
		min_final_cltv_expiry_delta,
		duration_since_epoch,
	)
}

const MAX_CHANNEL_HINTS: usize = 3;

fn _create_phantom_invoice<ES: Deref, NS: Deref, L: Deref>(
	amt_msat: Option<u64>, payment_hash: Option<PaymentHash>,
	description: Bolt11InvoiceDescription, invoice_expiry_delta_secs: u32,
	phantom_route_hints: Vec<PhantomRouteHints>, entropy_source: ES, node_signer: NS, logger: L,
	network: Currency, min_final_cltv_expiry_delta: Option<u16>, duration_since_epoch: Duration,
) -> Result<Bolt11Invoice, SignOrCreationError<()>>
where
	ES::Target: EntropySource,
	NS::Target: NodeSigner,
	L::Target: Logger,
{
	if phantom_route_hints.is_empty() {
		return Err(SignOrCreationError::CreationError(CreationError::MissingRouteHints));
	}

	if min_final_cltv_expiry_delta.is_some()
		&& min_final_cltv_expiry_delta.unwrap().saturating_add(3) < MIN_FINAL_CLTV_EXPIRY_DELTA
	{
		return Err(SignOrCreationError::CreationError(
			CreationError::MinFinalCltvExpiryDeltaTooShort,
		));
	}

	let invoice = match description {
		Bolt11InvoiceDescription::Direct(description) => {
			InvoiceBuilder::new(network).description(description.into_inner().0)
		},
		Bolt11InvoiceDescription::Hash(hash) => {
			InvoiceBuilder::new(network).description_hash(hash.0)
		},
	};

	let keys = node_signer.get_expanded_key();
	let (payment_hash, payment_secret) = if let Some(payment_hash) = payment_hash {
		let payment_secret = create_from_hash(
			&keys,
			amt_msat,
			payment_hash,
			invoice_expiry_delta_secs,
			duration_since_epoch.as_secs(),
			min_final_cltv_expiry_delta,
		)
		.map_err(|_| SignOrCreationError::CreationError(CreationError::InvalidAmount))?;
		(payment_hash, payment_secret)
	} else {
		create(
			&keys,
			amt_msat,
			invoice_expiry_delta_secs,
			&entropy_source,
			duration_since_epoch.as_secs(),
			min_final_cltv_expiry_delta,
		)
		.map_err(|_| SignOrCreationError::CreationError(CreationError::InvalidAmount))?
	};

	log_trace!(
		logger,
		"Creating phantom invoice from {} participating nodes with payment hash {}",
		phantom_route_hints.len(),
		&payment_hash
	);

	let mut invoice = invoice
		.duration_since_epoch(duration_since_epoch)
		.payment_hash(Hash::from_slice(&payment_hash.0).unwrap())
		.payment_secret(payment_secret)
		.min_final_cltv_expiry_delta(
			// Add a buffer of 3 to the delta if present, otherwise use LDK's minimum.
			min_final_cltv_expiry_delta
				.map(|x| x.saturating_add(3))
				.unwrap_or(MIN_FINAL_CLTV_EXPIRY_DELTA)
				.into(),
		)
		.expiry_time(Duration::from_secs(invoice_expiry_delta_secs.into()));
	if let Some(amt) = amt_msat {
		invoice = invoice.amount_milli_satoshis(amt);
	}

	for route_hint in
		select_phantom_hints(amt_msat, phantom_route_hints, logger).take(MAX_CHANNEL_HINTS)
	{
		invoice = invoice.private_route(route_hint);
	}

	let raw_invoice = match invoice.build_raw() {
		Ok(inv) => inv,
		Err(e) => return Err(SignOrCreationError::CreationError(e)),
	};
	let signature = node_signer.sign_invoice(&raw_invoice, Recipient::PhantomNode);
	let signed_raw_invoice = raw_invoice.sign(|_| signature);
	match signed_raw_invoice {
		Ok(inv) => Ok(Bolt11Invoice::from_signed(inv).unwrap()),
		Err(e) => Err(SignOrCreationError::SignError(e)),
	}
}

/// Utility to select route hints for phantom invoices.
/// See [`PhantomKeysManager`] for more information on phantom node payments.
///
/// To ensure that the phantom invoice is still readable by QR code, we limit to 3 hints per invoice:
/// * Select up to three channels per node.
/// * Select one hint from each node, up to three hints or until we run out of hints.
///
/// [`PhantomKeysManager`]: crate::sign::PhantomKeysManager
fn select_phantom_hints<L: Deref>(
	amt_msat: Option<u64>, phantom_route_hints: Vec<PhantomRouteHints>, logger: L,
) -> impl Iterator<Item = RouteHint>
where
	L::Target: Logger,
{
	let mut phantom_hints: Vec<_> = Vec::new();

	for PhantomRouteHints { channels, phantom_scid, real_node_pubkey } in phantom_route_hints {
		log_trace!(
			logger,
			"Generating phantom route hints for node {}",
			log_pubkey!(real_node_pubkey)
		);
		let route_hints = sort_and_filter_channels(channels, amt_msat, &logger);

		// If we have any public channel, the route hints from `sort_and_filter_channels` will be
		// empty. In that case we create a RouteHint on which we will push a single hop with the
		// phantom route into the invoice, and let the sender find the path to the `real_node_pubkey`
		// node by looking at our public channels.
		let empty_route_hints = route_hints.len() == 0;
		let mut have_pushed_empty = false;
		let route_hints = route_hints
			.chain(core::iter::from_fn(move || {
				if empty_route_hints && !have_pushed_empty {
					// set flag of having handled the empty route_hints and ensure empty vector
					// returned only once
					have_pushed_empty = true;
					Some(RouteHint(Vec::new()))
				} else {
					None
				}
			}))
			.map(move |mut hint| {
				hint.0.push(RouteHintHop {
					src_node_id: real_node_pubkey,
					short_channel_id: phantom_scid,
					fees: RoutingFees { base_msat: 0, proportional_millionths: 0 },
					cltv_expiry_delta: MIN_CLTV_EXPIRY_DELTA,
					htlc_minimum_msat: None,
					htlc_maximum_msat: None,
				});
				hint
			});

		phantom_hints.push(route_hints);
	}

	// We have one vector per real node involved in creating the phantom invoice. To distribute
	// the hints across our real nodes we add one hint from each in turn until no node has any hints
	// left (if one node has more hints than any other, these will accumulate at the end of the
	// vector).
	rotate_through_iterators(phantom_hints)
}

/// Draw items iteratively from multiple iterators.  The items are retrieved by index and
/// rotates through the iterators - first the zero index then the first index then second index, etc.
fn rotate_through_iterators<T, I: Iterator<Item = T>>(mut vecs: Vec<I>) -> impl Iterator<Item = T> {
	let mut iterations = 0;

	core::iter::from_fn(move || {
		let mut exhausted_iterators = 0;
		loop {
			if vecs.is_empty() {
				return None;
			}
			let next_idx = iterations % vecs.len();
			iterations += 1;
			if let Some(item) = vecs[next_idx].next() {
				return Some(item);
			}
			// exhausted_vectors increase when the "next_idx" vector is exhausted
			exhausted_iterators += 1;
			// The check for exhausted iterators gets reset to 0 after each yield of `Some()`
			// The loop will return None when all of the nested iterators are exhausted
			if exhausted_iterators == vecs.len() {
				return None;
			}
		}
	})
}

/// Sorts and filters the `channels` for an invoice, and returns the corresponding `RouteHint`s to include
/// in the invoice.
///
/// The filtering is based on the following criteria:
/// * Only one channel per counterparty node
/// * If the counterparty has a channel that is above the `min_inbound_capacity_msat` + 10% scaling
///   factor (to allow some margin for change in inbound), select the channel with the lowest
///   inbound capacity that is above this threshold.
/// * If no `min_inbound_capacity_msat` is specified, or the counterparty has no channels above the
///   minimum + 10% scaling factor, select the channel with the highest inbound capacity per counterparty.
/// * Prefer channels with capacity at least `min_inbound_capacity_msat` and where the channel
///   `is_usable` (i.e. the peer is connected).
/// * If any public channel exists, only public [`RouteHint`]s will be returned.
/// * If any public, announced, channel exists (i.e. a channel with 7+ confs, to ensure the
///   announcement has had a chance to propagate), no [`RouteHint`]s will be returned, as the
///   sender is expected to find the path by looking at the public channels instead.
/// * Limited to a total of 3 channels.
/// * Sorted by lowest inbound capacity if an online channel with the minimum amount requested exists,
///   otherwise sort by highest inbound capacity to give the payment the best chance of succeeding.
pub(super) fn sort_and_filter_channels<L: Deref>(
	channels: Vec<ChannelDetails>, min_inbound_capacity_msat: Option<u64>, logger: &L,
) -> impl ExactSizeIterator<Item = RouteHint>
where
	L::Target: Logger,
{
	let mut filtered_channels: BTreeMap<PublicKey, ChannelDetails> = BTreeMap::new();
	let min_inbound_capacity = min_inbound_capacity_msat.unwrap_or(0);
	let mut min_capacity_channel_exists = false;
	let mut online_channel_exists = false;
	let mut online_min_capacity_channel_exists = false;
	let mut has_pub_unconf_chan = false;

	let route_hint_from_channel = |channel: ChannelDetails| {
		let forwarding_info = channel.counterparty.forwarding_info.as_ref().unwrap();
		RouteHint(vec![RouteHintHop {
			src_node_id: channel.counterparty.node_id,
			short_channel_id: channel.get_inbound_payment_scid().unwrap(),
			fees: RoutingFees {
				base_msat: forwarding_info.fee_base_msat,
				proportional_millionths: forwarding_info.fee_proportional_millionths,
			},
			cltv_expiry_delta: forwarding_info.cltv_expiry_delta,
			htlc_minimum_msat: channel.inbound_htlc_minimum_msat,
			htlc_maximum_msat: channel.inbound_htlc_maximum_msat,
		}])
	};

	log_trace!(logger, "Considering {} channels for invoice route hints", channels.len());
	for channel in channels.into_iter().filter(|chan| chan.is_channel_ready) {
		let logger = WithChannelDetails::from(logger, &channel);
		if channel.get_inbound_payment_scid().is_none()
			|| channel.counterparty.forwarding_info.is_none()
		{
			log_trace!(logger, "Ignoring channel {} for invoice route hints", &channel.channel_id);
			continue;
		}

		if channel.is_announced {
			if channel.confirmations.is_some() && channel.confirmations < Some(7) {
				// If we have a public channel, but it doesn't have enough confirmations to (yet)
				// be in the public network graph (and have gotten a chance to propagate), include
				// route hints but only for public channels to protect private channel privacy.
				has_pub_unconf_chan = true;
			} else {
				// If any public channel exists, return no hints and let the sender
				// look at the public channels instead.
				log_trace!(
					logger,
					"Not including channels in invoice route hints on account of public channel {}",
					&channel.channel_id
				);
				return vec![].into_iter().take(MAX_CHANNEL_HINTS).map(route_hint_from_channel);
			}
		}

		if channel.inbound_capacity_msat >= min_inbound_capacity {
			if !min_capacity_channel_exists {
				log_trace!(
					logger,
					"Channel with enough inbound capacity exists for invoice route hints"
				);
				min_capacity_channel_exists = true;
			}

			if channel.is_usable {
				online_min_capacity_channel_exists = true;
			}
		}

		if channel.is_usable && !online_channel_exists {
			log_trace!(logger, "Channel with connected peer exists for invoice route hints");
			online_channel_exists = true;
		}

		match filtered_channels.entry(channel.counterparty.node_id) {
			btree_map::Entry::Occupied(mut entry) => {
				let current_max_capacity = entry.get().inbound_capacity_msat;
				// If this channel is public and the previous channel is not, ensure we replace the
				// previous channel to avoid announcing non-public channels.
				let new_now_public = channel.is_announced && !entry.get().is_announced;
				// Decide whether we prefer the currently selected channel with the node to the new one,
				// based on their inbound capacity.
				let prefer_current = prefer_current_channel(
					min_inbound_capacity_msat,
					current_max_capacity,
					channel.inbound_capacity_msat,
				);
				// If the public-ness of the channel has not changed (in which case simply defer to
				// `new_now_public), and this channel has more desirable inbound than the incumbent,
				// prefer to include this channel.
				let new_channel_preferable =
					channel.is_announced == entry.get().is_announced && !prefer_current;

				if new_now_public || new_channel_preferable {
					log_trace!(logger,
						"Preferring counterparty {} channel {} (SCID {:?}, {} msats) over {} (SCID {:?}, {} msats) for invoice route hints",
						log_pubkey!(channel.counterparty.node_id),
						&channel.channel_id, channel.short_channel_id,
						channel.inbound_capacity_msat,
						&entry.get().channel_id, entry.get().short_channel_id,
						current_max_capacity);
					entry.insert(channel);
				} else {
					log_trace!(logger,
						"Preferring counterparty {} channel {} (SCID {:?}, {} msats) over {} (SCID {:?}, {} msats) for invoice route hints",
						log_pubkey!(channel.counterparty.node_id),
						&entry.get().channel_id, entry.get().short_channel_id,
						current_max_capacity,
						&channel.channel_id, channel.short_channel_id,
						channel.inbound_capacity_msat);
				}
			},
			btree_map::Entry::Vacant(entry) => {
				entry.insert(channel);
			},
		}
	}

	// If all channels are private, prefer to return route hints which have a higher capacity than
	// the payment value and where we're currently connected to the channel counterparty.
	// Even if we cannot satisfy both goals, always ensure we include *some* hints, preferring
	// those which meet at least one criteria.
	let mut eligible_channels = filtered_channels
		.into_iter()
		.map(|(_, channel)| channel)
		.filter(|channel| {
			let logger = WithChannelDetails::from(logger, &channel);
			let has_enough_capacity = channel.inbound_capacity_msat >= min_inbound_capacity;
			let include_channel = if has_pub_unconf_chan {
				// If we have a public channel, but it doesn't have enough confirmations to (yet)
				// be in the public network graph (and have gotten a chance to propagate), include
				// route hints but only for public channels to protect private channel privacy.
				channel.is_announced
			} else if online_min_capacity_channel_exists {
				has_enough_capacity && channel.is_usable
			} else if min_capacity_channel_exists && online_channel_exists {
				// If there are some online channels and some min_capacity channels, but no
				// online-and-min_capacity channels, just include the min capacity ones and ignore
				// online-ness.
				has_enough_capacity
			} else if min_capacity_channel_exists {
				has_enough_capacity
			} else if online_channel_exists {
				channel.is_usable
			} else {
				true
			};

			if include_channel {
				log_trace!(
					logger,
					"Including channel {} in invoice route hints",
					&channel.channel_id
				);
			} else if !has_enough_capacity {
				log_trace!(
					logger,
					"Ignoring channel {} without enough capacity for invoice route hints",
					&channel.channel_id
				);
			} else {
				debug_assert!(!channel.is_usable || (has_pub_unconf_chan && !channel.is_announced));
				log_trace!(
					logger,
					"Ignoring channel {} with disconnected peer",
					&channel.channel_id
				);
			}

			include_channel
		})
		.collect::<Vec<ChannelDetails>>();

	eligible_channels.sort_unstable_by(|a, b| {
		if online_min_capacity_channel_exists {
			a.inbound_capacity_msat.cmp(&b.inbound_capacity_msat)
		} else {
			b.inbound_capacity_msat.cmp(&a.inbound_capacity_msat)
		}
	});

	eligible_channels.into_iter().take(MAX_CHANNEL_HINTS).map(route_hint_from_channel)
}

/// prefer_current_channel chooses a channel to use for route hints between a currently selected and candidate
/// channel based on the inbound capacity of each channel and the minimum inbound capacity requested for the hints,
/// returning true if the current channel should be preferred over the candidate channel.
/// * If no minimum amount is requested, the channel with the most inbound is chosen to maximize the chances that a
///   payment of any size will succeed.
/// * If we have channels with inbound above our minimum requested inbound (plus a 10% scaling factor, expressed as a
///   percentage) then we choose the lowest inbound channel with above this amount. If we have sufficient inbound
///   channels, we don't want to deplete our larger channels with small payments (the off-chain version of "grinding
///   our change").
/// * If no channel above our minimum amount exists, then we just prefer the channel with the most inbound to give
///   payments the best chance of succeeding in multiple parts.
fn prefer_current_channel(
	min_inbound_capacity_msat: Option<u64>, current_channel: u64, candidate_channel: u64,
) -> bool {
	// If no min amount is given for the hints, err of the side of caution and choose the largest channel inbound to
	// maximize chances of any payment succeeding.
	if min_inbound_capacity_msat.is_none() {
		return current_channel > candidate_channel;
	}

	let scaled_min_inbound = min_inbound_capacity_msat.unwrap() * 110;
	let current_sufficient = current_channel * 100 >= scaled_min_inbound;
	let candidate_sufficient = candidate_channel * 100 >= scaled_min_inbound;

	if current_sufficient && candidate_sufficient {
		return current_channel < candidate_channel;
	} else if current_sufficient {
		return true;
	} else if candidate_sufficient {
		return false;
	}

	current_channel > candidate_channel
}

/// Adds relevant context to a [`Record`] before passing it to the wrapped [`Logger`].
struct WithChannelDetails<'a, 'b, L: Deref>
where
	L::Target: Logger,
{
	/// The logger to delegate to after adding context to the record.
	logger: &'a L,
	/// The [`ChannelDetails`] for adding relevant context to the logged record.
	details: &'b ChannelDetails,
}

impl<'a, 'b, L: Deref> Logger for WithChannelDetails<'a, 'b, L>
where
	L::Target: Logger,
{
	fn log(&self, mut record: Record) {
		record.peer_id = Some(self.details.counterparty.node_id);
		record.channel_id = Some(self.details.channel_id);
		self.logger.log(record)
	}
}

impl<'a, 'b, L: Deref> WithChannelDetails<'a, 'b, L>
where
	L::Target: Logger,
{
	fn from(logger: &'a L, details: &'b ChannelDetails) -> Self {
		Self { logger, details }
	}
}

#[cfg(test)]
mod test {
	use super::*;
	use crate::chain::channelmonitor::HTLC_FAIL_BACK_BUFFER;
	use crate::ln::channelmanager::{
		Bolt11InvoiceParameters, PaymentId, PhantomRouteHints, RecipientOnionFields, Retry,
		MIN_FINAL_CLTV_EXPIRY_DELTA,
	};
	use crate::ln::functional_test_utils::*;
	use crate::ln::msgs::{BaseMessageHandler, ChannelMessageHandler, MessageSendEvent};
	use crate::routing::router::{PaymentParameters, RouteParameters};
	use crate::sign::PhantomKeysManager;
	use crate::types::payment::{PaymentHash, PaymentPreimage};
	use crate::util::config::UserConfig;
	use crate::util::dyn_signer::{DynKeysInterface, DynPhantomKeysInterface};
	use crate::util::test_utils;
	use bitcoin::hashes::sha256::Hash as Sha256;
	use bitcoin::hashes::{sha256, Hash};
	use bitcoin::network::Network;
	use core::time::Duration;
	use lightning_invoice::{
		Bolt11InvoiceDescriptionRef, CreationError, Currency, Description, SignOrCreationError,
	};
	use std::collections::HashSet;

	#[test]
	fn test_prefer_current_channel() {
		// No minimum, prefer larger candidate channel.
		assert_eq!(prefer_current_channel(None, 100, 200), false);

		// No minimum, prefer larger current channel.
		assert_eq!(prefer_current_channel(None, 200, 100), true);

		// Minimum set, prefer current channel over minimum + buffer.
		assert_eq!(prefer_current_channel(Some(100), 115, 100), true);

		// Minimum set, prefer candidate channel over minimum + buffer.
		assert_eq!(prefer_current_channel(Some(100), 105, 125), false);

		// Minimum set, both channels sufficient, prefer smaller current channel.
		assert_eq!(prefer_current_channel(Some(100), 115, 125), true);

		// Minimum set, both channels sufficient, prefer smaller candidate channel.
		assert_eq!(prefer_current_channel(Some(100), 200, 160), false);

		// Minimum set, neither sufficient, prefer larger current channel.
		assert_eq!(prefer_current_channel(Some(200), 100, 50), true);

		// Minimum set, neither sufficient, prefer larger candidate channel.
		assert_eq!(prefer_current_channel(Some(200), 100, 150), false);
	}

	#[test]
	fn create_and_pay_for_bolt11_invoice() {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
		create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);

		let node_a_id = nodes[0].node.get_our_node_id();

		let description =
			Bolt11InvoiceDescription::Direct(Description::new("test".to_string()).unwrap());
		let non_default_invoice_expiry_secs = 4200;
		let invoice_params = Bolt11InvoiceParameters {
			amount_msats: Some(10_000),
			description,
			invoice_expiry_delta_secs: Some(non_default_invoice_expiry_secs),
			..Default::default()
		};
		let invoice = nodes[1].node.create_bolt11_invoice(invoice_params).unwrap();
		assert_eq!(invoice.amount_milli_satoshis(), Some(10_000));
		// If no `min_final_cltv_expiry_delta` is specified, then it should be `MIN_FINAL_CLTV_EXPIRY_DELTA`.
		assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
		assert_eq!(
			invoice.description(),
			Bolt11InvoiceDescriptionRef::Direct(&Description::new("test".to_string()).unwrap())
		);
		assert_eq!(
			invoice.expiry_time(),
			Duration::from_secs(non_default_invoice_expiry_secs.into())
		);

		// Invoice SCIDs should always use inbound SCID aliases over the real channel ID, if one is
		// available.
		let chan = &nodes[1].node.list_usable_channels()[0];
		assert_eq!(invoice.route_hints().len(), 1);
		assert_eq!(invoice.route_hints()[0].0.len(), 1);
		assert_eq!(
			invoice.route_hints()[0].0[0].short_channel_id,
			chan.inbound_scid_alias.unwrap()
		);

		assert_eq!(invoice.route_hints()[0].0[0].htlc_minimum_msat, chan.inbound_htlc_minimum_msat);
		assert_eq!(invoice.route_hints()[0].0[0].htlc_maximum_msat, chan.inbound_htlc_maximum_msat);

		let retry = Retry::Attempts(0);
		nodes[0]
			.node
			.pay_for_bolt11_invoice(&invoice, PaymentId([42; 32]), None, Default::default(), retry)
			.unwrap();
		check_added_monitors(&nodes[0], 1);

		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
		assert_eq!(events.len(), 1);
		let payment_event = SendEvent::from_event(events.remove(0));
		nodes[1].node.handle_update_add_htlc(node_a_id, &payment_event.msgs[0]);
		nodes[1].node.handle_commitment_signed_batch_test(node_a_id, &payment_event.commitment_msg);
		check_added_monitors(&nodes[1], 1);
		let events = nodes[1].node.get_and_clear_pending_msg_events();
		assert_eq!(events.len(), 2);
	}

	fn do_create_invoice_min_final_cltv_delta(with_custom_delta: bool) {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
		let custom_min_final_cltv_expiry_delta = Some(50);

		let description = Bolt11InvoiceDescription::Direct(Description::empty());
		let min_final_cltv_expiry_delta =
			if with_custom_delta { custom_min_final_cltv_expiry_delta } else { None };
		let invoice_params = Bolt11InvoiceParameters {
			amount_msats: Some(10_000),
			description,
			invoice_expiry_delta_secs: Some(3600),
			min_final_cltv_expiry_delta,
			..Default::default()
		};
		let invoice = nodes[1].node.create_bolt11_invoice(invoice_params).unwrap();
		assert_eq!(
			invoice.min_final_cltv_expiry_delta(),
			if with_custom_delta {
				custom_min_final_cltv_expiry_delta.unwrap() + 3 /* Buffer */
			} else {
				MIN_FINAL_CLTV_EXPIRY_DELTA
			} as u64
		);
	}

	#[test]
	fn test_create_invoice_custom_min_final_cltv_delta() {
		do_create_invoice_min_final_cltv_delta(true);
		do_create_invoice_min_final_cltv_delta(false);
	}

	#[test]
	fn create_invoice_min_final_cltv_delta_equals_htlc_fail_buffer() {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

		let custom_min_final_cltv_expiry_delta = Some(HTLC_FAIL_BACK_BUFFER as u16);
		let description = Bolt11InvoiceDescription::Direct(Description::empty());
		let invoice_params = Bolt11InvoiceParameters {
			amount_msats: Some(10_000),
			description,
			invoice_expiry_delta_secs: Some(3600),
			min_final_cltv_expiry_delta: custom_min_final_cltv_expiry_delta,
			..Default::default()
		};
		let invoice = nodes[1].node.create_bolt11_invoice(invoice_params).unwrap();
		assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
	}

	#[test]
	fn test_create_invoice_with_description_hash() {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

		let description = Bolt11InvoiceDescription::Hash(Sha256(Hash::hash(
			"Testing description_hash".as_bytes(),
		)));
		let invoice_params = Bolt11InvoiceParameters {
			amount_msats: Some(10_000),
			description,
			invoice_expiry_delta_secs: Some(3600),
			..Default::default()
		};
		let invoice = nodes[1].node.create_bolt11_invoice(invoice_params).unwrap();
		assert_eq!(invoice.amount_milli_satoshis(), Some(10_000));
		assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
		assert_eq!(
			invoice.description(),
			Bolt11InvoiceDescriptionRef::Hash(&Sha256(Sha256::hash(
				"Testing description_hash".as_bytes()
			)))
		);
	}

	#[test]
	fn test_create_invoice_from_channelmanager_and_duration_since_epoch_with_payment_hash() {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

		let payment_hash = PaymentHash([0; 32]);
		let description =
			Bolt11InvoiceDescription::Direct(Description::new("test".to_string()).unwrap());
		let invoice_params = Bolt11InvoiceParameters {
			amount_msats: Some(10_000),
			description,
			invoice_expiry_delta_secs: Some(3600),
			payment_hash: Some(payment_hash),
			..Default::default()
		};
		let invoice = nodes[1].node.create_bolt11_invoice(invoice_params).unwrap();
		assert_eq!(invoice.amount_milli_satoshis(), Some(10_000));
		assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
		assert_eq!(
			invoice.description(),
			Bolt11InvoiceDescriptionRef::Direct(&Description::new("test".to_string()).unwrap())
		);
		assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&payment_hash.0[..]).unwrap());
	}

	#[cfg(not(feature = "std"))]
	#[test]
	fn creates_invoice_using_highest_seen_timestamp() {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

		let invoice_params = Bolt11InvoiceParameters::default();
		let invoice = nodes[1].node.create_bolt11_invoice(invoice_params).unwrap();
		let best_block = bitcoin::constants::genesis_block(Network::Testnet);
		assert_eq!(
			invoice.duration_since_epoch(),
			Duration::from_secs(best_block.header.time.into()),
		);
	}

	#[test]
	fn creates_invoice_using_currency_inferred_from_chain_hash() {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

		let invoice_params = Bolt11InvoiceParameters::default();
		let invoice = nodes[1].node.create_bolt11_invoice(invoice_params).unwrap();
		assert_eq!(invoice.currency(), Currency::BitcoinTestnet);
		assert_eq!(invoice.network(), Network::Testnet);
	}

	#[test]
	fn test_hints_has_only_public_confd_channels() {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let mut config = test_default_channel_config();
		config.channel_handshake_config.minimum_depth = 1;
		let node_chanmgrs =
			create_node_chanmgrs(2, &node_cfgs, &[Some(config.clone()), Some(config)]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

		let node_a_id = nodes[0].node.get_our_node_id();
		let node_b_id = nodes[1].node.get_our_node_id();

		// Create a private channel with lots of capacity and a lower value public channel (without
		// confirming the funding tx yet).
		let unannounced_scid =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 10_000_000, 0);
		let conf_tx = create_chan_between_nodes_with_value_init(&nodes[0], &nodes[1], 10_000, 0);

		// Before the channel is available, we should include the unannounced_scid.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(unannounced_scid.0.short_channel_id_alias.unwrap());
		match_invoice_routes(Some(5000), &nodes[1], scid_aliases.clone());

		// However after we mine the funding tx and exchange channel_ready messages for the public
		// channel we'll immediately switch to including it as a route hint, even though it isn't
		// yet announced.
		let pub_channel_scid = mine_transaction(&nodes[0], &conf_tx);
		let node_a_pub_channel_ready =
			get_event_msg!(nodes[0], MessageSendEvent::SendChannelReady, node_b_id);
		nodes[1].node.handle_channel_ready(node_a_id, &node_a_pub_channel_ready);

		assert_eq!(mine_transaction(&nodes[1], &conf_tx), pub_channel_scid);
		let events = nodes[1].node.get_and_clear_pending_msg_events();
		assert_eq!(events.len(), 2);
		if let MessageSendEvent::SendChannelReady { msg, .. } = &events[0] {
			nodes[0].node.handle_channel_ready(node_b_id, msg);
		} else {
			panic!();
		}
		if let MessageSendEvent::SendChannelUpdate { msg, .. } = &events[1] {
			nodes[0].node.handle_channel_update(node_b_id, msg);
		} else {
			panic!();
		}

		let as_update = get_event_msg!(nodes[0], MessageSendEvent::SendChannelUpdate, node_b_id);
		nodes[1].node.handle_channel_update(node_a_id, &as_update);

		expect_channel_ready_event(&nodes[0], &node_b_id);
		expect_channel_ready_event(&nodes[1], &node_a_id);

		scid_aliases.clear();
		scid_aliases.insert(node_a_pub_channel_ready.short_channel_id_alias.unwrap());
		match_invoice_routes(Some(5000), &nodes[1], scid_aliases.clone());
		// This also applies even if the amount is more than the payment amount, to ensure users
		// dont screw up their privacy.
		match_invoice_routes(Some(50_000_000), &nodes[1], scid_aliases.clone());

		// The same remains true until the channel has 7 confirmations, at which point we include
		// no hints.
		connect_blocks(&nodes[1], 5);
		match_invoice_routes(Some(5000), &nodes[1], scid_aliases.clone());
		connect_blocks(&nodes[1], 1);
		get_event_msg!(nodes[1], MessageSendEvent::SendAnnouncementSignatures, node_a_id);
		match_invoice_routes(Some(5000), &nodes[1], HashSet::new());
	}

	#[test]
	fn test_hints_includes_single_channels_to_nodes() {
		let chanmon_cfgs = create_chanmon_cfgs(3);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);

		let chan_1_0 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100000, 10001);
		let chan_2_0 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 100000, 10001);

		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_1_0.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_2_0.0.short_channel_id_alias.unwrap());

		match_invoice_routes(Some(5000), &nodes[0], scid_aliases);
	}

	#[test]
	fn test_hints_has_only_lowest_inbound_capacity_channel_above_minimum() {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

		let _chan_1_0_inbound_below_amt =
			create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 10_000, 0);
		let _chan_1_0_large_inbound_above_amt =
			create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 500_000, 0);
		let chan_1_0_low_inbound_above_amt =
			create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 200_000, 0);

		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_1_0_low_inbound_above_amt.0.short_channel_id_alias.unwrap());
		match_invoice_routes(Some(100_000_000), &nodes[0], scid_aliases);
	}

	#[test]
	fn test_hints_has_only_online_channels() {
		let chanmon_cfgs = create_chanmon_cfgs(4);
		let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
		let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
		let chan_a = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 10_000_000, 0);
		let chan_b = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 10_000_000, 0);
		let _chan_c = create_unannounced_chan_between_nodes_with_value(&nodes, 3, 0, 1_000_000, 0);

		// With all peers connected we should get all hints that have sufficient value
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_a.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_b.0.short_channel_id_alias.unwrap());

		match_invoice_routes(Some(1_000_000_000), &nodes[0], scid_aliases.clone());

		// With only one sufficient-value peer connected we should only get its hint
		scid_aliases.remove(&chan_b.0.short_channel_id_alias.unwrap());
		nodes[0].node.peer_disconnected(nodes[2].node.get_our_node_id());
		match_invoice_routes(Some(1_000_000_000), &nodes[0], scid_aliases.clone());

		// If we don't have any sufficient-value peers connected we should get all hints with
		// sufficient value, even though there is a connected insufficient-value peer.
		scid_aliases.insert(chan_b.0.short_channel_id_alias.unwrap());
		nodes[0].node.peer_disconnected(nodes[1].node.get_our_node_id());
		match_invoice_routes(Some(1_000_000_000), &nodes[0], scid_aliases);
	}

	#[test]
	fn test_insufficient_inbound_sort_by_highest_capacity() {
		let chanmon_cfgs = create_chanmon_cfgs(5);
		let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, None, None, None, None]);
		let nodes = create_network(5, &node_cfgs, &node_chanmgrs);
		let _chan_1_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100_000, 0);
		let chan_2_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 200_000, 0);
		let chan_3_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 3, 0, 300_000, 0);
		let chan_4_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 4, 0, 400_000, 0);

		// When no single channel has enough inbound capacity for the payment, we expect the three
		// highest inbound channels to be chosen.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_2_0.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_3_0.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_4_0.0.short_channel_id_alias.unwrap());

		match_invoice_routes(Some(1_000_000_000), &nodes[0], scid_aliases.clone());
	}

	#[test]
	fn test_sufficient_inbound_sort_by_lowest_capacity() {
		let chanmon_cfgs = create_chanmon_cfgs(5);
		let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, None, None, None, None]);
		let nodes = create_network(5, &node_cfgs, &node_chanmgrs);
		let chan_1_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100_000, 0);
		let chan_2_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 200_000, 0);
		let chan_3_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 3, 0, 300_000, 0);
		let _chan_4_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 4, 0, 400_000, 0);

		// When we have channels that have sufficient inbound for the payment, test that we sort
		// by lowest inbound capacity.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_1_0.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_2_0.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_3_0.0.short_channel_id_alias.unwrap());

		match_invoice_routes(Some(50_000_000), &nodes[0], scid_aliases.clone());
	}

	#[test]
	fn test_forwarding_info_not_assigned_channel_excluded_from_hints() {
		let chanmon_cfgs = create_chanmon_cfgs(3);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
		let chan_1_0 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100000, 10001);

		let node_a_id = nodes[0].node.get_our_node_id();
		let node_c_id = nodes[2].node.get_our_node_id();

		// Create an unannonced channel between `nodes[2]` and `nodes[0]`, for which the
		// `msgs::ChannelUpdate` is never handled for the node(s). As the `msgs::ChannelUpdate`
		// is never handled, the `channel.counterparty.forwarding_info` is never assigned.
		let mut private_chan_cfg = UserConfig::default();
		private_chan_cfg.channel_handshake_config.announce_for_forwarding = false;
		let temporary_channel_id = nodes[2]
			.node
			.create_channel(node_a_id, 1_000_000, 500_000_000, 42, None, Some(private_chan_cfg))
			.unwrap();
		let open_channel = get_event_msg!(nodes[2], MessageSendEvent::SendOpenChannel, node_a_id);
		nodes[0].node.handle_open_channel(node_c_id, &open_channel);
		let accept_channel =
			get_event_msg!(nodes[0], MessageSendEvent::SendAcceptChannel, node_c_id);
		nodes[2].node.handle_accept_channel(node_a_id, &accept_channel);

		let tx = sign_funding_transaction(&nodes[2], &nodes[0], 1_000_000, temporary_channel_id);

		let conf_height =
			core::cmp::max(nodes[2].best_block_info().1 + 1, nodes[0].best_block_info().1 + 1);
		confirm_transaction_at(&nodes[2], &tx, conf_height);
		connect_blocks(&nodes[2], CHAN_CONFIRM_DEPTH - 1);
		confirm_transaction_at(&nodes[0], &tx, conf_height);
		connect_blocks(&nodes[0], CHAN_CONFIRM_DEPTH - 1);
		let as_channel_ready =
			get_event_msg!(nodes[0], MessageSendEvent::SendChannelReady, node_c_id);
		let cs_channel_ready =
			get_event_msg!(nodes[2], MessageSendEvent::SendChannelReady, node_a_id);
		nodes[2].node.handle_channel_ready(node_a_id, &as_channel_ready);
		get_event_msg!(nodes[2], MessageSendEvent::SendChannelUpdate, node_a_id);
		nodes[0].node.handle_channel_ready(node_c_id, &cs_channel_ready);
		get_event_msg!(nodes[0], MessageSendEvent::SendChannelUpdate, node_c_id);
		expect_channel_ready_event(&nodes[0], &node_c_id);
		expect_channel_ready_event(&nodes[2], &node_a_id);

		// As `msgs::ChannelUpdate` was never handled for the participating node(s) of the second
		// channel, the channel will never be assigned any `counterparty.forwarding_info`.
		// Therefore only `chan_1_0` should be included in the hints.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_1_0.0.short_channel_id_alias.unwrap());
		match_invoice_routes(Some(5000), &nodes[0], scid_aliases);
	}

	#[test]
	fn test_no_hints_if_a_mix_between_public_and_private_channel_exists() {
		let chanmon_cfgs = create_chanmon_cfgs(3);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
		let _chan_1_0 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100000, 10001);

		let chan_2_0 = create_announced_chan_between_nodes_with_value(&nodes, 2, 0, 100000, 10001);
		nodes[2].node.handle_channel_update(nodes[0].node.get_our_node_id(), &chan_2_0.1);
		nodes[0].node.handle_channel_update(nodes[2].node.get_our_node_id(), &chan_2_0.0);

		// Ensure that the invoice doesn't include any route hints for any of `nodes[0]` channels,
		// even though all channels between `nodes[1]` and `nodes[0]` are private, as there is a
		// public channel between `nodes[2]` and `nodes[0]`
		match_invoice_routes(Some(5000), &nodes[0], HashSet::new());
	}

	#[test]
	fn test_only_public_channels_includes_no_channels_in_hints() {
		let chanmon_cfgs = create_chanmon_cfgs(3);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
		let chan_1_0 = create_announced_chan_between_nodes_with_value(&nodes, 1, 0, 100000, 10001);
		nodes[0].node.handle_channel_update(nodes[1].node.get_our_node_id(), &chan_1_0.0);
		nodes[1].node.handle_channel_update(nodes[0].node.get_our_node_id(), &chan_1_0.1);

		let chan_2_0 = create_announced_chan_between_nodes_with_value(&nodes, 2, 0, 100000, 10001);
		nodes[2].node.handle_channel_update(nodes[0].node.get_our_node_id(), &chan_2_0.1);
		nodes[0].node.handle_channel_update(nodes[2].node.get_our_node_id(), &chan_2_0.0);

		// As all of `nodes[0]` channels are public, no channels should be included in the hints
		match_invoice_routes(Some(5000), &nodes[0], HashSet::new());
	}

	#[test]
	fn test_channels_with_lower_inbound_capacity_than_invoice_amt_hints_filtering() {
		let chanmon_cfgs = create_chanmon_cfgs(3);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
		let chan_1_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100_000, 0);
		let chan_2_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 1_000_000, 0);

		// As the invoice amt is 1 msat above chan_1_0's inbound capacity, it shouldn't be included
		let mut scid_aliases_99_000_001_msat = HashSet::new();
		scid_aliases_99_000_001_msat.insert(chan_2_0.0.short_channel_id_alias.unwrap());

		match_invoice_routes(Some(99_000_001), &nodes[0], scid_aliases_99_000_001_msat);

		// As the invoice amt is exactly at chan_1_0's inbound capacity, it should be included
		let mut scid_aliases_99_000_000_msat = HashSet::new();
		scid_aliases_99_000_000_msat.insert(chan_1_0.0.short_channel_id_alias.unwrap());
		scid_aliases_99_000_000_msat.insert(chan_2_0.0.short_channel_id_alias.unwrap());

		match_invoice_routes(Some(99_000_000), &nodes[0], scid_aliases_99_000_000_msat);

		// As the invoice amt is above all channels' inbound capacity, they will still be included
		let mut scid_aliases_2_000_000_000_msat = HashSet::new();
		scid_aliases_2_000_000_000_msat.insert(chan_1_0.0.short_channel_id_alias.unwrap());
		scid_aliases_2_000_000_000_msat.insert(chan_2_0.0.short_channel_id_alias.unwrap());

		match_invoice_routes(Some(2_000_000_000), &nodes[0], scid_aliases_2_000_000_000_msat);

		// An invoice with no specified amount should include all channels in the route hints.
		let mut scid_aliases_no_specified_amount = HashSet::new();
		scid_aliases_no_specified_amount.insert(chan_1_0.0.short_channel_id_alias.unwrap());
		scid_aliases_no_specified_amount.insert(chan_2_0.0.short_channel_id_alias.unwrap());

		match_invoice_routes(None, &nodes[0], scid_aliases_no_specified_amount);
	}

	fn match_invoice_routes<'a, 'b: 'a, 'c: 'b>(
		invoice_amt: Option<u64>, invoice_node: &Node<'a, 'b, 'c>,
		mut chan_ids_to_match: HashSet<u64>,
	) {
		let description =
			Bolt11InvoiceDescription::Direct(Description::new("test".to_string()).unwrap());
		let invoice_params = Bolt11InvoiceParameters {
			amount_msats: invoice_amt,
			description,
			invoice_expiry_delta_secs: Some(3600),
			..Default::default()
		};
		let invoice = invoice_node.node.create_bolt11_invoice(invoice_params).unwrap();
		let hints = invoice.private_routes();

		for hint in hints {
			let hint_short_chan_id = hint.0[0].short_channel_id;
			assert!(chan_ids_to_match.remove(&hint_short_chan_id));
		}
		assert!(
			chan_ids_to_match.is_empty(),
			"Unmatched short channel ids: {:?}",
			chan_ids_to_match
		);
	}

	#[test]
	fn test_multi_node_receive() {
		do_test_multi_node_receive(true);
		do_test_multi_node_receive(false);
	}

	fn make_dyn_keys_interface(seed: &[u8; 32]) -> DynKeysInterface {
		let cross_node_seed = [44u8; 32];
		let inner = PhantomKeysManager::new(&seed, 43, 44, &cross_node_seed, true);
		let dyn_inner = DynPhantomKeysInterface::new(inner);
		DynKeysInterface::new(Box::new(dyn_inner))
	}

	fn do_test_multi_node_receive(user_generated_pmt_hash: bool) {
		use crate::events::{Event, EventsProvider};
		use core::cell::RefCell;

		let mut chanmon_cfgs = create_chanmon_cfgs(3);
		let seed_1 = [42u8; 32];
		let seed_2 = [43u8; 32];
		chanmon_cfgs[1].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
		let chan_0_1 = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
		nodes[0].node.handle_channel_update(nodes[1].node.get_our_node_id(), &chan_0_1.1);
		nodes[1].node.handle_channel_update(nodes[0].node.get_our_node_id(), &chan_0_1.0);
		let chan_0_2 = create_announced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
		nodes[0].node.handle_channel_update(nodes[2].node.get_our_node_id(), &chan_0_2.1);
		nodes[2].node.handle_channel_update(nodes[0].node.get_our_node_id(), &chan_0_2.0);

		let payment_amt = 10_000;
		let route_hints =
			vec![nodes[1].node.get_phantom_route_hints(), nodes[2].node.get_phantom_route_hints()];

		let user_payment_preimage = PaymentPreimage([1; 32]);
		let payment_hash = if user_generated_pmt_hash {
			Some(PaymentHash(Sha256::hash(&user_payment_preimage.0[..]).to_byte_array()))
		} else {
			None
		};
		let genesis_timestamp =
			bitcoin::constants::genesis_block(bitcoin::Network::Testnet).header.time as u64;
		let non_default_invoice_expiry_secs = 4200;

		let invoice = create_phantom_invoice::<
			&test_utils::TestKeysInterface,
			&test_utils::TestKeysInterface,
			&test_utils::TestLogger,
		>(
			Some(payment_amt),
			payment_hash,
			"test".to_string(),
			non_default_invoice_expiry_secs,
			route_hints,
			nodes[1].keys_manager,
			nodes[1].keys_manager,
			nodes[1].logger,
			Currency::BitcoinTestnet,
			None,
			Duration::from_secs(genesis_timestamp),
		)
		.unwrap();
		let (payment_hash, payment_secret) =
			(PaymentHash(invoice.payment_hash().to_byte_array()), *invoice.payment_secret());
		let payment_preimage = if user_generated_pmt_hash {
			user_payment_preimage
		} else {
			nodes[1].node.get_payment_preimage(payment_hash, payment_secret).unwrap()
		};

		assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
		assert_eq!(
			invoice.description(),
			Bolt11InvoiceDescriptionRef::Direct(&Description::new("test".to_string()).unwrap())
		);
		assert_eq!(invoice.route_hints().len(), 2);
		assert_eq!(
			invoice.expiry_time(),
			Duration::from_secs(non_default_invoice_expiry_secs.into())
		);
		assert!(!invoice.features().unwrap().supports_basic_mpp());

		let payment_params = PaymentParameters::from_node_id(
			invoice.recover_payee_pub_key(),
			invoice.min_final_cltv_expiry_delta() as u32,
		)
		.with_bolt11_features(invoice.features().unwrap().clone())
		.unwrap()
		.with_route_hints(invoice.route_hints())
		.unwrap();
		let params = RouteParameters::from_payment_params_and_value(
			payment_params,
			invoice.amount_milli_satoshis().unwrap(),
		);

		let payment_hash = PaymentHash(invoice.payment_hash().to_byte_array());
		let id = PaymentId(payment_hash.0);
		let onion = RecipientOnionFields::secret_only(*invoice.payment_secret());
		nodes[0].node.send_payment(payment_hash, onion, id, params, Retry::Attempts(0)).unwrap();
		check_added_monitors(&nodes[0], 1);

		let (send_event, fwd_idx) = {
			let mut events = nodes[0].node.get_and_clear_pending_msg_events();
			assert_eq!(events.len(), 1);
			let fwd_idx = match events[0] {
				MessageSendEvent::UpdateHTLCs { node_id, .. } => {
					if node_id == nodes[1].node.get_our_node_id() {
						1
					} else {
						2
					}
				},
				_ => panic!("Unexpected event"),
			};
			(SendEvent::from_event(events.remove(0)), fwd_idx)
		};
		nodes[fwd_idx]
			.node
			.handle_update_add_htlc(nodes[0].node.get_our_node_id(), &send_event.msgs[0]);
		commitment_signed_dance!(nodes[fwd_idx], nodes[0], &send_event.commitment_msg, false, true);

		// Note that we have to "forward pending HTLCs" twice before we see the PaymentClaimable as
		// this "emulates" the payment taking two hops, providing some privacy to make phantom node
		// payments "look real" by taking more time.
		nodes[fwd_idx].node.process_pending_htlc_forwards();
		nodes[fwd_idx].node.process_pending_htlc_forwards();

		let events = RefCell::new(Vec::new());
		let event_handler = |event: Event| {
			events.borrow_mut().push(event);
			Ok(())
		};

		nodes[fwd_idx].node.process_pending_events(&event_handler);
		nodes[fwd_idx].node.process_pending_events(&event_handler);

		let payment_preimage_opt =
			if user_generated_pmt_hash { None } else { Some(payment_preimage) };
		assert_eq!(events.borrow().len(), 1);
		check_payment_claimable(
			&events.borrow()[0],
			payment_hash,
			payment_secret,
			payment_amt,
			payment_preimage_opt,
			invoice.recover_payee_pub_key(),
		);
		do_claim_payment_along_route(ClaimAlongRouteArgs::new(
			&nodes[0],
			&[&[&nodes[fwd_idx]]],
			payment_preimage,
		));
		expect_payment_sent(&nodes[0], payment_preimage, None, true, true);
	}

	#[test]
	fn test_multi_node_hints_has_htlc_min_max_values() {
		let mut chanmon_cfgs = create_chanmon_cfgs(3);
		let seed_1 = [42u8; 32];
		let seed_2 = [43u8; 32];
		chanmon_cfgs[1].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);

		create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
		create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);

		let payment_amt = 20_000;
		let (payment_hash, _payment_secret) =
			nodes[1].node.create_inbound_payment(Some(payment_amt), 3600, None).unwrap();
		let route_hints =
			vec![nodes[1].node.get_phantom_route_hints(), nodes[2].node.get_phantom_route_hints()];

		let invoice = create_phantom_invoice::<
			&test_utils::TestKeysInterface,
			&test_utils::TestKeysInterface,
			&test_utils::TestLogger,
		>(
			Some(payment_amt),
			Some(payment_hash),
			"test".to_string(),
			3600,
			route_hints,
			nodes[1].keys_manager,
			nodes[1].keys_manager,
			nodes[1].logger,
			Currency::BitcoinTestnet,
			None,
			Duration::from_secs(1234567),
		)
		.unwrap();

		let chan_0_1 = &nodes[1].node.list_usable_channels()[0];
		assert_eq!(
			invoice.route_hints()[0].0[0].htlc_minimum_msat,
			chan_0_1.inbound_htlc_minimum_msat
		);
		assert_eq!(
			invoice.route_hints()[0].0[0].htlc_maximum_msat,
			chan_0_1.inbound_htlc_maximum_msat
		);

		let chan_0_2 = &nodes[2].node.list_usable_channels()[0];
		assert_eq!(
			invoice.route_hints()[1].0[0].htlc_minimum_msat,
			chan_0_2.inbound_htlc_minimum_msat
		);
		assert_eq!(
			invoice.route_hints()[1].0[0].htlc_maximum_msat,
			chan_0_2.inbound_htlc_maximum_msat
		);
	}

	#[test]
	fn test_create_phantom_invoice_with_description_hash() {
		let chanmon_cfgs = create_chanmon_cfgs(3);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);

		let payment_amt = 20_000;
		let route_hints =
			vec![nodes[1].node.get_phantom_route_hints(), nodes[2].node.get_phantom_route_hints()];

		let description_hash = Sha256(Hash::hash("Description hash phantom invoice".as_bytes()));
		let non_default_invoice_expiry_secs = 4200;
		let invoice = create_phantom_invoice_with_description_hash::<
			&test_utils::TestKeysInterface,
			&test_utils::TestKeysInterface,
			&test_utils::TestLogger,
		>(
			Some(payment_amt),
			None,
			non_default_invoice_expiry_secs,
			description_hash,
			route_hints,
			nodes[1].keys_manager,
			nodes[1].keys_manager,
			nodes[1].logger,
			Currency::BitcoinTestnet,
			None,
			Duration::from_secs(1234567),
		)
		.unwrap();
		assert_eq!(invoice.amount_milli_satoshis(), Some(20_000));
		assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
		assert_eq!(
			invoice.expiry_time(),
			Duration::from_secs(non_default_invoice_expiry_secs.into())
		);
		assert_eq!(
			invoice.description(),
			Bolt11InvoiceDescriptionRef::Hash(&Sha256(Sha256::hash(
				"Description hash phantom invoice".as_bytes()
			)))
		);
	}

	#[test]
	fn create_phantom_invoice_with_custom_payment_hash_and_custom_min_final_cltv_delta() {
		let chanmon_cfgs = create_chanmon_cfgs(3);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);

		let payment_amt = 20_000;
		let route_hints =
			vec![nodes[1].node.get_phantom_route_hints(), nodes[2].node.get_phantom_route_hints()];
		let user_payment_preimage = PaymentPreimage([1; 32]);
		let payment_hash =
			Some(PaymentHash(Sha256::hash(&user_payment_preimage.0[..]).to_byte_array()));
		let non_default_invoice_expiry_secs = 4200;
		let min_final_cltv_expiry_delta = Some(100);
		let duration_since_epoch = Duration::from_secs(1234567);
		let invoice = create_phantom_invoice::<
			&test_utils::TestKeysInterface,
			&test_utils::TestKeysInterface,
			&test_utils::TestLogger,
		>(
			Some(payment_amt),
			payment_hash,
			"".to_string(),
			non_default_invoice_expiry_secs,
			route_hints,
			nodes[1].keys_manager,
			nodes[1].keys_manager,
			nodes[1].logger,
			Currency::BitcoinTestnet,
			min_final_cltv_expiry_delta,
			duration_since_epoch,
		)
		.unwrap();
		assert_eq!(invoice.amount_milli_satoshis(), Some(20_000));
		assert_eq!(
			invoice.min_final_cltv_expiry_delta(),
			(min_final_cltv_expiry_delta.unwrap() + 3) as u64
		);
		assert_eq!(
			invoice.expiry_time(),
			Duration::from_secs(non_default_invoice_expiry_secs.into())
		);
	}

	#[test]
	fn test_multi_node_hints_includes_single_channels_to_participating_nodes() {
		let mut chanmon_cfgs = create_chanmon_cfgs(3);
		let seed_1 = [42u8; 32];
		let seed_2 = [43u8; 32];
		chanmon_cfgs[1].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);

		let chan_0_1 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
		let chan_0_2 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);

		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_0_1.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(10_000),
			&nodes[1],
			vec![&nodes[1], &nodes[2]],
			scid_aliases,
			false,
		);
	}

	#[test]
	fn test_multi_node_hints_includes_one_channel_of_each_counterparty_nodes_per_participating_node(
	) {
		let mut chanmon_cfgs = create_chanmon_cfgs(4);
		let seed_1 = [42u8; 32];
		let seed_2 = [43u8; 32];
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[3].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
		let nodes = create_network(4, &node_cfgs, &node_chanmgrs);

		let chan_0_2 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
		let chan_0_3 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 1000000, 10001);
		let chan_1_3 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 3_000_000, 10005);

		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_1_3.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(10_000),
			&nodes[2],
			vec![&nodes[2], &nodes[3]],
			scid_aliases,
			false,
		);
	}

	#[test]
	fn test_multi_node_forwarding_info_not_assigned_channel_excluded_from_hints() {
		let mut chanmon_cfgs = create_chanmon_cfgs(4);
		let seed_1 = [42u8; 32];
		let seed_2 = [43u8; 32];
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[3].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
		let nodes = create_network(4, &node_cfgs, &node_chanmgrs);

		let node_b_id = nodes[1].node.get_our_node_id();
		let node_d_id = nodes[3].node.get_our_node_id();

		let chan_0_2 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
		let chan_0_3 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 1000000, 10001);

		// Create an unannonced channel between `nodes[1]` and `nodes[3]`, for which the
		// `msgs::ChannelUpdate` is never handled for the node(s). As the `msgs::ChannelUpdate`
		// is never handled, the `channel.counterparty.forwarding_info` is never assigned.
		let mut private_chan_cfg = UserConfig::default();
		private_chan_cfg.channel_handshake_config.announce_for_forwarding = false;
		let temporary_channel_id = nodes[1]
			.node
			.create_channel(node_d_id, 1_000_000, 500_000_000, 42, None, Some(private_chan_cfg))
			.unwrap();
		let open_channel = get_event_msg!(nodes[1], MessageSendEvent::SendOpenChannel, node_d_id);
		nodes[3].node.handle_open_channel(nodes[1].node.get_our_node_id(), &open_channel);
		let accept_channel =
			get_event_msg!(nodes[3], MessageSendEvent::SendAcceptChannel, node_b_id);
		nodes[1].node.handle_accept_channel(nodes[3].node.get_our_node_id(), &accept_channel);

		let tx = sign_funding_transaction(&nodes[1], &nodes[3], 1_000_000, temporary_channel_id);

		let conf_height =
			core::cmp::max(nodes[1].best_block_info().1 + 1, nodes[3].best_block_info().1 + 1);
		confirm_transaction_at(&nodes[1], &tx, conf_height);
		connect_blocks(&nodes[1], CHAN_CONFIRM_DEPTH - 1);
		confirm_transaction_at(&nodes[3], &tx, conf_height);
		connect_blocks(&nodes[3], CHAN_CONFIRM_DEPTH - 1);

		let bs_channel_ready =
			get_event_msg!(nodes[1], MessageSendEvent::SendChannelReady, node_d_id);
		let ds_channel_ready =
			get_event_msg!(nodes[3], MessageSendEvent::SendChannelReady, node_b_id);
		nodes[1].node.handle_channel_ready(node_d_id, &ds_channel_ready);
		get_event_msg!(nodes[1], MessageSendEvent::SendChannelUpdate, node_d_id);
		nodes[3].node.handle_channel_ready(nodes[1].node.get_our_node_id(), &bs_channel_ready);
		get_event_msg!(nodes[3], MessageSendEvent::SendChannelUpdate, node_b_id);
		expect_channel_ready_event(&nodes[1], &nodes[3].node.get_our_node_id());
		expect_channel_ready_event(&nodes[3], &nodes[1].node.get_our_node_id());

		// As `msgs::ChannelUpdate` was never handled for the participating node(s) of the third
		// channel, the channel will never be assigned any `counterparty.forwarding_info`.
		// Therefore only `chan_0_3` should be included in the hints for `nodes[3]`.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(10_000),
			&nodes[2],
			vec![&nodes[2], &nodes[3]],
			scid_aliases,
			false,
		);
	}

	#[test]
	fn test_multi_node_with_only_public_channels_hints_includes_only_phantom_route() {
		let mut chanmon_cfgs = create_chanmon_cfgs(3);
		let seed_1 = [42u8; 32];
		let seed_2 = [43u8; 32];
		chanmon_cfgs[1].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);

		let chan_0_1 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);

		let chan_2_0 = create_announced_chan_between_nodes_with_value(&nodes, 2, 0, 100000, 10001);
		nodes[2].node.handle_channel_update(nodes[0].node.get_our_node_id(), &chan_2_0.1);
		nodes[0].node.handle_channel_update(nodes[2].node.get_our_node_id(), &chan_2_0.0);

		// Hints should include `chan_0_1` from as `nodes[1]` only have private channels, but not
		// `chan_0_2` as `nodes[2]` only has public channels.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_0_1.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(10_000),
			&nodes[1],
			vec![&nodes[1], &nodes[2]],
			scid_aliases,
			true,
		);
	}

	#[test]
	fn test_multi_node_with_mixed_public_and_private_channel_hints_includes_only_phantom_route() {
		let mut chanmon_cfgs = create_chanmon_cfgs(4);
		let seed_1 = [42u8; 32];
		let seed_2 = [43u8; 32];
		chanmon_cfgs[1].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
		let nodes = create_network(4, &node_cfgs, &node_chanmgrs);

		let chan_0_2 = create_announced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
		nodes[0].node.handle_channel_update(nodes[2].node.get_our_node_id(), &chan_0_2.1);
		nodes[2].node.handle_channel_update(nodes[0].node.get_our_node_id(), &chan_0_2.0);
		let _chan_1_2 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 1, 2, 100000, 10001);

		let chan_0_3 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 100000, 10001);

		// Hints should include `chan_0_3` from as `nodes[3]` only have private channels, and no
		// channels for `nodes[2]` as it contains a mix of public and private channels.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(10_000),
			&nodes[2],
			vec![&nodes[2], &nodes[3]],
			scid_aliases,
			true,
		);
	}

	#[test]
	fn test_multi_node_hints_has_only_lowest_inbound_channel_above_minimum() {
		let mut chanmon_cfgs = create_chanmon_cfgs(3);
		let seed_1 = [42u8; 32];
		let seed_2 = [43u8; 32];
		chanmon_cfgs[1].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
		let nodes = create_network(3, &node_cfgs, &node_chanmgrs);

		let _chan_0_1_below_amt =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100_000, 0);
		let _chan_0_1_above_amt_high_inbound =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 500_000, 0);
		let chan_0_1_above_amt_low_inbound =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 180_000, 0);
		let chan_0_2 =
			create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);

		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_0_1_above_amt_low_inbound.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(100_000_000),
			&nodes[1],
			vec![&nodes[1], &nodes[2]],
			scid_aliases,
			false,
		);
	}

	#[test]
	fn test_multi_node_channels_inbound_capacity_lower_than_invoice_amt_filtering() {
		let mut chanmon_cfgs = create_chanmon_cfgs(4);
		let seed_1 = [42u8; 32];
		let seed_2 = [43u8; 32];
		chanmon_cfgs[1].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
		let nodes = create_network(4, &node_cfgs, &node_chanmgrs);

		let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 1_000_000, 0);
		let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 100_000, 0);
		let chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 200_000, 0);

		// Since the invoice 1 msat above chan_0_3's inbound capacity, it should be filtered out.
		let mut scid_aliases_99_000_001_msat = HashSet::new();
		scid_aliases_99_000_001_msat.insert(chan_0_2.0.short_channel_id_alias.unwrap());
		scid_aliases_99_000_001_msat.insert(chan_1_3.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(99_000_001),
			&nodes[2],
			vec![&nodes[2], &nodes[3]],
			scid_aliases_99_000_001_msat,
			false,
		);

		// Since the invoice is exactly at chan_0_3's inbound capacity, it should be included.
		let mut scid_aliases_99_000_000_msat = HashSet::new();
		scid_aliases_99_000_000_msat.insert(chan_0_2.0.short_channel_id_alias.unwrap());
		scid_aliases_99_000_000_msat.insert(chan_0_3.0.short_channel_id_alias.unwrap());
		scid_aliases_99_000_000_msat.insert(chan_1_3.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(99_000_000),
			&nodes[2],
			vec![&nodes[2], &nodes[3]],
			scid_aliases_99_000_000_msat,
			false,
		);

		// Since the invoice is above all of `nodes[2]` channels' inbound capacity, all of
		// `nodes[2]` them should be included.
		let mut scid_aliases_300_000_000_msat = HashSet::new();
		scid_aliases_300_000_000_msat.insert(chan_0_2.0.short_channel_id_alias.unwrap());
		scid_aliases_300_000_000_msat.insert(chan_0_3.0.short_channel_id_alias.unwrap());
		scid_aliases_300_000_000_msat.insert(chan_1_3.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(300_000_000),
			&nodes[2],
			vec![&nodes[2], &nodes[3]],
			scid_aliases_300_000_000_msat,
			false,
		);

		// Since the no specified amount, all channels should included.
		let mut scid_aliases_no_specified_amount = HashSet::new();
		scid_aliases_no_specified_amount.insert(chan_0_2.0.short_channel_id_alias.unwrap());
		scid_aliases_no_specified_amount.insert(chan_0_3.0.short_channel_id_alias.unwrap());
		scid_aliases_no_specified_amount.insert(chan_1_3.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			None,
			&nodes[2],
			vec![&nodes[2], &nodes[3]],
			scid_aliases_no_specified_amount,
			false,
		);
	}

	#[test]
	fn test_multi_node_hints_limited_to_3() {
		let mut chanmon_cfgs = create_chanmon_cfgs(6);
		let seed_1 = [42 as u8; 32];
		let seed_2 = [43 as u8; 32];
		let seed_3 = [44 as u8; 32];
		let seed_4 = [45 as u8; 32];
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[3].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		chanmon_cfgs[4].keys_manager.backing = make_dyn_keys_interface(&seed_3);
		chanmon_cfgs[4].keys_manager.backing = make_dyn_keys_interface(&seed_4);
		let node_cfgs = create_node_cfgs(6, &chanmon_cfgs);
		let node_chanmgrs =
			create_node_chanmgrs(6, &node_cfgs, &[None, None, None, None, None, None]);
		let nodes = create_network(6, &node_cfgs, &node_chanmgrs);

		// Setup each phantom node with two channels from distinct peers.
		let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 10_000, 0);
		let chan_1_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 2, 20_000, 0);
		let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 20_000, 0);
		let _chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 10_000, 0);
		let chan_0_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 4, 20_000, 0);
		let _chan_1_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 4, 10_000, 0);
		let _chan_0_5 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 5, 20_000, 0);
		let _chan_1_5 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 5, 10_000, 0);

		// Set invoice amount > all channels inbound so that every one is eligible for inclusion
		// and hints will be sorted by largest inbound capacity.
		let invoice_amt = Some(100_000_000);

		// With 4 phantom nodes, assert that we include 1 hint per node, up to 3 nodes.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_1_2.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_0_4.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			invoice_amt,
			&nodes[3],
			vec![&nodes[2], &nodes[3], &nodes[4], &nodes[5]],
			scid_aliases,
			false,
		);

		// With 2 phantom nodes, assert that we include no more than 3 hints.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_1_2.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			invoice_amt,
			&nodes[3],
			vec![&nodes[2], &nodes[3]],
			scid_aliases,
			false,
		);
	}

	#[test]
	fn test_multi_node_hints_at_least_3() {
		let mut chanmon_cfgs = create_chanmon_cfgs(5);
		let seed_1 = [42 as u8; 32];
		let seed_2 = [43 as u8; 32];
		chanmon_cfgs[1].keys_manager.backing = make_dyn_keys_interface(&seed_1);
		chanmon_cfgs[2].keys_manager.backing = make_dyn_keys_interface(&seed_2);
		let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, None, None, None, None]);
		let nodes = create_network(5, &node_cfgs, &node_chanmgrs);

		let _chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 10_000, 0);
		let chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 20_000, 0);
		let chan_2_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 3, 30_000, 0);
		let chan_0_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 4, 10_000, 0);

		// Since the invoice amount is above all channels inbound, all four are eligible. Test that
		// we still include 3 hints from 2 distinct nodes sorted by inbound.
		let mut scid_aliases = HashSet::new();
		scid_aliases.insert(chan_1_3.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_2_3.0.short_channel_id_alias.unwrap());
		scid_aliases.insert(chan_0_4.0.short_channel_id_alias.unwrap());

		match_multi_node_invoice_routes(
			Some(100_000_000),
			&nodes[3],
			vec![&nodes[3], &nodes[4]],
			scid_aliases,
			false,
		);
	}

	fn match_multi_node_invoice_routes<'a, 'b: 'a, 'c: 'b>(
		invoice_amt: Option<u64>, invoice_node: &Node<'a, 'b, 'c>,
		network_multi_nodes: Vec<&Node<'a, 'b, 'c>>, mut chan_ids_to_match: HashSet<u64>,
		nodes_contains_public_channels: bool,
	) {
		let phantom_route_hints = network_multi_nodes
			.iter()
			.map(|node| node.node.get_phantom_route_hints())
			.collect::<Vec<PhantomRouteHints>>();
		let phantom_scids = phantom_route_hints
			.iter()
			.map(|route_hint| route_hint.phantom_scid)
			.collect::<HashSet<u64>>();

		let invoice = create_phantom_invoice::<
			&test_utils::TestKeysInterface,
			&test_utils::TestKeysInterface,
			&test_utils::TestLogger,
		>(
			invoice_amt,
			None,
			"test".to_string(),
			3600,
			phantom_route_hints,
			invoice_node.keys_manager,
			invoice_node.keys_manager,
			invoice_node.logger,
			Currency::BitcoinTestnet,
			None,
			Duration::from_secs(1234567),
		)
		.unwrap();

		let invoice_hints = invoice.private_routes();

		for hint in invoice_hints {
			let hints = &hint.0;
			match hints.len() {
				1 => {
					assert!(nodes_contains_public_channels);
					let phantom_scid = hints[0].short_channel_id;
					assert!(phantom_scids.contains(&phantom_scid));
				},
				2 => {
					let hint_short_chan_id = hints[0].short_channel_id;
					assert!(chan_ids_to_match.remove(&hint_short_chan_id));
					let phantom_scid = hints[1].short_channel_id;
					assert!(phantom_scids.contains(&phantom_scid));
				},
				_ => panic!("Incorrect hint length generated"),
			}
		}
		assert!(
			chan_ids_to_match.is_empty(),
			"Unmatched short channel ids: {:?}",
			chan_ids_to_match
		);
	}

	#[test]
	fn test_create_invoice_fails_with_invalid_custom_min_final_cltv_expiry_delta() {
		let chanmon_cfgs = create_chanmon_cfgs(2);
		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

		let description = Bolt11InvoiceDescription::Direct(
			Description::new("Some description".to_string()).unwrap(),
		);
		let invoice_params = Bolt11InvoiceParameters {
			amount_msats: Some(10_000),
			description,
			invoice_expiry_delta_secs: Some(3600),
			min_final_cltv_expiry_delta: Some(MIN_FINAL_CLTV_EXPIRY_DELTA - 4),
			..Default::default()
		};
		match nodes[1].node.create_bolt11_invoice(invoice_params) {
			Err(SignOrCreationError::CreationError(
				CreationError::MinFinalCltvExpiryDeltaTooShort,
			)) => {},
			_ => panic!(),
		}
	}

	#[test]
	fn test_rotate_through_iterators() {
		// two nested vectors
		let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec!["a1", "b1"].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a0", "a1", "b0", "b1", "c0"];
		assert_eq!(expected, result);

		// test single nested vector
		let a = vec![vec!["a0", "b0", "c0"].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a0", "b0", "c0"];
		assert_eq!(expected, result);

		// test second vector with only one element
		let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec!["a1"].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a0", "a1", "b0", "c0"];
		assert_eq!(expected, result);

		// test three nestend vectors
		let a = vec![
			vec!["a0"].into_iter(),
			vec!["a1", "b1", "c1"].into_iter(),
			vec!["a2"].into_iter(),
		];
		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a0", "a1", "a2", "b1", "c1"];
		assert_eq!(expected, result);

		// test single nested vector with a single value
		let a = vec![vec!["a0"].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a0"];
		assert_eq!(expected, result);

		// test single empty nested vector
		let a: Vec<std::vec::IntoIter<&str>> = vec![vec![].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<&str>>();
		let expected: Vec<&str> = vec![];

		assert_eq!(expected, result);

		// test first nested vector is empty
		let a: Vec<std::vec::IntoIter<&str>> =
			vec![vec![].into_iter(), vec!["a1", "b1", "c1"].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<&str>>();

		let expected = vec!["a1", "b1", "c1"];
		assert_eq!(expected, result);

		// test two empty vectors
		let a: Vec<std::vec::IntoIter<&str>> = vec![vec![].into_iter(), vec![].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<&str>>();

		let expected: Vec<&str> = vec![];
		assert_eq!(expected, result);

		// test an empty vector amongst other filled vectors
		let a = vec![
			vec!["a0", "b0", "c0"].into_iter(),
			vec![].into_iter(),
			vec!["a1", "b1", "c1"].into_iter(),
			vec!["a2", "b2", "c2"].into_iter(),
		];
		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a0", "a1", "a2", "b0", "b1", "b2", "c0", "c1", "c2"];
		assert_eq!(expected, result);

		// test a filled vector between two empty vectors
		let a = vec![vec![].into_iter(), vec!["a1", "b1", "c1"].into_iter(), vec![].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a1", "b1", "c1"];
		assert_eq!(expected, result);

		// test an empty vector at the end of the vectors
		let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec![].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a0", "b0", "c0"];
		assert_eq!(expected, result);

		// test multiple empty vectors amongst multiple filled vectors
		let a = vec![
			vec![].into_iter(),
			vec!["a1", "b1", "c1"].into_iter(),
			vec![].into_iter(),
			vec!["a3", "b3"].into_iter(),
			vec![].into_iter(),
		];

		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a1", "a3", "b1", "b3", "c1"];
		assert_eq!(expected, result);

		// test one element in the first nested vectore and two elements in the second nested
		// vector
		let a = vec![vec!["a0"].into_iter(), vec!["a1", "b1"].into_iter()];
		let result = rotate_through_iterators(a).collect::<Vec<_>>();

		let expected = vec!["a0", "a1", "b1"];
		assert_eq!(expected, result);
	}
}