spawn-lnd 0.2.0

use std::{collections::HashMap, net::Ipv4Addr};

use lnd_grpc_rust::{
    LndConnectError, LndNodeClients, LndNodeConfig,
    lnrpc::{Channel, ConnectPeerResponse},
};
use thiserror::Error;
use tokio::time::sleep;
use uuid::Uuid;

use crate::{
    BITCOIND_P2P_PORT, BitcoinCore, BitcoinCoreConfig, BitcoinCoreError, BitcoinRpcError,
    CleanupReport, ConfigError, DEFAULT_GENERATE_ADDRESS, DockerClient, DockerError, LND_P2P_PORT,
    LndConfig, LndDaemon, LndError, ManagedNetwork, NetworkSpec, NodeConfig, RetryPolicy,
    SpawnLndConfig, lnd::channel_point_string,
};

/// Default on-chain funding amount sent to each LND node.
pub const DEFAULT_FUNDING_AMOUNT_BTC: f64 = 1.0;
/// Default number of blocks mined after funding transactions.
pub const DEFAULT_FUNDING_CONFIRMATION_BLOCKS: u64 = 1;
/// Default public channel capacity opened by [`SpawnedCluster::open_channel`].
pub const DEFAULT_CHANNEL_CAPACITY_SAT: i64 = 100_000;
/// Default number of blocks mined after opening a channel.
pub const DEFAULT_CHANNEL_CONFIRMATION_BLOCKS: u64 = 6;
const SATOSHIS_PER_BTC: f64 = 100_000_000.0;
const GENERATED_SUBNET_ATTEMPTS: u32 = 64;

/// A running regtest cluster containing Bitcoin Core and LND containers.
#[derive(Debug)]
pub struct SpawnedCluster {
    docker: DockerClient,
    config: SpawnLndConfig,
    cluster_id: String,
    network: ManagedNetwork,
    bitcoinds: Vec<BitcoinCore>,
    nodes: HashMap<String, SpawnedNode>,
    node_order: Vec<String>,
    shutdown: bool,
}

impl SpawnedCluster {
    /// Spawn a cluster using a validated config and a default Docker connection.
    pub async fn spawn(config: SpawnLndConfig) -> Result<Self, SpawnError> {
        config.validate()?;
        let docker = DockerClient::connect().await?;
        Self::spawn_validated_with_docker(docker, config).await
    }

    /// Spawn a cluster using a caller-provided Docker client.
    pub async fn spawn_with_docker(
        docker: DockerClient,
        config: SpawnLndConfig,
    ) -> Result<Self, SpawnError> {
        config.validate()?;
        Self::spawn_validated_with_docker(docker, config).await
    }

    async fn spawn_validated_with_docker(
        docker: DockerClient,
        config: SpawnLndConfig,
    ) -> Result<Self, SpawnError> {
        let cluster_id = new_cluster_id();
        let cleanup_docker = docker.clone();
        let keep_containers = config.keep_containers;

        match spawn_inner(docker, config, cluster_id.clone()).await {
            Ok(cluster) => Ok(cluster),
            Err(error) => {
                if keep_containers {
                    return Err(error);
                }

                cleanup_docker
                    .cleanup_cluster(&cluster_id)
                    .await
                    .map_err(|source| SpawnError::StartupCleanup {
                        cluster_id,
                        startup_error: error.to_string(),
                        source: Box::new(source),
                    })?;
                Err(error)
            }
        }
    }

    /// Return the generated cluster id used in Docker labels.
    pub fn cluster_id(&self) -> &str {
        &self.cluster_id
    }

    /// Return the config used to spawn this cluster.
    pub fn config(&self) -> &SpawnLndConfig {
        &self.config
    }

    /// Return the managed Docker network used by this cluster.
    pub fn network(&self) -> &ManagedNetwork {
        &self.network
    }

    /// Return all spawned Bitcoin Core chain groups.
    pub fn bitcoinds(&self) -> &[BitcoinCore] {
        &self.bitcoinds
    }

    /// Look up a spawned LND node by alias.
    pub fn node(&self, alias: &str) -> Option<&SpawnedNode> {
        self.nodes.get(alias)
    }

    /// Iterate spawned LND nodes in configured order.
    pub fn nodes(&self) -> impl Iterator<Item = &SpawnedNode> {
        self.node_order
            .iter()
            .filter_map(|alias| self.nodes.get(alias))
    }

    /// Iterate node aliases in configured order.
    pub fn node_aliases(&self) -> impl Iterator<Item = &str> {
        self.node_order.iter().map(String::as_str)
    }

    /// Build connection configs for all LND nodes.
    pub fn node_configs(&self) -> Vec<LndNodeConfig> {
        self.nodes().map(SpawnedNode::node_config).collect()
    }

    /// Connect to all LND nodes with `lnd_grpc_rust`.
    pub async fn connect_nodes(&self) -> Result<LndNodeClients, SpawnError> {
        lnd_grpc_rust::connect_nodes(self.node_configs())
            .await
            .map_err(SpawnError::ConnectNodes)
    }

    /// Connect one LND node to another over the Docker bridge network.
    pub async fn connect_peer(
        &self,
        from_alias: &str,
        to_alias: &str,
    ) -> Result<PeerConnection, SpawnError> {
        let from = self.require_node(from_alias)?;
        let to = self.require_node(to_alias)?;
        let host = lnd_bridge_socket(to)?;
        let response = from
            .daemon
            .connect_peer(to.daemon.public_key.clone(), host.clone())
            .await
            .or_else(|error| already_connected_response(error, &to.daemon.public_key))
            .map_err(|source| SpawnError::Lnd {
                alias: from_alias.to_string(),
                source: Box::new(source),
            })?;

        Ok(PeerConnection {
            from_alias: from_alias.to_string(),
            to_alias: to_alias.to_string(),
            public_key: to.daemon.public_key.clone(),
            socket: host,
            status: response.status,
        })
    }

    /// Connect every LND node to every other LND node.
    pub async fn connect_all_peers(&self) -> Result<Vec<PeerConnection>, SpawnError> {
        let mut connections = Vec::new();

        for from_alias in &self.node_order {
            for to_alias in &self.node_order {
                if from_alias == to_alias {
                    continue;
                }

                connections.push(self.connect_peer(from_alias, to_alias).await?);
            }
        }

        Ok(connections)
    }

    /// Fund one LND node with [`DEFAULT_FUNDING_AMOUNT_BTC`].
    pub async fn fund_node(&self, alias: &str) -> Result<FundingReport, SpawnError> {
        self.fund_node_with_amount(alias, DEFAULT_FUNDING_AMOUNT_BTC)
            .await
    }

    /// Fund one LND node with a caller-provided BTC amount.
    pub async fn fund_node_with_amount(
        &self,
        alias: &str,
        amount_btc: f64,
    ) -> Result<FundingReport, SpawnError> {
        let mut reports = self.fund_nodes_with_amount([alias], amount_btc).await?;
        Ok(reports.remove(0))
    }

    /// Batch-fund multiple LND nodes with [`DEFAULT_FUNDING_AMOUNT_BTC`] each.
    pub async fn fund_nodes<I, S>(&self, aliases: I) -> Result<Vec<FundingReport>, SpawnError>
    where
        I: IntoIterator<Item = S>,
        S: AsRef<str>,
    {
        self.fund_nodes_with_amount(aliases, DEFAULT_FUNDING_AMOUNT_BTC)
            .await
    }

    /// Batch-fund multiple LND nodes with the same caller-provided BTC amount.
    pub async fn fund_nodes_with_amount<I, S>(
        &self,
        aliases: I,
        amount_btc: f64,
    ) -> Result<Vec<FundingReport>, SpawnError>
    where
        I: IntoIterator<Item = S>,
        S: AsRef<str>,
    {
        let amount_sat = btc_to_sat(amount_btc)?;
        let mut recipients = Vec::new();
        let mut amounts = HashMap::new();

        for alias in aliases {
            let alias = alias.as_ref().to_string();
            let node = self.require_node(&alias)?;
            let starting_balance_sat = node
                .daemon
                .wallet_balance(1)
                .await
                .map_err(|source| SpawnError::Lnd {
                    alias: alias.clone(),
                    source: Box::new(source),
                })?
                .confirmed_balance;
            let starting_utxos = node
                .daemon
                .list_unspent(1, i32::MAX)
                .await
                .map_err(|source| SpawnError::Lnd {
                    alias: alias.clone(),
                    source: Box::new(source),
                })?;
            let starting_utxo_total_sat: i64 =
                starting_utxos.iter().map(|utxo| utxo.amount_sat).sum();
            let required_balance_sat = starting_balance_sat
                .checked_add(amount_sat)
                .ok_or(SpawnError::InvalidFundingAmount { amount_btc })?;
            let required_utxo_total_sat = starting_utxo_total_sat
                .checked_add(amount_sat)
                .ok_or(SpawnError::InvalidFundingAmount { amount_btc })?;
            let address = node
                .daemon
                .new_address()
                .await
                .map_err(|source| SpawnError::Lnd {
                    alias: alias.clone(),
                    source: Box::new(source),
                })?;

            amounts.insert(address.clone(), amount_btc);
            recipients.push(FundingRecipient {
                alias,
                address,
                required_balance_sat,
                required_utxo_total_sat,
            });
        }

        if recipients.is_empty() {
            return Ok(Vec::new());
        }

        let funder = &self.bitcoinds[0];
        let txid = funder
            .wallet_rpc
            .send_many(&amounts)
            .await
            .map_err(|source| SpawnError::BitcoinRpc {
                group_index: 0,
                source: Box::new(source),
            })?;
        let confirmation_blocks = funder
            .rpc
            .generate_to_address(
                DEFAULT_FUNDING_CONFIRMATION_BLOCKS,
                DEFAULT_GENERATE_ADDRESS,
            )
            .await
            .map_err(|source| SpawnError::BitcoinRpc {
                group_index: 0,
                source: Box::new(source),
            })?;

        wait_bitcoind_groups_synced(&self.bitcoinds, &self.config.startup_retry).await?;
        wait_lnd_nodes_synced(&self.nodes, &self.node_order, &self.config.startup_retry).await?;

        let mut reports = Vec::with_capacity(recipients.len());
        for recipient in recipients {
            let node = self.require_node(&recipient.alias)?;
            let balance = node
                .daemon
                .wait_for_spendable_balance(recipient.required_balance_sat)
                .await
                .map_err(|source| SpawnError::Lnd {
                    alias: recipient.alias.clone(),
                    source: Box::new(source),
                })?;
            let utxos = node
                .daemon
                .wait_for_spendable_utxos(recipient.required_utxo_total_sat)
                .await
                .map_err(|source| SpawnError::Lnd {
                    alias: recipient.alias.clone(),
                    source: Box::new(source),
                })?;
            let spendable_utxo_total_sat = utxos.iter().map(|utxo| utxo.amount_sat).sum();

            reports.push(FundingReport {
                alias: recipient.alias,
                address: recipient.address,
                txid: txid.clone(),
                amount_btc,
                confirmation_blocks: confirmation_blocks.clone(),
                confirmed_balance_sat: balance.confirmed_balance,
                spendable_utxo_count: utxos.len(),
                spendable_utxo_total_sat,
            });
        }

        Ok(reports)
    }

    /// Open a public channel with [`DEFAULT_CHANNEL_CAPACITY_SAT`].
    pub async fn open_channel(
        &self,
        from_alias: &str,
        to_alias: &str,
    ) -> Result<ChannelReport, SpawnError> {
        self.open_channel_with_amount(from_alias, to_alias, DEFAULT_CHANNEL_CAPACITY_SAT)
            .await
    }

    /// Open a public channel with a caller-provided satoshi capacity.
    pub async fn open_channel_with_amount(
        &self,
        from_alias: &str,
        to_alias: &str,
        local_funding_amount_sat: i64,
    ) -> Result<ChannelReport, SpawnError> {
        let from = self.require_node(from_alias)?;
        let to = self.require_node(to_alias)?;
        let bitcoind = &self.bitcoinds[from.chain_group_index];

        self.connect_peer(from_alias, to_alias).await?;

        let channel_point = from
            .daemon
            .open_channel_sync(&to.daemon.public_key, local_funding_amount_sat, 0)
            .await
            .map_err(|source| SpawnError::Lnd {
                alias: from_alias.to_string(),
                source: Box::new(source),
            })?;
        let channel_point =
            channel_point_string(&channel_point).map_err(|source| SpawnError::Lnd {
                alias: from_alias.to_string(),
                source: Box::new(source),
            })?;

        from.daemon
            .wait_for_pending_channel(&to.daemon.public_key, &channel_point)
            .await
            .map_err(|source| SpawnError::Lnd {
                alias: from_alias.to_string(),
                source: Box::new(source),
            })?;

        let confirmation_blocks = bitcoind
            .rpc
            .generate_to_address(
                DEFAULT_CHANNEL_CONFIRMATION_BLOCKS,
                DEFAULT_GENERATE_ADDRESS,
            )
            .await
            .map_err(|source| SpawnError::BitcoinRpc {
                group_index: from.chain_group_index,
                source: Box::new(source),
            })?;

        wait_bitcoind_groups_synced(&self.bitcoinds, &self.config.startup_retry).await?;
        wait_lnd_nodes_synced(&self.nodes, &self.node_order, &self.config.startup_retry).await?;

        let from_channel = from
            .daemon
            .wait_for_active_channel(&to.daemon.public_key, &channel_point)
            .await
            .map_err(|source| SpawnError::Lnd {
                alias: from_alias.to_string(),
                source: Box::new(source),
            })?;
        let to_channel = to
            .daemon
            .wait_for_active_channel(&from.daemon.public_key, &channel_point)
            .await
            .map_err(|source| SpawnError::Lnd {
                alias: to_alias.to_string(),
                source: Box::new(source),
            })?;

        Ok(ChannelReport {
            from_alias: from_alias.to_string(),
            to_alias: to_alias.to_string(),
            channel_point,
            local_funding_amount_sat,
            confirmation_blocks,
            from_channel,
            to_channel,
        })
    }

    /// Stop an LND container without removing it.
    pub async fn stop_lnd(&self, alias: &str) -> Result<(), SpawnError> {
        let node = self.require_node(alias)?;
        node.daemon
            .stop(&self.docker)
            .await
            .map_err(|source| SpawnError::Lnd {
                alias: alias.to_string(),
                source: Box::new(source),
            })
    }

    /// Start an existing LND container and wait until it is synced to chain.
    pub async fn start_lnd(&mut self, alias: &str) -> Result<(), SpawnError> {
        let docker = self.docker.clone();
        let policy = self.config.startup_retry;
        let node = self.require_node_mut(alias)?;
        node.daemon
            .start(&docker, &policy)
            .await
            .map_err(|source| SpawnError::Lnd {
                alias: alias.to_string(),
                source: Box::new(source),
            })?;
        Ok(())
    }

    /// Restart an LND container and wait until it is synced to chain.
    pub async fn restart_lnd(&mut self, alias: &str) -> Result<(), SpawnError> {
        let docker = self.docker.clone();
        let policy = self.config.startup_retry;
        let node = self.require_node_mut(alias)?;
        node.daemon
            .restart(&docker, &policy)
            .await
            .map_err(|source| SpawnError::Lnd {
                alias: alias.to_string(),
                source: Box::new(source),
            })?;
        Ok(())
    }

    /// Stop a Bitcoin Core chain group container without removing it.
    pub async fn stop_bitcoind(&self, group_index: usize) -> Result<(), SpawnError> {
        let bitcoind = self.require_bitcoind(group_index)?;
        bitcoind
            .stop(&self.docker)
            .await
            .map_err(|source| SpawnError::BitcoinCore {
                group_index,
                source: Box::new(source),
            })
    }

    /// Start an existing Bitcoin Core chain group and wait for dependent nodes.
    pub async fn start_bitcoind(&mut self, group_index: usize) -> Result<(), SpawnError> {
        self.start_bitcoind_inner(group_index, false).await
    }

    /// Restart a Bitcoin Core chain group and wait for dependent nodes.
    pub async fn restart_bitcoind(&mut self, group_index: usize) -> Result<(), SpawnError> {
        self.start_bitcoind_inner(group_index, true).await
    }

    /// Stop and remove all containers in this cluster unless `keep_containers` is set.
    pub async fn shutdown(&mut self) -> Result<CleanupReport, SpawnError> {
        if self.shutdown || self.config.keep_containers {
            self.shutdown = true;
            return Ok(empty_cleanup_report());
        }

        let report = self.docker.cleanup_cluster(&self.cluster_id).await?;
        self.shutdown = true;
        Ok(report)
    }

    async fn start_bitcoind_inner(
        &mut self,
        group_index: usize,
        restart: bool,
    ) -> Result<(), SpawnError> {
        self.require_bitcoind(group_index)?;

        let docker = self.docker.clone();
        let policy = self.config.startup_retry;
        let bitcoind = self
            .bitcoinds
            .get_mut(group_index)
            .expect("validated bitcoind group");

        let result = if restart {
            bitcoind.restart(&docker, &policy).await
        } else {
            bitcoind.start(&docker, &policy).await
        };
        result.map_err(|source| SpawnError::BitcoinCore {
            group_index,
            source: Box::new(source),
        })?;

        connect_bitcoind_groups(&self.bitcoinds).await?;
        wait_bitcoind_groups_synced(&self.bitcoinds, &self.config.startup_retry).await?;
        wait_lnd_nodes_in_group_synced(
            &self.nodes,
            &self.node_order,
            group_index,
            &self.config.startup_retry,
        )
        .await?;

        Ok(())
    }

    fn require_node(&self, alias: &str) -> Result<&SpawnedNode, SpawnError> {
        self.nodes
            .get(alias)
            .ok_or_else(|| SpawnError::UnknownNode {
                alias: alias.to_string(),
            })
    }

    fn require_node_mut(&mut self, alias: &str) -> Result<&mut SpawnedNode, SpawnError> {
        self.nodes
            .get_mut(alias)
            .ok_or_else(|| SpawnError::UnknownNode {
                alias: alias.to_string(),
            })
    }

    fn require_bitcoind(&self, group_index: usize) -> Result<&BitcoinCore, SpawnError> {
        self.bitcoinds
            .get(group_index)
            .ok_or(SpawnError::UnknownBitcoindGroup { group_index })
    }
}

impl From<DockerError> for SpawnError {
    fn from(source: DockerError) -> Self {
        Self::Docker(Box::new(source))
    }
}

impl Drop for SpawnedCluster {
    fn drop(&mut self) {
        if !self.shutdown && !self.config.keep_containers {
            eprintln!(
                "spawn-lnd cluster {} dropped without shutdown(); call shutdown().await to remove managed containers",
                self.cluster_id
            );
        }
    }
}

/// A spawned LND node and its placement in the cluster.
#[derive(Clone, Debug)]
pub struct SpawnedNode {
    alias: String,
    node_index: usize,
    chain_group_index: usize,
    daemon: LndDaemon,
}

impl SpawnedNode {
    fn new(node_index: usize, chain_group_index: usize, daemon: LndDaemon) -> Self {
        Self {
            alias: daemon.alias.clone(),
            node_index,
            chain_group_index,
            daemon,
        }
    }

    /// Return the node alias.
    pub fn alias(&self) -> &str {
        &self.alias
    }

    /// Return the zero-based node index in spawn order.
    pub fn node_index(&self) -> usize {
        self.node_index
    }

    /// Return the Bitcoin Core chain group index backing this node.
    pub fn chain_group_index(&self) -> usize {
        self.chain_group_index
    }

    /// Return the underlying LND daemon handle.
    pub fn lnd(&self) -> &LndDaemon {
        &self.daemon
    }

    /// Build an `lnd_grpc_rust` node connection config for this node.
    pub fn node_config(&self) -> LndNodeConfig {
        self.daemon.node_config()
    }

    /// Return the LND identity public key.
    pub fn public_key(&self) -> &str {
        &self.daemon.public_key
    }
}

/// Result of connecting one LND node to another.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct PeerConnection {
    /// Source node alias.
    pub from_alias: String,
    /// Destination node alias.
    pub to_alias: String,
    /// Destination node identity public key.
    pub public_key: String,
    /// Destination P2P socket used for the connection.
    pub socket: String,
    /// LND connection status string.
    pub status: String,
}

/// Result of funding an LND wallet.
#[derive(Clone, Debug, PartialEq)]
pub struct FundingReport {
    /// Funded node alias.
    pub alias: String,
    /// On-chain address generated by the funded node.
    pub address: String,
    /// Funding transaction id.
    pub txid: String,
    /// Funding amount in BTC.
    pub amount_btc: f64,
    /// Block hashes mined to confirm the funding transaction.
    pub confirmation_blocks: Vec<String>,
    /// Confirmed LND wallet balance after funding.
    pub confirmed_balance_sat: i64,
    /// Spendable UTXO count after funding.
    pub spendable_utxo_count: usize,
    /// Total spendable UTXO value after funding.
    pub spendable_utxo_total_sat: i64,
}

#[derive(Clone, Debug, Eq, PartialEq)]
struct FundingRecipient {
    alias: String,
    address: String,
    required_balance_sat: i64,
    required_utxo_total_sat: i64,
}

/// Result of opening and confirming a public Lightning channel.
#[derive(Clone, Debug, PartialEq)]
pub struct ChannelReport {
    /// Channel opener alias.
    pub from_alias: String,
    /// Remote node alias.
    pub to_alias: String,
    /// Channel point in `funding_txid:output_index` form.
    pub channel_point: String,
    /// Local funding amount in satoshis.
    pub local_funding_amount_sat: i64,
    /// Block hashes mined to confirm the funding transaction.
    pub confirmation_blocks: Vec<String>,
    /// Channel as reported by the opener.
    pub from_channel: Channel,
    /// Channel as reported by the remote node.
    pub to_channel: Channel,
}

/// Error returned by cluster lifecycle and orchestration operations.
#[derive(Debug, Error)]
pub enum SpawnError {
    /// Invalid cluster configuration.
    #[error(transparent)]
    Config(#[from] ConfigError),

    /// Docker operation failed.
    #[error(transparent)]
    Docker(#[from] Box<DockerError>),

    /// Failed to spawn a Bitcoin Core chain group.
    #[error("failed to spawn Bitcoin Core chain group {group_index}")]
    BitcoinCore {
        /// Chain group index.
        group_index: usize,
        /// Underlying Bitcoin Core error.
        source: Box<BitcoinCoreError>,
    },

    /// Failed to connect two Bitcoin Core chain groups.
    #[error("failed to connect Bitcoin Core chain group {from_group} to group {to_group}")]
    BitcoinPeer {
        /// Source chain group index.
        from_group: usize,
        /// Destination chain group index.
        to_group: usize,
        /// Underlying Bitcoin RPC error.
        source: Box<BitcoinRpcError>,
    },

    /// Bitcoin Core RPC failed for a chain group.
    #[error("Bitcoin Core RPC failed for chain group {group_index}")]
    BitcoinRpc {
        /// Chain group index.
        group_index: usize,
        /// Underlying Bitcoin RPC error.
        source: Box<BitcoinRpcError>,
    },

    /// Bitcoin Core chain groups did not converge on a common tip.
    #[error(
        "Bitcoin Core chain groups did not sync to a common tip after {attempts} attempts; last tips: {last_tips:?}"
    )]
    BitcoinSyncTimeout {
        /// Number of sync attempts.
        attempts: usize,
        /// Last observed best block hashes.
        last_tips: Vec<String>,
    },

    /// A Bitcoin Core container had no Docker bridge IP.
    #[error("Bitcoin Core chain group {group_index} did not expose a bridge IP address")]
    MissingBitcoindIp {
        /// Chain group index.
        group_index: usize,
    },

    /// A requested LND node alias does not exist.
    #[error("unknown LND node alias: {alias}")]
    UnknownNode {
        /// Missing alias.
        alias: String,
    },

    /// A requested Bitcoin Core chain group does not exist.
    #[error("unknown Bitcoin Core chain group: {group_index}")]
    UnknownBitcoindGroup {
        /// Missing chain group index.
        group_index: usize,
    },

    /// A funding amount was not positive and finite.
    #[error("funding amount must be positive and finite, got {amount_btc} BTC")]
    InvalidFundingAmount {
        /// Invalid amount in BTC.
        amount_btc: f64,
    },

    /// An LND container had no Docker bridge IP.
    #[error("LND node {alias} did not expose a bridge IP address")]
    MissingLndIp {
        /// Node alias.
        alias: String,
    },

    /// LND operation failed.
    #[error("failed to spawn LND node {alias}")]
    Lnd {
        /// Node alias.
        alias: String,
        /// Underlying LND error.
        source: Box<LndError>,
    },

    /// Connecting to all LND nodes failed.
    #[error(transparent)]
    ConnectNodes(#[from] LndConnectError),

    /// The managed Docker network did not report a usable IPv4 subnet.
    #[error("cluster network subnet {subnet} is not usable for static IP assignment: {message}")]
    InvalidClusterNetworkSubnet {
        /// Docker network subnet.
        subnet: String,
        /// Validation failure.
        message: String,
    },

    /// The managed Docker network subnet was too small for this cluster.
    #[error(
        "cluster network subnet {subnet} cannot assign static IP offset {offset}; largest usable offset is {largest_usable_offset}"
    )]
    StaticIpUnavailable {
        /// Docker network subnet.
        subnet: String,
        /// Requested host offset.
        offset: u32,
        /// Largest usable host offset in the subnet.
        largest_usable_offset: u32,
    },

    /// Startup failed and the attempted cleanup also failed.
    #[error(
        "startup failed for cluster {cluster_id}, then cleanup failed; startup error: {startup_error}"
    )]
    StartupCleanup {
        /// Cluster id.
        cluster_id: String,
        /// Original startup error as text.
        startup_error: String,
        /// Cleanup failure.
        source: Box<DockerError>,
    },
}

async fn spawn_inner(
    docker: DockerClient,
    config: SpawnLndConfig,
    cluster_id: String,
) -> Result<SpawnedCluster, SpawnError> {
    let network = create_cluster_network(&docker, &config, &cluster_id).await?;
    let subnet = Ipv4Subnet::parse(&network.subnet).map_err(|message| {
        SpawnError::InvalidClusterNetworkSubnet {
            subnet: network.subnet.clone(),
            message,
        }
    })?;

    ensure_static_ip_capacity(&config, &subnet)?;

    let bitcoinds = spawn_bitcoinds(&docker, &config, &cluster_id, &network, &subnet).await?;
    connect_bitcoind_groups(&bitcoinds).await?;
    prepare_primary_wallet(&bitcoinds).await?;
    wait_bitcoind_groups_synced(&bitcoinds, &config.startup_retry).await?;
    let (nodes, node_order) =
        spawn_lnd_nodes(&docker, &config, &cluster_id, &network, &subnet, &bitcoinds).await?;
    wait_bitcoind_groups_synced(&bitcoinds, &config.startup_retry).await?;
    wait_lnd_nodes_synced(&nodes, &node_order, &config.startup_retry).await?;

    Ok(SpawnedCluster {
        docker,
        config,
        cluster_id,
        network,
        bitcoinds,
        nodes,
        node_order,
        shutdown: false,
    })
}

async fn create_cluster_network(
    docker: &DockerClient,
    config: &SpawnLndConfig,
    cluster_id: &str,
) -> Result<ManagedNetwork, SpawnError> {
    if let Some(subnet) = &config.cluster_subnet {
        let spec = NetworkSpec::new(cluster_id).subnet(subnet.clone());
        return docker.create_network(spec).await.map_err(SpawnError::from);
    }

    let mut last_overlap = None;
    for attempt in 0..GENERATED_SUBNET_ATTEMPTS {
        let subnet = generated_cluster_subnet(cluster_id, attempt);
        let spec = NetworkSpec::new(cluster_id).subnet(subnet);

        match docker.create_network(spec).await {
            Ok(network) => return Ok(network),
            Err(error) if error.is_network_pool_overlap() => {
                last_overlap = Some(error);
            }
            Err(error) => return Err(SpawnError::from(error)),
        }
    }

    Err(SpawnError::from(
        last_overlap.expect("at least one generated subnet attempt"),
    ))
}

async fn spawn_bitcoinds(
    docker: &DockerClient,
    config: &SpawnLndConfig,
    cluster_id: &str,
    network: &ManagedNetwork,
    subnet: &Ipv4Subnet,
) -> Result<Vec<BitcoinCore>, SpawnError> {
    let mut bitcoinds = Vec::with_capacity(config.chain_group_count());

    for group_index in 0..config.chain_group_count() {
        let bitcoind = BitcoinCore::spawn(
            docker,
            BitcoinCoreConfig::new(cluster_id, group_index)
                .image(config.bitcoind_image.clone())
                .startup_retry_policy(config.startup_retry)
                .network(network.name.clone())
                .ipv4_address(static_bitcoind_ip(subnet, group_index)?),
        )
        .await
        .map_err(|source| SpawnError::BitcoinCore {
            group_index,
            source: Box::new(source),
        })?;
        bitcoinds.push(bitcoind);
    }

    Ok(bitcoinds)
}

async fn connect_bitcoind_groups(bitcoinds: &[BitcoinCore]) -> Result<(), SpawnError> {
    for (from_group, from) in bitcoinds.iter().enumerate() {
        for (to_group, to) in bitcoinds.iter().enumerate() {
            if from_group == to_group {
                continue;
            }

            let socket = bitcoind_bridge_socket(to_group, to)?;
            from.rpc
                .add_node(&socket)
                .await
                .map_err(|source| SpawnError::BitcoinPeer {
                    from_group,
                    to_group,
                    source: Box::new(source),
                })?;
        }
    }

    Ok(())
}

async fn prepare_primary_wallet(bitcoinds: &[BitcoinCore]) -> Result<(), SpawnError> {
    bitcoinds[0]
        .prepare_mining_wallet()
        .await
        .map_err(|source| SpawnError::BitcoinCore {
            group_index: 0,
            source: Box::new(source),
        })?;

    Ok(())
}

async fn wait_bitcoind_groups_synced(
    bitcoinds: &[BitcoinCore],
    policy: &RetryPolicy,
) -> Result<(), SpawnError> {
    if bitcoinds.len() <= 1 {
        return Ok(());
    }

    let mut last_tips = Vec::new();

    for _ in 0..policy.attempts {
        let mut tips = Vec::with_capacity(bitcoinds.len());

        for (group_index, bitcoind) in bitcoinds.iter().enumerate() {
            let info = bitcoind.rpc.get_blockchain_info().await.map_err(|source| {
                SpawnError::BitcoinRpc {
                    group_index,
                    source: Box::new(source),
                }
            })?;
            tips.push((info.blocks, info.bestblockhash));
        }

        last_tips = tips
            .iter()
            .map(|(height, hash)| format!("{height}:{hash}"))
            .collect();

        if let Some((target_height, target_hash)) = tips.iter().max_by_key(|(height, _)| *height)
            && tips
                .iter()
                .all(|(height, hash)| height == target_height && hash == target_hash)
        {
            return Ok(());
        }

        sleep(policy.interval()).await;
    }

    Err(SpawnError::BitcoinSyncTimeout {
        attempts: policy.attempts,
        last_tips,
    })
}

async fn spawn_lnd_nodes(
    docker: &DockerClient,
    config: &SpawnLndConfig,
    cluster_id: &str,
    network: &ManagedNetwork,
    subnet: &Ipv4Subnet,
    bitcoinds: &[BitcoinCore],
) -> Result<(HashMap<String, SpawnedNode>, Vec<String>), SpawnError> {
    let mut nodes = HashMap::with_capacity(config.nodes.len());
    let mut node_order = Vec::with_capacity(config.nodes.len());

    for (node_index, node_config) in config.nodes.iter().enumerate() {
        let chain_group_index = chain_group_index(node_index, config.nodes_per_bitcoind);
        let bitcoind = &bitcoinds[chain_group_index];
        let lnd_config = lnd_config(cluster_id, node_index, node_config, config, network, subnet)?;
        let daemon = LndDaemon::spawn_with_startup_cleanup(
            docker,
            bitcoind,
            lnd_config,
            !config.keep_containers,
        )
        .await
        .map_err(|source| SpawnError::Lnd {
            alias: node_config.alias.clone(),
            source: Box::new(source),
        })?;
        wait_bitcoind_groups_synced(bitcoinds, &config.startup_retry).await?;
        let node = SpawnedNode::new(node_index, chain_group_index, daemon);

        node_order.push(node.alias.clone());
        nodes.insert(node.alias.clone(), node);
    }

    Ok((nodes, node_order))
}

async fn wait_lnd_nodes_synced(
    nodes: &HashMap<String, SpawnedNode>,
    node_order: &[String],
    policy: &RetryPolicy,
) -> Result<(), SpawnError> {
    for alias in node_order {
        let node = &nodes[alias];
        node.daemon
            .wait_synced_to_chain_with_policy(policy)
            .await
            .map_err(|source| SpawnError::Lnd {
                alias: alias.clone(),
                source: Box::new(source),
            })?;
    }

    Ok(())
}

async fn wait_lnd_nodes_in_group_synced(
    nodes: &HashMap<String, SpawnedNode>,
    node_order: &[String],
    group_index: usize,
    policy: &RetryPolicy,
) -> Result<(), SpawnError> {
    for alias in node_order {
        let node = &nodes[alias];
        if node.chain_group_index != group_index {
            continue;
        }

        node.daemon
            .wait_synced_to_chain_with_policy(policy)
            .await
            .map_err(|source| SpawnError::Lnd {
                alias: alias.clone(),
                source: Box::new(source),
            })?;
    }

    Ok(())
}

fn lnd_config(
    cluster_id: &str,
    node_index: usize,
    node_config: &NodeConfig,
    config: &SpawnLndConfig,
    network: &ManagedNetwork,
    subnet: &Ipv4Subnet,
) -> Result<LndConfig, SpawnError> {
    Ok(
        LndConfig::new(cluster_id, node_config.alias.clone(), node_index)
            .image(config.lnd_image.clone())
            .extra_args(node_config.lnd_args.clone())
            .startup_retry_policy(config.startup_retry)
            .network(network.name.clone())
            .ipv4_address(static_lnd_ip(
                subnet,
                config.chain_group_count(),
                node_index,
            )?),
    )
}

fn chain_group_index(node_index: usize, nodes_per_bitcoind: usize) -> usize {
    node_index / nodes_per_bitcoind
}

fn btc_to_sat(amount_btc: f64) -> Result<i64, SpawnError> {
    if !amount_btc.is_finite() || amount_btc <= 0.0 {
        return Err(SpawnError::InvalidFundingAmount { amount_btc });
    }

    let amount_sat = (amount_btc * SATOSHIS_PER_BTC).round();
    if amount_sat < 1.0 || amount_sat > i64::MAX as f64 {
        return Err(SpawnError::InvalidFundingAmount { amount_btc });
    }

    Ok(amount_sat as i64)
}

#[derive(Clone, Debug, Eq, PartialEq)]
struct Ipv4Subnet {
    cidr: String,
    network: u32,
    prefix: u8,
}

impl Ipv4Subnet {
    fn parse(cidr: &str) -> Result<Self, String> {
        let (address, prefix) = cidr
            .split_once('/')
            .ok_or_else(|| "missing CIDR prefix".to_string())?;
        let address = address
            .parse::<Ipv4Addr>()
            .map_err(|error| format!("invalid IPv4 address: {error}"))?;
        let prefix = prefix
            .parse::<u8>()
            .map_err(|error| format!("invalid prefix length: {error}"))?;
        if prefix > 30 {
            return Err("prefix must be 30 or less".to_string());
        }

        let mask = ipv4_mask(prefix);
        Ok(Self {
            cidr: cidr.to_string(),
            network: u32::from(address) & mask,
            prefix,
        })
    }

    fn static_ip(&self, offset: u32) -> Result<String, SpawnError> {
        let largest_usable_offset = self.largest_usable_offset();
        if offset < 2 || offset > largest_usable_offset {
            return Err(SpawnError::StaticIpUnavailable {
                subnet: self.cidr.clone(),
                offset,
                largest_usable_offset,
            });
        }

        Ok(Ipv4Addr::from(self.network + offset).to_string())
    }

    fn largest_usable_offset(&self) -> u32 {
        let size = 1u64 << (32 - self.prefix);
        size.saturating_sub(2).min(u32::MAX as u64) as u32
    }
}

fn ipv4_mask(prefix: u8) -> u32 {
    if prefix == 0 {
        0
    } else {
        u32::MAX << (32 - prefix)
    }
}

fn ensure_static_ip_capacity(
    config: &SpawnLndConfig,
    subnet: &Ipv4Subnet,
) -> Result<(), SpawnError> {
    let required_offset = first_static_ip_offset()
        .checked_add(config.chain_group_count() as u32)
        .and_then(|offset| offset.checked_add(config.nodes.len() as u32))
        .and_then(|offset| offset.checked_sub(1))
        .ok_or_else(|| SpawnError::StaticIpUnavailable {
            subnet: subnet.cidr.clone(),
            offset: u32::MAX,
            largest_usable_offset: subnet.largest_usable_offset(),
        })?;

    subnet.static_ip(required_offset).map(|_| ())
}

fn static_bitcoind_ip(subnet: &Ipv4Subnet, group_index: usize) -> Result<String, SpawnError> {
    let offset = first_static_ip_offset()
        .checked_add(group_index as u32)
        .ok_or_else(|| SpawnError::StaticIpUnavailable {
            subnet: subnet.cidr.clone(),
            offset: u32::MAX,
            largest_usable_offset: subnet.largest_usable_offset(),
        })?;
    subnet.static_ip(offset)
}

fn static_lnd_ip(
    subnet: &Ipv4Subnet,
    chain_group_count: usize,
    node_index: usize,
) -> Result<String, SpawnError> {
    let offset = first_static_ip_offset()
        .checked_add(chain_group_count as u32)
        .and_then(|offset| offset.checked_add(node_index as u32))
        .ok_or_else(|| SpawnError::StaticIpUnavailable {
            subnet: subnet.cidr.clone(),
            offset: u32::MAX,
            largest_usable_offset: subnet.largest_usable_offset(),
        })?;
    subnet.static_ip(offset)
}

fn first_static_ip_offset() -> u32 {
    10
}

fn generated_cluster_subnet(cluster_id: &str, attempt: u32) -> String {
    let slot = fnv1a_u32(cluster_id, attempt) % (64 * 16);
    let second_octet = 64 + slot / 16;
    let third_octet = (slot % 16) * 16;

    format!("10.{second_octet}.{third_octet}.0/20")
}

fn fnv1a_u32(input: &str, attempt: u32) -> u32 {
    let mut hash = 0x811c9dc5u32;
    for byte in input
        .as_bytes()
        .iter()
        .copied()
        .chain(attempt.to_le_bytes())
    {
        hash ^= byte as u32;
        hash = hash.wrapping_mul(0x01000193);
    }

    hash
}

fn bitcoind_bridge_socket(
    group_index: usize,
    bitcoind: &BitcoinCore,
) -> Result<String, SpawnError> {
    let ip = bitcoind
        .container
        .ip_address
        .as_deref()
        .ok_or(SpawnError::MissingBitcoindIp { group_index })?;

    Ok(format!("{ip}:{BITCOIND_P2P_PORT}"))
}

fn lnd_bridge_socket(node: &SpawnedNode) -> Result<String, SpawnError> {
    let ip =
        node.daemon
            .container
            .ip_address
            .as_deref()
            .ok_or_else(|| SpawnError::MissingLndIp {
                alias: node.alias.clone(),
            })?;

    Ok(format!("{ip}:{LND_P2P_PORT}"))
}

fn already_connected_response(
    error: LndError,
    public_key: &str,
) -> Result<ConnectPeerResponse, LndError> {
    match error {
        LndError::Rpc { message, .. } if message.contains("already connected") => {
            Ok(ConnectPeerResponse {
                status: format!("already connected to {public_key}"),
            })
        }
        error => Err(error),
    }
}

fn new_cluster_id() -> String {
    format!("cluster-{}", Uuid::new_v4().simple())
}

fn empty_cleanup_report() -> CleanupReport {
    CleanupReport {
        matched: 0,
        removed: 0,
        failures: Vec::new(),
    }
}

#[cfg(test)]
mod tests {
    use super::{
        Ipv4Subnet, SpawnedCluster, already_connected_response, btc_to_sat, chain_group_index,
        empty_cleanup_report, generated_cluster_subnet, lnd_config, static_bitcoind_ip,
        static_lnd_ip,
    };
    use crate::{DockerClient, LndError, ManagedNetwork};
    use crate::{NodeConfig, RetryPolicy, SpawnLndConfig};

    #[test]
    fn assigns_nodes_to_chain_groups() {
        let groups = (0..8)
            .map(|node_index| chain_group_index(node_index, 3))
            .collect::<Vec<_>>();

        assert_eq!(groups, [0, 0, 0, 1, 1, 1, 2, 2]);
    }

    #[test]
    fn builds_lnd_config_from_node_config() {
        let node = NodeConfig::new("alice").with_lnd_args(["--alias=Alice", "--color=#3399ff"]);
        let spawn_config = SpawnLndConfig {
            nodes: vec![node.clone()],
            bitcoind_image: "custom/bitcoin:30".to_string(),
            lnd_image: "custom/lnd:v1".to_string(),
            nodes_per_bitcoind: 3,
            keep_containers: false,
            startup_retry: RetryPolicy::new(12, 250),
            cluster_subnet: None,
        };
        let network = ManagedNetwork {
            id: "network-id".to_string(),
            name: "spawn-lnd-cluster-1".to_string(),
            subnet: "172.28.0.0/16".to_string(),
        };
        let subnet = Ipv4Subnet::parse(&network.subnet).expect("valid subnet");
        let config =
            lnd_config("cluster-1", 2, &node, &spawn_config, &network, &subnet).expect("config");

        assert_eq!(config.cluster_id, "cluster-1");
        assert_eq!(config.alias, "alice");
        assert_eq!(config.node_index, 2);
        assert_eq!(config.image, "custom/lnd:v1");
        assert_eq!(config.extra_args, ["--alias=Alice", "--color=#3399ff"]);
        assert_eq!(config.startup_retry, RetryPolicy::new(12, 250));
        assert_eq!(config.network.as_deref(), Some("spawn-lnd-cluster-1"));
        assert_eq!(config.ipv4_address.as_deref(), Some("172.28.0.13"));
    }

    #[test]
    fn assigns_static_ips_from_network_subnet() {
        let subnet = Ipv4Subnet::parse("172.28.0.0/16").expect("valid subnet");

        assert_eq!(static_bitcoind_ip(&subnet, 0).unwrap(), "172.28.0.10");
        assert_eq!(static_bitcoind_ip(&subnet, 1).unwrap(), "172.28.0.11");
        assert_eq!(static_lnd_ip(&subnet, 2, 0).unwrap(), "172.28.0.12");
        assert_eq!(static_lnd_ip(&subnet, 2, 1).unwrap(), "172.28.0.13");
    }

    #[test]
    fn generates_private_cluster_subnets_with_user_configured_prefixes() {
        let first = generated_cluster_subnet("cluster-1", 0);
        let second = generated_cluster_subnet("cluster-1", 1);

        assert_ne!(first, second);
        assert!(first.starts_with("10."));
        assert!(first.ends_with(".0/20"));
        assert!(Ipv4Subnet::parse(&first).is_ok());
    }

    #[test]
    fn validates_lifecycle_targets() {
        let docker = DockerClient::from_bollard(
            bollard::Docker::connect_with_http(
                "http://127.0.0.1:65535",
                1,
                bollard::API_DEFAULT_VERSION,
            )
            .expect("construct Docker client"),
        );
        let cluster = SpawnedCluster {
            docker,
            config: SpawnLndConfig {
                nodes: vec![NodeConfig::new("alice")],
                bitcoind_image: "custom/bitcoin:30".to_string(),
                lnd_image: "custom/lnd:v1".to_string(),
                nodes_per_bitcoind: 3,
                keep_containers: false,
                startup_retry: RetryPolicy::default(),
                cluster_subnet: None,
            },
            cluster_id: "cluster-1".to_string(),
            network: ManagedNetwork {
                id: "network-id".to_string(),
                name: "spawn-lnd-cluster-1".to_string(),
                subnet: "172.28.0.0/16".to_string(),
            },
            bitcoinds: Vec::new(),
            nodes: Default::default(),
            node_order: Vec::new(),
            shutdown: true,
        };

        assert!(matches!(
            cluster.require_node("alice"),
            Err(super::SpawnError::UnknownNode { alias }) if alias == "alice"
        ));
        assert!(matches!(
            cluster.require_bitcoind(0),
            Err(super::SpawnError::UnknownBitcoindGroup { group_index: 0 })
        ));
        assert_eq!(empty_cleanup_report().removed, 0);
    }

    #[test]
    fn treats_already_connected_peer_as_success() {
        let response = already_connected_response(
            LndError::Rpc {
                socket: "127.0.0.1:10009".to_string(),
                method: "ConnectPeer",
                message: "already connected to peer".to_string(),
            },
            "pubkey",
        )
        .expect("already connected is success");

        assert_eq!(response.status, "already connected to pubkey");
    }

    #[test]
    fn converts_btc_amount_to_sats() {
        assert_eq!(btc_to_sat(1.0).expect("sats"), 100_000_000);
        assert_eq!(btc_to_sat(0.000_000_01).expect("sats"), 1);
        assert!(btc_to_sat(0.0).is_err());
        assert!(btc_to_sat(f64::NAN).is_err());
    }
}