anya-core 1.2.0

//! Lightning Network implementation for Anya Core
//! 
//! This module provides Lightning Network functionality including channel management,
//! payment routing, and invoice handling.

use crate::bitcoin::error::BitcoinResult;
use bitcoin::{Amount, Network, PublicKey, PrivateKey};
use lightning::{
    ln::msgs::{ChannelAnnouncement, ChannelUpdate, NodeAnnouncement},
    routing::router::Router,
    util::logger::Logger,
};
use lightning_invoice::{Invoice, PaymentRequest};
use std::collections::HashMap;
use std::sync::Arc;
use tokio::sync::RwLock;

/// Lightning Network error types
#[derive(Debug, thiserror::Error)]
pub enum LightningError {
    #[error("Channel not found: {0}")]
    ChannelNotFound(String),
    #[error("Insufficient funds: {0}")]
    InsufficientFunds(String),
    #[error("Payment failed: {0}")]
    PaymentFailed(String),
    #[error("Invalid invoice: {0}")]
    InvalidInvoice(String),
    #[error("Network error: {0}")]
    NetworkError(String),
    #[error("Channel closed: {0}")]
    ChannelClosed(String),
}

/// Lightning Network result type
pub type LightningResult<T> = Result<T, LightningError>;

/// Lightning Network implementation
pub struct LightningNetwork {
    /// Network configuration
    network: Network,
    /// Channel manager
    channel_manager: Arc<ChannelManager>,
    /// Payment router
    router: Arc<Router>,
    /// Node announcements
    node_announcements: Arc<RwLock<HashMap<PublicKey, NodeAnnouncement>>>,
    /// Channel announcements
    channel_announcements: Arc<RwLock<HashMap<String, ChannelAnnouncement>>>,
    /// Payment requests
    payment_requests: Arc<RwLock<HashMap<String, PaymentRequest>>>,
}

/// Channel manager for Lightning Network
pub struct ChannelManager {
    /// Active channels
    channels: HashMap<String, Channel>,
    /// Channel capacity
    total_capacity: Amount,
    /// Available balance
    available_balance: Amount,
}

/// Lightning channel
#[derive(Debug, Clone)]
pub struct Channel {
    /// Channel ID
    pub channel_id: String,
    /// Remote node public key
    pub remote_pubkey: PublicKey,
    /// Channel capacity
    pub capacity: Amount,
    /// Local balance
    pub local_balance: Amount,
    /// Remote balance
    pub remote_balance: Amount,
    /// Channel state
    pub state: ChannelState,
    /// Channel flags
    pub flags: u16,
}

/// Channel state
#[derive(Debug, Clone, PartialEq)]
pub enum ChannelState {
    /// Channel is opening
    Opening,
    /// Channel is open
    Open,
    /// Channel is closing
    Closing,
    /// Channel is closed
    Closed,
    /// Channel is in dispute
    Disputed,
}

/// Payment result
#[derive(Debug, Clone)]
pub struct PaymentResult {
    /// Payment hash
    pub payment_hash: String,
    /// Payment amount
    pub amount_msat: u64,
    /// Payment status
    pub status: PaymentStatus,
    /// Fee paid
    pub fee_msat: u64,
    /// Route taken
    pub route: Vec<String>,
}

/// Payment status
#[derive(Debug, Clone, PartialEq)]
pub enum PaymentStatus {
    /// Payment is pending
    Pending,
    /// Payment is in flight
    InFlight,
    /// Payment succeeded
    Succeeded,
    /// Payment failed
    Failed,
}

impl LightningNetwork {
    /// Create a new Lightning Network instance
    pub fn new(network: Network) -> Self {
        Self {
            network,
            channel_manager: Arc::new(ChannelManager::new()),
            router: Arc::new(Router::new()),
            node_announcements: Arc::new(RwLock::new(HashMap::new())),
            channel_announcements: Arc::new(RwLock::new(HashMap::new())),
            payment_requests: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    /// Create a Lightning invoice
    pub async fn create_invoice(
        &self,
        amount_msat: u64,
        description: &str,
        expiry_seconds: Option<u64>,
    ) -> LightningResult<PaymentRequest> {
        // Create invoice with Lightning invoice library
        let invoice = Invoice::new(
            self.network,
            amount_msat,
            description.to_string(),
            expiry_seconds.unwrap_or(3600), // Default 1 hour
        )
        .map_err(|e| LightningError::InvalidInvoice(e.to_string()))?;

        let payment_request = PaymentRequest::from_invoice(invoice)
            .map_err(|e| LightningError::InvalidInvoice(e.to_string()))?;

        // Store payment request
        let payment_hash = payment_request.payment_hash().to_string();
        self.payment_requests.write().await.insert(payment_hash.clone(), payment_request.clone());

        Ok(payment_request)
    }

    /// Send a Lightning payment
    pub async fn send_payment(
        &self,
        payment_request: &str,
        max_fee_msat: Option<u64>,
    ) -> LightningResult<PaymentResult> {
        // Parse payment request
        let request = PaymentRequest::from_str(payment_request)
            .map_err(|e| LightningError::InvalidInvoice(e.to_string()))?;

        let amount_msat = request.amount_msat()
            .ok_or_else(|| LightningError::InvalidInvoice("No amount specified".to_string()))?;

        // Check if we have sufficient funds
        let available = self.channel_manager.get_available_balance().await;
        if available < amount_msat {
            return Err(LightningError::InsufficientFunds(
                format!("Required: {} msat, Available: {} msat", amount_msat, available)
            ));
        }

        // Find route to destination
        let route = self.find_route(&request).await?;

        // Calculate fee
        let fee_msat = self.calculate_fee(&route).await;

        // Check if fee is within limits
        if let Some(max_fee) = max_fee_msat {
            if fee_msat > max_fee {
                return Err(LightningError::PaymentFailed(
                    format!("Fee {} msat exceeds maximum {} msat", fee_msat, max_fee)
                ));
            }
        }

        // Send payment through channels
        let payment_hash = request.payment_hash().to_string();
        let result = self.send_payment_through_channels(&route, amount_msat, &payment_hash).await?;

        Ok(PaymentResult {
            payment_hash,
            amount_msat,
            status: PaymentStatus::Succeeded,
            fee_msat,
            route: route.iter().map(|node| node.to_string()).collect(),
        })
    }

    /// Get Lightning balance
    pub async fn get_balance(&self) -> LightningResult<u64> {
        Ok(self.channel_manager.get_available_balance().await)
    }

    /// Open a Lightning channel
    pub async fn open_channel(
        &self,
        remote_pubkey: &str,
        capacity_sat: u64,
        push_msat: Option<u64>,
    ) -> LightningResult<String> {
        let pubkey = PublicKey::from_str(remote_pubkey)
            .map_err(|e| LightningError::NetworkError(format!("Invalid public key: {}", e)))?;

        let capacity = Amount::from_sat(capacity_sat);
        let push_amount = push_msat.map(Amount::from_millisat);

        // Create channel
        let channel_id = self.channel_manager.create_channel(pubkey, capacity, push_amount).await?;

        Ok(channel_id)
    }

    /// Close a Lightning channel
    pub async fn close_channel(&self, channel_id: &str) -> LightningResult<()> {
        self.channel_manager.close_channel(channel_id).await?;
        Ok(())
    }

    /// Get channel information
    pub async fn get_channel(&self, channel_id: &str) -> LightningResult<Channel> {
        self.channel_manager.get_channel(channel_id).await
    }

    /// List all channels
    pub async fn list_channels(&self) -> LightningResult<Vec<Channel>> {
        Ok(self.channel_manager.list_channels().await)
    }

    /// Find route to destination
    async fn find_route(&self, request: &PaymentRequest) -> LightningResult<Vec<PublicKey>> {
        let destination = request.destination();
        
        // Get node announcements
        let announcements = self.node_announcements.read().await;
        
        // Simple routing algorithm (in production, use proper routing)
        let mut route = Vec::new();
        
        // Add intermediate nodes (simplified)
        if let Some(intermediate) = announcements.keys().next() {
            route.push(*intermediate);
        }
        
        route.push(destination);
        
        Ok(route)
    }

    /// Calculate fee for route
    async fn calculate_fee(&self, route: &[PublicKey]) -> u64 {
        // Simple fee calculation (in production, use proper fee estimation)
        let base_fee = 1000; // 1 sat base fee
        let fee_rate = 1; // 1 msat per hop
        
        base_fee + (route.len() as u64 * fee_rate)
    }

    /// Send payment through channels
    async fn send_payment_through_channels(
        &self,
        route: &[PublicKey],
        amount_msat: u64,
        payment_hash: &str,
    ) -> LightningResult<()> {
        // Simulate payment through channels
        // In production, this would use the Lightning protocol
        
        // Update channel balances
        self.channel_manager.update_channel_balances(amount_msat).await;
        
        Ok(())
    }
}

impl ChannelManager {
    /// Create a new channel manager
    pub fn new() -> Self {
        Self {
            channels: HashMap::new(),
            total_capacity: Amount::from_sat(0),
            available_balance: Amount::from_sat(0),
        }
    }

    /// Get available balance
    pub async fn get_available_balance(&self) -> u64 {
        self.available_balance.to_sat()
    }

    /// Create a new channel
    pub async fn create_channel(
        &mut self,
        remote_pubkey: PublicKey,
        capacity: Amount,
        push_amount: Option<Amount>,
    ) -> LightningResult<String> {
        let channel_id = format!("channel_{}", uuid::Uuid::new_v4());
        
        let local_balance = capacity - push_amount.unwrap_or(Amount::from_sat(0));
        let remote_balance = push_amount.unwrap_or(Amount::from_sat(0));
        
        let channel = Channel {
            channel_id: channel_id.clone(),
            remote_pubkey,
            capacity,
            local_balance,
            remote_balance,
            state: ChannelState::Opening,
            flags: 0,
        };
        
        self.channels.insert(channel_id.clone(), channel);
        self.total_capacity += capacity;
        self.available_balance += local_balance;
        
        Ok(channel_id)
    }

    /// Close a channel
    pub async fn close_channel(&mut self, channel_id: &str) -> LightningResult<()> {
        if let Some(channel) = self.channels.get_mut(channel_id) {
            channel.state = ChannelState::Closing;
            // In production, this would initiate channel closure
            Ok(())
        } else {
            Err(LightningError::ChannelNotFound(channel_id.to_string()))
        }
    }

    /// Get channel information
    pub async fn get_channel(&self, channel_id: &str) -> LightningResult<Channel> {
        self.channels.get(channel_id)
            .cloned()
            .ok_or_else(|| LightningError::ChannelNotFound(channel_id.to_string()))
    }

    /// List all channels
    pub async fn list_channels(&self) -> Vec<Channel> {
        self.channels.values().cloned().collect()
    }

    /// Update channel balances after payment
    pub async fn update_channel_balances(&mut self, amount_msat: u64) {
        // Simulate balance update
        // In production, this would update actual channel balances
        let amount = Amount::from_millisat(amount_msat);
        
        if self.available_balance >= amount {
            self.available_balance -= amount;
        }
    }
}

impl std::str::FromStr for PublicKey {
    type Err = lightning::ln::msgs::DecodeError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        // Parse public key from string
        // This is a simplified implementation
        let bytes = hex::decode(s)
            .map_err(|_| lightning::ln::msgs::DecodeError::InvalidValue)?;
        
        PublicKey::from_slice(&bytes)
            .map_err(|_| lightning::ln::msgs::DecodeError::InvalidValue)
    }
}

impl std::fmt::Display for PublicKey {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", hex::encode(self.serialize()))
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_create_invoice() {
        let lightning = LightningNetwork::new(Network::Testnet);
        
        let invoice = lightning.create_invoice(1000, "Test payment", None).await.unwrap();
        assert!(invoice.amount_msat().is_some());
        assert_eq!(invoice.amount_msat().unwrap(), 1000);
    }

    #[tokio::test]
    async fn test_open_channel() {
        let mut lightning = LightningNetwork::new(Network::Testnet);
        
        let remote_pubkey = "02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619";
        let channel_id = lightning.open_channel(remote_pubkey, 100000, None).await.unwrap();
        
        assert!(!channel_id.is_empty());
    }

    #[tokio::test]
    async fn test_get_balance() {
        let lightning = LightningNetwork::new(Network::Testnet);
        
        let balance = lightning.get_balance().await.unwrap();
        assert_eq!(balance, 0); // No channels initially
    }
}