//! Network service.

use std::collections::HashMap;
use std::net::SocketAddr;
use std::sync::Arc;
use std::time::Duration;

use libp2p::{Multiaddr, PeerId};
use tokio::sync::{broadcast, RwLock};
use tracing::{debug, error, info, warn};

use synor_network::{
    BlockAnnouncement, ChainId, NetworkConfig, NetworkEvent, NetworkHandle,
    NetworkService as SynorNetworkService, SyncStatus, TransactionAnnouncement,
};
use synor_types::{BlockHeader, BlockId};

use crate::config::NodeConfig;

/// Peer connection info.
#[derive(Clone, Debug)]
pub struct PeerInfo {
    /// Peer ID.
    pub id: String,
    /// Remote address.
    pub address: Option<SocketAddr>,
    /// Is inbound connection.
    pub inbound: bool,
    /// Protocol version.
    pub version: u32,
    /// User agent.
    pub user_agent: String,
    /// Last seen timestamp.
    pub last_seen: u64,
    /// Ping latency in ms.
    pub latency_ms: u32,
    /// Is syncing.
    pub syncing: bool,
}

/// Network message types.
#[derive(Clone, Debug)]
pub enum NetworkMessage {
    /// Block announcement.
    BlockAnnounce { hash: [u8; 32] },
    /// Transaction announcement.
    TxAnnounce { hash: [u8; 32] },
    /// Block request.
    GetBlocks { hashes: Vec<[u8; 32]> },
    /// Block response.
    Blocks { data: Vec<Vec<u8>> },
    /// Headers request.
    GetHeaders { locator: Vec<[u8; 32]>, stop: [u8; 32] },
    /// Headers response.
    Headers { headers: Vec<Vec<u8>> },
}

/// Network service manages P2P connections.
pub struct NetworkService {
    /// Network handle from synor-network (interior mutability for start()).
    handle: RwLock<Option<NetworkHandle>>,

    /// Configuration.
    listen_addr: String,

    /// Seed nodes.
    seeds: Vec<String>,

    /// Maximum inbound connections.
    #[allow(dead_code)]
    max_inbound: usize,

    /// Maximum outbound connections.
    #[allow(dead_code)]
    max_outbound: usize,

    /// Connected peers (cached locally).
    peers: RwLock<HashMap<String, PeerInfo>>,

    /// Is running.
    running: RwLock<bool>,

    /// Shutdown sender for the network task.
    #[allow(dead_code)]
    shutdown_tx: Option<broadcast::Sender<()>>,

    /// Shutdown receiver.
    #[allow(dead_code)]
    shutdown_rx: RwLock<Option<broadcast::Receiver<()>>>,

    /// Message broadcast channel.
    message_tx: broadcast::Sender<(String, NetworkMessage)>,

    /// Network configuration for synor-network.
    network_config: NetworkConfig,
}

impl NetworkService {
    /// Creates a new network service.
    pub async fn new(
        config: &NodeConfig,
        shutdown_rx: broadcast::Receiver<()>,
    ) -> anyhow::Result<Self> {
        let (message_tx, _) = broadcast::channel(1000);
        let (shutdown_tx, _) = broadcast::channel(1);

        // Build synor-network configuration from node config
        let chain_id = match config.network.as_str() {
            "mainnet" => ChainId::Mainnet,
            "testnet" => ChainId::Testnet,
            _ => ChainId::Devnet,
        };

        // Parse listen address
        let listen_addr_parsed: Multiaddr = config
            .p2p
            .listen_addr
            .parse()
            .unwrap_or_else(|_| format!("/ip4/0.0.0.0/tcp/{}", synor_network::DEFAULT_PORT).parse().unwrap());

        // Parse seed/bootstrap peers
        let bootstrap_peers: Vec<Multiaddr> = config
            .p2p
            .seeds
            .iter()
            .filter_map(|s| s.parse().ok())
            .collect();

        let network_config = NetworkConfig {
            chain_id,
            listen_addresses: vec![listen_addr_parsed],
            bootstrap_peers,
            max_inbound: config.p2p.max_inbound,
            max_outbound: config.p2p.max_outbound,
            enable_mdns: config.network == "devnet",
            enable_kad: config.network != "devnet",
            idle_timeout: Duration::from_secs(30),
            ping_interval: Duration::from_secs(15),
            gossipsub: synor_network::config::GossipsubConfig::default(),
            sync: synor_network::config::SyncConfig::default(),
            external_address: None,
            node_name: Some(format!("synord-{}", &config.network)),
        };

        Ok(NetworkService {
            handle: RwLock::new(None),
            listen_addr: config.p2p.listen_addr.clone(),
            seeds: config.p2p.seeds.clone(),
            max_inbound: config.p2p.max_inbound,
            max_outbound: config.p2p.max_outbound,
            peers: RwLock::new(HashMap::new()),
            running: RwLock::new(false),
            shutdown_tx: Some(shutdown_tx),
            shutdown_rx: RwLock::new(Some(shutdown_rx)),
            message_tx,
            network_config,
        })
    }

    /// Starts the network service.
    pub async fn start(&self) -> anyhow::Result<()> {
        info!(addr = %self.listen_addr, "Starting network service");

        // Create the synor-network service
        let (network_service, handle) = SynorNetworkService::new(self.network_config.clone())
            .await
            .map_err(|e| anyhow::anyhow!("Failed to create network service: {}", e))?;

        // Store the handle
        *self.handle.write().await = Some(handle.clone());

        // Subscribe to network events
        let mut event_rx = handle.subscribe();
        let message_tx = self.message_tx.clone();
        let peers = Arc::new(RwLock::new(HashMap::<String, PeerInfo>::new()));
        let peers_clone = peers.clone();

        // Spawn event handler
        tokio::spawn(async move {
            while let Ok(event) = event_rx.recv().await {
                match event {
                    NetworkEvent::NewBlock(announcement) => {
                        debug!("Received block announcement: {}", announcement.hash);
                        let msg = NetworkMessage::BlockAnnounce {
                            hash: *announcement.hash.as_bytes(),
                        };
                        let _ = message_tx.send(("network".to_string(), msg));
                    }
                    NetworkEvent::NewTransaction(announcement) => {
                        debug!("Received transaction announcement: {}", announcement.txid);
                        let msg = NetworkMessage::TxAnnounce {
                            hash: *announcement.txid.as_bytes(),
                        };
                        let _ = message_tx.send(("network".to_string(), msg));
                    }
                    NetworkEvent::PeerConnected(peer_id) => {
                        info!("Peer connected: {}", peer_id);
                        let info = PeerInfo {
                            id: peer_id.to_string(),
                            address: None,
                            inbound: false,
                            version: 1,
                            user_agent: String::new(),
                            last_seen: std::time::SystemTime::now()
                                .duration_since(std::time::UNIX_EPOCH)
                                .unwrap()
                                .as_secs(),
                            latency_ms: 0,
                            syncing: false,
                        };
                        peers_clone.write().await.insert(peer_id.to_string(), info);
                    }
                    NetworkEvent::PeerDisconnected(peer_id) => {
                        info!("Peer disconnected: {}", peer_id);
                        peers_clone.write().await.remove(&peer_id.to_string());
                    }
                    NetworkEvent::SyncStatusChanged(status) => {
                        info!("Sync status changed: {:?}", status);
                    }
                    NetworkEvent::BlocksReceived(blocks) => {
                        debug!("Received {} blocks", blocks.len());
                    }
                    NetworkEvent::HeadersReceived(headers) => {
                        debug!("Received {} headers", headers.len());
                    }
                }
            }
        });

        // Spawn the network service runner
        tokio::spawn(async move {
            if let Err(e) = network_service.run().await {
                error!("Network service error: {}", e);
            }
        });

        *self.running.write().await = true;

        // Connect to seed nodes
        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            for seed in &self.seeds {
                if let Ok(addr) = seed.parse::<Multiaddr>() {
                    info!(seed = %seed, "Connecting to seed node");
                    if let Err(e) = handle.dial(addr).await {
                        warn!("Failed to connect to seed node {}: {}", seed, e);
                    }
                }
            }
        }

        info!("Network service started");
        Ok(())
    }

    /// Stops the network service.
    pub async fn stop(&self) -> anyhow::Result<()> {
        info!("Stopping network service");

        *self.running.write().await = false;

        // Shutdown the network service via handle
        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            if let Err(e) = handle.shutdown().await {
                warn!("Error during network shutdown: {}", e);
            }
        }

        // Clear peers
        self.peers.write().await.clear();

        info!("Network service stopped");
        Ok(())
    }

    /// Returns the number of connected peers.
    pub async fn peer_count(&self) -> usize {
        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            handle.peer_count().await.unwrap_or(0)
        } else {
            self.peers.read().await.len()
        }
    }

    /// Returns all peer info.
    pub async fn peers(&self) -> Vec<PeerInfo> {
        self.peers.read().await.values().cloned().collect()
    }

    /// Gets a specific peer.
    pub async fn get_peer(&self, id: &str) -> Option<PeerInfo> {
        self.peers.read().await.get(id).cloned()
    }

    /// Connects to a peer.
    pub async fn connect_peer(&self, address: &str) -> anyhow::Result<String> {
        info!(address = %address, "Connecting to peer");

        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            let addr: Multiaddr = address
                .parse()
                .map_err(|e| anyhow::anyhow!("Invalid address: {}", e))?;
            handle
                .dial(addr)
                .await
                .map_err(|e| anyhow::anyhow!("Failed to dial: {}", e))?;
            Ok(format!("dialing-{}", address))
        } else {
            Err(anyhow::anyhow!("Network service not started"))
        }
    }

    /// Disconnects a peer.
    pub async fn disconnect_peer(&self, id: &str) {
        info!(peer = %id, "Disconnecting peer");

        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            if let Ok(peer_id) = id.parse::<PeerId>() {
                if let Err(e) = handle.disconnect(peer_id).await {
                    warn!("Failed to disconnect peer {}: {}", id, e);
                }
            }
        }

        self.peers.write().await.remove(id);
    }

    /// Bans a peer.
    pub async fn ban_peer(&self, id: &str, reason: &str) {
        warn!(peer = %id, reason = %reason, "Banning peer");

        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            if let Ok(peer_id) = id.parse::<PeerId>() {
                if let Err(e) = handle.ban(peer_id).await {
                    warn!("Failed to ban peer {}: {}", id, e);
                }
            }
        }

        self.disconnect_peer(id).await;
    }

    /// Broadcasts a message to all peers.
    pub async fn broadcast(&self, message: NetworkMessage) {
        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            match message {
                NetworkMessage::BlockAnnounce { hash } => {
                    // Create a minimal BlockAnnouncement
                    // In practice, you'd get this from the actual block
                    let header = BlockHeader::default();
                    let announcement = BlockAnnouncement::new(header, 0, 0);
                    // Note: The hash from the message won't match the header hash
                    // This is a placeholder - real implementation should use actual block data
                    let _ = hash; // Suppress unused warning
                    if let Err(e) = handle.broadcast_block(announcement).await {
                        warn!("Failed to broadcast block: {}", e);
                    }
                }
                NetworkMessage::TxAnnounce { hash } => {
                    let announcement = TransactionAnnouncement::id_only(
                        synor_types::TransactionId::from_bytes(hash)
                    );
                    if let Err(e) = handle.broadcast_transaction(announcement).await {
                        warn!("Failed to broadcast transaction: {}", e);
                    }
                }
                _ => {
                    debug!("Broadcast not implemented for this message type");
                }
            }
        }
    }

    /// Sends a message to a specific peer.
    pub async fn send(&self, peer_id: &str, _message: NetworkMessage) -> anyhow::Result<()> {
        debug!(peer = %peer_id, "Sending message");
        // For now, direct sends would be handled via request/response
        // This would need to be implemented based on the message type
        Ok(())
    }

    /// Subscribes to network messages.
    pub fn subscribe(&self) -> broadcast::Receiver<(String, NetworkMessage)> {
        self.message_tx.subscribe()
    }

    /// Returns the network handle for advanced operations.
    pub async fn handle(&self) -> Option<NetworkHandle> {
        self.handle.read().await.clone()
    }

    /// Announces a new block.
    pub async fn announce_block(&self, hash: [u8; 32]) {
        self.broadcast(NetworkMessage::BlockAnnounce { hash }).await;
    }

    /// Announces a new transaction.
    pub async fn announce_tx(&self, hash: [u8; 32]) {
        self.broadcast(NetworkMessage::TxAnnounce { hash }).await;
    }

    /// Requests blocks from a peer.
    pub async fn request_blocks(
        &self,
        peer_id: &str,
        hashes: Vec<[u8; 32]>,
    ) -> anyhow::Result<()> {
        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            let peer: PeerId = peer_id
                .parse()
                .map_err(|_| anyhow::anyhow!("Invalid peer ID"))?;
            let block_ids: Vec<BlockId> = hashes.iter().map(|h| BlockId::from_bytes(*h)).collect();
            handle
                .request_blocks(peer, block_ids)
                .await
                .map_err(|e| anyhow::anyhow!("Request failed: {}", e))?;
        }
        Ok(())
    }

    /// Requests headers from a peer.
    pub async fn request_headers(
        &self,
        peer_id: &str,
        locator: Vec<[u8; 32]>,
        _stop: [u8; 32],
    ) -> anyhow::Result<()> {
        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            let peer: PeerId = peer_id
                .parse()
                .map_err(|_| anyhow::anyhow!("Invalid peer ID"))?;
            let start = if locator.is_empty() {
                BlockId::from_bytes([0u8; 32])
            } else {
                BlockId::from_bytes(locator[0])
            };
            handle
                .request_headers(peer, start, 500)
                .await
                .map_err(|e| anyhow::anyhow!("Request failed: {}", e))?;
        }
        Ok(())
    }

    /// Gets the sync status.
    pub async fn sync_status(&self) -> Option<SyncStatus> {
        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            handle.sync_status().await.ok()
        } else {
            None
        }
    }

    /// Starts synchronization.
    pub async fn start_sync(&self) -> anyhow::Result<()> {
        let handle_guard = self.handle.read().await;
        if let Some(ref handle) = *handle_guard {
            handle
                .start_sync()
                .await
                .map_err(|e| anyhow::anyhow!("Failed to start sync: {}", e))?;
        }
        Ok(())
    }
}

/// Network statistics.
#[derive(Clone, Debug)]
pub struct NetworkStats {
    pub total_peers: usize,
    pub inbound_peers: usize,
    pub outbound_peers: usize,
    pub bytes_sent: u64,
    pub bytes_received: u64,
    pub messages_sent: u64,
    pub messages_received: u64,
}

impl NetworkService {
    /// Gets network statistics.
    pub async fn stats(&self) -> NetworkStats {
        let peers = self.peers.read().await;
        let inbound = peers.values().filter(|p| p.inbound).count();

        NetworkStats {
            total_peers: peers.len(),
            inbound_peers: inbound,
            outbound_peers: peers.len() - inbound,
            bytes_sent: 0,
            bytes_received: 0,
            messages_sent: 0,
            messages_received: 0,
        }
    }
}