use crate::network::{RoomState, NetError, PeerState, RoomEvent, PeerSpeakTicket};
use iroh::{Endpoint, EndpointId};
use iroh_gossip::net::Gossip;
use iroh_gossip::proto::TopicId;
use tokio::sync::mpsc;
use tokio::sync::mpsc::Receiver;
use std::sync::{Arc, Mutex};
use std::collections::HashMap;
use async_trait::async_trait;
use tokio_stream::StreamExt;
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct GossipPayload {
    pub author: EndpointId,
    pub msg: GossipMessage,
}

#[derive(Serialize, Deserialize, Clone, Debug)]
pub enum GossipMessage {
    Announce(PeerState),
    Leave,
    /// A room text-chat message: the author's display name, the text, and a
    /// sender-stamped millisecond timestamp.
    Chat { name: String, text: String, ts: u64 },
}

pub struct IrohGossipState {
    _endpoint: Endpoint,
    gossip: Gossip,
    address_lookup: iroh::address_lookup::memory::MemoryLookup,
    self_state: Arc<Mutex<Option<PeerState>>>,
    peers: Arc<Mutex<HashMap<EndpointId, PeerState>>>,
    event_tx: mpsc::Sender<RoomEvent>,
    event_rx: Mutex<Option<mpsc::Receiver<RoomEvent>>>,
    active_topic: Mutex<Option<tokio::task::JoinHandle<()>>>,
    active_topic_id: Mutex<Option<TopicId>>,
    active_sender: Mutex<Option<iroh_gossip::api::GossipSender>>,
}

impl IrohGossipState {
    pub fn new(
        endpoint: Endpoint,
        gossip: Gossip,
        address_lookup: iroh::address_lookup::memory::MemoryLookup,
    ) -> Self {
        let (event_tx, event_rx) = mpsc::channel(100);
        Self {
            _endpoint: endpoint,
            gossip,
            address_lookup,
            self_state: Arc::new(Mutex::new(None)),
            peers: Arc::new(Mutex::new(HashMap::new())),
            event_tx,
            event_rx: Mutex::new(Some(event_rx)),
            active_topic: Mutex::new(None),
            active_topic_id: Mutex::new(None),
            active_sender: Mutex::new(None),
        }
    }
}

#[async_trait]
impl RoomState for IrohGossipState {
    async fn join(&self, ticket_str: &str, self_state: PeerState) -> Result<(), NetError> {
        crate::log_msg(&format!("RoomState::join: self_id={:?}, self_name={:?}, ticket={}", self_state.addr.id, self_state.name, ticket_str));
        let ticket = ticket_str.parse::<PeerSpeakTicket>()?;
        let topic_id = TopicId::from_bytes(ticket.topic_id);

        crate::log_msg(&format!("Parsed ticket. host_id={:?}, host_addrs={:?}, topic={:?}", ticket.host_addr.id, ticket.host_addr.addrs, topic_id));

        // Stop any currently running topic
        let _ = self.leave().await;

        // Add the host to the address book
        self.address_lookup.add_endpoint_info(ticket.host_addr.clone());

        // Join the gossip topic. If we are the host, bootstrap list will be empty
        // or contain ourselves (which is fine), but let's bootstrap to the ticket host.
        let bootstrap_peers = if ticket.host_addr.id == self_state.addr.id {
            crate::log_msg("We are the host. Bootstrap peers list is empty.");
            vec![]
        } else {
            crate::log_msg(&format!("We are a client. Bootstrapping to host ID={:?}", ticket.host_addr.id));
            vec![ticket.host_addr.id]
        };

        let gossip_topic = self.gossip.subscribe(topic_id, bootstrap_peers).await
            .map_err(|e| {
                let err = format!("Failed to join gossip topic: {}", e);
                crate::log_msg(&err);
                NetError::Gossip(err)
            })?;

        let (gossip_sender, mut gossip_receiver) = gossip_topic.split();

        *self.self_state.lock().unwrap() = Some(self_state.clone());
        *self.active_topic_id.lock().unwrap() = Some(topic_id);
        *self.active_sender.lock().unwrap() = Some(gossip_sender.clone());

        let event_tx = self.event_tx.clone();
        let peers = self.peers.clone();
        let address_lookup = self.address_lookup.clone();
        let self_state_clone = self.self_state.clone();
        let gossip_sender_clone = gossip_sender.clone();
        let self_id = self_state.addr.id;

        let handle = tokio::spawn(async move {
            crate::log_msg(&format!("Spawned gossip topic loop for self_id={:?}", self_id));

            // Broadcast initial state
            let initial_payload = {
                let guard = self_state_clone.lock().unwrap();
                guard.as_ref().map(|s| GossipPayload {
                    author: s.addr.id,
                    msg: GossipMessage::Announce(s.clone()),
                })
            };

            if let Some(payload) = initial_payload
                && let Ok(bytes) = serde_json::to_vec(&payload) {
                    crate::log_msg(&format!("Broadcasting initial state from self_id={:?}", self_id));
                    let _ = gossip_sender_clone.broadcast(bytes.into()).await;
                }

            // Stream topic messages
            while let Some(res) = gossip_receiver.next().await {
                match res {
                    Ok(iroh_gossip::api::Event::Received(msg)) => {
                        crate::log_msg(&format!("Gossip received Event::Received from delivery={:?}", msg.delivered_from));
                        match serde_json::from_slice::<GossipPayload>(&msg.content) {
                            Ok(payload) => {
                                let our_id = {
                                    self_state_clone.lock().unwrap()
                                        .as_ref()
                                        .map(|s| s.addr.id)
                                };
                                
                                if Some(payload.author) == our_id {
                                    crate::log_msg("Gossip Event::Received from ourselves; ignoring");
                                    continue;
                                }

                                crate::log_msg(&format!("Gossip Event::Received from author={:?}, payload={:?}", payload.author, payload.msg));

                                match payload.msg {
                                    GossipMessage::Announce(state) => {
                                        let (is_new, state_changed) = {
                                            let mut peer_map = peers.lock().unwrap();
                                            let is_new = !peer_map.contains_key(&payload.author);
                                            let state_changed = peer_map.get(&payload.author) != Some(&state);
                                            if is_new || state_changed {
                                                peer_map.insert(payload.author, state.clone());
                                            }
                                            (is_new, state_changed)
                                        };

                                        if is_new {
                                            crate::log_msg(&format!("Gossip new peer joined: {:?}, state: {:?}", payload.author, state));
                                            address_lookup.add_endpoint_info(state.addr.clone());
                                            let _ = event_tx.send(RoomEvent::PeerJoined(payload.author, state)).await;
                                        } else if state_changed {
                                            crate::log_msg(&format!("Gossip peer state updated: {:?}, state: {:?}", payload.author, state));
                                            let _ = event_tx.send(RoomEvent::PeerUpdated(payload.author, state)).await;
                                        }
                                    }
                                    GossipMessage::Leave => {
                                        crate::log_msg(&format!("Gossip peer leave request from author={:?}", payload.author));
                                        let removed = peers.lock().unwrap().remove(&payload.author).is_some();
                                        if removed {
                                            let _ = event_tx.send(RoomEvent::PeerLeft(payload.author)).await;
                                        }
                                    }
                                    GossipMessage::Chat { name, text, ts } => {
                                        crate::log_msg(&format!("Gossip chat from author={:?}", payload.author));
                                        let _ = event_tx.send(RoomEvent::ChatMessage {
                                            from: payload.author,
                                            name,
                                            text,
                                            ts,
                                        }).await;
                                    }
                                }
                            }
                            Err(e) => {
                                crate::log_msg(&format!("Gossip failed to deserialize payload: {:?}", e));
                            }
                        }
                    }
                    Ok(iroh_gossip::api::Event::NeighborUp(peer_id)) => {
                        crate::log_msg(&format!("Gossip event: NeighborUp={:?}", peer_id));
                        // Resend state on new neighbor connection to guarantee synchronization
                        let payload_opt = {
                            let guard = self_state_clone.lock().unwrap();
                            guard.as_ref().map(|state| GossipPayload {
                                author: state.addr.id,
                                msg: GossipMessage::Announce(state.clone()),
                            })
                        };
                        if let Some(payload) = payload_opt
                            && let Ok(bytes) = serde_json::to_vec(&payload) {
                                crate::log_msg(&format!("Broadcasting state to new neighbor={:?}", peer_id));
                                let _ = gossip_sender_clone.broadcast(bytes.into()).await;
                            }
                    }
                    Ok(iroh_gossip::api::Event::NeighborDown(peer_id)) => {
                        crate::log_msg(&format!("Gossip event: NeighborDown={:?}", peer_id));
                        // A NeighborDown is a *transient* loss, not a graceful
                        // leave: emit PeerConnectionLost so the core marks the peer
                        // "reconnecting" and keeps its audio supervisor redialing,
                        // rather than tearing everything down. (Treating this as a
                        // PeerLeft is exactly what defeated reconnect in the field —
                        // it aborted the supervisor ~30s in.) We still drop our
                        // cached presence entry; a rejoin re-announces as new.
                        let removed = peers.lock().unwrap().remove(&peer_id).is_some();
                        if removed {
                            crate::log_msg(&format!("Peer connection lost (NeighborDown): {:?}", peer_id));
                            let _ = event_tx.send(RoomEvent::PeerConnectionLost(peer_id)).await;
                        }
                    }
                    Ok(other) => {
                        crate::log_msg(&format!("Gossip other event: {:?}", other));
                    }
                    Err(e) => {
                        crate::log_msg(&format!("Gossip error event: {:?}", e));
                    }
                }
            }
            crate::log_msg("Gossip topic loop terminated");
        });

        *self.active_topic.lock().unwrap() = Some(handle);
        Ok(())
    }

    async fn update_self_state(&self, self_state: PeerState) -> Result<(), NetError> {
        crate::log_msg(&format!("RoomState::update_self_state: state={:?}", self_state));
        *self.self_state.lock().unwrap() = Some(self_state.clone());

        let sender_opt = self.active_sender.lock().unwrap().clone();
        if let Some(sender) = sender_opt {
            let payload = GossipPayload {
                author: self_state.addr.id,
                msg: GossipMessage::Announce(self_state),
            };
            if let Ok(bytes) = serde_json::to_vec(&payload) {
                crate::log_msg("Broadcasting updated self state to gossip");
                sender.broadcast(bytes.into()).await
                    .map_err(|e| NetError::Gossip(e.to_string()))?;
            }
        }
        Ok(())
    }

    async fn send_chat(&self, text: String) -> Result<(), NetError> {
        let (name, author) = {
            let guard = self.self_state.lock().unwrap();
            match guard.as_ref() {
                Some(s) => (s.name.clone(), s.addr.id),
                None => return Err(NetError::Other("Not in a room".to_string())),
            }
        };
        let ts = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .map(|d| d.as_millis() as u64)
            .unwrap_or(0);

        let sender_opt = self.active_sender.lock().unwrap().clone();
        if let Some(sender) = sender_opt {
            let payload = GossipPayload {
                author,
                msg: GossipMessage::Chat { name, text, ts },
            };
            if let Ok(bytes) = serde_json::to_vec(&payload) {
                sender.broadcast(bytes.into()).await
                    .map_err(|e| NetError::Gossip(e.to_string()))?;
            }
        }
        Ok(())
    }

    async fn leave(&self) -> Result<(), NetError> {
        crate::log_msg("RoomState::leave called");
        {
            let mut handle_guard = self.active_topic.lock().unwrap();
            if let Some(handle) = handle_guard.take() {
                crate::log_msg("Aborting active gossip topic background task");
                handle.abort();
            }
        }

        *self.active_topic_id.lock().unwrap() = None;

        let sender_opt = self.active_sender.lock().unwrap().take();
        if let Some(sender) = sender_opt {
            let self_state_opt = self.self_state.lock().unwrap().clone();
            if let Some(self_state) = self_state_opt {
                let payload = GossipPayload {
                    author: self_state.addr.id,
                    msg: GossipMessage::Leave,
                };
                if let Ok(bytes) = serde_json::to_vec(&payload) {
                    crate::log_msg("Broadcasting Leave message to gossip");
                    let _ = sender.broadcast(bytes.into()).await;
                }
            }
        }

        self.peers.lock().unwrap().clear();
        Ok(())
    }

    fn active_peers(&self) -> Vec<(EndpointId, PeerState)> {
        let guard = self.peers.lock().unwrap();
        guard.iter().map(|(k, v)| (*k, v.clone())).collect()
    }

    async fn subscribe_events(&self) -> Result<Receiver<RoomEvent>, NetError> {
        let mut rx_guard = self.event_rx.lock().unwrap();
        if let Some(rx) = rx_guard.take() {
            Ok(rx)
        } else {
            Err(NetError::Other("Events already subscribed".to_string()))
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::network::PeerState;
    use iroh::SecretKey;

    fn sample_peer_state() -> PeerState {
        let secret = SecretKey::generate();
        let public = secret.public();
        let addr = iroh::EndpointAddr::from(public);
        PeerState {
            name: "TestPeerGossip".to_string(),
            is_muted: true,
            addr,
            sharing: None,
        }
    }

    #[test]
    fn test_gossip_message_leave_round_trip() {
        let original = GossipMessage::Leave;
        let serialized = serde_json::to_string(&original).unwrap();
        let deserialized: GossipMessage = serde_json::from_str(&serialized).unwrap();
        assert!(matches!(deserialized, GossipMessage::Leave));
    }

    #[test]
    fn test_gossip_payload_announce_round_trip() {
        let peer_state = sample_peer_state();
        let author = peer_state.addr.id;
        let payload = GossipPayload {
            author,
            msg: GossipMessage::Announce(peer_state.clone()),
        };

        let serialized = serde_json::to_string(&payload).unwrap();
        let deserialized: GossipPayload = serde_json::from_str(&serialized).unwrap();

        assert_eq!(deserialized.author, author);
        match deserialized.msg {
            GossipMessage::Announce(state) => {
                assert_eq!(state, peer_state);
            }
            GossipMessage::Leave | GossipMessage::Chat { .. } => {
                panic!("Expected GossipMessage::Announce");
            }
        }
    }

    #[test]
    fn test_gossip_message_chat_round_trip() {
        // Test normal chat message
        let original = GossipMessage::Chat {
            name: "Alice".to_string(),
            text: "Hello".to_string(),
            ts: 123456789,
        };
        let serialized = serde_json::to_string(&original).unwrap();
        let deserialized: GossipMessage = serde_json::from_str(&serialized).unwrap();
        if let GossipMessage::Chat { name, text, ts } = deserialized {
            assert_eq!(name, "Alice");
            assert_eq!(text, "Hello");
            assert_eq!(ts, 123456789);
        } else {
            panic!("Expected GossipMessage::Chat");
        }

        // Test empty strings and large timestamp
        let original_empty = GossipMessage::Chat {
            name: "".to_string(),
            text: "".to_string(),
            ts: u64::MAX,
        };
        let serialized_empty = serde_json::to_string(&original_empty).unwrap();
        let deserialized_empty: GossipMessage = serde_json::from_str(&serialized_empty).unwrap();
        if let GossipMessage::Chat { name, text, ts } = deserialized_empty {
            assert_eq!(name, "");
            assert_eq!(text, "");
            assert_eq!(ts, u64::MAX);
        } else {
            panic!("Expected GossipMessage::Chat");
        }
    }

    #[test]
    fn test_gossip_payload_chat_round_trip() {
        let peer_state = sample_peer_state();
        let author = peer_state.addr.id;
        let payload = GossipPayload {
            author,
            msg: GossipMessage::Chat {
                name: "Bob".to_string(),
                text: "Hi there".to_string(),
                ts: 987654321,
            },
        };

        let serialized = serde_json::to_string(&payload).unwrap();
        let deserialized: GossipPayload = serde_json::from_str(&serialized).unwrap();

        assert_eq!(deserialized.author, author);
        if let GossipMessage::Chat { name, text, ts } = deserialized.msg {
            assert_eq!(name, "Bob");
            assert_eq!(text, "Hi there");
            assert_eq!(ts, 987654321);
        } else {
            panic!("Expected GossipMessage::Chat");
        }
    }

    #[test]
    fn test_gossip_chat_unicode_round_trip() {
        let original = GossipMessage::Chat {
            name: "🎙 User".to_string(),
            text: "héllo 🎙 世界".to_string(),
            ts: 1717171717,
        };
        let serialized = serde_json::to_string(&original).unwrap();
        let deserialized: GossipMessage = serde_json::from_str(&serialized).unwrap();
        if let GossipMessage::Chat { name, text, ts } = deserialized {
            assert_eq!(name, "🎙 User");
            assert_eq!(text, "héllo 🎙 世界");
            assert_eq!(ts, 1717171717);
        } else {
            panic!("Expected GossipMessage::Chat");
        }
    }
}