use iroh::{EndpointId, EndpointAddr};
use bytes::Bytes;
use thiserror::Error;
use tokio::sync::mpsc::Receiver;
use async_trait::async_trait;
use serde::{Serialize, Deserialize};
use std::str::FromStr;

#[derive(Error, Debug)]
pub enum NetError {
    #[error("Failed to initialize network: {0}")]
    Init(String),
    #[error("Failed to connect/dial peer: {0}")]
    Connection(String),
    #[error("Gossip swarm error: {0}")]
    Gossip(String),
    #[error("Serialization / Deserialization error: {0}")]
    Serde(String),
    #[error("Invalid ticket: {0}")]
    InvalidTicket(String),
    #[error("Other network error: {0}")]
    Other(String),
}

#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct PeerState {
    pub name: String,
    pub is_muted: bool,
    pub addr: iroh::EndpointAddr,
    /// When this peer is sharing their screen, the pixelpass relay ticket a
    /// viewer needs to watch it; `None` when not sharing. Riding presence means
    /// the existing gossip re-announce delivers it to late joiners for free, and
    /// a `PeerUpdated` fires automatically on share start/stop. Defaulted so
    /// older configs / peers that predate the field still deserialize.
    #[serde(default)]
    pub sharing: Option<String>,
    /// This peer's chosen avatar (W4). Rides presence so it reaches everyone
    /// (incl. late joiners) with no server, like `sharing`. Defaulted so older
    /// peers/configs that predate the field still deserialize (→ monogram).
    #[serde(default)]
    pub avatar: crate::avatar::Avatar,
}

#[derive(Debug, Clone)]
pub enum RoomEvent {
    PeerJoined(EndpointId, PeerState),
    /// A peer left *gracefully* (it broadcast a `Leave`). Evict it immediately.
    PeerLeft(EndpointId),
    PeerUpdated(EndpointId, PeerState),
    /// A peer's gossip neighbour link dropped without a graceful `Leave` (network
    /// blip, crash, walked out of range). This is transient: the audio supervisor
    /// keeps redialing, so the core marks the peer "reconnecting" and only evicts
    /// it if the link hasn't recovered within the reconnect grace window. Distinct
    /// from `PeerLeft` precisely so a momentary `NeighborDown` can't tear down the
    /// reconnect path the way it used to.
    PeerConnectionLost(EndpointId),
    /// A peer sent a room text-chat message. Carries the sender's id, their
    /// display name (embedded so it shows even without a presence entry), the
    /// text, and a sender-stamped millisecond timestamp.
    ChatMessage {
        from: EndpointId,
        name: String,
        text: String,
        ts: u64,
        /// Optional file attachment descriptor; the bytes are fetched off-gossip
        /// on the file plane. Already filename-sanitized + size-capped on ingest.
        attachment: Option<crate::files::ChatAttachment>,
    },
}

/// Transport-level link state for a peer, surfaced so the UI can show when a
/// peer's audio connection is being (re)established versus actually carrying
/// audio. Distinct from `RoomEvent`: a peer can be present in the gossip room
/// while its audio link is momentarily down and reconnecting.
#[derive(Debug, Clone)]
pub enum ConnEvent {
    /// No live audio link yet — initial connect or reconnecting after a drop.
    Connecting(EndpointId),
    /// A live audio link is established and carrying datagrams.
    Connected(EndpointId),
    /// The peer closed its link *gracefully* (an explicit QUIC application close,
    /// which only happens on an intentional leave/quit — a network drop yields a
    /// timeout, not this). Distinct from a transient drop so the core can evict
    /// the peer immediately instead of waiting out the reconnect grace window.
    /// This is the prompt, reliable leave signal; the gossip `Leave` is too slow.
    Left(EndpointId),
}

#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct PeerSpeakTicket {
    pub host_addr: iroh::EndpointAddr,
    pub topic_id: [u8; 32],
    /// Cosmetic room label (W7), chosen by the creator and carried in the ticket
    /// so everyone who joins via it inherits the same label and reports "in
    /// HangOut" in presence. Untrusted on receipt (it rides a peer-shared ticket)
    /// — sanitize before display. `#[serde(default)]` keeps older, pre-label
    /// tickets parseable (they decode to an empty label).
    #[serde(default)]
    pub name: String,
}

impl PeerSpeakTicket {
    /// Member-issued ticket (W7 P3): re-stamp an existing ticket string with our
    /// OWN address while keeping its room `topic_id` AND its cosmetic `name`, so
    /// any member can hand out a working door that bootstraps off themselves — the
    /// mechanism that lets a room outlive its creator. A no-op (returns the input
    /// unchanged) if the string can't be parsed. Re-stamping with the same address
    /// is idempotent.
    pub fn restamp(ticket_str: &str, my_addr: iroh::EndpointAddr) -> String {
        match ticket_str.parse::<PeerSpeakTicket>() {
            Ok(t) => {
                PeerSpeakTicket { host_addr: my_addr, topic_id: t.topic_id, name: t.name }
                    .to_string()
            }
            Err(_) => ticket_str.to_string(),
        }
    }

    /// The cosmetic room label embedded in a ticket string, or `""` if the ticket
    /// can't be parsed or carries no label. Pure; used to label the gathering both
    /// in the room UI and in the presence we report to friends.
    pub fn label_of(ticket_str: &str) -> String {
        ticket_str.parse::<PeerSpeakTicket>().map(|t| t.name).unwrap_or_default()
    }

    /// The room's `topic_id` embedded in a ticket string, or `None` if the ticket
    /// can't be parsed. Pure; used as the stable room identity for de-duplicating
    /// the recents list (the host address and label change between members/sessions,
    /// but the topic uniquely identifies the gathering).
    pub fn topic_of(ticket_str: &str) -> Option<[u8; 32]> {
        ticket_str.parse::<PeerSpeakTicket>().ok().map(|t| t.topic_id)
    }
}

impl std::fmt::Display for PeerSpeakTicket {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        // serde_json on a struct of String/[u8;32] fields is infallible in practice,
        // but Display can't surface an error, so fall back to an empty ticket body.
        let serialized = serde_json::to_vec(self).unwrap_or_default();
        let encoded = base64::Engine::encode(
            &base64::engine::general_purpose::URL_SAFE_NO_PAD,
            &serialized,
        );
        f.write_str(&encoded)
    }
}

impl FromStr for PeerSpeakTicket {
    type Err = NetError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let decoded = base64::Engine::decode(&base64::engine::general_purpose::URL_SAFE_NO_PAD, s)
            .map_err(|e| NetError::InvalidTicket(e.to_string()))?;
        let ticket: PeerSpeakTicket = serde_json::from_slice(&decoded)
            .map_err(|e| NetError::InvalidTicket(e.to_string()))?;
        Ok(ticket)
    }
}

#[async_trait]
pub trait NetworkTransport: Send + Sync {
    /// Establish (or ensure) a connection to a peer and set up its send path.
    /// Idempotent; safe to call again for an already-connected peer — a repeat
    /// call refreshes the retained dial address, so calling it again when a peer
    /// re-announces (e.g. on a new address) keeps the dialer able to re-reach it.
    /// The full `EndpointAddr` (relay + direct addrs) is retained so reconnects
    /// dial it directly instead of depending on a lookup that a transient gossip
    /// `Leave`/`NeighborDown` may have purged.
    async fn connect_peer(&self, addr: iroh::EndpointAddr);

    /// Tear down the connection and send path for a peer that has left.
    async fn disconnect_peer(&self, peer_id: EndpointId);

    /// Fan a single audio datagram out to every connected peer. Non-blocking:
    /// per-peer queues drop the oldest-pending frame when full, so a slow link
    /// can never stall the capture/encode thread. Callable from any thread.
    fn broadcast(&self, data: Bytes);

    /// Subscribes to incoming datagrams from any peer.
    async fn receive_datagrams(&self) -> Result<Receiver<(EndpointId, Bytes)>, NetError>;

    /// Subscribes to per-peer link-state changes (connecting / connected).
    async fn subscribe_conn_events(&self) -> Result<Receiver<ConnEvent>, NetError>;
}

#[async_trait]
pub trait RoomState: Send + Sync {
    /// Joins a room using a gossip ticket string and announces our state.
    ///
    /// `extra_bootstrap` are additional peer addresses to dial when entering the
    /// gossip swarm, on top of the ticket's host. This is what lets the ROOM
    /// CREATOR rejoin a room they left: their own ticket lists only themselves as
    /// host, so without retained peers they'd have no dial target and never
    /// re-enter the swarm (bug A8). Callers with no prior peers pass `vec![]`.
    async fn join(
        &self,
        ticket: &str,
        self_state: PeerState,
        extra_bootstrap: Vec<EndpointAddr>,
    ) -> Result<(), NetError>;

    /// Updates our local state (e.g. when user mutes/unmutes) and broadcasts it.
    async fn update_self_state(&self, self_state: PeerState) -> Result<(), NetError>;

    /// Ask the active gossip topic to connect to retained peer addresses without
    /// leaving or replacing the subscription. This is a recovery primitive only:
    /// it does not add peers to the authenticated room roster. A peer becomes
    /// active only after its normal signed `Announce` is received and verified.
    async fn rebootstrap_peers(&self, peers: Vec<EndpointAddr>) -> Result<(), NetError>;

    /// Remove a peer from the authenticated live roster before background
    /// recovery. This only revokes membership; a fresh verified `Announce` is
    /// required to add the peer again.
    fn mark_peer_disconnected(&self, peer_id: EndpointId);

    /// Broadcasts a room text-chat message authored by us (our display name is
    /// taken from the current self-state), optionally carrying a file attachment
    /// descriptor whose bytes are served separately on the file plane.
    async fn send_chat(
        &self,
        text: String,
        attachment: Option<crate::files::ChatAttachment>,
    ) -> Result<(), NetError>;

    /// Leaves the room and announces departure.
    async fn leave(&self) -> Result<(), NetError>;

    /// Returns a list of currently active peers in the room.
    fn active_peers(&self) -> Vec<(EndpointId, PeerState)>;

    /// Subscribes to room events (peer joined, peer left, peer updated).
    async fn subscribe_events(&self) -> Result<Receiver<RoomEvent>, NetError>;
}

pub mod iroh_impl;
pub mod gossip;

#[cfg(test)]
mod tests {
    use super::*;
    use iroh::{SecretKey, EndpointAddr};

    fn sample_peer_state() -> PeerState {
        let secret = SecretKey::generate();
        let public = secret.public();
        let addr = EndpointAddr::from(public);
        PeerState {
            name: "TestPeer".to_string(),
            is_muted: false,
            addr,
            sharing: None,
            avatar: crate::avatar::Avatar::default(),
        }
    }

    #[test]
    fn test_ticket_round_trip() {
        let state = sample_peer_state();
        let topic_id = [7u8; 32];
        let original_ticket = PeerSpeakTicket {
            host_addr: state.addr.clone(),
            topic_id,
            name: "HangOut".to_string(),
        };
        let ticket_str = original_ticket.to_string();
        let parsed_ticket = ticket_str.parse::<PeerSpeakTicket>().unwrap();
        assert_eq!(parsed_ticket.host_addr.id, original_ticket.host_addr.id);
        assert_eq!(parsed_ticket.topic_id, original_ticket.topic_id);
        assert_eq!(parsed_ticket.name, "HangOut");
    }

    #[test]
    fn test_ticket_label_helpers_and_backcompat() {
        let host = SecretKey::generate().public();
        let topic_id = [3u8; 32];
        // A labelled ticket: restamp keeps the label, label_of reads it.
        let labelled =
            PeerSpeakTicket { host_addr: EndpointAddr::from(host), topic_id, name: "HangOut".into() }
                .to_string();
        assert_eq!(PeerSpeakTicket::label_of(&labelled), "HangOut");
        let member = SecretKey::generate().public();
        let restamped = PeerSpeakTicket::restamp(&labelled, EndpointAddr::from(member));
        assert_eq!(PeerSpeakTicket::label_of(&restamped), "HangOut");
        // An unparseable ticket has no label rather than panicking.
        assert_eq!(PeerSpeakTicket::label_of("not-a-ticket"), "");
        // topic_of reads the room identity, and returns None for a bad ticket.
        assert_eq!(PeerSpeakTicket::topic_of(&labelled), Some(topic_id));
        assert_eq!(PeerSpeakTicket::topic_of(&restamped), Some(topic_id));
        assert_eq!(PeerSpeakTicket::topic_of("not-a-ticket"), None);
        // Backward-compat: a pre-label ticket JSON (no `name` key) still parses,
        // defaulting the label to "".
        let legacy_json = serde_json::json!({
            "host_addr": serde_json::to_value(EndpointAddr::from(host)).unwrap(),
            "topic_id": topic_id.to_vec(),
        });
        let legacy_str = base64::Engine::encode(
            &base64::engine::general_purpose::URL_SAFE_NO_PAD,
            serde_json::to_vec(&legacy_json).unwrap(),
        );
        let parsed = legacy_str.parse::<PeerSpeakTicket>().unwrap();
        assert_eq!(parsed.name, "");
    }

    #[test]
    fn test_malformed_rejection() {
        // empty string
        let res1 = "".parse::<PeerSpeakTicket>();
        assert!(matches!(res1, Err(NetError::InvalidTicket(_))));

        // non-base64 garbage
        let res2 = "!!!not base64!!!".parse::<PeerSpeakTicket>();
        assert!(matches!(res2, Err(NetError::InvalidTicket(_))));

        // valid URL-safe-base64 that decodes to non-JSON bytes
        let bad_json = b"hello world";
        let encoded = base64::Engine::encode(
            &base64::engine::general_purpose::URL_SAFE_NO_PAD,
            bad_json,
        );
        let res3 = encoded.parse::<PeerSpeakTicket>();
        assert!(matches!(res3, Err(NetError::InvalidTicket(_))));
    }

    #[test]
    fn test_restamp_swaps_addr_keeps_topic() {
        // A ticket "from" the host, then re-stamped by another member.
        let host = SecretKey::generate().public();
        let member = SecretKey::generate().public();
        let topic_id = [42u8; 32];
        let original =
            PeerSpeakTicket { host_addr: EndpointAddr::from(host), topic_id, name: "HangOut".into() }
                .to_string();

        let restamped_str = PeerSpeakTicket::restamp(&original, EndpointAddr::from(member));
        let restamped = restamped_str.parse::<PeerSpeakTicket>().unwrap();
        // Same room (and label), but the door now points at the member, not the host.
        assert_eq!(restamped.topic_id, topic_id);
        assert_eq!(restamped.host_addr.id, member);
        assert_ne!(restamped.host_addr.id, host);
        assert_eq!(restamped.name, "HangOut");
    }

    #[test]
    fn test_restamp_is_idempotent_for_same_addr() {
        let me = SecretKey::generate().public();
        let topic_id = [7u8; 32];
        let mine =
            PeerSpeakTicket { host_addr: EndpointAddr::from(me), topic_id, name: String::new() }
                .to_string();
        // Re-stamping my own ticket with my own addr changes nothing.
        assert_eq!(PeerSpeakTicket::restamp(&mine, EndpointAddr::from(me)), mine);
    }

    #[test]
    fn test_restamp_passes_through_unparseable() {
        let me = SecretKey::generate().public();
        // A malformed ticket is returned unchanged (the join will fail anyway).
        assert_eq!(PeerSpeakTicket::restamp("not-a-ticket", EndpointAddr::from(me)), "not-a-ticket");
    }

    #[test]
    fn test_peer_state_serde_round_trip() {
        let original = sample_peer_state();
        let serialized = serde_json::to_string(&original).unwrap();
        let deserialized: PeerState = serde_json::from_str(&serialized).unwrap();
        assert_eq!(original, deserialized);
    }
}