//! WebSocket relay handlers
//!
//! Handles WebSocket connections from agents and viewers,
//! relaying video frames and input events between them.

use axum::{
    extract::{
        ws::{Message, WebSocket, WebSocketUpgrade},
        Query, State,
    },
    response::IntoResponse,
};
use futures_util::{SinkExt, StreamExt};
use prost::Message as ProstMessage;
use serde::Deserialize;
use tracing::{error, info, warn};

use crate::proto;
use crate::session::SessionManager;
use crate::AppState;

#[derive(Debug, Deserialize)]
pub struct AgentParams {
    agent_id: String,
    #[serde(default)]
    agent_name: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct ViewerParams {
    session_id: String,
}

/// WebSocket handler for agent connections
pub async fn agent_ws_handler(
    ws: WebSocketUpgrade,
    State(state): State<AppState>,
    Query(params): Query<AgentParams>,
) -> impl IntoResponse {
    let agent_id = params.agent_id;
    let agent_name = params.agent_name.unwrap_or_else(|| agent_id.clone());
    let sessions = state.sessions.clone();

    ws.on_upgrade(move |socket| handle_agent_connection(socket, sessions, agent_id, agent_name))
}

/// WebSocket handler for viewer connections
pub async fn viewer_ws_handler(
    ws: WebSocketUpgrade,
    State(state): State<AppState>,
    Query(params): Query<ViewerParams>,
) -> impl IntoResponse {
    let session_id = params.session_id;
    let sessions = state.sessions.clone();

    ws.on_upgrade(move |socket| handle_viewer_connection(socket, sessions, session_id))
}

/// Handle an agent WebSocket connection
async fn handle_agent_connection(
    socket: WebSocket,
    sessions: SessionManager,
    agent_id: String,
    agent_name: String,
) {
    info!("Agent connected: {} ({})", agent_name, agent_id);

    // Register the agent and get channels
    let (session_id, frame_tx, mut input_rx) = sessions.register_agent(agent_id.clone(), agent_name.clone()).await;

    info!("Session created: {}", session_id);

    let (mut ws_sender, mut ws_receiver) = socket.split();

    // Task to forward input events from viewers to agent
    let input_forward = tokio::spawn(async move {
        while let Some(input_data) = input_rx.recv().await {
            if ws_sender.send(Message::Binary(input_data.into())).await.is_err() {
                break;
            }
        }
    });

    let sessions_cleanup = sessions.clone();

    // Main loop: receive frames from agent and broadcast to viewers
    while let Some(msg) = ws_receiver.next().await {
        match msg {
            Ok(Message::Binary(data)) => {
                // Try to decode as protobuf message
                match proto::Message::decode(data.as_ref()) {
                    Ok(proto_msg) => {
                        if let Some(proto::message::Payload::VideoFrame(_)) = &proto_msg.payload {
                            // Broadcast frame to all viewers
                            let _ = frame_tx.send(data.to_vec());
                        }
                    }
                    Err(e) => {
                        warn!("Failed to decode agent message: {}", e);
                    }
                }
            }
            Ok(Message::Close(_)) => {
                info!("Agent disconnected: {}", agent_id);
                break;
            }
            Ok(Message::Ping(data)) => {
                // Pong is handled automatically by axum
                let _ = data;
            }
            Ok(_) => {}
            Err(e) => {
                error!("WebSocket error from agent {}: {}", agent_id, e);
                break;
            }
        }
    }

    // Cleanup
    input_forward.abort();
    sessions_cleanup.remove_session(session_id).await;
    info!("Session {} ended", session_id);
}

/// Handle a viewer WebSocket connection
async fn handle_viewer_connection(
    socket: WebSocket,
    sessions: SessionManager,
    session_id_str: String,
) {
    // Parse session ID
    let session_id = match uuid::Uuid::parse_str(&session_id_str) {
        Ok(id) => id,
        Err(_) => {
            warn!("Invalid session ID: {}", session_id_str);
            return;
        }
    };

    // Join the session
    let (mut frame_rx, input_tx) = match sessions.join_session(session_id).await {
        Some(channels) => channels,
        None => {
            warn!("Session not found: {}", session_id);
            return;
        }
    };

    info!("Viewer joined session: {}", session_id);

    let (mut ws_sender, mut ws_receiver) = socket.split();

    // Task to forward frames from agent to this viewer
    let frame_forward = tokio::spawn(async move {
        while let Ok(frame_data) = frame_rx.recv().await {
            if ws_sender.send(Message::Binary(frame_data.into())).await.is_err() {
                break;
            }
        }
    });

    let sessions_cleanup = sessions.clone();

    // Main loop: receive input from viewer and forward to agent
    while let Some(msg) = ws_receiver.next().await {
        match msg {
            Ok(Message::Binary(data)) => {
                // Try to decode as protobuf message
                match proto::Message::decode(data.as_ref()) {
                    Ok(proto_msg) => {
                        match &proto_msg.payload {
                            Some(proto::message::Payload::MouseEvent(_)) |
                            Some(proto::message::Payload::KeyEvent(_)) => {
                                // Forward input to agent
                                let _ = input_tx.send(data.to_vec()).await;
                            }
                            _ => {}
                        }
                    }
                    Err(e) => {
                        warn!("Failed to decode viewer message: {}", e);
                    }
                }
            }
            Ok(Message::Close(_)) => {
                info!("Viewer disconnected from session: {}", session_id);
                break;
            }
            Ok(_) => {}
            Err(e) => {
                error!("WebSocket error from viewer: {}", e);
                break;
            }
        }
    }

    // Cleanup
    frame_forward.abort();
    sessions_cleanup.leave_session(session_id).await;
    info!("Viewer left session: {}", session_id);
}