//! 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 uuid::Uuid;

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>,
    #[serde(default)]
    support_code: Option<String>,
    #[serde(default)]
    hostname: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct ViewerParams {
    session_id: String,
    #[serde(default = "default_viewer_name")]
    viewer_name: String,
}

fn default_viewer_name() -> String {
    "Technician".to_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.hostname.or(params.agent_name).unwrap_or_else(|| agent_id.clone());
    let support_code = params.support_code;
    let sessions = state.sessions.clone();
    let support_codes = state.support_codes.clone();

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

/// 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 viewer_name = params.viewer_name;
    let sessions = state.sessions.clone();

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

/// Handle an agent WebSocket connection
async fn handle_agent_connection(
    socket: WebSocket,
    sessions: SessionManager,
    support_codes: crate::support_codes::SupportCodeManager,
    agent_id: String,
    agent_name: String,
    support_code: Option<String>,
) {
    info!("Agent connected: {} ({})", agent_name, agent_id);

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

    // If a support code was provided, check if it's valid
    if let Some(ref code) = support_code {
        // Check if the code is cancelled or invalid
        if support_codes.is_cancelled(code).await {
            warn!("Agent tried to connect with cancelled code: {}", code);
            // Send disconnect message to agent
            let disconnect_msg = proto::Message {
                payload: Some(proto::message::Payload::Disconnect(proto::Disconnect {
                    reason: "Support session was cancelled by technician".to_string(),
                })),
            };
            let mut buf = Vec::new();
            if prost::Message::encode(&disconnect_msg, &mut buf).is_ok() {
                let _ = ws_sender.send(Message::Binary(buf.into())).await;
            }
            let _ = ws_sender.close().await;
            return;
        }
    }

    // Register the agent and get channels
    // Persistent agents (no support code) keep their session when disconnected
    let is_persistent = support_code.is_none();
    let (session_id, frame_tx, mut input_rx) = sessions.register_agent(agent_id.clone(), agent_name.clone(), is_persistent).await;

    info!("Session created: {} (agent in idle mode)", session_id);

    // If a support code was provided, mark it as connected
    if let Some(ref code) = support_code {
        info!("Linking support code {} to session {}", code, session_id);
        support_codes.mark_connected(code, Some(agent_name.clone()), Some(agent_id.clone())).await;
        support_codes.link_session(code, session_id).await;
    }

    // Use Arc<Mutex> for sender so we can use it from multiple places
    let ws_sender = std::sync::Arc::new(tokio::sync::Mutex::new(ws_sender));
    let ws_sender_input = ws_sender.clone();
    let ws_sender_cancel = ws_sender.clone();

    // 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 {
            let mut sender = ws_sender_input.lock().await;
            if sender.send(Message::Binary(input_data.into())).await.is_err() {
                break;
            }
        }
    });

    let sessions_cleanup = sessions.clone();
    let sessions_status = sessions.clone();
    let support_codes_cleanup = support_codes.clone();
    let support_code_cleanup = support_code.clone();
    let support_code_check = support_code.clone();
    let support_codes_check = support_codes.clone();

    // Task to check for cancellation every 2 seconds
    let cancel_check = tokio::spawn(async move {
        let mut interval = tokio::time::interval(std::time::Duration::from_secs(2));
        loop {
            interval.tick().await;
            if let Some(ref code) = support_code_check {
                if support_codes_check.is_cancelled(code).await {
                    info!("Support code {} was cancelled, disconnecting agent", code);
                    // Send disconnect message
                    let disconnect_msg = proto::Message {
                        payload: Some(proto::message::Payload::Disconnect(proto::Disconnect {
                            reason: "Support session was cancelled by technician".to_string(),
                        })),
                    };
                    let mut buf = Vec::new();
                    if prost::Message::encode(&disconnect_msg, &mut buf).is_ok() {
                        let mut sender = ws_sender_cancel.lock().await;
                        let _ = sender.send(Message::Binary(buf.into())).await;
                        let _ = sender.close().await;
                    }
                    break;
                }
            }
        }
    });

    // Main loop: receive messages from 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::VideoFrame(_)) => {
                                // Broadcast frame to all viewers (only sent when streaming)
                                let _ = frame_tx.send(data.to_vec());
                            }
                            Some(proto::message::Payload::ChatMessage(chat)) => {
                                // Broadcast chat message to all viewers
                                info!("Chat from client: {}", chat.content);
                                let _ = frame_tx.send(data.to_vec());
                            }
                            Some(proto::message::Payload::AgentStatus(status)) => {
                                // Update session with agent status
                                sessions_status.update_agent_status(
                                    session_id,
                                    Some(status.os_version.clone()),
                                    status.is_elevated,
                                    status.uptime_secs,
                                    status.display_count,
                                    status.is_streaming,
                                ).await;
                                info!("Agent status update: {} - streaming={}, uptime={}s",
                                    status.hostname, status.is_streaming, status.uptime_secs);
                            }
                            Some(proto::message::Payload::Heartbeat(_)) => {
                                // Update heartbeat timestamp
                                sessions_status.update_heartbeat(session_id).await;
                            }
                            Some(proto::message::Payload::HeartbeatAck(_)) => {
                                // Agent acknowledged our heartbeat
                                sessions_status.update_heartbeat(session_id).await;
                            }
                            _ => {}
                        }
                    }
                    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();
    cancel_check.abort();
    // Mark agent as disconnected (persistent agents stay in list as offline)
    sessions_cleanup.mark_agent_disconnected(session_id).await;

    // Mark support code as completed if one was used (unless cancelled)
    if let Some(ref code) = support_code_cleanup {
        if !support_codes_cleanup.is_cancelled(code).await {
            support_codes_cleanup.mark_completed(code).await;
            info!("Support code {} marked as completed", code);
        }
    }

    info!("Session {} ended", session_id);
}

/// Handle a viewer WebSocket connection
async fn handle_viewer_connection(
    socket: WebSocket,
    sessions: SessionManager,
    session_id_str: String,
    viewer_name: 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;
        }
    };

    // Generate unique viewer ID
    let viewer_id = Uuid::new_v4().to_string();

    // Join the session (this sends StartStream to agent if first viewer)
    let (mut frame_rx, input_tx) = match sessions.join_session(session_id, viewer_id.clone(), viewer_name.clone()).await {
        Some(channels) => channels,
        None => {
            warn!("Session not found: {}", session_id);
            return;
        }
    };

    info!("Viewer {} ({}) joined session: {}", viewer_name, viewer_id, 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();
    let viewer_id_cleanup = viewer_id.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(_)) |
                            Some(proto::message::Payload::SpecialKey(_)) => {
                                // Forward input to agent
                                let _ = input_tx.send(data.to_vec()).await;
                            }
                            Some(proto::message::Payload::ChatMessage(chat)) => {
                                // Forward chat message to agent
                                info!("Chat from technician: {}", chat.content);
                                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: {}", viewer_id, session_id);
                break;
            }
            Ok(_) => {}
            Err(e) => {
                error!("WebSocket error from viewer {}: {}", viewer_id, e);
                break;
            }
        }
    }

    // Cleanup (this sends StopStream to agent if last viewer)
    frame_forward.abort();
    sessions_cleanup.leave_session(session_id, &viewer_id_cleanup).await;
    info!("Viewer {} left session: {}", viewer_id_cleanup, session_id);
}