use std::sync::Arc;
use axum::extract::ws::{WebSocket, WebSocketUpgrade, Message as WsMessage};
use axum::extract::State;
use axum::response::Response;
use futures_util::{SinkExt, StreamExt};
use tokio::sync::{mpsc, Mutex};
use crate::bus::ChatMessage;
use crate::protocol::{parse_inbound, serialize_outbound, WsInbound, WsOutbound};
use super::{GatewayState, session::Session};

pub async fn ws_handler(ws: WebSocketUpgrade, State(state): State<Arc<GatewayState>>) -> Response {
    ws.on_upgrade(|socket| async {
        handle_socket(socket, state).await;
    })
}

async fn handle_socket(ws: WebSocket, state: Arc<GatewayState>) {
    let (sender, receiver) = mpsc::channel::<WsOutbound>(100);

    let provider_config = match state.config.get_provider_config("default") {
        Ok(cfg) => cfg,
        Err(e) => {
            eprintln!("Failed to get provider config: {}", e);
            return;
        }
    };

    // CLI 使用独立的 session，channel_name = "cli-{uuid}"
    let channel_name = format!("cli-{}", uuid::Uuid::new_v4());

    // 创建 CLI session
    let session = match Session::new(channel_name.clone(), provider_config, sender).await {
        Ok(s) => Arc::new(Mutex::new(s)),
        Err(e) => {
            eprintln!("Failed to create session: {}", e);
            return;
        }
    };

    let session_id = session.lock().await.id;

    let _ = session.lock().await.send(WsOutbound::SessionEstablished {
        session_id: session_id.to_string(),
    }).await;

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

    let mut receiver = receiver;
    tokio::spawn(async move {
        while let Some(msg) = receiver.recv().await {
            if let Ok(text) = serialize_outbound(&msg) {
                if ws_sender.send(WsMessage::Text(text.into())).await.is_err() {
                    break;
                }
            }
        }
    });

    while let Some(msg) = ws_receiver.next().await {
        match msg {
            Ok(WsMessage::Text(text)) => {
                let text = text.to_string();
                match parse_inbound(&text) {
                    Ok(inbound) => {
                        handle_inbound(&session, inbound).await;
                    }
                    Err(e) => {
                        let _ = session.lock().await.send(WsOutbound::Error {
                            code: "PARSE_ERROR".to_string(),
                            message: e.to_string(),
                        }).await;
                    }
                }
            }
            Ok(WsMessage::Close(_)) | Err(_) => {
                break;
            }
            _ => {}
        }
    }
}

async fn handle_inbound(session: &Arc<Mutex<Session>>, inbound: WsInbound) {
    let inbound_clone = inbound.clone();

    // 提取 content 和 chat_id（CLI 使用 session id 作为 chat_id）
    let (content, chat_id) = match inbound_clone {
        WsInbound::UserInput { content, channel: _, chat_id, sender_id: _ } => {
            // CLI 使用 session 中的 channel_name 作为标识
            // chat_id 使用传入的或使用默认
            let chat_id = chat_id.unwrap_or_else(|| "default".to_string());
            (content, chat_id)
        }
        _ => return,
    };

    let user_msg = ChatMessage::user(content);

    let mut session_guard = session.lock().await;
    let agent = match session_guard.get_or_create_agent(&chat_id).await {
        Ok(a) => a,
        Err(e) => {
            let _ = session_guard.send(WsOutbound::Error {
                code: "AGENT_ERROR".to_string(),
                message: e.to_string(),
            }).await;
            return;
        }
    };
    drop(session_guard);

    let mut agent = agent.lock().await;
    match agent.process(user_msg).await {
        Ok(response) => {
            let _ = session.lock().await.send(WsOutbound::AssistantResponse {
                id: response.id,
                content: response.content,
                role: response.role,
            }).await;
        }
        Err(e) => {
            let _ = session.lock().await.send(WsOutbound::Error {
                code: "LLM_ERROR".to_string(),
                message: e.to_string(),
            }).await;
        }
    }
}