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::protocol::{parse_inbound, serialize_outbound, SessionSummary, 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) => {
            tracing::error!(error = %e, "Failed to get provider config");
            return;
        }
    };

    let initial_record = match state.session_manager.create_cli_session(None) {
        Ok(record) => record,
        Err(e) => {
            tracing::error!(error = %e, "Failed to create initial CLI session");
            return;
        }
    };

    let channel_name = "cli".to_string();

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

    if let Err(e) = session.lock().await.ensure_chat_loaded(&initial_record.id) {
        tracing::error!(error = %e, session_id = %initial_record.id, "Failed to load initial CLI session history");
        return;
    }

    let runtime_session_id = session.lock().await.id;
    let mut current_session_id = initial_record.id.clone();
    tracing::info!(runtime_session_id = %runtime_session_id, session_id = %current_session_id, "CLI session established");

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

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

    let mut receiver = receiver;
    let session_id_for_sender = runtime_session_id;
    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() {
                    #[cfg(debug_assertions)]
                    tracing::debug!(session_id = %session_id_for_sender, "WebSocket send error");
                    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) => {
                        if let Err(e) = handle_inbound(&state, &session, &mut current_session_id, inbound).await {
                            tracing::warn!(error = %e, session_id = %current_session_id, "Failed to handle inbound message");
                            let _ = session
                                .lock()
                                .await
                                .send(WsOutbound::Error {
                                    code: "SESSION_ERROR".to_string(),
                                    message: e.to_string(),
                                })
                                .await;
                        }
                    }
                    Err(e) => {
                        tracing::warn!(error = %e, "Failed to parse inbound message");
                        let _ = session
                            .lock()
                            .await
                            .send(WsOutbound::Error {
                                code: "PARSE_ERROR".to_string(),
                                message: e.to_string(),
                            })
                            .await;
                    }
                }
            }
            Ok(WsMessage::Close(_)) | Err(_) => {
                #[cfg(debug_assertions)]
                tracing::debug!(session_id = %runtime_session_id, "WebSocket closed");
                break;
            }
            _ => {}
        }
    }

    tracing::info!(session_id = %runtime_session_id, current_session_id = %current_session_id, "CLI session ended");
}

fn to_session_summary(record: crate::storage::SessionRecord) -> SessionSummary {
    SessionSummary {
        session_id: record.id,
        title: record.title,
        channel_name: record.channel_name,
        chat_id: record.chat_id,
        message_count: record.message_count,
        last_active_at: record.last_active_at,
        archived_at: record.archived_at,
    }
}

async fn handle_inbound(
    state: &Arc<GatewayState>,
    session: &Arc<Mutex<Session>>,
    current_session_id: &mut String,
    inbound: WsInbound,
) -> Result<(), crate::agent::AgentError> {
    match inbound {
        WsInbound::UserInput { content, chat_id, .. } => {
            let chat_id = chat_id.unwrap_or_else(|| current_session_id.clone());
            let mut session_guard = session.lock().await;

            session_guard.ensure_persistent_session(&chat_id)?;
            session_guard.ensure_chat_loaded(&chat_id)?;

            let user_message = session_guard.create_user_message(&content, Vec::new());
            session_guard.append_persisted_message(&chat_id, user_message)?;

            let raw_history = session_guard.get_or_create_history(&chat_id).clone();
            let history = match session_guard
                .compressor()
                .compress_if_needed(raw_history, session_guard.provider_config())
                .await
            {
                Ok(history) => history,
                Err(error) => {
                    tracing::warn!(chat_id = %chat_id, error = %error, "Compression failed, using original history");
                    session_guard.get_or_create_history(&chat_id).clone()
                }
            };

            let agent = session_guard.create_agent()?;
            match agent.process(history).await {
                Ok(response) => {
                    session_guard.append_persisted_message(&chat_id, response.clone())?;
                    let _ = session_guard
                        .send(WsOutbound::AssistantResponse {
                            id: response.id,
                            content: response.content,
                            role: response.role,
                        })
                        .await;
                }
                Err(error) => {
                    tracing::error!(chat_id = %chat_id, error = %error, "Agent process error");
                    let _ = session_guard
                        .send(WsOutbound::Error {
                            code: "LLM_ERROR".to_string(),
                            message: error.to_string(),
                        })
                        .await;
                }
            }

            Ok(())
        }
        WsInbound::ClearHistory { session_id, chat_id } => {
            let target = session_id.or(chat_id).unwrap_or_else(|| current_session_id.clone());
            state.session_manager.clear_session_messages(&target)?;

            let mut session_guard = session.lock().await;
            session_guard.remove_history(&target);
            let _ = session_guard
                .send(WsOutbound::HistoryCleared {
                    session_id: target,
                })
                .await;
            Ok(())
        }
        WsInbound::CreateSession { title } => {
            let record = state.session_manager.create_cli_session(title.as_deref())?;
            *current_session_id = record.id.clone();

            let mut session_guard = session.lock().await;
            session_guard.ensure_chat_loaded(&record.id)?;
            let _ = session_guard
                .send(WsOutbound::SessionCreated {
                    session_id: record.id,
                    title: record.title,
                })
                .await;
            Ok(())
        }
        WsInbound::ListSessions { include_archived } => {
            let records = state.session_manager.list_cli_sessions(include_archived)?;
            let summaries = records.into_iter().map(to_session_summary).collect();

            let session_guard = session.lock().await;
            let _ = session_guard
                .send(WsOutbound::SessionList {
                    sessions: summaries,
                    current_session_id: Some(current_session_id.clone()),
                })
                .await;
            Ok(())
        }
        WsInbound::LoadSession { session_id } => {
            let Some(record) = state.session_manager.get_session_record(&session_id)? else {
                let session_guard = session.lock().await;
                let _ = session_guard
                    .send(WsOutbound::Error {
                        code: "SESSION_NOT_FOUND".to_string(),
                        message: format!("Session not found: {}", session_id),
                    })
                    .await;
                return Ok(());
            };

            *current_session_id = record.id.clone();
            let mut session_guard = session.lock().await;
            session_guard.ensure_chat_loaded(&record.id)?;
            let _ = session_guard
                .send(WsOutbound::SessionLoaded {
                    session_id: record.id,
                    title: record.title,
                    message_count: record.message_count,
                })
                .await;
            Ok(())
        }
        WsInbound::RenameSession { session_id, title } => {
            let target = session_id.unwrap_or_else(|| current_session_id.clone());
            state.session_manager.rename_session(&target, &title)?;
            let session_guard = session.lock().await;
            let _ = session_guard
                .send(WsOutbound::SessionRenamed {
                    session_id: target,
                    title,
                })
                .await;
            Ok(())
        }
        WsInbound::ArchiveSession { session_id } => {
            let target = session_id.unwrap_or_else(|| current_session_id.clone());
            state.session_manager.archive_session(&target)?;
            let session_guard = session.lock().await;
            let _ = session_guard
                .send(WsOutbound::SessionArchived { session_id: target })
                .await;
            Ok(())
        }
        WsInbound::DeleteSession { session_id } => {
            let target = session_id.unwrap_or_else(|| current_session_id.clone());
            state.session_manager.delete_session(&target)?;

            let replacement = if target == *current_session_id {
                Some(state.session_manager.create_cli_session(None)?)
            } else {
                None
            };

            let mut session_guard = session.lock().await;
            session_guard.remove_history(&target);
            let _ = session_guard
                .send(WsOutbound::SessionDeleted {
                    session_id: target.clone(),
                })
                .await;

            if let Some(record) = replacement {
                *current_session_id = record.id.clone();
                session_guard.ensure_chat_loaded(&record.id)?;
                let _ = session_guard
                    .send(WsOutbound::SessionCreated {
                        session_id: record.id,
                        title: record.title,
                    })
                    .await;
            }

            Ok(())
        }
        WsInbound::Ping => {
            let session_guard = session.lock().await;
            let _ = session_guard.send(WsOutbound::Pong).await;
            Ok(())
        }
    }
}