/**
 * WebSocket Handler
 *
 * 处理实时双向通信，主要用于 AI 对话流
 */

import type { WSContext } from 'hono/ws';
import { getSessionManager } from './session/manager.js';
import { processMessage, cancelProcessing } from './agent/index.js';
import type { ClientMessage, ServerMessage } from './types.js';

// 存储活跃的 WebSocket 连接
const connections: Map<string, Set<WSContext>> = new Map();

/**
 * 获取会话的所有连接
 */
export function getSessionConnections(sessionId: string): Set<WSContext> {
  return connections.get(sessionId) || new Set();
}

/**
 * 向会话的所有连接发送消息
 */
export function broadcastToSession(sessionId: string, message: ServerMessage): void {
  const conns = connections.get(sessionId);
  if (!conns) return;

  const data = JSON.stringify(message);
  for (const ws of conns) {
    try {
      ws.send(data);
    } catch (error) {
      console.error('Failed to send message:', error);
    }
  }
}

/**
 * WebSocket 连接处理器
 */
export function handleWebSocket(ws: WSContext, sessionId: string): void {
  const sessionManager = getSessionManager();

  // 验证会话
  if (!sessionManager.exists(sessionId)) {
    ws.send(
      JSON.stringify({
        type: 'error',
        sessionId,
        payload: { message: 'Session not found' },
      } as ServerMessage)
    );
    ws.close(4004, 'Session not found');
    return;
  }

  // 注册连接
  if (!connections.has(sessionId)) {
    connections.set(sessionId, new Set());
  }
  connections.get(sessionId)!.add(ws);

  // 更新会话状态
  sessionManager.updateStatus(sessionId, 'active');

  // 发送连接成功消息
  ws.send(
    JSON.stringify({
      type: 'connected',
      sessionId,
      payload: { message: 'Connected to session' },
    } as ServerMessage)
  );

  console.log(`[WS] Client connected to session: ${sessionId}`);
}

/**
 * WebSocket 消息处理器
 */
export async function handleWebSocketMessage(
  ws: WSContext,
  sessionId: string,
  data: unknown
): Promise<void> {
  const sessionManager = getSessionManager();

  try {
    // 处理不同类型的数据
    let text: string;
    if (typeof data === 'string') {
      text = data;
    } else if (data instanceof ArrayBuffer || data instanceof SharedArrayBuffer) {
      text = new TextDecoder().decode(data as ArrayBuffer);
    } else if (data instanceof Blob) {
      text = await data.text();
    } else {
      text = String(data);
    }

    const message: ClientMessage = JSON.parse(text);

    switch (message.type) {
      case 'message': {
        // 用户发送消息
        const content = message.payload?.content || '';
        const userMessage = sessionManager.addMessage(sessionId, {
          role: 'user',
          content,
        });

        if (userMessage) {
          // 广播用户消息
          broadcastToSession(sessionId, {
            type: 'message_received',
            sessionId,
            payload: userMessage,
          });

          // 调用 Agent 处理消息（异步，不阻塞）
          processMessage(sessionId, content).catch((error) => {
            console.error('[WS] Agent processing error:', error);
          });
        }
        break;
      }

      case 'cancel': {
        // 取消当前操作
        cancelProcessing(sessionId);
        broadcastToSession(sessionId, {
          type: 'cancelled',
          sessionId,
          payload: { message: 'Operation cancelled' },
        });
        break;
      }

      case 'tool_response': {
        // 工具执行结果 (用于人工确认场景)
        // TODO: 处理工具响应
        break;
      }

      default:
        ws.send(
          JSON.stringify({
            type: 'error',
            sessionId,
            payload: { message: `Unknown message type: ${(message as any).type}` },
          } as ServerMessage)
        );
    }
  } catch (error) {
    ws.send(
      JSON.stringify({
        type: 'error',
        sessionId,
        payload: {
          message: error instanceof Error ? error.message : 'Failed to process message',
        },
      } as ServerMessage)
    );
  }
}

/**
 * WebSocket 关闭处理器
 */
export function handleWebSocketClose(ws: WSContext, sessionId: string): void {
  const conns = connections.get(sessionId);
  if (conns) {
    conns.delete(ws);
    if (conns.size === 0) {
      connections.delete(sessionId);
      // 当没有连接时，更新会话状态
      const sessionManager = getSessionManager();
      sessionManager.updateStatus(sessionId, 'idle');
    }
  }

  console.log(`[WS] Client disconnected from session: ${sessionId}`);
}

/**
 * 获取连接统计
 */
export function getConnectionStats(): { sessions: number; connections: number } {
  let totalConnections = 0;
  for (const conns of connections.values()) {
    totalConnections += conns.size;
  }
  return {
    sessions: connections.size,
    connections: totalConnections,
  };
}