/**
 * 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, getOrCreateAgent, submitUserInput, clearAgentHistory } from './agent/index.js';
import { handlePermissionResponse, setSessionAutoApprove } from './permission/handler.js';
import type { ClientMessage, ServerMessage } from './types.js';
import {
  isSystemCommand,
  executeSystemCommand,
  initializeSystemCommands,
  MessageStorage,
} from '@ai-assistant/core';

// 初始化系统命令
initializeSystemCommands();

// 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
        let content = message.payload?.content || '';
        const agentMode = message.payload?.agentMode as 'build' | 'plan' | undefined;
        const autoApprove = message.payload?.autoApprove as boolean | undefined;

        // 检测系统命令（: 前缀）
        if (isSystemCommand(content)) {
          await handleSystemCommand(sessionId, content);
          break;
        }

        // 将 @filepath 转换为 ./filepath 格式（方便 AI 识别为文件路径）
        content = content.replace(/@([\w./-]+)/g, './$1');

        // 广播确认收到消息
        broadcastToSession(sessionId, {
          type: 'message_received',
          sessionId,
          payload: { content: message.payload?.content || '' }, // 广播原始内容
        });

        // 调用 Agent 处理消息（异步，不阻塞）
        // 消息存储由 Core Agent 负责
        processMessage(sessionId, content, { agentMode, autoApprove }).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;
      }

      case 'permission_response': {
        // 处理权限确认响应
        const { requestId, allow, remember } = message.payload || {};
        if (requestId) {
          const handled = handlePermissionResponse(requestId, allow ?? false, remember);
          if (!handled) {
            console.warn(`[WS] Permission response for unknown request: ${requestId}`);
          }
        }
        break;
      }

      case 'config_update': {
        // 实时配置更新（如 Auto Edit 开关）
        const autoApprove = message.payload?.autoApprove;
        if (typeof autoApprove === 'boolean') {
          if (autoApprove) {
            setSessionAutoApprove(sessionId, {
              file: { write: 'allow', edit: 'allow' },
            });
          } else {
            setSessionAutoApprove(sessionId, null);
          }
          console.log(`[WS] Config updated for session ${sessionId}: autoApprove=${autoApprove}`);
        }
        break;
      }

      case 'mode_switch': {
        // 动态模式切换（Build ↔ Plan）
        const mode = message.payload?.agentMode as 'build' | 'plan' | undefined;
        if (mode === 'build' || mode === 'plan') {
          try {
            const agent = await getOrCreateAgent(sessionId);
            if (agent && typeof agent.switchMode === 'function') {
              agent.switchMode(mode, true); // 保留对话历史
              broadcastToSession(sessionId, {
                type: 'mode_switched',
                sessionId,
                payload: { mode },
              });
              console.log(`[WS] Mode switched for session ${sessionId}: ${mode}`);
            } else {
              console.warn(`[WS] Agent does not support switchMode for session ${sessionId}`);
            }
          } catch (error) {
            console.error(`[WS] Failed to switch mode for session ${sessionId}:`, error);
            broadcastToSession(sessionId, {
              type: 'error',
              sessionId,
              payload: { message: 'Failed to switch mode' },
            });
          }
        }
        break;
      }

      case 'user_input_response': {
        // 处理用户输入响应（用于 ask_user_question 等工具）
        const toolCallId = message.payload?.toolCallId;
        const answer = message.payload?.answer;

        if (toolCallId && answer !== undefined) {
          const handled = submitUserInput(toolCallId, answer);
          if (!handled) {
            console.warn(`[WS] User input response for unknown tool call: ${toolCallId}`);
            broadcastToSession(sessionId, {
              type: 'error',
              sessionId,
              payload: { message: `No pending input request for tool call: ${toolCallId}` },
            });
          } else {
            console.log(`[WS] User input submitted for tool call: ${toolCallId}`);
          }
        } else {
          broadcastToSession(sessionId, {
            type: 'error',
            sessionId,
            payload: { message: 'Missing toolCallId or answer in user_input_response' },
          });
        }
        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,
  };
}

/**
 * 处理系统命令（: 前缀）
 */
async function handleSystemCommand(sessionId: string, content: string): Promise<void> {
  const sessionManager = getSessionManager();

  console.log(`[WS] System command: ${content}`);

  // 执行系统命令
  const result = await executeSystemCommand(content, { sessionId });

  // 处理特殊操作
  if (result.success && result.action) {
    switch (result.action.type) {
      case 'clear_messages': {
        // 清空存储的消息
        await MessageStorage.removeBySession(sessionId);

        // 清空 Agent 内存中的对话历史
        clearAgentHistory(sessionId);

        // 重置会话状态
        sessionManager.updateStatus(sessionId, 'idle');
        break;
      }

      case 'new_session': {
        // 获取当前会话信息以复用配置
        const currentSession = sessionManager.get(sessionId);
        const workdir = currentSession?.workdir || process.cwd();

        // 创建新会话
        const newSession = await sessionManager.create({ workdir });

        // 更新 action 中的 sessionId
        result.action = { type: 'new_session', sessionId: newSession.id };
        break;
      }
    }
  }

  // 发送结果给客户端
  broadcastToSession(sessionId, {
    type: 'system_command_result',
    sessionId,
    payload: {
      success: result.success,
      message: result.message,
      error: result.error,
      action: result.action,
    },
  });
}