/**
 * Session Manager
 *
 * 管理所有活跃的会话
 */

import { v4 as uuidv4 } from 'uuid';
import type { Session, CreateSessionInput, Message, SessionStatus } from '../types.js';

export class SessionManager {
  private sessions: Map<string, Session> = new Map();
  private messages: Map<string, Message[]> = new Map();

  /**
   * 创建新会话
   */
  create(input: CreateSessionInput = {}): Session {
    const now = new Date().toISOString();
    const session: Session = {
      id: uuidv4(),
      name: input.name,
      workdir: input.workdir || process.cwd(),
      createdAt: now,
      updatedAt: now,
      status: 'idle',
      messageCount: 0,
    };

    this.sessions.set(session.id, session);
    this.messages.set(session.id, []);

    return session;
  }

  /**
   * 获取所有会话
   */
  list(): Session[] {
    return Array.from(this.sessions.values()).sort(
      (a, b) => new Date(b.updatedAt).getTime() - new Date(a.updatedAt).getTime()
    );
  }

  /**
   * 获取单个会话
   */
  get(id: string): Session | undefined {
    return this.sessions.get(id);
  }

  /**
   * 删除会话
   */
  delete(id: string): boolean {
    this.messages.delete(id);
    return this.sessions.delete(id);
  }

  /**
   * 更新会话状态
   */
  updateStatus(id: string, status: SessionStatus): Session | undefined {
    const session = this.sessions.get(id);
    if (!session) return undefined;

    session.status = status;
    session.updatedAt = new Date().toISOString();
    return session;
  }

  /**
   * 获取会话消息
   */
  getMessages(sessionId: string): Message[] {
    return this.messages.get(sessionId) || [];
  }

  /**
   * 添加消息
   */
  addMessage(sessionId: string, message: Omit<Message, 'id' | 'sessionId' | 'createdAt'>): Message | undefined {
    const session = this.sessions.get(sessionId);
    if (!session) return undefined;

    const fullMessage: Message = {
      ...message,
      id: uuidv4(),
      sessionId,
      createdAt: new Date().toISOString(),
    };

    const messages = this.messages.get(sessionId) || [];
    messages.push(fullMessage);
    this.messages.set(sessionId, messages);

    // 更新会话
    session.messageCount = messages.length;
    session.updatedAt = new Date().toISOString();

    return fullMessage;
  }

  /**
   * 获取会话数量
   */
  count(): number {
    return this.sessions.size;
  }

  /**
   * 检查会话是否存在
   */
  exists(id: string): boolean {
    return this.sessions.has(id);
  }
}

// 单例
let instance: SessionManager | null = null;

export function getSessionManager(): SessionManager {
  if (!instance) {
    instance = new SessionManager();
  }
  return instance;
}