/**
 * 会话管理器
 * 作为编排器，委托具体工作给各个子模块
 */

import type { ModelMessage } from 'ai';
import * as storage from './storage/index.js';
import type { TodoItem } from './storage/index.js';

// 子模块
import { SessionStore, type SessionData, type SessionSummary } from './session-store.js';
import { ProjectManager, type ProjectMetadata } from './project-manager.js';
import { SessionAutoSave } from './session-auto-save.js';

// 重新导出类型
export type { SessionData, SessionSummary, ProjectMetadata };

/**
 * 会话管理器
 * 提供高级会话操作接口，使用新的三层存储结构
 */
export class SessionManager {
  private currentSession: SessionData | null = null;
  private storageDir?: string;

  // 子模块
  private store: SessionStore;
  private projectManager: ProjectManager;
  private autoSave: SessionAutoSave;

  constructor(storageDir?: string) {
    this.storageDir = storageDir;
    this.store = new SessionStore();
    this.projectManager = new ProjectManager();
    this.autoSave = new SessionAutoSave();
  }

  // ============================================================================
  // 初始化
  // ============================================================================

  /**
   * 初始化 - 尝试恢复或创建新会话
   */
  async init(workdir: string): Promise<SessionData> {
    // 初始化存储
    await storage.initStorage(this.storageDir);

    // 获取或创建项目
    await this.projectManager.getOrCreate(workdir);

    // 尝试加载当前会话
    const currentSessionId = await this.getCurrentSessionId();

    if (currentSessionId) {
      const projectId = this.projectManager.getProjectId()!;
      const existing = await this.store.load(projectId, currentSessionId);

      if (existing && existing.workdir === workdir) {
        this.currentSession = existing;
        this.startAutoSave();
        return this.currentSession;
      }
    }

    // 创建新会话
    const projectId = this.projectManager.getProjectId()!;
    this.currentSession = await this.store.create(projectId, workdir);
    await this.store.save(this.currentSession);
    await this.setCurrentSessionPointer(this.currentSession.id);

    this.startAutoSave();
    return this.currentSession;
  }

  // ============================================================================
  // 会话获取
  // ============================================================================

  /**
   * 获取当前会话
   */
  getSession(): SessionData | null {
    return this.currentSession;
  }

  /**
   * 获取当前项目
   */
  getProject(): ProjectMetadata | null {
    return this.projectManager.getProject();
  }

  /**
   * 获取当前会话 ID
   */
  getSessionId(): string | undefined {
    return this.currentSession?.id;
  }

  // ============================================================================
  // 会话操作
  // ============================================================================

  /**
   * 保存当前会话
   */
  async save(): Promise<void> {
    if (!this.currentSession) return;
    await this.store.save(this.currentSession);
  }

  /**
   * 清空当前会话并创建新会话
   */
  async newSession(workdir?: string): Promise<SessionData> {
    if (!this.projectManager.isInitialized()) {
      throw new Error('Project not initialized. Call init() first.');
    }

    const newWorkdir = workdir || this.currentSession?.workdir || process.cwd();

    // 如果工作目录变化，需要切换项目
    if (workdir && workdir !== this.projectManager.getProject()?.workdir) {
      await this.projectManager.switchProject(workdir);
    }

    const projectId = this.projectManager.getProjectId()!;
    this.currentSession = await this.store.create(projectId, newWorkdir);
    await this.store.save(this.currentSession);
    await this.setCurrentSessionPointer(this.currentSession.id);

    return this.currentSession;
  }

  /**
   * 恢复指定会话
   */
  async restoreSession(sessionId: string): Promise<SessionData | null> {
    if (!this.projectManager.isInitialized()) {
      throw new Error('Project not initialized. Call init() first.');
    }

    const projectId = this.projectManager.getProjectId()!;
    const session = await this.store.load(projectId, sessionId);
    if (!session) return null;

    this.currentSession = session;
    await this.setCurrentSessionPointer(sessionId);

    return session;
  }

  /**
   * 列出当前项目的历史会话
   */
  async listSessions(): Promise<SessionSummary[]> {
    const projectId = this.projectManager.getProjectId();
    if (!projectId) {
      return this.listAllSessions();
    }
    return this.store.listByProject(projectId);
  }

  /**
   * 列出所有项目的会话
   */
  async listAllSessions(): Promise<SessionSummary[]> {
    return this.store.listAll();
  }

  /**
   * 删除历史会话
   */
  async deleteSession(sessionId: string): Promise<boolean> {
    const projectId = this.projectManager.getProjectId();
    if (!projectId) return false;
    return this.store.delete(projectId, sessionId);
  }

  // ============================================================================
  // 消息操作
  // ============================================================================

  /**
   * 批量设置消息（用于同步整个对话历史）
   */
  async setMessages(messages: ModelMessage[]): Promise<void> {
    if (!this.currentSession) return;
    this.currentSession.messages = messages;
    await this.store.syncMessages(this.currentSession.id, messages);
    await this.store.save(this.currentSession);
  }

  /**
   * 添加消息
   */
  async addMessage(message: ModelMessage): Promise<void> {
    if (!this.currentSession) return;
    this.currentSession.messages.push(message);
    await this.setMessages(this.currentSession.messages);
  }

  /**
   * 获取对话历史
   */
  getMessages(): ModelMessage[] {
    return this.currentSession?.messages || [];
  }

  // ============================================================================
  // 工具和待办操作
  // ============================================================================

  /**
   * 设置已发现的工具
   */
  async setDiscoveredTools(tools: string[]): Promise<void> {
    if (!this.currentSession) return;
    this.currentSession.discoveredTools = tools;
    await this.store.save(this.currentSession);
  }

  /**
   * 获取已发现的工具
   */
  getDiscoveredTools(): string[] {
    return this.currentSession?.discoveredTools || [];
  }

  /**
   * 更新待办事项
   */
  async setTodos(
    todos: Array<{ content: string; status: 'pending' | 'in_progress' | 'completed' }>
  ): Promise<void> {
    if (!this.currentSession) return;
    const items = await this.store.setTodos(this.currentSession.id, todos);
    this.currentSession.todos = items;
  }

  /**
   * 获取待办事项
   */
  getTodos(): TodoItem[] {
    return this.currentSession?.todos || [];
  }

  // ============================================================================
  // 子会话操作
  // ============================================================================

  /**
   * 创建子会话（用于 Task 工具）
   */
  createChildSession(parentId: string, agentName: string, title?: string): SessionData {
    if (!this.projectManager.isInitialized()) {
      throw new Error('Project not initialized. Call init() first.');
    }

    const projectId = this.projectManager.getProjectId()!;
    const workdir = this.currentSession?.workdir || process.cwd();
    return this.store.createChildSession(projectId, parentId, agentName, workdir, title);
  }

  /**
   * 保存子会话
   */
  async saveChildSession(session: SessionData): Promise<void> {
    await this.store.saveChildSession(session);
  }

  // ============================================================================
  // 自动保存
  // ============================================================================

  /**
   * 启动自动保存
   */
  private startAutoSave(): void {
    this.autoSave.start(() => this.save());
  }

  /**
   * 停止自动保存
   */
  stopAutoSave(): void {
    this.autoSave.stop();
  }

  /**
   * 关闭管理器（保存并停止自动保存）
   */
  async close(): Promise<void> {
    this.stopAutoSave();
    await this.save();
  }

  // ============================================================================
  // 清理
  // ============================================================================

  /**
   * 清理旧会话
   */
  async cleanup(keepCount: number = 50): Promise<number> {
    const sessions = await this.listAllSessions();
    if (sessions.length <= keepCount) {
      return 0;
    }

    const toDelete = sessions.slice(keepCount);
    let deletedCount = 0;

    for (const session of toDelete) {
      if (await this.deleteSession(session.id)) {
        deletedCount++;
      }
    }

    return deletedCount;
  }

  // ============================================================================
  // 辅助方法
  // ============================================================================

  /**
   * 获取当前会话 ID（从存储）
   */
  private async getCurrentSessionId(): Promise<string | null> {
    try {
      const pointer = await storage.read<{ sessionId: string }>(['current-session']);
      return pointer.sessionId;
    } catch {
      return null;
    }
  }

  /**
   * 设置当前会话指针
   */
  private async setCurrentSessionPointer(sessionId: string): Promise<void> {
    await storage.write(['current-session'], { sessionId });
  }

  /**
   * 获取存储目录
   */
  getStorageDir(): string {
    return this.storageDir || storage.getDefaultStorageDir();
  }
}

// 导出默认实例
export const sessionManager = new SessionManager();