// utils/todoStorage.ts

export interface ITodo {
  id: string;
  text: string;
  completed: boolean;
  priority: 'high' | 'medium' | 'low';
  createdAt: number;
  completedAt?: number;
  category?: string;
  deadline?: number;
  note?: string;
}

export interface ITodoStats {
  total: number;
  completed: number;
  pending: number;
  completionRate: number;
  todayCompleted: number;
}

class TodoStorage {
  private readonly STORAGE_KEY = 'pure_todo_data';
  private readonly STATS_KEY = 'pure_todo_stats';

  // 获取所有待办事项
  getAllTodos(): ITodo[] {
    try {
      const data = wx.getStorageSync(this.STORAGE_KEY);
      return data ? JSON.parse(data) : [];
    } catch (error) {
      console.error('获取待办事项失败:', error);
      return [];
    }
  }

  // 保存所有待办事项
  saveAllTodos(todos: ITodo[]): void {
    try {
      wx.setStorageSync(this.STORAGE_KEY, JSON.stringify(todos));
      this.updateStats(todos);
    } catch (error) {
      console.error('保存待办事项失败:', error);
    }
  }

  // 添加新待办事项
  addTodo(
    text: string, 
    priority: 'high' | 'medium' | 'low' = 'medium', 
    category?: string,
    deadline?: number,
    note?: string
  ): ITodo {
    const todos = this.getAllTodos();
    const newTodo: ITodo = {
      id: this.generateId(),
      text: text.trim(),
      completed: false,
      priority,
      createdAt: Date.now(),
      category,
      deadline,
      note
    };
    
    todos.unshift(newTodo);
    this.saveAllTodos(todos);
    return newTodo;
  }

  // 更新待办事项
  updateTodo(id: string, updates: Partial<ITodo>): boolean {
    const todos = this.getAllTodos();
    const index = todos.findIndex(todo => todo.id === id);
    
    if (index !== -1) {
      todos[index] = { ...todos[index], ...updates };
      if (updates.completed !== undefined) {
        todos[index].completedAt = updates.completed ? Date.now() : undefined;
      }
      this.saveAllTodos(todos);
      return true;
    }
    return false;
  }

  // 删除待办事项
  deleteTodo(id: string): boolean {
    const todos = this.getAllTodos();
    const filteredTodos = todos.filter(todo => todo.id !== id);
    
    if (filteredTodos.length !== todos.length) {
      this.saveAllTodos(filteredTodos);
      return true;
    }
    return false;
  }

  // 切换完成状态
  toggleTodo(id: string): boolean {
    const todos = this.getAllTodos();
    const todo = todos.find(t => t.id === id);
    
    if (todo) {
      return this.updateTodo(id, { 
        completed: !todo.completed,
        completedAt: !todo.completed ? Date.now() : undefined
      });
    }
    return false;
  }

  // 获取统计信息
  getStats(): ITodoStats {
    try {
      const data = wx.getStorageSync(this.STATS_KEY);
      return data ? JSON.parse(data) : this.calculateStats();
    } catch (error) {
      return this.calculateStats();
    }
  }

  // 计算统计信息
  private calculateStats(): ITodoStats {
    const todos = this.getAllTodos();
    const total = todos.length;
    const completed = todos.filter(todo => todo.completed).length;
    const pending = total - completed;
    const completionRate = total > 0 ? Math.round((completed / total) * 100) : 0;
    
    // 计算今日完成的任务
    const today = new Date();
    today.setHours(0, 0, 0, 0);
    const todayCompleted = todos.filter(todo => 
      todo.completed && todo.completedAt && todo.completedAt >= today.getTime()
    ).length;

    return {
      total,
      completed,
      pending,
      completionRate,
      todayCompleted
    };
  }

  // 更新统计信息
  private updateStats(todos: ITodo[]): void {
    const stats = this.calculateStats();
    try {
      wx.setStorageSync(this.STATS_KEY, JSON.stringify(stats));
    } catch (error) {
      console.error('更新统计信息失败:', error);
    }
  }

  // 生成唯一ID
  private generateId(): string {
    return Date.now().toString(36) + Math.random().toString(36).substr(2);
  }

  // 按优先级获取待办事项
  getTodosByPriority(priority?: 'high' | 'medium' | 'low'): ITodo[] {
    const todos = this.getAllTodos();
    if (priority) {
      return todos.filter(todo => todo.priority === priority);
    }
    return todos;
  }

  // 获取今日待办事项
  getTodayTodos(): ITodo[] {
    const todos = this.getAllTodos();
    const today = new Date();
    today.setHours(0, 0, 0, 0);
    
    return todos.filter(todo => {
      const todoDate = new Date(todo.createdAt);
      todoDate.setHours(0, 0, 0, 0);
      return todoDate.getTime() === today.getTime();
    });
  }

  // 清空所有数据
  clearAllData(): void {
    try {
      wx.removeStorageSync(this.STORAGE_KEY);
      wx.removeStorageSync(this.STATS_KEY);
    } catch (error) {
      console.error('清空数据失败:', error);
    }
  }

  // 导出数据
  exportData(): string {
    const todos = this.getAllTodos();
    const stats = this.getStats();
    return JSON.stringify({ todos, stats, exportTime: Date.now() });
  }

  // 导入数据
  importData(dataString: string): boolean {
    try {
      const data = JSON.parse(dataString);
      if (data.todos && Array.isArray(data.todos)) {
        this.saveAllTodos(data.todos);
        return true;
      }
      return false;
    } catch (error) {
      console.error('导入数据失败:', error);
      return false;
    }
  }
}

export const todoStorage = new TodoStorage();