import { VideoItem } from './VideoItem';

/**
 * 上传任务状态枚举
 */
export enum UploadTaskStatus {
  Pending = 0,    // 等待中
  Uploading = 1,  // 上传中
  Success = 2,    // 成功
  Failed = 3,     // 失败
  Paused = 4      // 已暂停
}

/**
 * 上传任务数据源（用于LazyForEach优化）
 */
export class UploadTaskDataSource implements IDataSource {
  private tasks: VideoItem[] = [];
  private listeners: DataChangeListener[] = [];

  public totalCount(): number {
    return this.tasks.length;
  }

  public getData(index: number): VideoItem {
    return this.tasks[index];
  }

  public registerDataChangeListener(listener: DataChangeListener): void {
    if (this.listeners.indexOf(listener) < 0) {
      this.listeners.push(listener);
    }
  }

  public unregisterDataChangeListener(listener: DataChangeListener): void {
    const pos = this.listeners.indexOf(listener);
    if (pos >= 0) {
      this.listeners.splice(pos, 1);
    }
  }

  /**
   * 更新数据源
   * @param tasks 新的任务列表
   */
  public updateTasks(tasks: VideoItem[]): void {
    this.tasks = tasks;
    this.notifyDataReload();
  }

  /**
   * 添加任务
   * @param task 任务
   */
  public addTask(task: VideoItem): void {
    this.tasks.push(task);
    this.notifyDataAdd(this.tasks.length - 1);
  }

  /**
   * 移除任务
   * @param index 索引
   */
  public removeTask(index: number): void {
    if (index >= 0 && index < this.tasks.length) {
      this.tasks.splice(index, 1);
      this.notifyDataDelete(index);
    }
  }

  /**
   * 清空任务
   */
  public clearTasks(): void {
    this.tasks = [];
    this.notifyDataReload();
  }

  /**
   * 通知数据重新加载
   */
  private notifyDataReload(): void {
    this.listeners.forEach(listener => {
      listener.onDataReloaded();
    });
  }

  /**
   * 通知数据添加
   * @param index 索引
   */
  private notifyDataAdd(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataAdd(index);
    });
  }

  /**
   * 通知数据删除
   * @param index 索引
   */
  private notifyDataDelete(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataDelete(index);
    });
  }

  /**
   * 通知数据变更
   * @param index 索引
   */
  private notifyDataChange(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataChange(index);
    });
  }
}