class BasicDataSource implements IDataSource {
  private listeners: DataChangeListener[] = [];
  private originDataArray: StringData[] = [];

  public totalCount(): number {
    return 0;
  }

  public getData(index: number): StringData {
    return this.originDataArray[index];
  }

  registerDataChangeListener(listener: DataChangeListener): void {
    if (this.listeners.indexOf(listener) < 0) {
      console.info('add listener');
      this.listeners.push(listener);
    }
  }

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

  notifyDataReload(): void {
    this.listeners.forEach(listener => {
      listener.onDataReloaded();
    })
  }

  notifyDataAdd(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataAdd(index);
    })
  }

  notifyDataChange(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataChange(index);
    })
  }

  notifyDataDelete(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataDelete(index);
    })
  }

  notifyDataMove(from: number, to: number): void {
    this.listeners.forEach(listener => {
      listener.onDataMove(from, to);
    })
  }
}

class MyDataSource extends BasicDataSource {
  private dataArray: StringData[] = [];

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

  public getData(index: number): StringData {
    return this.dataArray[index];
  }

  public addData(index: number, data: StringData): void {
    this.dataArray.splice(index, 0, data);
    this.notifyDataAdd(index);
  }

  public pushData(data: StringData): void {
    this.dataArray.push(data);
    this.notifyDataAdd(this.dataArray.length - 1);
  }

  public reloadData(): void {
    this.notifyDataReload();
  }
}

@ObservedV2
class StringData {
  @Trace message: string;
  @Trace imgSrc: Resource;
  constructor(message: string, imgSrc: Resource) {
    this.message = message;
    this.imgSrc = imgSrc;
  }
}

@Entry
@Component
struct MyComponent {
  private moved: number[] = [];
  private data: MyDataSource = new MyDataSource();

  aboutToAppear() {
    for (let i = 0; i <= 1; i++) {
      this.data.pushData(new StringData(`Hello ${i}`, $r('app.media.app_icon')));
    }
  }

  build() {
    List({ space: 3 }) {
      LazyForEach(this.data, (item: StringData, index: number) => {
        ListItem() {
          MyComp({ item: item })
        }
      }, (item: StringData, index: number) => JSON.stringify(item))
    }.cachedCount(5)
  }
}

@ObservedV2
class V1ToV2 {
  @Trace item?: StringData;
}

@Reusable
@Component struct MyComp {
  item: StringData = new StringData("1", $r('app.media.app_icon'))
  v12v2: V1ToV2 = new V1ToV2()
  aboutToAppear(): void {
    console.log( "=====reusecomp=====" + JSON.stringify(this.item ));
    this.v12v2.item = this.item
  }
  aboutToReuse(params: ESObject): void {
    this.v12v2.item = params["item"] as StringData
    console.log( "======Reuse data:" + this.item.message )
  }
  build() {
    MyCompV2({v12v2: this.v12v2})
  }
}


@ComponentV2 struct MyCompV2 {
  public v12v2?: V1ToV2
  get item() : StringData {
    return this.v12v2?.item!
  }
  aboutToAppear(): void {
    console.log( "==========" + JSON.stringify(this.item ));
  }
  build() {
    Column() {
      Text(this.item!.message).fontSize(50)
        .onAppear(() => {
          console.info("appear:" + this.item!.message)
        })
      Image(this.item!.imgSrc)
        .width(500)
        .height(200)
    }.margin({ left: 10, right: 10 })
  }
}