import {Injectable} from '@angular/core';
import {ThumbnailLoaderService, ThumbnailLoadingListener, ThumbnailLoadingPriority, ThumbnailTaskEntity} from './thumnailLoader.service';
import {Media} from './Media';
import {MediaIcon} from './MediaIcon';


@Injectable()
export class ThumbnailManagerService {


  constructor(private thumbnailLoader: ThumbnailLoaderService) {
  }

  public getThumbnail(photo: Media): Thumbnail {
    return new Thumbnail(photo, this.thumbnailLoader);
  }

  public getLazyThumbnail(photo: Media): Thumbnail {
    return new Thumbnail(photo, this.thumbnailLoader, false);
  }


  public getIcon(photo: MediaIcon) {
    return new IconThumbnail(photo, this.thumbnailLoader);
  }
}


export abstract class ThumbnailBase {

  protected available = false;
  protected src: string = null;
  public loading = false;
  protected error = false;
  protected onLoad: Function = null;
  protected thumbnailTask: ThumbnailTaskEntity = null;


  protected constructor(protected thumbnailService: ThumbnailLoaderService) {
  }

  abstract set Visible(visible: boolean);

  set OnLoad(onLoad: Function) {
    this.onLoad = onLoad;
  }


  get Available(): boolean {
    return this.available;
  }

  get Src(): string {
    return this.src;
  }

  get Loading(): boolean {
    return this.loading;
  }

  get Error(): boolean {
    return this.error;
  }

  destroy() {
    if (this.thumbnailTask != null) {
      this.thumbnailService.removeTask(this.thumbnailTask);
      this.thumbnailTask = null;
    }
  }
}


export class IconThumbnail extends ThumbnailBase {

  constructor(private media: MediaIcon, thumbnailService: ThumbnailLoaderService) {
    super(thumbnailService);
    this.src = '';
    this.error = false;
    if (this.media.isIconAvailable()) {
      this.src = this.media.getIconPath();
      this.available = true;
      if (this.onLoad) {
        this.onLoad();
      }
    }

    if (!this.media.isIconAvailable()) {
      setTimeout(() => {

        const listener: ThumbnailLoadingListener = {
          onStartedLoading: () => { // onLoadStarted
            this.loading = true;
          },
          onLoad: () => {// onLoaded
            this.src = this.media.getIconPath();
            if (this.onLoad) {
              this.onLoad();
            }
            this.available = true;
            this.loading = false;
            this.thumbnailTask = null;
          },
          onError: (error) => {// onError
            this.thumbnailTask = null;
            this.loading = false;
            this.error = true;
          }
        };
        this.thumbnailTask = this.thumbnailService.loadIcon(this.media, ThumbnailLoadingPriority.high, listener);


      }, 0);
    }

  }

  set Visible(visible: boolean) {
    if (!this.thumbnailTask) {
      return;
    }
    if (visible === true) {
      this.thumbnailTask.priority = ThumbnailLoadingPriority.high;
    } else {
      this.thumbnailTask.priority = ThumbnailLoadingPriority.medium;
    }
  }


}

export class Thumbnail extends ThumbnailBase {


  constructor(private media: Media, thumbnailService: ThumbnailLoaderService, autoLoad: boolean = true) {
    super(thumbnailService);
    if (this.media.isThumbnailAvailable()) {
      this.src = this.media.getThumbnailPath();
      this.available = true;
      if (this.onLoad) {
        this.onLoad();
      }
    } else if (this.media.isReplacementThumbnailAvailable()) {
      this.src = this.media.getReplacementThumbnailPath();
      this.available = true;
    }
    if (autoLoad) {
      this.load();
    }
  }

  set CurrentlyWaiting(value: boolean) {
    if (!this.thumbnailTask) {
      return;
    }
    if (value === true) {
      if (this.media.isReplacementThumbnailAvailable()) {
        this.thumbnailTask.priority = ThumbnailLoadingPriority.medium;
      } else {
        this.thumbnailTask.priority = ThumbnailLoadingPriority.extraHigh;
      }
    } else {
      if (this.media.isReplacementThumbnailAvailable()) {
        this.thumbnailTask.priority = ThumbnailLoadingPriority.low;
      } else {
        this.thumbnailTask.priority = ThumbnailLoadingPriority.medium;
      }
    }
  }

  set Visible(visible: boolean) {
    if (!this.thumbnailTask) {
      return;
    }
    if (visible === true) {
      if (this.media.isReplacementThumbnailAvailable()) {
        this.thumbnailTask.priority = ThumbnailLoadingPriority.medium;
      } else {
        this.thumbnailTask.priority = ThumbnailLoadingPriority.high;
      }
    } else {
      if (this.media.isReplacementThumbnailAvailable()) {
        this.thumbnailTask.priority = ThumbnailLoadingPriority.low;
      } else {
        this.thumbnailTask.priority = ThumbnailLoadingPriority.medium;
      }
    }
  }

  public load() {
    if (!this.media.isThumbnailAvailable() && this.thumbnailTask == null) {
      //    setTimeout(() => {
      const listener: ThumbnailLoadingListener = {
        onStartedLoading: () => { // onLoadStarted
          this.loading = true;
        },
        onLoad: () => {// onLoaded
          this.src = this.media.getThumbnailPath();
          if (this.onLoad) {
            this.onLoad();
          }
          this.available = true;
          this.loading = false;
          this.thumbnailTask = null;
        },
        onError: (error) => {// onError
          this.thumbnailTask = null;
          this.loading = false;
          this.error = true;
        }
      };
      if (this.media.isReplacementThumbnailAvailable()) {
        this.thumbnailTask = this.thumbnailService.loadImage(this.media, ThumbnailLoadingPriority.medium, listener);
      } else {
        this.thumbnailTask = this.thumbnailService.loadImage(this.media, ThumbnailLoadingPriority.high, listener);
      }
      // }, 0);
    }
  }

}