preview.manager.ts

'use strict';
import {Uri} from 'vscode';
import {DataPreview} from './data.preview';

export class PreviewManager {
    
  // singleton instance
  private static _instance: PreviewManager;
  // tracked previews for config/restore updates
  private _previews: DataPreview[] = [];

  private constructor() {
  }

  /**
   * Creates preview manager singleton instance.
   */
  public static get Instance() {
    return this._instance || (this._instance = new this());
  }

  /**
   * Adds new preview instance for config/restore tracking.
   * @param preview preview instance to add.
   */
  public add(preview: DataPreview): void {
    this._previews.push(preview!);
  }

  /**
   * Removes preview instance from previews tracking collection.
   * @param preview preview instance to remove.
   */
  public remove(preview: DataPreview): void {
    let found = this._previews.indexOf(preview!);
    if (found >= 0) {
      this._previews.splice(found, 1);
    }
  }

  /**
   * Returns matching preview for the specified data uri.
   * @param dataUri Data Uri to find for open data previews.
   */
  public find(dataUri: Uri): Array<DataPreview> {
    const dataUrl: string = dataUri.toString(true); // skip uri encoding
    return this._previews.filter(p => p.dataUrl === dataUrl);
  }

  /**
   * Returns active preview instance.
   */
  public active(): DataPreview {
    return this._previews.find(p => p.visible);
  }
    
  /**
   * Reloads open previews on extension config changes.
   */
  public configure(): void {
    this._previews.forEach(p => p.configure());
  }
}

// export preview manager singleton
export const previewManager = PreviewManager.Instance;