/**
 * Copyright (c) 2019 The xterm.js authors. All rights reserved.
 * @license MIT
 */

import { IRenderer } from './Types';
import { RenderDebouncer } from '../ui/RenderDebouncer';
import { EventEmitter2, IEvent } from '../common/EventEmitter2';

export class RenderCoordinator {
  private _renderDebouncer: RenderDebouncer;

  private _onCanvasResize = new EventEmitter2<{ width: number, height: number }>();
  public get onCanvasResize(): IEvent<{ width: number, height: number }> { return this._onCanvasResize.event; }
  private _onRender = new EventEmitter2<{ start: number, end: number }>();
  public get onRender(): IEvent<{ start: number, end: number }> { return this._onRender.event; }

  private _canvasWidth: number = 0;
  private _canvasHeight: number = 0;

  constructor(
    private _renderer: IRenderer,
    private _rowCount: number
  ) {
    this._renderDebouncer = new RenderDebouncer((start, end) => this._renderRows(start, end));
  }

  public refreshRows(start: number, end: number): void {
    this._renderDebouncer.refresh(start, end, this._rowCount);
  }

  private _renderRows(start: number, end: number): void {
    this._renderer.renderRows(start, end);
    this._onRender.fire({ start, end });
  }

  public resize(cols: number, rows: number): void {
    this._rowCount = rows;
    this._fireOnCanvasResize();
  }

  public changeOptions(): void {
    this._renderer.onOptionsChanged();
    this._fireOnCanvasResize();
  }

  private _fireOnCanvasResize(): void {
    // Don't fire the event if the dimensions haven't changed
    if (this._renderer.dimensions.canvasWidth === this._canvasWidth && this._renderer.dimensions.canvasHeight === this._canvasHeight) {
      return;
    }
    this._canvasWidth = this._renderer.dimensions.canvasWidth;
    this._canvasHeight = this._renderer.dimensions.canvasHeight;
    this._onCanvasResize.fire({
      width: this._canvasWidth,
      height: this._canvasHeight
    });
  }

  public setRenderer(renderer: IRenderer): void {
    this._renderer = renderer;
  }
}