import { vec2 } from 'gl-matrix';
import { UniversalRenderingContext } from '../universal-rendering-context';

export abstract class FrameBuffer {
  public renderScale = 1;
  public enableHighDpiRendering = false;

  protected size = vec2.create();

  // null means the default framebuffer
  protected frameBuffer: WebGLFramebuffer | null = null;

  constructor(protected readonly gl: UniversalRenderingContext) {}

  public bindAndClear(inputTextures: Array<WebGLTexture>) {
    this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, this.frameBuffer);

    inputTextures.forEach((t, i) => {
      this.gl.activeTexture(this.gl.TEXTURE0 + i);
      this.gl.bindTexture(this.gl.TEXTURE_2D, t);
    });

    this.gl.viewport(0, 0, this.size.x, this.size.y);
    this.gl.clearColor(0, 0, 0, 0);
    this.gl.clear(this.gl.COLOR_BUFFER_BIT | this.gl.DEPTH_BUFFER_BIT);
  }

  public destroy(): void {
    this.gl.deleteFramebuffer(this.frameBuffer);
  }

  public setSize(): boolean {
    const realToCssPixels =
      (this.enableHighDpiRendering ? window.devicePixelRatio : 1) * this.renderScale;

    const canvasWidth = (this.gl.canvas as HTMLCanvasElement).clientWidth;
    const canvasHeight = (this.gl.canvas as HTMLCanvasElement).clientHeight;

    const displayWidth = Math.floor(canvasWidth * realToCssPixels);
    const displayHeight = Math.floor(canvasHeight * realToCssPixels);

    const oldSize = vec2.clone(this.getSize());
    this.size = vec2.fromValues(displayWidth, displayHeight);

    return this.size.x != oldSize.x || this.size.y != oldSize.y;
  }

  public getSize(): vec2 {
    return this.size;
  }
}