import {mat3} from 'gl-matrix';

// Computes the transformation matrix that is used to render scaled
// elements to the DOM and draw the view.
export class TraceView {
  public x: number;
  public y: number;
  public width: number;
  public height: number;

  constructor(x: number, y: number, width: number, height: number) {
    this.x = x;
    this.y = y;
    this.width = width;
    this.height = height;
  }

  static From(view: TraceView): TraceView {
    return new TraceView(view.x, view.y, view.width, view.height);
  }
  static Empty(): TraceView {
    return new TraceView(0, 0, 1000, 1);
  }

  serialize() {
    return [this.x, this.y, this.width, this.height];
  }

  between(to: TraceView): mat3 {
    return mat3.fromValues(
      to.width / this.width,
      0,
      0,
      to.height / this.height,
      0,
      0,
      to.x - this.x * (to.width / this.width),
      to.y - this.y * (to.height / this.height),
      1
    );
  }

  transform(mat: mat3): [number, number, number, number] {
    const x = this.x * mat[0] + this.y * mat[3] + mat[6];
    const y = this.x * mat[1] + this.y * mat[4] + mat[7];
    const width = this.width * mat[0] + this.height * mat[3];
    const height = this.width * mat[1] + this.height * mat[4];
    return [x, y, width, height];
  }

  get center() {
    return this.x + this.width / 2;
  }

  get left() {
    return this.x;
  }
  get right() {
    return this.x + this.width;
  }
  get top() {
    return this.y;
  }
  get bottom() {
    return this.y + this.height;
  }
}