import type { GPUVegaCanvasContext } from '../types/context.js';

/**
 * The ratio a canvas asks for, before the renderer caps or locks it. A
 * detached canvas has no display to follow, so it stays at 1.
 */
export function pixelRatio(canvas: HTMLCanvasElement, scaleFactor?: number): number {
  if (scaleFactor != null) {
    return scaleFactor;
  }
  const inDOM = typeof HTMLElement !== 'undefined' && canvas instanceof HTMLElement && canvas.parentNode != null;
  return inDOM ? window.devicePixelRatio || 1 : 1;
}

/**
 * Sizes the WebGPU canvas to the view and mirrors the coordinate transform
 * onto the detached pick canvas so geometric hit-testing (isPointInPath)
 * matches what is rendered.
 */
export default function resize(
  canvas: HTMLCanvasElement,
  context: GPUVegaCanvasContext,
  width: number,
  height: number,
  origin: readonly [number, number],
  pickCanvas: HTMLCanvasElement,
  pickContext: CanvasRenderingContext2D,
  ratio: number,
): void {
  canvas.width = width * ratio;
  canvas.height = height * ratio;

  pickCanvas.width = width * ratio;
  pickCanvas.height = height * ratio;
  // vega's canvas picking reads pixelRatio off the context and tests paths
  // in the same transformed space the marks are drawn in.
  (pickContext as CanvasRenderingContext2D & { pixelRatio: number }).pixelRatio = ratio;
  pickContext.setTransform(ratio, 0, 0, ratio, ratio * origin[0], ratio * origin[1]);

  if (ratio !== 1) {
    canvas.style.width = `${width}px`;
    canvas.style.height = `${height}px`;
  }

  context._origin = origin;
  context._ratio = ratio;
}