import * as THREE from 'three';

/** Supersample low-DPI GPU displays too; software WebGL keeps its latency budget. */
export function viewerPixelRatio(dpr: number, software: boolean): number {
  const ratio = Number.isFinite(dpr) && dpr > 0 ? dpr : 1;
  return software ? Math.min(ratio, 1.75) : Math.min(Math.max(ratio, 1.5), 2);
}

/** Fit shadow texels to the loaded scene instead of a default 10 m / 512 px map. */
export function fitSceneShadow(
  light: THREE.DirectionalLight,
  center: readonly number[],
  extent: number,
): void {
  const radius = Math.max(1, extent);
  light.target.position.set(center[0], center[1], center[2]);
  light.position
    .set(4, -3, 7)
    .normalize()
    .multiplyScalar(radius * 2)
    .add(light.target.position);
  const shadow = light.shadow;
  shadow.mapSize.set(2048, 2048);
  Object.assign(shadow.camera, {
    left: -radius,
    right: radius,
    top: radius,
    bottom: -radius,
    near: radius * 0.01,
    far: radius * 4,
  });
  shadow.bias = -0.00005;
  shadow.normalBias = radius / 4096;
  shadow.camera.updateProjectionMatrix();
  shadow.needsUpdate = true;
}

/** DataTexture defaults to nearest-neighbour; oblique camera views need mipmaps. */
export function filterSurfaceTexture(texture: THREE.DataTexture, maxAnisotropy: number): void {
  texture.magFilter = THREE.LinearFilter;
  texture.minFilter = THREE.LinearMipmapLinearFilter;
  texture.generateMipmaps = true;
  texture.anisotropy = Math.min(8, maxAnisotropy);
  texture.needsUpdate = true;
}