export type RenderScale = "adaptive" | 1 | 1.5 | 2;
export type TextureFiltering = 1 | 4 | 16;
export type ShadowQuality = "off" | "standard" | "high";
export type AmbientFill = "low" | "authored" | "high";

export interface GraphicsSettings {
  readonly renderScale: RenderScale;
  readonly textureFiltering: TextureFiltering;
  readonly shadowQuality: ShadowQuality;
  readonly ambientFill: AmbientFill;
}

export const DEFAULT_GRAPHICS_SETTINGS: GraphicsSettings = Object.freeze({
  renderScale: "adaptive",
  textureFiltering: 1,
  shadowQuality: "standard",
  ambientFill: "authored",
});

export const RENDER_SCALES: readonly RenderScale[] = ["adaptive", 1, 1.5, 2];
export const TEXTURE_FILTERING_LEVELS: readonly TextureFiltering[] = [1, 4, 16];
export const SHADOW_QUALITIES: readonly ShadowQuality[] = ["off", "standard", "high"];
export const AMBIENT_FILL_LEVELS: readonly AmbientFill[] = ["low", "authored", "high"];

export function normalizeGraphicsSettings(
  current: GraphicsSettings,
  patch: Partial<GraphicsSettings>,
): GraphicsSettings {
  return {
    renderScale: RENDER_SCALES.includes(patch.renderScale as RenderScale)
      ? patch.renderScale! : current.renderScale,
    textureFiltering: TEXTURE_FILTERING_LEVELS.includes(patch.textureFiltering as TextureFiltering)
      ? patch.textureFiltering! : current.textureFiltering,
    shadowQuality: SHADOW_QUALITIES.includes(patch.shadowQuality as ShadowQuality)
      ? patch.shadowQuality! : current.shadowQuality,
    ambientFill: AMBIENT_FILL_LEVELS.includes(patch.ambientFill as AmbientFill)
      ? patch.ambientFill! : current.ambientFill,
  };
}

export function ambientFillMultiplier(fill: AmbientFill): number {
  return fill === "low" ? 0.6 : fill === "high" ? 1.4 : 1;
}

export function nextGraphicsChoice<T>(current: T, choices: readonly T[]): T {
  return choices[(choices.indexOf(current) + 1) % choices.length];
}