Recordly/src/utils/aspectRatioUtils.ts

export const ASPECT_RATIOS = ['native', '16:9', '9:16', '1:1', '4:3', '4:5', '16:10', '10:16'] as const;

type PresetAspectRatio = typeof ASPECT_RATIOS[number];
type CustomAspectRatio = `${number}:${number}`;

export type AspectRatio = PresetAspectRatio | CustomAspectRatio;

const CUSTOM_ASPECT_RATIO_REGEX = /^(\d+):(\d+)$/;

export function isCustomAspectRatio(aspectRatio: string): aspectRatio is CustomAspectRatio {
  if ((ASPECT_RATIOS as readonly string[]).includes(aspectRatio)) {
    return false;
  }
  const match = aspectRatio.match(CUSTOM_ASPECT_RATIO_REGEX);
  if (!match) {
    return false;
  }
  const width = Number(match[1]);
  const height = Number(match[2]);
  return Number.isFinite(width) && Number.isFinite(height) && width > 0 && height > 0;
}

function parseCustomAspectRatioValue(aspectRatio: string): number | null {
  if (!isCustomAspectRatio(aspectRatio)) {
    return null;
  }
  const [widthText, heightText] = aspectRatio.split(':');
  const width = Number(widthText);
  const height = Number(heightText);
  if (!Number.isFinite(width) || !Number.isFinite(height) || width <= 0 || height <= 0) {
    return null;
  }
  return width / height;
}

/**
 * Returns the numeric value of an aspect ratio.
 * Uses exhaustive type checking to ensure all AspectRatio cases are handled.
 * If TypeScript errors here, a new ratio was added to the type but not handled.
 */
export function getAspectRatioValue(aspectRatio: AspectRatio, nativeAspectRatio = 16 / 9): number {
  switch (aspectRatio) {
    case 'native': return nativeAspectRatio > 0 ? nativeAspectRatio : 16 / 9;
    case '16:9': return 16 / 9;
    case '9:16': return 9 / 16;
    case '1:1':  return 1;
    case '4:3':  return 4 / 3;
    case '4:5':  return 4 / 5;
    case '16:10': return 16 / 10;
    case '10:16': return 10 / 16;
    default:
      return parseCustomAspectRatioValue(aspectRatio) ?? 16 / 9;
  }
}

export function getAspectRatioDimensions(
  aspectRatio: AspectRatio,
  baseWidth: number,
  nativeAspectRatio?: number,
): { width: number; height: number } {
  const ratio = getAspectRatioValue(aspectRatio, nativeAspectRatio);
  return {
    width: baseWidth,
    height: baseWidth / ratio,
  };
}

export function getAspectRatioLabel(aspectRatio: AspectRatio): string {
  if (aspectRatio === 'native') {
    return 'Native';
  }
  if (isCustomAspectRatio(aspectRatio)) {
    return `Custom ${aspectRatio}`;
  }
  return aspectRatio;
}


export function formatAspectRatioForCSS(aspectRatio: AspectRatio, nativeAspectRatio = 16 / 9): string {
  if (aspectRatio === 'native') {
    return `${nativeAspectRatio > 0 ? nativeAspectRatio : 16 / 9}`;
  }
  return aspectRatio.replace(':', '/');
}