export const MARKDOWN_IMAGE_MAX_WIDTH = 480;
export const MARKDOWN_IMAGE_MAX_HEIGHT = 480;

export interface MarkdownImageDisplaySize {
  readonly width: number;
  readonly height: number;
}

/** Keeps small images intrinsic while fitting larger images inside the chat viewport. */
export function resolveMarkdownImageDisplaySize(input: {
  readonly sourceWidth: number;
  readonly sourceHeight: number;
  readonly availableWidth: number;
}): MarkdownImageDisplaySize | null {
  if (
    !Number.isFinite(input.sourceWidth) ||
    !Number.isFinite(input.sourceHeight) ||
    !Number.isFinite(input.availableWidth) ||
    input.sourceWidth <= 0 ||
    input.sourceHeight <= 0 ||
    input.availableWidth <= 0
  ) {
    return null;
  }

  const scale = Math.min(
    1,
    input.availableWidth / input.sourceWidth,
    MARKDOWN_IMAGE_MAX_WIDTH / input.sourceWidth,
    MARKDOWN_IMAGE_MAX_HEIGHT / input.sourceHeight,
  );

  return {
    width: input.sourceWidth * scale,
    height: input.sourceHeight * scale,
  };
}