export type GlyphHash = GlyphHashFragment[];
type GlyphHashFragment = {
	glyph: string;
	color: string;
};

const internals = {
	kDehyphenRegex: /[-]/g,
	kSplitterRegex: /.{1,8}/g,
	kGlyphs: ['☽', '☆', '♢', '♡', '╱', '╲', '╳', '〰', '▷', '⏊', '〒', '▢', '◯', '⏃', '⏀', '⏆'],
	unexpectedUUIDLength: class UnexpectedUUIDLength extends Error {
		name = 'UnexpectedUUIDLength';
		message =
			'The provided string was not a valid UUIDv4, please provide a 32 character long string';
	}
};

// Return a glyph with color based on a 4 byte fragment of a UUIDv4
const getGlyphHashFragment = function (uuidFragment: string): GlyphHashFragment {
	const glyphIndex = parseInt(uuidFragment.substring(0, 2), 16) % 16;
	return {
		glyph: internals.kGlyphs[glyphIndex],
		color: `#${uuidFragment.substring(2, 8)}`
	};
};

// Return an array of glyphs based on a UUIDv4
export const getGlyphHash = function (uuid: string): GlyphHash {
	const dehyphenedUuid = uuid.replace(/[-]/g, '');

	if (dehyphenedUuid.length !== 32) {
		throw new internals.unexpectedUUIDLength();
	}

	const hashFragments = dehyphenedUuid.match(internals.kSplitterRegex);
	return hashFragments.map(getGlyphHashFragment);
};