lindell / JsBarcode

// Match Set functions

const matchSetALength = (string) => string.match(new RegExp(`^${A_CHARS}*`))[0].length;

const matchSetBLength = (string) => string.match(new RegExp(`^${B_CHARS}*`))[0].length;

const matchSetC = (string) => string.match(new RegExp(`^${C_CHARS}*`))[0];

// CODE128A or CODE128B

function autoSelectFromAB(string, isA){

	const ranges = isA ? A_CHARS : B_CHARS;

	const untilC = string.match(new RegExp(`^(${ranges}+?)(([0-9]{2}){2,})([^0-9]|$)`));

	if (untilC) {

		return (

			untilC[1] +

			String.fromCharCode(204) +

			autoSelectFromC(string.substring(untilC[1].length))

		);

	}

	const chars = string.match(new RegExp(`^${ranges}+`))[0];

	if (chars.length === string.length) {

		return string;

	}

	return (

		chars +

		String.fromCharCode(isA ? 205 : 206) +

		autoSelectFromAB(string.substring(chars.length), !isA)

	);

}

// CODE128C

function autoSelectFromC(string) {

	const cMatch = matchSetC(string);

	const length = cMatch.length;

	if (length === string.length) {

		return string;

	}

	string = string.substring(length);

	// Select A/B depending on the longest match

	const isA = matchSetALength(string) >= matchSetBLength(string);

	return cMatch + String.fromCharCode(isA ? 206 : 205) + autoSelectFromAB(string, isA);

}

// Detect Code Set (A, B or C) and format the string

export default (string) => {

	let newString;

	const cLength = matchSetC(string).length;

	// Select 128C if the string start with enough digits

	if (cLength >= 2) {

		newString = C_START_CHAR + autoSelectFromC(string);

	} else {

		// Select A/B depending on the longest match

		const isA = matchSetALength(string) > matchSetBLength(string);

		newString = (isA ? A_START_CHAR : B_START_CHAR) + autoSelectFromAB(string, isA);

	}

	return newString.replace(

		/[\xCD\xCE]([^])[\xCD\xCE]/, // Any sequence between 205 and 206 characters

};