@iabtechlabtcf/core/lib/mjs/encoder/field/LangEncoder.js

Ensures consistent encoding and decoding of TC Signals for the iab. Transparency and Consent Framework (TCF).

import { IntEncoder, } from './IntEncoder.js';
import { DecodingError, EncodingError, } from '../../errors/index.js';
export class LangEncoder {
    static encode(value, numBits) {
        value = value.toUpperCase();
        const ASCII_START = 65;
        const firstLetter = value.charCodeAt(0) - ASCII_START;
        const secondLetter = value.charCodeAt(1) - ASCII_START;
        // check some things to throw some good errors
        if (firstLetter < 0 || firstLetter > 25 || secondLetter < 0 || secondLetter > 25) {
            throw new EncodingError(`invalid language code: ${value}`);
        }
        if (numBits % 2 === 1) {
            throw new EncodingError(`numBits must be even, ${numBits} is not valid`);
        }
        numBits = numBits / 2;
        const firstLetterBString = IntEncoder.encode(firstLetter, numBits);
        const secondLetterBString = IntEncoder.encode(secondLetter, numBits);
        return firstLetterBString + secondLetterBString;
    }
    static decode(value, numBits) {
        let retr;
        // is it an even number of bits? we have to divide it
        if (numBits === value.length && !(value.length % 2)) {
            const ASCII_START = 65;
            const mid = value.length / 2;
            const firstLetter = IntEncoder.decode(value.slice(0, mid), mid) + ASCII_START;
            const secondLetter = IntEncoder.decode(value.slice(mid), mid) + ASCII_START;
            retr = String.fromCharCode(firstLetter) + String.fromCharCode(secondLetter);
        }
        else {
            throw new DecodingError('invalid bit length for language');
        }
        return retr;
    }
}