private const val hex255 = 0xFF
private const val binaryRadix = 2
private const val bitGroupsSize = 5
private const val padLength = 8

/**
 * Generates the package family name for a given identity name and identity publisher.
 *
 * The algorithm takes the following steps:
 * 1. Calculate the SHA-256 hash of the byte representation of the UTF-16 identity publisher.
 * 2. Take the first 8 bytes (64 bits) of the SHA-256 hash.
 * 3. Concatenate each byte of the first 8 bytes, and convert them to binary representation.
 * 4. Pad the binary value by a single zero bit to the right (left shift all bits).
 * 5. Group the bits in groups of 5.
 * 6. For each group, convert the bit representation to an index of the string "0123456789ABCDEFGHJKMNPQRSTVWXYZ"
 * 7. Join the letters together and make them lowercase.
 * 8. Append the hash part to the identity name with an underscore as a separator.
 *
 * @param identityName a string representing the identity name.
 * @param identityPublisher a UTF-16 string representing the identity publisher.
 * @return the package family name generated using the algorithm.
 */
fun getPackageFamilyName(identityName: String, identityPublisher: String): String {
    val hashPart = identityPublisher.encode(Charsets.UTF_16LE)
        .sha256()
        .substring(0, 8)
        .toByteArray()
        .map { it.toInt() and hex255 }
        .joinToString("") { it.toString(binaryRadix).padStart(padLength, '0') }
        .plus('0')
        .chunked(bitGroupsSize)
        .map { "0123456789ABCDEFGHJKMNPQRSTVWXYZ"[it.toInt(binaryRadix)] }
        .joinToString("")
        .lowercase()
    return "${identityName}_$hashPart"
}