OpenEUICC/app-common/src/main/java/im/angry/openeuicc/util/StringUtils.kt

package im.angry.openeuicc.util

fun String.decodeHex(): ByteArray {
    require(length % 2 == 0) { "Must have an even length" }

    val decodedLength = length / 2
    val out = ByteArray(decodedLength)
    for (i in 0 until decodedLength) {
        val i2 = i * 2
        out[i] = substring(i2, i2 + 2).toInt(16).toByte()
    }
    return out
}

fun ByteArray.encodeHex(): String {
    val sb = StringBuilder()
    val length = size
    for (i in 0 until length) {
        sb.append(String.format("%02X", this[i]))
    }
    return sb.toString()
}

fun formatFreeSpace(size: Int): String =
    // SIM cards probably won't have much more space anytime soon.
    if (size >= 1024) {
        "%.2f KiB".format(size.toDouble() / 1024)
    } else {
        "$size B"
    }

/**
 * Decode a list of potential ISDR AIDs, one per line. Lines starting with '#' are ignored.
 * If none is found, at least EUICC_DEFAULT_ISDR_AID is returned
 */
fun parseIsdrAidList(s: String): List<ByteArray> =
    s.split('\n')
        .map(String::trim)
        .filter { !it.startsWith('#') }
        .map(String::trim)
        .filter(String::isNotEmpty)
        .mapNotNull { runCatching(it::decodeHex).getOrNull() }
        .ifEmpty { listOf(EUICC_DEFAULT_ISDR_AID.decodeHex()) }