package com.infendro.hash.blake

import com.infendro.bytes.longarray.copyInto
import com.infendro.bytes.ulong.copyInto
import com.infendro.hash.HashFunction
import com.infendro.hash.util.align

object `Blake-384` : HashFunction {
    override val bytes: Int
        get() = 48

    override val block: Int
        get() = 128

    private val initial = ulongArrayOf(
        0xcbbb9d5dc1059ed8U, 0x629a292a367cd507U,
        0x9159015a3070dd17U, 0x152fecd8f70e5939U,
        0x67332667ffc00b31U, 0x8eb44a8768581511U,
        0xdb0c2e0d64f98fa7U, 0x47b5481dbefa4fa4U,
    ).asLongArray()

    override fun hashInto(value: ByteArray, destination: ByteArray, destinationOffset: Int) {
        val length = value.size.toULong() * 8UL
        val input = pad(value)
        val h = initial.copyOf()
        val m = LongArray(16)
        val v = LongArray(16)
        var t = 0UL

        for (i in input.indices step block) {
            t += minOf(length - t, 1024UL)
            `Blake-512`.compress(h, input, i, m, v, t)
        }
        h.copyInto(destination, destinationOffset, endIndex = 6)
    }

    private fun pad(value: ByteArray): ByteArray {
        val length = value.size.toULong() * 8UL

        val size = (value.size + 17).align(block)
        val result = ByteArray(size)
        value.copyInto(result)
        result[value.size] = 0x80U.toByte()
        length.copyInto(result, result.size - 8)
        return result
    }
}