package com.infendro.hash.sha2

import com.infendro.bytes.bytearray.copyInto
import com.infendro.bytes.longarray.copyInto
import com.infendro.hash.HashFunction
import com.infendro.hash.sha2.`SHA-512`.Companion.c

class `SHA-384` : HashFunction(48, 128) {
    private val h = initial.copyOf()

    private val w = LongArray(80)
    private val v = LongArray(8)

    override fun reset() {
        super.reset()
        initial.copyInto(h)
    }

    override fun process() = process(buffer.value)

    private fun finalize() {
        buffer.append(0x80.toByte())
        if (buffer.free < 16) {
            process(buffer.value)
            buffer.reset()
        }
        buffer.jumpTo(112)
        buffer.append(length * 8)

        process(buffer.value)
    }

    override fun digestInto(destination: ByteArray, destinationOffset: Int) {
        finalize()
        h.copyInto(destination, destinationOffset, endIndex = 6)
        reset()
    }

    private fun process(block: ByteArray) {
        block.copyInto(w)
        for (i in 16..<80) {
            val s0 = w[i - 15].rotateRight(1) xor w[i - 15].rotateRight(8) xor (w[i - 15] ushr 7)
            val s1 = w[i - 2].rotateRight(19) xor w[i - 2].rotateRight(61) xor (w[i - 2] ushr 6)
            w[i] = (w[i - 16] + s0 + w[i - 7] + s1)
        }
        h.copyInto(v)

        repeat(80) { i ->
            val s0 = v[0].rotateRight(28) xor v[0].rotateRight(34) xor v[0].rotateRight(39)
            val s1 = v[4].rotateRight(14) xor v[4].rotateRight(18) xor v[4].rotateRight(41)
            val ch = (v[4] and v[5]) xor (v[4].inv() and v[6])
            val temp1 = v[7] + s1 + ch + c[i] + w[i]
            val maj = (v[0] and v[1]) xor (v[0] and v[2]) xor (v[1] and v[2])
            val temp2 = s0 + maj

            v[7] = v[6]
            v[6] = v[5]
            v[5] = v[4]
            v[4] = v[3] + temp1
            v[3] = v[2]
            v[2] = v[1]
            v[1] = v[0]
            v[0] = temp1 + temp2
        }

        for (i in 0..<8) {
            h[i] += v[i]
        }
    }

    companion object {
        private val initial = longArrayOf(
            -0x344462a23efa6128, +0x629a292a367cd507,
            -0x6ea6fea5cf8f22e9, +0x152fecd8f70e5939,
            +0x67332667ffc00b31, -0x714bb57897a7eaef,
            -0x24f3d1f29b067059, +0x47b5481dbefa4fa4,
        )
    }
}