package com.infendro.hash.sha2

import com.infendro.bytes.bytearray.copyInto
import com.infendro.bytes.intarray.copyInto
import com.infendro.hash.HashFunction
import com.infendro.hash.sha2.`SHA-256`.Companion.c

class `SHA-224` : HashFunction(28, 64) {
    private val h = initial.copyOf()

    private val w = IntArray(64)
    private val v = IntArray(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 < 8) {
            process(buffer.value)
            buffer.reset()
        }
        buffer.jumpTo(56)
        buffer.append(length * 8)

        process(buffer.value)
    }

    override fun digestInto(destination: ByteArray, destinationOffset: Int) {
        finalize()
        h.copyInto(destination, destinationOffset, endIndex = 7)
        reset()
    }

    private fun process(block: ByteArray) {
        block.copyInto(w)
        for (i in 16..<64) {
            val s0 = w[i - 15].rotateRight(7) xor w[i - 15].rotateRight(18) xor (w[i - 15] ushr 3)
            val s1 = w[i - 2].rotateRight(17) xor w[i - 2].rotateRight(19) xor (w[i - 2] ushr 10)
            w[i] = (w[i - 16] + s0 + w[i - 7] + s1)
        }
        h.copyInto(v)

        repeat(64) { i ->
            val s0 = v[0].rotateRight(2) xor v[0].rotateRight(13) xor v[0].rotateRight(22)
            val s1 = v[4].rotateRight(6) xor v[4].rotateRight(11) xor v[4].rotateRight(25)
            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 = intArrayOf(
            -0x3efa6128, +0x367cd507,
            +0x3070dd17, -0x08f1a6c7,
            -0x003ff4cf, +0x68581511,
            +0x64f98fa7, -0x4105b05c,
        )
    }
}