package com.infendro.hash.sha2

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

object `SHA-512` : HashFunction {
    override val bytes: Int
        get() = 64

    override val block: Int
        get() = 128

    private val initial = ulongArrayOf(
        0x6a09e667f3bcc908UL, 0xbb67ae8584caa73bUL,
        0x3c6ef372fe94f82bUL, 0xa54ff53a5f1d36f1UL,
        0x510e527fade682d1UL, 0x9b05688c2b3e6c1fUL,
        0x1f83d9abfb41bd6bUL, 0x5be0cd19137e2179UL,
    ).asLongArray()

    private val c = ulongArrayOf(
        0x428a2f98d728ae22UL, 0x7137449123ef65cdUL, 0xb5c0fbcfec4d3b2fUL, 0xe9b5dba58189dbbcUL,
        0x3956c25bf348b538UL, 0x59f111f1b605d019UL, 0x923f82a4af194f9bUL, 0xab1c5ed5da6d8118UL,
        0xd807aa98a3030242UL, 0x12835b0145706fbeUL, 0x243185be4ee4b28cUL, 0x550c7dc3d5ffb4e2UL,
        0x72be5d74f27b896fUL, 0x80deb1fe3b1696b1UL, 0x9bdc06a725c71235UL, 0xc19bf174cf692694UL,
        0xe49b69c19ef14ad2UL, 0xefbe4786384f25e3UL, 0x0fc19dc68b8cd5b5UL, 0x240ca1cc77ac9c65UL,
        0x2de92c6f592b0275UL, 0x4a7484aa6ea6e483UL, 0x5cb0a9dcbd41fbd4UL, 0x76f988da831153b5UL,
        0x983e5152ee66dfabUL, 0xa831c66d2db43210UL, 0xb00327c898fb213fUL, 0xbf597fc7beef0ee4UL,
        0xc6e00bf33da88fc2UL, 0xd5a79147930aa725UL, 0x06ca6351e003826fUL, 0x142929670a0e6e70UL,
        0x27b70a8546d22ffcUL, 0x2e1b21385c26c926UL, 0x4d2c6dfc5ac42aedUL, 0x53380d139d95b3dfUL,
        0x650a73548baf63deUL, 0x766a0abb3c77b2a8UL, 0x81c2c92e47edaee6UL, 0x92722c851482353bUL,
        0xa2bfe8a14cf10364UL, 0xa81a664bbc423001UL, 0xc24b8b70d0f89791UL, 0xc76c51a30654be30UL,
        0xd192e819d6ef5218UL, 0xd69906245565a910UL, 0xf40e35855771202aUL, 0x106aa07032bbd1b8UL,
        0x19a4c116b8d2d0c8UL, 0x1e376c085141ab53UL, 0x2748774cdf8eeb99UL, 0x34b0bcb5e19b48a8UL,
        0x391c0cb3c5c95a63UL, 0x4ed8aa4ae3418acbUL, 0x5b9cca4f7763e373UL, 0x682e6ff3d6b2b8a3UL,
        0x748f82ee5defb2fcUL, 0x78a5636f43172f60UL, 0x84c87814a1f0ab72UL, 0x8cc702081a6439ecUL,
        0x90befffa23631e28UL, 0xa4506cebde82bde9UL, 0xbef9a3f7b2c67915UL, 0xc67178f2e372532bUL,
        0xca273eceea26619cUL, 0xd186b8c721c0c207UL, 0xeada7dd6cde0eb1eUL, 0xf57d4f7fee6ed178UL,
        0x06f067aa72176fbaUL, 0x0a637dc5a2c898a6UL, 0x113f9804bef90daeUL, 0x1b710b35131c471bUL,
        0x28db77f523047d84UL, 0x32caab7b40c72493UL, 0x3c9ebe0a15c9bebcUL, 0x431d67c49c100d4cUL,
        0x4cc5d4becb3e42b6UL, 0x597f299cfc657e2aUL, 0x5fcb6fab3ad6faecUL, 0x6c44198c4a475817UL,
    ).asLongArray()

    override fun hashInto(value: ByteArray, destination: ByteArray, destinationOffset: Int) {
        val input = pad(value)
        val h = initial.copyOf()
        val w = LongArray(80)
        val v = LongArray(8)

        for (i in input.indices step block) {
            process(h, input, i, w, v)
        }
        h.copyInto(destination, destinationOffset)
    }

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

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

    internal fun process(h: LongArray, value: ByteArray, offset: Int, w: LongArray, v: LongArray) {
        value.copyInto(w, startIndex = offset, endIndex = offset + block)
        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]
        }
    }
}