package com.infendro.hash.blake

import com.infendro.bytearray.toUByteArray
import com.infendro.bytearray.toULongArray
import com.infendro.hash.HashFunction

object `Blake-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,
    )

    private val c = ulongArrayOf(
        0x243f6a8885a308d3UL, 0x13198a2e03707344UL,
        0xa4093822299f31d0UL, 0x082efa98ec4e6c89UL,
        0x452821e638d01377UL, 0xbe5466cf34e90c6cUL,
        0xc0ac29b7c97c50ddUL, 0x3f84d5b5b5470917UL,
        0x9216d5d98979fb1bUL, 0xd1310ba698dfb5acUL,
        0x2ffd72dbd01adfb7UL, 0xb8e1afed6a267e96UL,
        0xba7c9045f12c7f99UL, 0x24a19947b3916cf7UL,
        0x0801f2e2858efc16UL, 0x636920d871574e69UL,
    )

    private val sigma = arrayOf(
        intArrayOf(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15),
        intArrayOf(14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3),
        intArrayOf(11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4),
        intArrayOf(7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8),
        intArrayOf(9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13),
        intArrayOf(2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9),
        intArrayOf(12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11),
        intArrayOf(13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10),
        intArrayOf(6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5),
        intArrayOf(10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0),
    )

    override fun hash(value: UByteArray): UByteArray {
        val l = value.size.toULong() * 8UL
        val h = initial.copyOf()
        var t = 0UL

        val blocks = pad(value)
            .chunked(128) { it.toUByteArray() }
        for (block in blocks) {
            t += minOf(l - t, 1024UL)
            compress(h, block, t)
        }

        return h.toUByteArray()
    }

    private fun pad(
        value: UByteArray,
    ): UByteArray {
        val l = value.size.toULong() * 8UL
        return buildList {
            addAll(value)
            add(0x80U)
            while (size % 128 != 111) {
                add(0x00U)
            }
            add(0x01U)
            repeat(8) { add(0x00U) }
            addAll(l.toUByteArray())
        }.toUByteArray()
    }

    private fun compress(
        h: ULongArray,
        block: UByteArray,
        t: ULong,
    ) {
        val m = block.toULongArray()
        val v = ULongArray(16)
        for (i in 0..<8) v[i] = h[i]
        for (i in 0..<4) v[i + 8] = c[i]
        for (i in 0..<2) v[i + 12] = c[i + 4] xor t
        for (i in 0..<2) v[i + 14] = c[i + 6]

        repeat(16) { r ->
            val s = sigma[r % 10]

            g(v, 0, 4, 8, 12, m[s[0]] xor c[s[1]], m[s[1]] xor c[s[0]])
            g(v, 1, 5, 9, 13, m[s[2]] xor c[s[3]], m[s[3]] xor c[s[2]])
            g(v, 2, 6, 10, 14, m[s[4]] xor c[s[5]], m[s[5]] xor c[s[4]])
            g(v, 3, 7, 11, 15, m[s[6]] xor c[s[7]], m[s[7]] xor c[s[6]])

            g(v, 0, 5, 10, 15, m[s[8]] xor c[s[9]], m[s[9]] xor c[s[8]])
            g(v, 1, 6, 11, 12, m[s[10]] xor c[s[11]], m[s[11]] xor c[s[10]])
            g(v, 2, 7, 8, 13, m[s[12]] xor c[s[13]], m[s[13]] xor c[s[12]])
            g(v, 3, 4, 9, 14, m[s[14]] xor c[s[15]], m[s[15]] xor c[s[14]])
        }

        for (i in 0..7) {
            h[i] = h[i] xor v[i] xor v[i + 8]
        }
    }

    private fun g(
        v: ULongArray,
        a: Int,
        b: Int,
        c: Int,
        d: Int,
        x: ULong,
        y: ULong,
    ) {
        v[a] += v[b] + x
        v[d] = (v[d] xor v[a]).rotateRight(32)
        v[c] += v[d]
        v[b] = (v[b] xor v[c]).rotateRight(25)
        v[a] += v[b] + y
        v[d] = (v[d] xor v[a]).rotateRight(16)
        v[c] += v[d]
        v[b] = (v[b] xor v[c]).rotateRight(11)
    }
}