package com.infendro.random.prng

import com.infendro.bytes.bytearray.toLongArray
import com.infendro.hash.sha2.`SHA-256`
import com.infendro.random.PRNG
import kotlin.properties.Delegates.notNull

class Xoshiro256pp : PRNG() {
    private val function = `SHA-256`()

    private var s: LongArray by notNull()

    override fun seed(seed: ByteArray) {
        s = function.hash(seed).toLongArray()
    }

    override fun generate(): Int {
        val result = (s[0] + s[3]).rotateLeft(23) + s[0]

        val t = s[1] shl 17
        s[2] = s[2] xor s[0]
        s[3] = s[3] xor s[1]
        s[1] = s[1] xor s[2]
        s[0] = s[0] xor s[3]
        s[2] = s[2] xor t
        s[3] = s[3].rotateLeft(45)

        return (result ushr 32).toInt()
    }
}