local Hex = require(".crypto.util.hex")

local k512 = {
0x428a2f98d728ae22,0x7137449123ef65cd,0xb5c0fbcfec4d3b2f,0xe9b5dba58189dbbc,
0x3956c25bf348b538,0x59f111f1b605d019,0x923f82a4af194f9b,0xab1c5ed5da6d8118,
0xd807aa98a3030242,0x12835b0145706fbe,0x243185be4ee4b28c,0x550c7dc3d5ffb4e2,
0x72be5d74f27b896f,0x80deb1fe3b1696b1,0x9bdc06a725c71235,0xc19bf174cf692694,
0xe49b69c19ef14ad2,0xefbe4786384f25e3,0x0fc19dc68b8cd5b5,0x240ca1cc77ac9c65,
0x2de92c6f592b0275,0x4a7484aa6ea6e483,0x5cb0a9dcbd41fbd4,0x76f988da831153b5,
0x983e5152ee66dfab,0xa831c66d2db43210,0xb00327c898fb213f,0xbf597fc7beef0ee4,
0xc6e00bf33da88fc2,0xd5a79147930aa725,0x06ca6351e003826f,0x142929670a0e6e70,
0x27b70a8546d22ffc,0x2e1b21385c26c926,0x4d2c6dfc5ac42aed,0x53380d139d95b3df,
0x650a73548baf63de,0x766a0abb3c77b2a8,0x81c2c92e47edaee6,0x92722c851482353b,
0xa2bfe8a14cf10364,0xa81a664bbc423001,0xc24b8b70d0f89791,0xc76c51a30654be30,
0xd192e819d6ef5218,0xd69906245565a910,0xf40e35855771202a,0x106aa07032bbd1b8,
0x19a4c116b8d2d0c8,0x1e376c085141ab53,0x2748774cdf8eeb99,0x34b0bcb5e19b48a8,
0x391c0cb3c5c95a63,0x4ed8aa4ae3418acb,0x5b9cca4f7763e373,0x682e6ff3d6b2b8a3,
0x748f82ee5defb2fc,0x78a5636f43172f60,0x84c87814a1f0ab72,0x8cc702081a6439ec,
0x90befffa23631e28,0xa4506cebde82bde9,0xbef9a3f7b2c67915,0xc67178f2e372532b,
0xca273eceea26619c,0xd186b8c721c0c207,0xeada7dd6cde0eb1e,0xf57d4f7fee6ed178,
0x06f067aa72176fba,0x0a637dc5a2c898a6,0x113f9804bef90dae,0x1b710b35131c471b,
0x28db77f523047d84,0x32caab7b40c72493,0x3c9ebe0a15c9bebc,0x431d67c49c100d4c,
0x4cc5d4becb3e42b6,0x597f299cfc657e2a,0x5fcb6fab3ad6faec,0x6c44198c4a475817
}

local function pad128(msg, len)
	local extra = 128 - ((len + 1 + 8) % 128)
	len = string.pack(">I8", len * 8)
	msg = msg .. "\128" .. string.rep("\0", extra) .. len
	assert(#msg % 128 == 0)
	return msg
end

local ww512 = {}

--- SHA-512 hash function.
--- @param msg string - The message to hash.
--- @returns table - A table containing the hash in bytes, string, and hex formats.
local function sha512 (msg)
	msg = pad128(msg, #msg)
	local h1, h2, h3, h4, h5, h6, h7, h8 = 
		0x6a09e667f3bcc908, 0xbb67ae8584caa73b,
		0x3c6ef372fe94f82b, 0xa54ff53a5f1d36f1,
		0x510e527fade682d1, 0x9b05688c2b3e6c1f,
		0x1f83d9abfb41bd6b, 0x5be0cd19137e2179
	local k = k512
	local w = ww512
	local mlen = #msg

	for i = 1, mlen, 128 do
		w[1], w[2], w[3], w[4], w[5], w[6], w[7], w[8], 
		w[9], w[10], w[11], w[12], w[13], w[14], w[15], w[16]
		= string.unpack(">i8i8i8i8i8i8i8i8i8i8i8i8i8i8i8i8", msg, i)
		-- mix msg block in state

		for j = 17, 80 do
			local a = w[j-15]
			local b = w[j-2]
			w[j] = (a >> 1 ~ a >> 7 ~ a >> 8 ~ a << 56 ~ a << 63)
			  + (b >> 6 ~ b >> 19 ~ b >> 61 ~ b << 3 ~ b << 45) 
			  + w[j-7] + w[j-16]
		end
		local a, b, c, d, e, f, g, h = h1, h2, h3, h4, h5, h6, h7, h8
		-- main state permutation
		for j = 1, 80 do
			local z = (e >> 14 ~ e >> 18 ~ e >> 41 ~ e << 23 
				   ~ e << 46 ~ e << 50) 
				+ (g ~ e & (f ~ g)) + h + k[j] + w[j]
			h = g
			g = f
			f = e
			e = z + d
			d = c
			c = b
			b = a
			a = z + ((a ~ c) & d ~ a & c) 
			      + (a >> 28 ~ a >> 34 ~ a >> 39 ~ a << 25 
				~ a << 30 ~ a << 36)
		end
		h1 = h1 + a
		h2 = h2 + b 
		h3 = h3 + c 
		h4 = h4 + d 
		h5 = h5 + e 
		h6 = h6 + f 
		h7 = h7 + g 
		h8 = h8 + h 
	end

	local public = {}

	public.asBytes = function()
		return { h1, h2, h3, h4, h5, h6, h7, h8}
	end

	public.asString = function()
		return string.pack(">i8i8i8i8i8i8i8i8", h1, h2, h3, h4, h5, h6, h7, h8)
	end

	public.asHex = function()
		return Hex.stringToHex(string.pack(">i8i8i8i8i8i8i8i8", h1, h2, h3, h4, h5, h6, h7, h8))
	end

	return public
end

return sha512