package experiment

// return x·y
func DotProd(x, y []byte) byte {
	var z byte
	for i := 0; i < len(x); i++ {
		z ^= x[i] & y[i]
	}
	return z
}

var M1 = [][]byte{
	{0, 0, 1, 1, 0, 0, 1, 0},
	{0, 0, 0, 1, 0, 1, 0, 0},
	{1, 0, 1, 1, 1, 1, 1, 0},
	{1, 0, 0, 1, 1, 1, 0, 1},
	{0, 1, 0, 1, 1, 0, 0, 0},
	{0, 1, 0, 0, 0, 1, 0, 0},
	{0, 0, 0, 0, 1, 0, 1, 0},
	{1, 0, 1, 1, 1, 0, 1, 0},
}
var M2 = [][]byte{
	{0, 0, 0, 1, 0, 0, 1, 0},
	{0, 1, 1, 1, 0, 0, 0, 0},
	{0, 0, 1, 1, 0, 0, 1, 0},
	{1, 1, 1, 0, 0, 0, 1, 0},
	{1, 0, 1, 0, 0, 1, 1, 0},
	{1, 0, 1, 1, 1, 0, 0, 0},
	{0, 1, 0, 1, 1, 1, 0, 1},
	{1, 1, 0, 0, 1, 0, 1, 1},
}

var A = [][]byte{
	{1, 0, 0, 0, 1, 1, 1, 1},
	{1, 1, 0, 0, 0, 1, 1, 1},
	{1, 1, 1, 0, 0, 0, 1, 1},
	{1, 1, 1, 1, 0, 0, 0, 1},
	{1, 1, 1, 1, 1, 0, 0, 0},
	{0, 1, 1, 1, 1, 1, 0, 0},
	{0, 0, 1, 1, 1, 1, 1, 0},
	{0, 0, 0, 1, 1, 1, 1, 1},
}

var M2A = [][]byte{
	{1, 1, 0, 0, 1, 1, 1, 1},
	{1, 1, 0, 1, 0, 1, 0, 1},
	{0, 0, 1, 0, 1, 1, 0, 0},
	{1, 0, 0, 1, 0, 1, 0, 1},
	{0, 0, 1, 0, 1, 1, 1, 0},
	{0, 1, 1, 0, 0, 1, 0, 1},
	{1, 0, 1, 0, 1, 1, 0, 1},
	{1, 0, 0, 1, 0, 0, 0, 1},
}
var c = []byte{1, 1, 0, 0, 0, 1, 1, 0}
var c2 = []byte{0, 0, 1, 1, 0, 1, 1, 0}
var c3 = []byte{1, 1, 0, 0, 1, 0, 1, 1}

func MatrixMulVector(M [][]byte, N []byte) []byte {
	r := make([]byte, 8)
	for i := 0; i < 8; i++ {
		r[i] = DotProd(M[i], N)
	}
	return r
}
func MatrixMul(M, N [][]byte) [][]byte {
	R := make([][]byte, 8)
	for i := 0; i < 8; i++ {
		R[i] = make([]byte, 8)
	}
	for i := 0; i < 8; i++ {
		for j := 0; j < 8; j++ {
			s := byte(0)
			for k := 0; k < 8; k++ {
				s += M[i][k] * N[k][j]
			}
			R[i][j] = s % 2
		}
	}
	return R
}

// 8*4
func CreatTable(M [][]byte, D byte) ([]byte, []byte) {
	var ml, mh [16]byte
	for i := byte(0); i < 16; i++ {
		var buf = []byte{i & 1, (i >> 1) & 1, (i >> 2) & 1, (i >> 3) & 1}
		// ml[i] = ((DotProd(M[0][:4], buf) << 0) | (DotProd(M[1][:4], buf) << 1) |
		// 	(DotProd(M[2][:4], buf) << 2) | (DotProd(M[3][:4], buf) << 3) |
		// 	(DotProd(M[4][:4], buf) << 4) | (DotProd(M[5][:4], buf) << 5) |
		// 	(DotProd(M[6][:4], buf) << 6) | (DotProd(M[7][:4], buf) << 7)) ^ 0x0e // C1=[0, 1, 1, 1, 1, 1, 0, 0]

		// mh[i] = ((DotProd(M[0][4:], buf) << 0) | (DotProd(M[1][4:], buf) << 1) |
		// 	(DotProd(M[2][4:], buf) << 2) | (DotProd(M[3][4:], buf) << 3) |
		// 	(DotProd(M[4][4:], buf) << 4) | (DotProd(M[5][4:], buf) << 5) |
		// 	(DotProd(M[6][4:], buf) << 6) | (DotProd(M[7][4:], buf) << 7)) ^ 0x30 // C1=[0, 1, 1, 1, 1, 1, 0, 0]
		ml[i] = ((DotProd(M[0][:4], buf) << 0) | (DotProd(M[1][:4], buf) << 1) |
			(DotProd(M[2][:4], buf) << 2) | (DotProd(M[3][:4], buf) << 3) |
			(DotProd(M[4][:4], buf) << 4) | (DotProd(M[5][:4], buf) << 5) |
			(DotProd(M[6][:4], buf) << 6) | (DotProd(M[7][:4], buf) << 7)) ^ (D & 0xf)

		mh[i] = ((DotProd(M[0][4:], buf) << 0) | (DotProd(M[1][4:], buf) << 1) |
			(DotProd(M[2][4:], buf) << 2) | (DotProd(M[3][4:], buf) << 3) |
			(DotProd(M[4][4:], buf) << 4) | (DotProd(M[5][4:], buf) << 5) |
			(DotProd(M[6][4:], buf) << 6) | (DotProd(M[7][4:], buf) << 7)) ^ (D & 0xf0)
	}
	return ml[:], mh[:]
}

// return A*v in GF(2)^8
func Transform(A [][]byte, in *ffe) *ffe {
	r := new(ffe)
	for i := 0; i < 8; i++ {
		for j := 0; j < 8; j++ {
			r.v[i] += A[i][j] * in.v[j]
		}
		r.v[i] = r.v[i] % 2
	}
	return r
}

func M1Transform(a byte) byte {
	var M1 = [][]byte{
		{0, 0, 1, 1, 0, 0, 1, 0},
		{0, 0, 0, 1, 0, 1, 0, 0},
		{1, 0, 1, 1, 1, 1, 1, 0},
		{1, 0, 0, 1, 1, 1, 0, 1},
		{0, 1, 0, 1, 1, 0, 0, 0},
		{0, 1, 0, 0, 0, 1, 0, 0},
		{0, 0, 0, 0, 1, 0, 1, 0},
		{1, 0, 1, 1, 1, 0, 1, 0},
	}

	ml, mh := CreatTable(M1, 0x3e)
	return ml[a&0xf] ^ mh[a>>4]
}