package yu_tencent

import (
	yu_bytes "gogs.qqck.cn/s/tools/bytes"
	yu_rand "gogs.qqck.cn/s/tools/rand"
)

type Tea struct {
	key [4]uint32
}

func NewTea() (t *Tea) {
	t = &Tea{}
	return
}

func (t *Tea) SetKey(key [16]byte) *Tea {
	t.key[3] = uint32(key[15]) | uint32(key[14])<<8 | uint32(key[13])<<16 | uint32(key[12])<<24
	t.key[2] = uint32(key[11]) | uint32(key[10])<<8 | uint32(key[9])<<16 | uint32(key[8])<<24
	t.key[1] = uint32(key[7]) | uint32(key[6])<<8 | uint32(key[5])<<16 | uint32(key[4])<<24
	t.key[0] = uint32(key[3]) | uint32(key[2])<<8 | uint32(key[1])<<16 | uint32(key[0])<<24
	return t
}

func (t *Tea) SetKeyB(key []byte) *Tea {
	var j_key [16]byte
	copy(j_key[:], key)
	return t.SetKey(j_key)
}

func (t *Tea) GetKey() (key [16]byte) {
	key[0] = byte(t.key[0] >> 24)
	key[1] = byte(t.key[0] >> 16)
	key[2] = byte(t.key[0] >> 8)
	key[3] = byte(t.key[0])

	key[4] = byte(t.key[1] >> 24)
	key[5] = byte(t.key[1] >> 16)
	key[6] = byte(t.key[1] >> 8)
	key[7] = byte(t.key[1])

	key[8] = byte(t.key[2] >> 24)
	key[9] = byte(t.key[2] >> 16)
	key[10] = byte(t.key[2] >> 8)
	key[11] = byte(t.key[2])

	key[12] = byte(t.key[3] >> 24)
	key[13] = byte(t.key[3] >> 16)
	key[14] = byte(t.key[3] >> 8)
	key[15] = byte(t.key[3])

	return
}

func (t *Tea) GetKeyB() []byte {
	j_key := t.GetKey()
	return j_key[:]
}

func (t *Tea) rand() byte {
	return byte(yu_rand.Uint32())
}

func (t *Tea) En(data []byte) []byte {
	j_fill := 0x0a - (len(data)+1)%8             // 计算头部填充字节数
	j_encode := make([]byte, j_fill+len(data)+7) // 计算输出的密文长度

	// 这里的操作把 j_fill 存到了 j_encode 的第一个字节里面
	// 0xF8 后面三位是空的，正好留给 j_fill 因为 j_fill 是 0 到 7 的值，表示文本开始的字节位置
	j_encode[0] = byte(j_fill-3) | (t.rand() & 0xf8) // 存储pad长度

	// 这里用随机产生的数填充 j_encode[1] 到 j_encode[j_fill] 之间的内容
	for j_i := 1; j_i < j_fill; j_i++ {
		j_encode[j_i] = t.rand()
	}

	copy(j_encode[j_fill:], data)
	var j_iv1, j_iv2, j_holder uint64
	for j_i := 0; j_i < len(j_encode); j_i += 8 {
		j_holder = (uint64(j_encode[j_i+7]) | uint64(j_encode[j_i+6])<<8 |
			uint64(j_encode[j_i+5])<<16 | uint64(j_encode[j_i+4])<<24 |
			uint64(j_encode[j_i+3])<<32 | uint64(j_encode[j_i+2])<<40 |
			uint64(j_encode[j_i+1])<<48 | uint64(j_encode[j_i])<<56) ^ j_iv1
		j_iv1 = t.encode(j_holder)
		j_iv1 ^= j_iv2
		j_iv2 = j_holder
		j_encode[j_i] = byte(j_iv1 >> 56)
		j_encode[j_i+1] = byte(j_iv1 >> 48)
		j_encode[j_i+2] = byte(j_iv1 >> 40)
		j_encode[j_i+3] = byte(j_iv1 >> 32)
		j_encode[j_i+4] = byte(j_iv1 >> 24)
		j_encode[j_i+5] = byte(j_iv1 >> 16)
		j_encode[j_i+6] = byte(j_iv1 >> 8)
		j_encode[j_i+7] = byte(j_iv1)
	}
	return j_encode
}

//go:nosplit
func (t *Tea) encode(n uint64) uint64 {
	v0, v1 := uint32(n>>32), uint32(n)
	v0 += (v1 + 0x9e3779b9) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x9e3779b9) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0x3c6ef372) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x3c6ef372) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0xdaa66d2b) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0xdaa66d2b) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0x78dde6e4) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x78dde6e4) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0x1715609d) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x1715609d) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0xb54cda56) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0xb54cda56) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0x5384540f) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x5384540f) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0xf1bbcdc8) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0xf1bbcdc8) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0x8ff34781) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x8ff34781) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0x2e2ac13a) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x2e2ac13a) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0xcc623af3) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0xcc623af3) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0x6a99b4ac) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x6a99b4ac) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0x08d12e65) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x08d12e65) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0xa708a81e) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0xa708a81e) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0x454021d7) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0x454021d7) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 += (v1 + 0xe3779b90) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 += (v0 + 0xe3779b90) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	return uint64(v0)<<32 | uint64(v1)
}

func (t *Tea) De(data []byte) []byte {
	j_data_len := len(data)
	if j_data_len < 9 || j_data_len%8 != 0 {
		return nil
	}
	j_decode := make([]byte, j_data_len)
	var j_iv1, j_iv2, j_holder uint64
	for j_i := 0; j_i < j_data_len; j_i += 8 {
		j_iv1 = uint64(data[j_i+7]) | uint64(data[j_i+6])<<8 |
			uint64(data[j_i+5])<<16 | uint64(data[j_i+4])<<24 |
			uint64(data[j_i+3])<<32 | uint64(data[j_i+2])<<40 |
			uint64(data[j_i+1])<<48 | uint64(data[j_i])<<56
		j_iv2 = t.decode(j_iv2 ^ j_iv1)
		j_holder ^= j_iv2
		j_decode[j_i] = byte(j_holder >> 56)
		j_decode[j_i+1] = byte(j_holder >> 48)
		j_decode[j_i+2] = byte(j_holder >> 40)
		j_decode[j_i+3] = byte(j_holder >> 32)
		j_decode[j_i+4] = byte(j_holder >> 24)
		j_decode[j_i+5] = byte(j_holder >> 16)
		j_decode[j_i+6] = byte(j_holder >> 8)
		j_decode[j_i+7] = byte(j_holder)
		j_holder = j_iv1
	}
	j_iv2_bytes := make([]byte, 8)
	j_iv2_bytes[0] = byte(j_iv2 >> 56)
	j_iv2_bytes[1] = byte(j_iv2 >> 48)
	j_iv2_bytes[2] = byte(j_iv2 >> 40)
	j_iv2_bytes[3] = byte(j_iv2 >> 32)
	j_iv2_bytes[4] = byte(j_iv2 >> 24)
	j_iv2_bytes[5] = byte(j_iv2 >> 16)
	j_iv2_bytes[6] = byte(j_iv2 >> 8)
	j_iv2_bytes[7] = byte(j_iv2)
	if !yu_bytes.Equals(j_iv2_bytes[1:8], data[j_data_len-15:j_data_len-8]) {
		return nil
	}
	return j_decode[j_decode[0]&7+3 : j_data_len-7]
}

//go:nosplit
func (t *Tea) decode(n uint64) uint64 {
	v0, v1 := uint32(n>>32), uint32(n)
	v1 -= (v0 + 0xe3779b90) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0xe3779b90) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x454021d7) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x454021d7) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0xa708a81e) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0xa708a81e) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x08d12e65) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x08d12e65) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x6a99b4ac) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x6a99b4ac) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0xcc623af3) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0xcc623af3) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x2e2ac13a) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x2e2ac13a) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x8ff34781) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x8ff34781) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0xf1bbcdc8) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0xf1bbcdc8) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x5384540f) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x5384540f) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0xb54cda56) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0xb54cda56) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x1715609d) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x1715609d) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x78dde6e4) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x78dde6e4) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0xdaa66d2b) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0xdaa66d2b) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x3c6ef372) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x3c6ef372) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	v1 -= (v0 + 0x9e3779b9) ^ (v0<<4 + t.key[2]) ^ (v0>>5 + t.key[3])
	v0 -= (v1 + 0x9e3779b9) ^ (v1<<4 + t.key[0]) ^ (v1>>5 + t.key[1])
	return uint64(v0)<<32 | uint64(v1)
}