package crypto

import (
	"crypto/hmac"
	"crypto/md5"
	"crypto/rand"
	"crypto/sha1"
	"crypto/sha256"
	"crypto/sha512"
	"encoding/base64"
	"encoding/hex"
	"math/big"

	luajit "git.sharkk.net/Sky/LuaJIT-to-Go"
	"github.com/google/uuid"
)

func GetFunctionList() map[string]luajit.GoFunction {
	return map[string]luajit.GoFunction{
		"base64_encode":     base64_encode,
		"base64_decode":     base64_decode,
		"base64_url_encode": base64_url_encode,
		"base64_url_decode": base64_url_decode,
		"hex_encode":        hex_encode,
		"hex_decode":        hex_decode,
		"md5_hash":          md5_hash,
		"sha1_hash":         sha1_hash,
		"sha256_hash":       sha256_hash,
		"sha512_hash":       sha512_hash,
		"hmac_sha256":       hmac_sha256,
		"hmac_sha1":         hmac_sha1,
		"uuid_generate":     uuid_generate,
		"uuid_generate_v4":  uuid_generate_v4,
		"uuid_validate":     uuid_validate,
		"random_bytes":      random_bytes,
		"random_hex":        random_hex,
		"random_string":     random_string,
		"secure_compare":    secure_compare,
	}
}

func base64_encode(s *luajit.State) int {
	str := s.ToString(1)
	encoded := base64.StdEncoding.EncodeToString([]byte(str))
	s.PushString(encoded)
	return 1
}

func base64_decode(s *luajit.State) int {
	str := s.ToString(1)
	decoded, err := base64.StdEncoding.DecodeString(str)
	if err != nil {
		s.PushNil()
		s.PushString("invalid base64 data")
		return 2
	}
	s.PushString(string(decoded))
	return 1
}

func base64_url_encode(s *luajit.State) int {
	str := s.ToString(1)
	encoded := base64.URLEncoding.EncodeToString([]byte(str))
	s.PushString(encoded)
	return 1
}

func base64_url_decode(s *luajit.State) int {
	str := s.ToString(1)
	decoded, err := base64.URLEncoding.DecodeString(str)
	if err != nil {
		s.PushNil()
		s.PushString("invalid base64url data")
		return 2
	}
	s.PushString(string(decoded))
	return 1
}

func hex_encode(s *luajit.State) int {
	str := s.ToString(1)
	encoded := hex.EncodeToString([]byte(str))
	s.PushString(encoded)
	return 1
}

func hex_decode(s *luajit.State) int {
	str := s.ToString(1)
	decoded, err := hex.DecodeString(str)
	if err != nil {
		s.PushNil()
		s.PushString("invalid hex data")
		return 2
	}
	s.PushString(string(decoded))
	return 1
}

func md5_hash(s *luajit.State) int {
	str := s.ToString(1)
	hash := md5.Sum([]byte(str))
	s.PushString(hex.EncodeToString(hash[:]))
	return 1
}

func sha1_hash(s *luajit.State) int {
	str := s.ToString(1)
	hash := sha1.Sum([]byte(str))
	s.PushString(hex.EncodeToString(hash[:]))
	return 1
}

func sha256_hash(s *luajit.State) int {
	str := s.ToString(1)
	hash := sha256.Sum256([]byte(str))
	s.PushString(hex.EncodeToString(hash[:]))
	return 1
}

func sha512_hash(s *luajit.State) int {
	str := s.ToString(1)
	hash := sha512.Sum512([]byte(str))
	s.PushString(hex.EncodeToString(hash[:]))
	return 1
}

func hmac_sha256(s *luajit.State) int {
	message := s.ToString(1)
	key := s.ToString(2)
	h := hmac.New(sha256.New, []byte(key))
	h.Write([]byte(message))
	s.PushString(hex.EncodeToString(h.Sum(nil)))
	return 1
}

func hmac_sha1(s *luajit.State) int {
	message := s.ToString(1)
	key := s.ToString(2)
	h := hmac.New(sha1.New, []byte(key))
	h.Write([]byte(message))
	s.PushString(hex.EncodeToString(h.Sum(nil)))
	return 1
}

func uuid_generate(s *luajit.State) int {
	id := uuid.New()
	s.PushString(id.String())
	return 1
}

func uuid_generate_v4(s *luajit.State) int {
	id := uuid.New()
	s.PushString(id.String())
	return 1
}

func uuid_validate(s *luajit.State) int {
	str := s.ToString(1)
	_, err := uuid.Parse(str)
	s.PushBoolean(err == nil)
	return 1
}

func random_bytes(s *luajit.State) int {
	length := int(s.ToNumber(1))
	if length < 0 || length > 65536 {
		s.PushNil()
		s.PushString("invalid length")
		return 2
	}
	bytes := make([]byte, length)
	if _, err := rand.Read(bytes); err != nil {
		s.PushNil()
		s.PushString("failed to generate random bytes")
		return 2
	}
	s.PushString(string(bytes))
	return 1
}

func random_hex(s *luajit.State) int {
	length := int(s.ToNumber(1))
	if length < 0 || length > 32768 {
		s.PushNil()
		s.PushString("invalid length")
		return 2
	}
	bytes := make([]byte, length)
	if _, err := rand.Read(bytes); err != nil {
		s.PushNil()
		s.PushString("failed to generate random bytes")
		return 2
	}
	s.PushString(hex.EncodeToString(bytes))
	return 1
}

func random_string(s *luajit.State) int {
	length := int(s.ToNumber(1))
	if length < 0 || length > 65536 {
		s.PushNil()
		s.PushString("invalid length")
		return 2
	}

	charset := "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	if s.GetTop() >= 2 && !s.IsNil(2) {
		charset = s.ToString(2)
	}

	if len(charset) == 0 {
		s.PushNil()
		s.PushString("empty charset")
		return 2
	}

	result := make([]byte, length)
	charsetLen := big.NewInt(int64(len(charset)))
	for i := range result {
		n, err := rand.Int(rand.Reader, charsetLen)
		if err != nil {
			s.PushNil()
			s.PushString("failed to generate random number")
			return 2
		}
		result[i] = charset[n.Int64()]
	}
	s.PushString(string(result))
	return 1
}

func secure_compare(s *luajit.State) int {
	a := s.ToString(1)
	b := s.ToString(2)
	s.PushBoolean(hmac.Equal([]byte(a), []byte(b)))
	return 1
}