// Copyright 2021 dudaodong@gmail.com. All rights reserved.
// Use of this source code is governed by MIT license

// Package cryptor implements some util functions to encrypt and decrypt.
// Contain base64, hmac, sha, aes, des, and rsa
package cryptor

import (
	"bufio"
	"crypto/hmac"
	"crypto/md5"
	"crypto/sha1"
	"crypto/sha256"
	"crypto/sha512"
	"encoding/base64"
	"encoding/hex"
	"fmt"
	"io"
	"os"
)

// Base64StdEncode encode string with base64 encoding.
// Play: https://go.dev/play/p/VOaUyQUreoK
func Base64StdEncode(s string) string {
	return base64.StdEncoding.EncodeToString([]byte(s))
}

// Base64StdDecode decode a base64 encoded string.
// Play: https://go.dev/play/p/RWQylnJVgIe
func Base64StdDecode(s string) string {
	b, _ := base64.StdEncoding.DecodeString(s)
	return string(b)
}

// Md5String return the md5 value of string.
// Play: https://go.dev/play/p/1bLcVetbTOI
func Md5String(s string) string {
	h := md5.New()
	h.Write([]byte(s))
	return hex.EncodeToString(h.Sum(nil))
}

// Md5File return the md5 value of file.
func Md5File(filename string) (string, error) {
	if fileInfo, err := os.Stat(filename); err != nil {
		return "", err
	} else if fileInfo.IsDir() {
		return "", nil
	}

	file, err := os.Open(filename)
	if err != nil {
		return "", err
	}
	defer file.Close()

	hash := md5.New()

	chunkSize := 65536
	for buf, reader := make([]byte, chunkSize), bufio.NewReader(file); ; {
		n, err := reader.Read(buf)
		if err != nil {
			if err == io.EOF {
				break
			}
			return "", err
		}
		hash.Write(buf[:n])
	}

	checksum := fmt.Sprintf("%x", hash.Sum(nil))
	return checksum, nil
}

// HmacMd5 return the hmac hash of string use md5.
// Play: https://go.dev/play/p/uef0q1fz53I
func HmacMd5(data, key string) string {
	h := hmac.New(md5.New, []byte(key))
	h.Write([]byte(data))
	return hex.EncodeToString(h.Sum([]byte("")))
}

// HmacSha1 return the hmac hash of string use sha1.
// Play: https://go.dev/play/p/1UI4oQ4WXKM
func HmacSha1(data, key string) string {
	h := hmac.New(sha1.New, []byte(key))
	h.Write([]byte(data))
	return hex.EncodeToString(h.Sum([]byte("")))
}

// HmacSha256 return the hmac hash of string use sha256.
// Play: https://go.dev/play/p/HhpwXxFhhC0
func HmacSha256(data, key string) string {
	h := hmac.New(sha256.New, []byte(key))
	h.Write([]byte(data))
	return hex.EncodeToString(h.Sum([]byte("")))
}

// HmacSha512 return the hmac hash of string use sha512.
// Play: https://go.dev/play/p/59Od6m4A0Ud
func HmacSha512(data, key string) string {
	h := hmac.New(sha512.New, []byte(key))
	h.Write([]byte(data))
	return hex.EncodeToString(h.Sum([]byte("")))
}

// Sha1 return the sha1 value (SHA-1 hash algorithm) of string.
// Play: https://go.dev/play/p/_m_uoD1deMT
func Sha1(data string) string {
	sha1 := sha1.New()
	sha1.Write([]byte(data))
	return hex.EncodeToString(sha1.Sum([]byte("")))
}

// Sha256 return the sha256 value (SHA256 hash algorithm) of string.
// Play: https://go.dev/play/p/tU9tfBMIAr1
func Sha256(data string) string {
	sha256 := sha256.New()
	sha256.Write([]byte(data))
	return hex.EncodeToString(sha256.Sum([]byte("")))
}

// Sha512 return the sha512 value (SHA512 hash algorithm) of string.
// Play: https://go.dev/play/p/3WsvLYZxsHa
func Sha512(data string) string {
	sha512 := sha512.New()
	sha512.Write([]byte(data))
	return hex.EncodeToString(sha512.Sum([]byte("")))
}