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// Copyright 2013 com authors
//
// Licensed under the Apache License, Version 2.0 (the "License"): you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.
package com
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"errors"
r "math/rand"
"strconv"
"strings"
"time"
"unicode"
"unicode/utf8"
)
// AESGCMEncrypt encrypts plaintext with the given key using AES in GCM mode.
func AESGCMEncrypt(key, plaintext []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
nonce := make([]byte, gcm.NonceSize())
if _, err := rand.Read(nonce); err != nil {
return nil, err
}
ciphertext := gcm.Seal(nil, nonce, plaintext, nil)
return append(nonce, ciphertext...), nil
}
// AESGCMDecrypt decrypts ciphertext with the given key using AES in GCM mode.
func AESGCMDecrypt(key, ciphertext []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
size := gcm.NonceSize()
if len(ciphertext)-size <= 0 {
return nil, errors.New("Ciphertext is empty")
}
nonce := ciphertext[:size]
ciphertext = ciphertext[size:]
plainText, err := gcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
return nil, err
}
return plainText, nil
}
// IsLetter returns true if the 'l' is an English letter.
func IsLetter(l uint8) bool {
n := (l | 0x20) - 'a'
if n >= 0 && n < 26 {
return true
}
return false
}
// Expand replaces {k} in template with match[k] or subs[atoi(k)] if k is not in match.
func Expand(template string, match map[string]string, subs ...string) string {
var p []byte
var i int
for {
i = strings.Index(template, "{")
if i < 0 {
break
}
p = append(p, template[:i]...)
template = template[i+1:]
i = strings.Index(template, "}")
if s, ok := match[template[:i]]; ok {
p = append(p, s...)
} else {
j, _ := strconv.Atoi(template[:i])
if j >= len(subs) {
p = append(p, []byte("Missing")...)
} else {
p = append(p, subs[j]...)
}
}
template = template[i+1:]
}
p = append(p, template...)
return string(p)
}
// Reverse s string, support unicode
func Reverse(s string) string {
n := len(s)
runes := make([]rune, n)
for _, rune := range s {
n--
runes[n] = rune
}
return string(runes[n:])
}
// RandomCreateBytes generate random []byte by specify chars.
func RandomCreateBytes(n int, alphabets ...byte) []byte {
const alphanum = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
var bytes = make([]byte, n)
var randby bool
if num, err := rand.Read(bytes); num != n || err != nil {
r.Seed(time.Now().UnixNano())
randby = true
}
for i, b := range bytes {
if len(alphabets) == 0 {
if randby {
bytes[i] = alphanum[r.Intn(len(alphanum))]
} else {
bytes[i] = alphanum[b%byte(len(alphanum))]
}
} else {
if randby {
bytes[i] = alphabets[r.Intn(len(alphabets))]
} else {
bytes[i] = alphabets[b%byte(len(alphabets))]
}
}
}
return bytes
}
// ToSnakeCase can convert all upper case characters in a string to
// underscore format.
//
// Some samples.
// "FirstName" => "first_name"
// "HTTPServer" => "http_server"
// "NoHTTPS" => "no_https"
// "GO_PATH" => "go_path"
// "GO PATH" => "go_path" // space is converted to underscore.
// "GO-PATH" => "go_path" // hyphen is converted to underscore.
//
// From https://github.com/huandu/xstrings
func ToSnakeCase(str string) string {
if len(str) == 0 {
return ""
}
buf := &bytes.Buffer{}
var prev, r0, r1 rune
var size int
r0 = '_'
for len(str) > 0 {
prev = r0
r0, size = utf8.DecodeRuneInString(str)
str = str[size:]
switch {
case r0 == utf8.RuneError:
buf.WriteByte(byte(str[0]))
case unicode.IsUpper(r0):
if prev != '_' {
buf.WriteRune('_')
}
buf.WriteRune(unicode.ToLower(r0))
if len(str) == 0 {
break
}
r0, size = utf8.DecodeRuneInString(str)
str = str[size:]
if !unicode.IsUpper(r0) {
buf.WriteRune(r0)
break
}
// find next non-upper-case character and insert `_` properly.
// it's designed to convert `HTTPServer` to `http_server`.
// if there are more than 2 adjacent upper case characters in a word,
// treat them as an abbreviation plus a normal word.
for len(str) > 0 {
r1 = r0
r0, size = utf8.DecodeRuneInString(str)
str = str[size:]
if r0 == utf8.RuneError {
buf.WriteRune(unicode.ToLower(r1))
buf.WriteByte(byte(str[0]))
break
}
if !unicode.IsUpper(r0) {
if r0 == '_' || r0 == ' ' || r0 == '-' {
r0 = '_'
buf.WriteRune(unicode.ToLower(r1))
} else {
buf.WriteRune('_')
buf.WriteRune(unicode.ToLower(r1))
buf.WriteRune(r0)
}
break
}
buf.WriteRune(unicode.ToLower(r1))
}
if len(str) == 0 || r0 == '_' {
buf.WriteRune(unicode.ToLower(r0))
break
}
default:
if r0 == ' ' || r0 == '-' {
r0 = '_'
}
buf.WriteRune(r0)
}
}
return buf.String()
}
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