package wechat

import (
	"fmt"
	"math/rand"
	"sort"
	"strings"
	"time"

	"git.chuangxin1.com/cx/myth"
)

// Sign 微信计算签名的函数
func Sign(req map[string]interface{}, key string) (sign string) {
	keys := make([]string, 0)

	for k := range req {
		keys = append(keys, k)
	}

	sort.Strings(keys)

	var s string
	for _, k := range keys {
		value := fmt.Sprintf("%v", req[k])
		if value != "" {
			s = s + k + "=" + value + "&"
		}
	}

	if key != "" {
		s = s + "key=" + key
	}

	sign = strings.ToUpper(myth.MD5(s))

	return
}

// Random 指定长度的随机字符串(字母或数字)
func Random(n int) string {
	str := "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	bytes := []byte(str)
	result := []byte{}

	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	n1 := len(bytes)
	for i := 0; i < n; i++ {
		result = append(result, bytes[r.Intn(n1)])
	}
	return string(result)
}

// makeSignature echo 签名验证
func makeSignature(token, signature, timestamp, nonce string) bool {
	sl := []string{token, timestamp, nonce}
	sort.Strings(sl)
	return strings.Compare(signature, myth.SHA1(strings.Join(sl, ""))) == 0
}