package aes

import (
	"applet/app/lib/aes/md"
	"applet/app/utils"
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"github.com/gin-gonic/gin"
	"io/ioutil"
	"strconv"
	"strings"
	"time"
)

func CheckSign(c *gin.Context) error {
	var query = map[string]string{}
	//1、从请求头中获取必传参数
	query["timestamp"] = c.GetHeader("timestamp")
	query["nonce"] = c.GetHeader("nonce")
	if len(query["nonce"]) != 32 {
		return errors.New("随机字符串有误！")
	}
	sign := c.GetHeader("sign")

	//2、判断请求方式，以获取请求参数
	if c.Request.Method == "GET" {
		queryParams := c.Request.URL.Query()
		for key, values := range queryParams {
			if len(values) > 0 {
				query[key] = values[0]
			}
		}
	} else {
		body, _ := ioutil.ReadAll(c.Request.Body)
		if string(body) != "" {
			str, err := AesDecryptByECB(md.AesKey, string(body))
			if err != nil {
				return err
			}
			if str != "" {
				c.Request.Body = ioutil.NopCloser(bytes.NewBuffer([]byte(str)))

				var bodyParams = map[string]string{}
				err = json.Unmarshal([]byte(str), &bodyParams)
				if err != nil {
					return err
				}
				for key, value := range bodyParams {
					query[key] = value
				}
			}
		}
	}

	//3.query参数按照 ASCII 码从小到大排序
	str := utils.JoinStringsInASCII(query, "&", false, false, "")

	//4.md5加密 转小写
	signValue := strings.ToLower(utils.Md5(str))

	//5.判断跟前端传来的sign是否一致
	if sign != signValue {
		return errors.New("非法签名！")
	}

	//6、判断时效性
	currentTimestamp := time.Now().Unix()
	storedTimestamp, err := strconv.ParseInt(query["timestamp"], 10, 64)
	if err != nil {
		return err
	}
	if currentTimestamp-storedTimestamp > 300 { // 5分钟
		return fmt.Errorf("签名过期！")
	}
	return nil
}