package utils

import (
	"crypto/sha1"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"lzyd-message-api/models"
	mathRand "math/rand"
	"net/http"
	"strconv"
	"time"
)

var (
	AppID           string = "wx47b83b24cf3b5e25"
	AppSecret       string = "bbcbc2cafbcf6e9cfe9a15aef5444d28"
	AccessTokenHost string = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appID=" + AppID + "&secret=" + AppSecret
	JsAPITicketHost string = "https://api.weixin.qq.com/cgi-bin/ticket/getticket"
)


func GetWxSign(url string) (err error, data WxSignature){
	var (
		noncestr, jsapi_ticket, timestamp, signature, signatureStr, access_token string
		wxAccessToken                                                                 WxAccessToken
		wxJsApiTicket                                                                 WxJsApiTicket
		wxSignature                                                                   WxSignature
		wxSignRtn WxSignRtn
	)

	noncestr = RandStringBytes(16)
	timestamp = strconv.FormatInt(time.Now().Unix(), 10)

	//获取access_token，如果缓存中有，则直接取出数据使用；否则重新调用微信端接口获取
	client := &http.Client{}
	if models.MemoryCacheVar.Get("access_token") == nil {
		request, _ := http.NewRequest("GET", AccessTokenHost, nil)
		response, _ := client.Do(request)
		defer response.Body.Close()
		body, err := ioutil.ReadAll(response.Body)
		if err != nil {
			wxSignRtn.Code = 1
			wxSignRtn.Msg = err.Error()
			return err, data
		}
		err = json.Unmarshal(body, &wxAccessToken)
		if err != nil {
			wxSignRtn.Code = 1
			wxSignRtn.Msg = err.Error()
			return err, data
		}
		if wxAccessToken.Errcode == 0 {
			access_token = wxAccessToken.Access_token
		} else {
			wxSignRtn.Code = 1
			wxSignRtn.Msg = wxAccessToken.Errmsg
			return err, data
		}
		models.MemoryCacheVar.Put("access_token", access_token, time.Duration(wxAccessToken.Expires_in)*time.Second)

		//获取 jsapi_ticket
		requestJs, _ := http.NewRequest("GET", JsAPITicketHost+"?access_token="+access_token+"&type=jsapi", nil)
		responseJs, _ := client.Do(requestJs)
		defer responseJs.Body.Close()
		bodyJs, err := ioutil.ReadAll(responseJs.Body)
		if err != nil {
			wxSignRtn.Code = 1
			wxSignRtn.Msg = err.Error()
			return err, data
		}
		err = json.Unmarshal(bodyJs, &wxJsApiTicket)
		if err != nil {
			wxSignRtn.Code = 1
			wxSignRtn.Msg = err.Error()
			return err, data
		}
		if wxJsApiTicket.Errcode == 0 {
			jsapi_ticket = wxJsApiTicket.Ticket
		} else {
			wxSignRtn.Code = 1
			wxSignRtn.Msg = wxJsApiTicket.Errmsg
			return err, data
		}
		models.MemoryCacheVar.Put("jsapi_ticket", jsapi_ticket, time.Duration(wxJsApiTicket.Expires_in)*time.Second)
	} else {
		//缓存中存在access_token，直接读取
		access_token = models.MemoryCacheVar.Get("access_token").(*models.Item).Value
		jsapi_ticket = models.MemoryCacheVar.Get("jsapi_ticket").(*models.Item).Value
	}
	//fmt.Println("access_token:",access_token)
	//fmt.Println("jsapi_ticket:",jsapi_ticket)

	// 获取 signature
	signatureStr = "jsapi_ticket=" + jsapi_ticket + "&noncestr=" + noncestr + "&timestamp=" + timestamp + "&url=" + url
	signature = GetSha1(signatureStr)

	wxSignature.Url = url
	wxSignature.Noncestr = noncestr
	wxSignature.Timestamp = timestamp
	wxSignature.Signature = signature
	wxSignature.AppID = AppID

	// 返回前端需要的数据
	//wxSignRtn.Code = 0
	//wxSignRtn.Msg = "success"
	//wxSignRtn.Data = wxSignature

	return err, wxSignature
}

//生成指定长度的字符串
func RandStringBytes(n int) string {
	const letterBytes = "1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
	b := make([]byte, n)
	for i := range b {
		b[i] = letterBytes[mathRand.Intn(len(letterBytes))]
	}
	return string(b)
}

//SHA1加密
func GetSha1(data string) string {
	t := sha1.New()
	io.WriteString(t, data)
	return fmt.Sprintf("%x", t.Sum(nil))
}

type WxAccessToken struct {
	Access_token string `json:"access_token"`
	Expires_in   int    `json:"expires_in"`
	Errcode      int    `json:"errcode"`
	Errmsg       string `json:"errmsg"`
}
type WxJsApiTicket struct {
	Ticket     string `json:"ticket"`
	Expires_in int    `json:"expires_in"`
	Errcode    int    `json:"errcode"`
	Errmsg     string `json:"errmsg"`
}
type WxSignature struct {
	Noncestr  string `json:"noncestr"`
	Timestamp string `json:"timestamp"`
	Url       string `json:"url"`
	Signature string `json:"signature"`
	AppID     string `json:"appId"`
}

type WxSignRtn struct {
	Code int         `json:"code"`
	Msg  string      `json:"msg"`
	Data WxSignature `json:"data"`
}