package main

import (
	"crypto/sha1"
	"encoding/xml"
	"fmt"
	"log"
	"net/http"
	"sort"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
)

const (
	appID  = "wxc39301065b66300c"
	secret = "7fee3a1cba8c555cf6c4caec4f05844c"
	token  = "qwertyuiopasdfghjkl"
)

//////
type messageEntity struct {
	Signature string `form:"signature"`
	Timestamp string `form:"timestamp"`
	Nonce     string `form:"nonce"`
	EchoStr   string `form:"echostr"`
}

func (m *messageEntity) CheckSignature(token string) bool {
	item := []string{token, m.Timestamp, m.Nonce}
	sort.Strings(item)
	itemByte := strings.Join(item, "")
	signature := fmt.Sprintf("%x", sha1.Sum([]byte(itemByte)))
	return signature == m.Signature
}

func Check(c *gin.Context) {
	me := &messageEntity{}
	me.Signature = c.Query("signature")
	me.Timestamp = c.Query("timestamp")
	me.Nonce = c.Query("nonce")
	me.EchoStr = c.Query("echostr")
	log.Println("signature:", me.Signature, "timestamp:", me.Timestamp, "noce:", me.Nonce, "echostr:", me.EchoStr)
	if !me.CheckSignature(token) {
		log.Println("token is not ok")
		c.AbortWithError(http.StatusForbidden, fmt.Errorf("token invalid"))
		return
	}
	c.Next()
}

////
type foucsData struct {
	ToUserName   string `xml:"ToUserName"`
	FromUserName string `xml:"FromUserName"`
	CreateTime   int64  `xml:"CreateTime"`
	MsgType      string `xml:"MsgType"`
	Event        string `xml:"Event"`
}

////
type textMessage struct {
	ToUserName   string `xml:"ToUserName"`
	FromUserName string `xml:"FromUserName"`
	CreateTime   int64  `xml:"CreateTime"`
	MsgType      string `xml:"MsgType"`
	Content        string `xml:"Content"`
}

func cdata(data string)string{
	return fmt.Sprintf(`<![CDATA[%s]]>`, data)
}

func handleGet(c *gin.Context) {
	me := &messageEntity{}
	me.Signature = c.Query("signature")
	me.Timestamp = c.Query("timestamp")
	me.Nonce = c.Query("nonce")
	me.EchoStr = c.Query("echostr")
	log.Println("signature:", me.Signature, "timestamp:", me.Timestamp, "noce:", me.Nonce, "echostr:", me.EchoStr)
	log.Println("token is ok")
	c.String(http.StatusOK, me.EchoStr)
}
func handlePost(c *gin.Context) {
	data := foucsData{}
	err := c.BindXML(&data)
	if err != nil {
		log.Println(err)
	}
	log.Println("data: ", data)
	openID := c.Query("openid")
	log.Println("openid is ", openID)
	t := textMessage{
		ToUserName: cdata(data.FromUserName),
		FromUserName: cdata(data.ToUserName),
		CreateTime: time.Now().Unix(),
		MsgType: cdata("text"),
		Content: cdata("你关注了我！"),
	}
	d, err := xml.Marshal(&t)
	if err != nil {
		log.Println("marshar message faild", err)
	}
	c.String(http.StatusOK, string(d))
}

func handlePut(c *gin.Context) {
	data :=foucsData{}
	err := c.BindXML(&data)
	if err != nil {
		log.Println(err)
	}
	log.Println("data: ", data)
	c.String(http.StatusOK, "success")
}

func handleDelete(c *gin.Context) {
	data := foucsData{}
	err := c.BindXML(&data)
	if err != nil {
		log.Println(err)
	}
	log.Println("data: ", data)
	c.String(http.StatusOK, "success")
}


func main() {
	engine := gin.Default()
	engine.Use(Check)
	engine.GET("/api/wechat/signature", handleGet)
	engine.POST("/api/wechat/signature", handlePost)
	engine.PUT("/api/wechat/signature", handlePut)
	engine.DELETE("/api/wechat/signature", handleDelete)
	engine.Run("0.0.0.0:15043")
}