LoginSystem/main.go

package main

import (
	"encoding/json"
	"flag"
	"log"
	"net/http"

	"github.com/gorilla/sessions"
)

var store = sessions.NewCookieStore([]byte("secret-key"))

type Status struct {
	LoggedIn bool
}

type Password struct {
	Matched bool
}

func loginHandler(rw http.ResponseWriter, req *http.Request) {
	if req.Method == "GET" {
		password := req.FormValue("password")
		log.Println("The typed password is:" + password)
		var typed Password

		if password == "admin" {
			log.Println("Password is correct")

			session, err := store.Get(req, "session-name")
			if err != nil {
				http.Error(rw, err.Error(), http.StatusInternalServerError)
				return
			}
			session.Values["auth"] = true
			err = session.Save(req, rw)
			if err != nil {
				http.Error(rw, err.Error(), http.StatusInternalServerError)
				return
			}

			typed.Matched = true
			log.Println("Logged in")
		} else {
			typed.Matched = false
			log.Println("WRONG password!!")
		}
		send_message, _ := json.Marshal(typed)
		rw.Write(send_message)
	}
}

func logoutHandler(rw http.ResponseWriter, req *http.Request) {
	session, err := store.Get(req, "session-name")
	if err != nil {
		http.Error(rw, err.Error(), http.StatusInternalServerError)
		return
	}
	session.Values["auth"] = nil
	err = session.Save(req, rw)
	if err != nil {
		http.Error(rw, err.Error(), http.StatusInternalServerError)
		return
	}

	http.Redirect(rw, req, "/login.html", http.StatusSeeOther)
	log.Println("Logged out successfully")
}

func checkloginHandler(rw http.ResponseWriter, req *http.Request) {
	log.Println("Check button is clicked")
	session, err := store.Get(req, "session-name")
	if err != nil {
		http.Error(rw, err.Error(), http.StatusInternalServerError)
		return
	}
	var result Status
	if session.Values["auth"] == true {
		log.Println("Checked that auth = true")
		result.LoggedIn = true
	} else {
		log.Println("Checked that auth = false")
		result.LoggedIn = false
	}
	send_message, _ := json.Marshal(result)
	rw.Write(send_message)
}

func main() {
	portPointer := flag.String("port", "8000", "An integer")
	flag.Parse()
	log.Println("Port Number: " + *portPointer)
	httpFileServer := http.FileServer(http.Dir("./files"))
	http.Handle("/", httpFileServer)

	http.HandleFunc("/login", loginHandler)
	http.HandleFunc("/logout", logoutHandler)
	http.HandleFunc("/checklogin", checkloginHandler)

	log.Printf("Listening http://localhost:%s\n", *portPointer)
	if error := http.ListenAndServe(":"+*portPointer, nil); error != nil {
		log.Printf("Error: %s\n", error)
	}
}