package main

import (
	"fmt"
	"html/template"
	"io/ioutil"
	"log"
	"net/http"
	"path/filepath"
	"strings"
	"time"

	"github.com/dgrijalva/jwt-go"
)

var (
	password          = "hardcodedpassword"
	lootPath          = "Loot"
	sessionCookieName = "auth_session"
	secretKey         = []byte("key"))

type PageData struct {
	UIDs  []string
	Files []string
}

type Claims struct {
	Username string `json:"username"`
	jwt.StandardClaims
}

func main() {
	http.HandleFunc("/", logMiddleware(loginHandler))
	http.HandleFunc("/loot", logMiddleware(lootHandler))
	http.HandleFunc("/logout", logMiddleware(logoutHandler))
	http.HandleFunc("/files/", logMiddleware(fileHandler))

	log.Fatal(http.ListenAndServe(":5647", nil))
	fmt.Println("Server started")
}

func logMiddleware(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		log.Printf("[%s] %s %s\n", r.Method, r.RemoteAddr, r.URL.Path)
		next(w, r)
	}
}

func loginHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		renderTemplate(w, "login.html", nil)
		return
	}

	if r.FormValue("password") == password {
		expirationTime := time.Now().Add(1 * time.Hour)
		claims := &Claims{
			Username: "root",
			StandardClaims: jwt.StandardClaims{
				ExpiresAt: expirationTime.Unix(),
			},
		}

		token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
		tokenString, err := token.SignedString(secretKey)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		http.SetCookie(w, &http.Cookie{
			Name:    sessionCookieName,
			Value:   tokenString,
			Expires: expirationTime,
			Path:    "/",
		})

		http.Redirect(w, r, "/loot", http.StatusSeeOther)
		return
	}

	renderTemplate(w, "login.html", "Incorrect password")
}

func lootHandler(w http.ResponseWriter, r *http.Request) {
	checkAuth(w, r)

	uids, err := getDeviceUIDs()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	data := PageData{UIDs: uids}
	renderTemplate(w, "loot.html", data)
}

func fileHandler(w http.ResponseWriter, r *http.Request) {
	checkAuth(w, r)

	requestedPath := strings.TrimPrefix(r.URL.Path, "/files/")
	filePath := filepath.Join(lootPath, requestedPath)
	http.ServeFile(w, r, filePath)
}

func logoutHandler(w http.ResponseWriter, r *http.Request) {
	http.SetCookie(w, &http.Cookie{
		Name:   sessionCookieName,
		Value:  "",
		Path:   "/",
		MaxAge: -1,
	})
	http.Redirect(w, r, "/", http.StatusSeeOther)
}

func renderTemplate(w http.ResponseWriter, tmpl string, data interface{}) {
	t, err := template.ParseFiles(tmpl)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	t.Execute(w, data)
}

func isAuthenticated(r *http.Request) bool {
	sessionCookie, err := r.Cookie(sessionCookieName)
	if err != nil {
		return false
	}

	tokenString := sessionCookie.Value
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		return secretKey, nil
	})

	if err != nil || !token.Valid {
		return false
	}

	return true
}

func getDeviceUIDs() ([]string, error) {
	var uids []string
	files, err := ioutil.ReadDir(lootPath)
	if err != nil {
		return nil, err
	}
	for _, file := range files {
		if file.IsDir() {
			uids = append(uids, file.Name())
		}
	}
	return uids, nil
}

func checkAuth(w http.ResponseWriter, r *http.Request) {
	if !isAuthenticated(r) {
		http.Redirect(w, r, "/", http.StatusSeeOther)
		return
	}
}