package main

import (
	"encoding/base64"
	"flag"
	"fmt"
	"html/template"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"regexp"
	"strings"

	"github.com/gorilla/mux"
)

var (
	port                 *int     // port the http server listens on
	usernames            []string // list of usernames
	currentVpnRemotePort *int
)

// Credentials stores user credentials
type Credentials struct {
	Username   string
	Accesscode string
	Hostname   string
}

func registerHTTPFlags() {
	port = flag.Int("port", 8081, "The port the http server should listen on")
	currentVpnRemotePort = flag.Int("initialVPNPort", 1194, "the initial vpn port")
}

func setupHTTPServer() http.Server {
	r := mux.NewRouter()

	r.HandleFunc("/", indexHandler)
	r.HandleFunc("/register", registerGetHandler).Methods("GET")
	r.HandleFunc("/register", registerPostHandler).Methods("POST")
	r.HandleFunc("/credentials", credentialsGetHandler).Methods("GET")

	return http.Server{
		Addr:    fmt.Sprintf("0.0.0.0:%d", *port),
		Handler: r,
	}
}

// Host of the index file
func indexHandler(w http.ResponseWriter, r *http.Request) {
	readFileToReponse(w, "/index.html")
}

// Read register page
func registerGetHandler(w http.ResponseWriter, r *http.Request) {
	readFileToReponse(w, "/register.html")
}

// Process a registration
func registerPostHandler(w http.ResponseWriter, r *http.Request) {
	r.ParseForm()

	username := r.Form.Get("username")

	// test if the username has already been chosen
	if !isUniq(username) {
		log.Println("redirecting to usernameTaken")
		usernameTakenGetHandler(w, r)
		return
	}

	if !isValid(username) {
		return
	}

	// add the new username to the list of usernames
	usernames = append(usernames, username)

	// generate a new accesscode
	accesscode := newAccessCode(16)
	log.Printf("Generated a new AccessCode for user \"%s\": \"%s\"", username, accesscode)

	// generate a new companion
	spawnCompanion(username, accesscode)

	log.Println("---")
	log.Println("Done generating the containers, filling the credentials page using a template")

	usernameBytes := []byte(username)
	usernameBase64 := base64.StdEncoding.EncodeToString(usernameBytes)

	accesscodeBytes := []byte(accesscode)
	accesscodeBase64 := base64.StdEncoding.EncodeToString(accesscodeBytes)

	// insert the username and the accesscode into the http request parameters
	r.Form["username"] = []string{usernameBase64}
	r.Form["accesscode"] = []string{accesscodeBase64}

	credentialsGetHandler(w, r)
}

func usernameTakenGetHandler(w http.ResponseWriter, r *http.Request) {
	log.Println("[usernameTaken]")
	readFileToReponse(w, "/usernameTaken.html")
}

func isUniq(username string) bool {
	for _, user := range usernames {
		if username == user {
			return false
		}
	}
	return true
}

func isValid(username string) bool {
	// reserved subdomains
	if username == "traefik" || username == "register" || username == "scoreboard" || username == "grafana" {
		return false
	}

	// valid Format
	var validFormat = regexp.MustCompile("^[a-zA-Z0-9]{1,60}$")
	if validFormat.MatchString(username) == false {
		return false
	}
	return true
}

func readFileToReponse(w http.ResponseWriter, path string) {
	requestedFile := strings.Replace(path, "..", "", -1)

	contents, readError := ioutil.ReadFile(fmt.Sprintf("hosted/%s", requestedFile))

	if readError != nil {
		w.Write([]byte(fmt.Sprintf("unable to read %s", requestedFile)))
	} else {
		w.Write([]byte(contents))
	}
}

func credentialsGetHandler(w http.ResponseWriter, r *http.Request) {
	r.ParseForm()
	usernameBase64 := r.Form.Get("username")
	username, err := base64.StdEncoding.DecodeString(usernameBase64)
	if err != nil {
		fmt.Println("error decoding username base64:", err)
	}

	accesscodeBase64 := r.Form.Get("accesscode")
	accesscode, err := base64.StdEncoding.DecodeString(accesscodeBase64)
	if err != nil {
		fmt.Println("error decoding accesscode base64:", err)
	}

	log.Println("[ ] Credentials GET Handler")
	log.Println("%#v", r.Form)
	log.Printf("username: %s", username)
	log.Printf("accesscode: %s", accesscode)

	// create a new template reading the credentials template file
	// the template then gets executed inserting the username and the accesscode
	log.Println("creating new template")
	t := template.New("")
	log.Println("parsing template file")
	t, err = t.ParseFiles("./hosted/credentials.html")
	if err != nil {
		log.Println(err)
	}
	log.Println("creating a credentials struct")
	creds := Credentials{
		Username:   string(username),
		Accesscode: string(accesscode),
		Hostname:   string(os.Getenv("HOSTNAME")),
	}
	log.Println("executing the template")
	t.ExecuteTemplate(w, "credentials", creds)
	log.Println("done executing the template")
}