package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	_ "github.com/breml/rootcerts"
	"github.com/davecgh/go-spew/spew"

	"github.com/gorilla/mux"
	"github.com/gorilla/sessions"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/microsoft"
)

var config = oauth2.Config{
	ClientID:     "dccb4b93-3f75-4775-a94a-da39216d7daf",
	ClientSecret: "XN98Q~Wrp1RfakkihA1BaTKfokOSX9fuB01unanr",
	Endpoint:     microsoft.AzureADEndpoint("ceeae22e-f163-4ac9-b7c2-45972d3aed4f"),
	RedirectURL:  "https://alias.spamasaurus.com/callback",
	Scopes:       []string{"User.Read", "Profile"},
}

var sessionStore = sessions.NewCookieStore([]byte("xDDBjhYwyndZty3exGNq2ahE8wHRCR4DfdCJCSoWXAYncfWw2UQDH63QcJ9CkrGx"))

func rootHandler(w http.ResponseWriter, r *http.Request) {
	session, _ := sessionStore.Get(r, "spamasaurusRex")
	if token, ok := session.Values["token"]; ok {
		w.Write([]byte(spew.Sdump(token)))
	} else {
		url := config.AuthCodeURL("state", oauth2.AccessTypeOffline)
		http.Redirect(w, r, url, http.StatusFound)
	}
}

func callbackHandler(w http.ResponseWriter, r *http.Request) {
	// Handle the callback after successful authentication
	token, err := config.Exchange(r.Context(), r.URL.Query().Get("code"))
	if err != nil {
		if retrieveErr, ok := err.(*oauth2.RetrieveError); ok {
			w.Write([]byte(retrieveErr.ErrorDescription + " (" + retrieveErr.ErrorCode + ")"))
		}
		http.Error(w, "Error exchanging code for token", http.StatusInternalServerError)
		return
	}

	// Store the token in the session
	session, _ := sessionStore.Get(r, "spamasaurusRex")
	session.Values["token"] = token
	session.Save(r, w)

	fmt.Fprintln(w, "Authentication successful!")

	url := "https://alias.spamasaurus.com"
	http.Redirect(w, r, url, http.StatusAccepted)
}

func healthHandler(w http.ResponseWriter, r *http.Request) {
	w.WriteHeader(http.StatusOK)
}

func readinessHandler(w http.ResponseWriter, r *http.Request) {
	w.WriteHeader(http.StatusOK)
}

func main() {
	r := mux.NewRouter()

	r.HandleFunc("/", rootHandler)
	r.HandleFunc("/health", healthHandler)
	r.HandleFunc("/callback", callbackHandler)
	r.HandleFunc("/readiness", readinessHandler)

	srv := &http.Server{
		Handler:      r,
		Addr:         ":8080",
		ReadTimeout:  10 * time.Second,
		WriteTimeout: 10 * time.Second,
	}

	// Start Server
	go func() {
		log.Println("Starting Server")
		if err := srv.ListenAndServe(); err != nil {
			log.Fatal(err)
		}
	}()

	// Graceful Shutdown
	waitForShutdown(srv)
}

func waitForShutdown(srv *http.Server) {
	interruptChan := make(chan os.Signal, 1)
	signal.Notify(interruptChan, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)

	// Block until we receive our signal.
	<-interruptChan

	// create a deadline to wait for.
	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()
	srv.Shutdown(ctx)

	log.Println("Shutting down")
	os.Exit(0)
}