package main

import (
	"context"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/endpoints"

	"git.sr.ht/~muirrum/gompei-verification/bot"
	"github.com/bwmarrin/discordgo"
	"github.com/gleich/logoru"
	"github.com/joho/godotenv"
)

var ()

var azureConfig oauth2.Config
var discordConfig oauth2.Config

var verifyChan chan string

func LandingPage(w http.ResponseWriter, r *http.Request) {
	logoru.Info("Starting auth process")
	azureUrl := azureConfig.AuthCodeURL("xyz")
	http.Redirect(w, r, azureUrl, http.StatusFound)
}

// Azure landing page
func AzureAuth(w http.ResponseWriter, r *http.Request) {
	r.ParseForm()
	state := r.Form.Get("state")
	if state != "xyz" {
		http.Error(w, "Invalid state", http.StatusBadRequest)
		return
	}

	code := r.Form.Get("code")
	if code == "" {
		http.Error(w, "Code not found", http.StatusBadRequest)
		return
	}
	_, err := azureConfig.Exchange(context.Background(), code)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	discordUrl := discordConfig.AuthCodeURL("xyz")
	http.Redirect(w, r, discordUrl, http.StatusFound)
}

// Discord landing page
func DiscordAuth(w http.ResponseWriter, r *http.Request) {
	r.ParseForm()
	state := r.Form.Get("state")
	if state != "xyz" {
		http.Error(w, "Invalid state", http.StatusBadRequest)
		return
	}

	code := r.Form.Get("code")
	if code == "" {
		http.Error(w, "Code not found", http.StatusBadRequest)
		return
	}
	token, err := discordConfig.Exchange(context.Background(), code)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	req, err := http.NewRequest("GET", "https://discord.com/api/users/@me", nil)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	token.SetAuthHeader(req)

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer res.Body.Close()
	body, _ := ioutil.ReadAll(res.Body)
	bytes := []byte(body)
	var user discordgo.User
	err = json.Unmarshal(bytes, &user)

	verifyChan <- user.ID

	http.Redirect(w, r, fmt.Sprintf("%s/success", os.Getenv("BASE_URL")), http.StatusFound)
}

func Success(w http.ResponseWriter, r *http.Request) {
	http.Redirect(w, r, os.Getenv("SUCCESS_URL"), http.StatusFound)
}

func main() {
	err := godotenv.Load()
	if err != nil {
		logoru.Critical("Could not load environment file")
	}

	azureConfig = oauth2.Config{
		ClientID:     os.Getenv("AZURE_CLIENT_ID"),
		ClientSecret: os.Getenv("AZURE_CLIENT_SECRET"),
		Scopes:       []string{".default"},
		RedirectURL:  fmt.Sprintf("%s/oauth/microsoft", os.Getenv("BASE_URL")),
		Endpoint:     endpoints.AzureAD(os.Getenv("AZURE_TENANT_ID")),
	}

	discordConfig = oauth2.Config{
		ClientID:     os.Getenv("DISCORD_CLIENT_ID"),
		ClientSecret: os.Getenv("DISCORD_CLIENT_SECRET"),
		Scopes:       []string{"identify"},
		RedirectURL:  fmt.Sprintf("%s/oauth/discord", os.Getenv("BASE_URL")),
		Endpoint: oauth2.Endpoint{
			AuthURL:   "https://discord.com/api/oauth2/authorize",
			TokenURL:  "https://discord.com/api/oauth2/token",
			AuthStyle: 0,
		},
	}

	http.HandleFunc("/", LandingPage)
	http.HandleFunc("/oauth/microsoft", AzureAuth)
	http.HandleFunc("/oauth/discord", DiscordAuth)
	http.HandleFunc("/success", Success)

	verifyChan = make(chan string)

	go bot.StartDiscordBot(verifyChan)

	logoru.Info("Starting client")
	logoru.Critical(http.ListenAndServe(fmt.Sprintf(":%s", os.Getenv("LISTEN_PORT")), nil))
}