package oauth2

import (
	"encoding/json"
	"io/ioutil"
	"log"
	"net/http"
	"time"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
	auth "imuslab.com/arozos/mod/auth"
	syncdb "imuslab.com/arozos/mod/auth/oauth2/syncdb"
	reg "imuslab.com/arozos/mod/auth/register"
)

type OauthHandler struct {
	googleOauthConfig *oauth2.Config
	syncDb            *syncdb.SyncDB
	oauthStateString  string
	DefaultUserGroup  string
	ag                *auth.AuthAgent
	reg               *reg.RegisterHandler
}

type GoogleField struct {
	ID            string `json:"id"`
	Email         string `json:"email"`
	VerifiedEmail bool   `json:"verified_email"`
	Name          string `json:"name"`
	GivenName     string `json:"given_name"`
	FamilyName    string `json:"family_name"`
	Picture       string `json:"picture"`
	Locale        string `json:"locale"`
}

//NewOauthHandler xxx
func NewOauthHandler(authAgent *auth.AuthAgent, register *reg.RegisterHandler) *OauthHandler {
	NewlyCreatedOauthHandler := OauthHandler{
		googleOauthConfig: &oauth2.Config{
			RedirectURL:  "http://localhost:8080/system/auth/oauth/authorize",
			ClientID:     "682431817920-nkmfn7m6uq0qbdo00hr2944m6r3hj8ua.apps.googleusercontent.com",
			ClientSecret: "Obdlr2S5n8rj_qwsPLhToD3h",
			Scopes: []string{"https://www.googleapis.com/auth/userinfo.profile",
				"https://www.googleapis.com/auth/userinfo.email"},
			Endpoint: google.Endpoint,
		},
		// Some random string, random for each request
		DefaultUserGroup: "default",
		ag:               authAgent,
		syncDb:           syncdb.NewSyncDB(),
		reg:              register,
	}

	return &NewlyCreatedOauthHandler
}

//HandleOauthLogin xxx
func (oh *OauthHandler) HandleLogin(w http.ResponseWriter, r *http.Request) {
	//add cookies
	redirect, e := r.URL.Query()["redirect"]
	uuid := ""
	if !e || len(redirect[0]) < 1 {
		uuid = oh.syncDb.Store("/")
	} else {
		uuid = oh.syncDb.Store(redirect[0])
	}
	oh.addCookie(w, "uuid_login", uuid, 30*time.Minute)
	//handle redirect
	url := oh.googleOauthConfig.AuthCodeURL(uuid)
	http.Redirect(w, r, url, http.StatusTemporaryRedirect)
}

//OauthAuthorize xxx
func (oh *OauthHandler) HandleAuthorize(w http.ResponseWriter, r *http.Request) {
	//read the uuid(aka the state parameter)
	uuid, err := r.Cookie("uuid_login")
	if err != nil {
		w.Header().Set("Content-Type", "text/html; charset=UTF-8")
		w.Write([]byte("Invalid redirect URI."))
	}

	state := r.FormValue("state")
	if state != uuid.Value {
		w.Header().Set("Content-Type", "text/html; charset=UTF-8")
		w.Write([]byte("Invalid oauth state."))
		return
	}

	code := r.FormValue("code")
	token, err := oh.googleOauthConfig.Exchange(oauth2.NoContext, code)
	if err != nil {
		w.Header().Set("Content-Type", "text/html; charset=UTF-8")
		w.Write([]byte("Code exchange failed."))
		return
	}

	response, err := http.Get("https://www.googleapis.com/oauth2/v2/userinfo?access_token=" + token.AccessToken)

	defer response.Body.Close()
	contents, err := ioutil.ReadAll(response.Body)
	var data GoogleField
	json.Unmarshal([]byte(contents), &data)

	if !oh.ag.UserExists(data.Email) {
		//register user if not already exists
		//random pwd to prevent ppl bypassing the OAuth handler
		if oh.reg.AllowRegistry {
			http.Redirect(w, r, "/public/register/register.system?user="+data.Email, 302)
		} else {
			w.Header().Set("Content-Type", "text/html; charset=UTF-8")
			w.Write([]byte("You are not allowed to register in this system.&nbsp;<a href=\"/\">Back</a>"))
		}
	} else {
		log.Println(data.Email + " logged in via OAuth.")
		oh.ag.LoginUserByRequest(w, r, data.Email, true)
		//clear the cooke
		oh.addCookie(w, "uuid_login", "-invaild-", -1)
		//read the value from db and delete it from db
		url := oh.syncDb.Read(uuid.Value)
		oh.syncDb.Delete(uuid.Value)
		//redirect to the desired page
		http.Redirect(w, r, url, 302)
	}
}

func (oh *OauthHandler) CheckOAuth(w http.ResponseWriter, r *http.Request) {
	sendJSONResponse(w, "true")
}

//https://golangcode.com/add-a-http-cookie/
func (oh *OauthHandler) addCookie(w http.ResponseWriter, name, value string, ttl time.Duration) {
	expire := time.Now().Add(ttl)
	cookie := http.Cookie{
		Name:    name,
		Value:   value,
		Expires: expire,
	}
	http.SetCookie(w, &cookie)
}