Facebook login

auth/facebook.go

@@ -0,0 +1,172 @@
+package auth
+
+import (
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+	"strings"
+
+	"github.com/aerogo/aero"
+	"github.com/animenotifier/arn"
+	"github.com/animenotifier/notify.moe/utils"
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/facebook"
+)
+
+// FacebookUser is the user data we receive from Facebook
+type FacebookUser struct {
+	ID        string `json:"id"`
+	Email     string `json:"email"`
+	FirstName string `json:"first_name"`
+	LastName  string `json:"last_name"`
+	Gender    string `json:"gender"`
+}
+
+// InstallFacebookAuth enables Facebook login for the app.
+func InstallFacebookAuth(app *aero.Application) {
+	config := &oauth2.Config{
+		ClientID:     arn.APIKeys.Facebook.ID,
+		ClientSecret: arn.APIKeys.Facebook.Secret,
+		RedirectURL:  "https://" + app.Config.Domain + "/auth/facebook/callback",
+		Scopes: []string{
+			"public_profile",
+			"email",
+		},
+		Endpoint: facebook.Endpoint,
+	}
+
+	// Auth
+	app.Get("/auth/facebook", func(ctx *aero.Context) string {
+		state := ctx.Session().ID()
+		url := config.AuthCodeURL(state)
+		ctx.Redirect(url)
+		return ""
+	})
+
+	// Auth Callback
+	app.Get("/auth/facebook/callback", func(ctx *aero.Context) string {
+		if !ctx.HasSession() {
+			return ctx.Error(http.StatusUnauthorized, "Facebook login failed", errors.New("Session does not exist"))
+		}
+
+		session := ctx.Session()
+
+		if session.ID() != ctx.Query("state") {
+			return ctx.Error(http.StatusUnauthorized, "Facebook login failed", errors.New("Incorrect state"))
+		}
+
+		// Handle the exchange code to initiate a transport
+		token, err := config.Exchange(oauth2.NoContext, ctx.Query("code"))
+
+		if err != nil {
+			return ctx.Error(http.StatusBadRequest, "Could not obtain OAuth token", err)
+		}
+
+		// Construct the OAuth client
+		client := config.Client(oauth2.NoContext, token)
+
+		// Fetch user data from Facebook
+		resp, err := client.Get("https://graph.facebook.com/me?fields=email,first_name,last_name,gender")
+
+		if err != nil {
+			return ctx.Error(http.StatusBadRequest, "Failed requesting user data from Facebook", err)
+		}
+
+		defer resp.Body.Close()
+		body, _ := ioutil.ReadAll(resp.Body)
+
+		// Construct a FacebookUser object
+		fbUser := FacebookUser{}
+		err = json.Unmarshal(body, &fbUser)
+
+		if err != nil {
+			return ctx.Error(http.StatusBadRequest, "Failed parsing user data (JSON)", err)
+		}
+
+		// Change googlemail.com to gmail.com
+		fbUser.Email = strings.Replace(fbUser.Email, "googlemail.com", "gmail.com", 1)
+
+		// Is this an existing user connecting another social account?
+		user := utils.GetUser(ctx)
+
+		if user != nil {
+			// Add FacebookToUser reference
+			err = user.ConnectFacebook(fbUser.ID)
+
+			if err != nil {
+				ctx.Error(http.StatusInternalServerError, "Could not connect account to Facebook account", err)
+			}
+
+			authLog.Info("Added Facebook ID to existing account", user.ID, user.Nick, ctx.RealIP(), user.Email, user.RealName())
+
+			return ctx.Redirect("/")
+		}
+
+		var getErr error
+
+		// Try to find an existing user via the Facebook user ID
+		user, getErr = arn.GetUserFromTable("FacebookToUser", fbUser.ID)
+
+		if getErr == nil && user != nil {
+			authLog.Info("User logged in via Facebook ID", user.ID, user.Nick, ctx.RealIP(), user.Email, user.RealName())
+
+			user.LastLogin = arn.DateTimeUTC()
+			user.Save()
+
+			session.Set("userId", user.ID)
+			return ctx.Redirect("/")
+		}
+
+		// Try to find an existing user via the associated e-mail address
+		user, getErr = arn.GetUserByEmail(fbUser.Email)
+
+		if getErr == nil && user != nil {
+			authLog.Info("User logged in via Email", user.ID, user.Nick, ctx.RealIP(), user.Email, user.RealName())
+
+			user.LastLogin = arn.DateTimeUTC()
+			user.Save()
+
+			session.Set("userId", user.ID)
+			return ctx.Redirect("/")
+		}
+
+		// Register new user
+		user = arn.NewUser()
+		user.Nick = "fb" + fbUser.ID
+		user.Email = fbUser.Email
+		user.FirstName = fbUser.FirstName
+		user.LastName = fbUser.LastName
+		user.Gender = fbUser.Gender
+		user.LastLogin = arn.DateTimeUTC()
+
+		// Save basic user info already to avoid data inconsistency problems
+		user.Save()
+
+		// Register user
+		err = arn.RegisterUser(user)
+
+		if err != nil {
+			ctx.Error(http.StatusInternalServerError, "Could not register a new user", err)
+		}
+
+		// Connect account to a Facebook account
+		err = user.ConnectFacebook(fbUser.ID)
+
+		if err != nil {
+			ctx.Error(http.StatusInternalServerError, "Could not connect account to Facebook account", err)
+		}
+
+		// Save user object again with updated data
+		user.Save()
+
+		// Login
+		session.Set("userId", user.ID)
+
+		// Log
+		authLog.Info("Registered new user via Facebook", user.ID, user.Nick, ctx.RealIP(), user.Email, user.RealName())
+
+		// Redirect to frontpage
+		return ctx.Redirect("/")
+	})
+}