Refactor oauth login

internal/middleware/session.go

@@ -4,7 +4,12 @@ package middleware
 import (
 	"context"
 	"crypto/rand"
+	"log"
 	"net/http"
+
+	urls "forgejo.gwairfelin.com/max/gispatcho"
+	"forgejo.gwairfelin.com/max/gonotes/internal/auth"
+	"golang.org/x/oauth2"
 )
 
 type Session struct {
@@ -13,12 +18,26 @@ type Session struct {
 
 type SessionStore struct {
 	sessions map[string]Session
+	oauth    *oauth2.Config
+	Routes   urls.URLs
 }
 
 type ContextKey string
 
-func NewSessionStore() SessionStore {
-	return SessionStore{sessions: make(map[string]Session, 10)}
+func NewSessionStore(oauth *oauth2.Config, prefix string) SessionStore {
+	store := SessionStore{
+		sessions: make(map[string]Session, 10),
+		oauth:    oauth,
+	}
+	store.Routes = urls.URLs{
+		Prefix: prefix,
+		URLs: map[string]urls.URL{
+			"login":    {Path: "/login/", Protocol: "GET", Handler: store.LoginViewOAUTH},
+			"callback": {Path: "/callback/", Protocol: "GET", Handler: store.CallbackViewOAUTH},
+			"logout":   {Path: "/logout/", Protocol: "GET", Handler: store.Logout},
+		},
+	}
+	return store
 }
 
 func (s *SessionStore) Login(user string, w http.ResponseWriter) string {
@@ -47,6 +66,57 @@ func (s *SessionStore) Logout(w http.ResponseWriter, r *http.Request) {
 	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
 }
 
+func (s *SessionStore) LoginViewOAUTH(w http.ResponseWriter, r *http.Request) {
+	log.Printf("%+v", *s.oauth)
+
+	oauthState := auth.GenerateStateOAUTHCookie(w, s.Routes.Prefix)
+
+	url := s.oauth.AuthCodeURL(oauthState)
+	log.Printf("Redirecting to %s", url)
+	http.Redirect(w, r, url, http.StatusTemporaryRedirect)
+}
+
+func (s *SessionStore) CallbackViewOAUTH(w http.ResponseWriter, r *http.Request) {
+	// Read oauthState from Cookie
+	oauthState, err := r.Cookie("oauthstate")
+	if err != nil {
+		log.Printf("An error occured during login: %s", err)
+		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+		return
+	}
+
+	log.Printf("%v", oauthState)
+
+	if r.FormValue("state") != oauthState.Value {
+		log.Println("invalid oauth state")
+		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+		return
+	}
+
+	data, err := auth.GetUserData(r.FormValue("code"), s.oauth)
+	if err != nil {
+		log.Println(err.Error())
+		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+		return
+	}
+
+	username, ok := data["preferred_username"]
+	if !ok {
+		log.Println("No username in auth response")
+		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+		return
+	}
+	userStr, ok := username.(string)
+	if !ok {
+		log.Println("Username not interpretable as string")
+		http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+		return
+	}
+
+	s.Login(userStr, w)
+	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+}
+
 func (s *SessionStore) AsMiddleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		sessionCookie, err := r.Cookie("id")