Implement login/logout flow

httpserver/handler.go

@@ -5,6 +5,8 @@ package httpserver
 
 import (
 	"context"
+	"encoding/gob"
+	"html/template"
 	"net/http"
 	"time"
 
@@ -14,11 +16,27 @@ import (
 	"git.netflux.io/rob/elon-eats-my-tweets/twitter"
 	"github.com/go-chi/chi"
 	"github.com/go-chi/chi/middleware"
+	"github.com/google/uuid"
 	"github.com/gorilla/sessions"
 	"go.uber.org/zap"
 	"golang.org/x/oauth2"
 )
 
+func init() {
+	gob.Register(CurrentUser{})
+}
+
+type CurrentUser struct {
+	ID                           uuid.UUID
+	TwitterName, TwitterUsername string
+}
+
+func (cu CurrentUser) IsNil() bool {
+	return cu.ID == uuid.Nil
+}
+
+type contextKey string
+
 const (
 	sessionName            = "elon_session"
 	sessionKeyState        = "state"
@@ -27,6 +45,19 @@ const (
 	pkceVerifierLen        = 256
 )
 
+const (
+	sessionKeyCurrentUser            = "current_user"
+	contextKeyCurrentUser contextKey = sessionKeyCurrentUser
+)
+
+func getCurrentUser(r *http.Request, sessionStore sessions.Store) (CurrentUser, bool) {
+	session, _ := sessionStore.Get(r, sessionName)
+	if cu, ok := session.Values[sessionKeyCurrentUser]; ok {
+		return cu.(CurrentUser), true
+	}
+	return CurrentUser{}, false
+}
+
 type TwitterAPIClient interface {
 	GetMe() (*twitter.User, error)
 }
@@ -35,6 +66,7 @@ type handler struct {
 	store                twitter.Store
 	twitterAPIClientFunc func(c *http.Client) TwitterAPIClient
 	oauth2Config         *oauth2.Config
+	renderer             *templates.Renderer
 	sessionStore         sessions.Store
 	tokenGenerator       TokenGenerator
 	logger               *zap.SugaredLogger
@@ -44,7 +76,7 @@ func NewHandler(cfg config.Config, store twitter.Store, twitterAPIClientFunc fun
 	r := chi.NewRouter()
 	r.Use(middleware.RequestID)
 	r.Use(middleware.RealIP)
-	r.Use(loggerMiddleware(logger))
+	r.Use(loggerMiddleware(logger, sessionStore))
 	r.Use(middleware.Recoverer)
 
 	h := handler{
@@ -61,6 +93,7 @@ func NewHandler(cfg config.Config, store twitter.Store, twitterAPIClientFunc fun
 				AuthStyle: oauth2.AuthStyleInHeader,
 			},
 		},
+		renderer:       templates.NewRenderer(logger.Sugar()),
 		sessionStore:   sessionStore,
 		tokenGenerator: tokenGenerator,
 		logger:         logger.Sugar(),
@@ -68,17 +101,26 @@ func NewHandler(cfg config.Config, store twitter.Store, twitterAPIClientFunc fun
 
 	r.Get("/", h.getIndex)
 	r.Get("/login", h.getLogin)
+	r.Post("/logout", h.postLogout)
 	r.Get("/callback", h.getCallback)
 
 	return r
 }
 
 func (h *handler) getIndex(w http.ResponseWriter, r *http.Request) {
-	if err := templates.Execute(w, "index.html", nil); err != nil {
-		h.logger.With("err", err).Error("error rendering template")
-		http.Error(w, "error rendering template", http.StatusInternalServerError)
-		return
+	cu, _ := getCurrentUser(r, h.sessionStore)
+	var template *template.Template
+	if cu.IsNil() {
+		template = templates.Index
+	} else {
+		template = templates.Dashboard
 	}
+
+	type data struct {
+		CurrentUser CurrentUser
+	}
+
+	h.renderer.Render(w, template, data{CurrentUser: cu})
 }
 
 func (h *handler) getLogin(w http.ResponseWriter, r *http.Request) {
@@ -153,7 +195,7 @@ func (h *handler) getCallback(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if _, err := h.store.CreateUser(r.Context(), store.CreateUserParams{
+	user, err := h.store.CreateUser(r.Context(), store.CreateUserParams{
 		TwitterID:    twitterUser.ID,
 		Username:     twitterUser.Username,
 		Name:         twitterUser.Name,
@@ -161,12 +203,44 @@ func (h *handler) getCallback(w http.ResponseWriter, r *http.Request) {
 		RefreshToken: token.RefreshToken,
 		CreatedAt:    time.Now().UTC(),
 		UpdatedAt:    time.Now().UTC(),
-	}); err != nil {
+	})
+	if err != nil {
 		h.logger.With("err", err).Error("error upserting user")
 		http.Error(w, "error saving user", http.StatusInternalServerError)
 		return
 	}
 
-	w.WriteHeader(http.StatusOK)
-	w.Write([]byte("ok"))
+	// finally, save in the session. To avoid hitting the database on most
+	// requests we'll store the Twitter name and username in the session.
+	session.Values[sessionKeyCurrentUser] = CurrentUser{
+		ID:              user.ID,
+		TwitterName:     twitterUser.Name,
+		TwitterUsername: twitterUser.Username,
+	}
+	if err := session.Save(r, w); err != nil {
+		h.logger.With("err", err).Error("error saving session")
+		http.Error(w, "error saving user", http.StatusInternalServerError)
+		return
+	}
+
+	http.Redirect(w, r, "/", http.StatusFound)
+}
+
+func (h *handler) postLogout(w http.ResponseWriter, r *http.Request) {
+	session, err := h.sessionStore.Get(r, sessionName)
+	if err != nil {
+		h.logger.With("err", err).Error("error reading session")
+		http.Error(w, "error reading session", http.StatusBadRequest)
+		return
+	}
+
+	delete(session.Values, sessionKeyCurrentUser)
+
+	if err := session.Save(r, w); err != nil {
+		h.logger.With("err", err).Error("error saving session")
+		http.Error(w, "error saving user", http.StatusInternalServerError)
+		return
+	}
+
+	http.Redirect(w, r, "/", http.StatusFound)
 }

httpserver/handler_test.go

@@ -12,6 +12,7 @@ import (
 	"git.netflux.io/rob/elon-eats-my-tweets/generated/store"
 	"git.netflux.io/rob/elon-eats-my-tweets/httpserver"
 	"git.netflux.io/rob/elon-eats-my-tweets/twitter"
+	"github.com/google/uuid"
 	"github.com/gorilla/sessions"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
@@ -35,29 +36,56 @@ func (g *mockTokenGenerator) GenerateToken(_ int) string {
 }
 
 func TestGetIndex(t *testing.T) {
-	req := httptest.NewRequest(http.MethodGet, "/", nil)
-	rec := httptest.NewRecorder()
+	testCases := []struct {
+		name        string
+		currentUser httpserver.CurrentUser
+		wantBody    string
+	}{
+		{
+			name:        "logged out",
+			currentUser: httpserver.CurrentUser{},
+			wantBody:    "Sign in with Twitter",
+		},
+		{
+			name:        "logged out",
+			currentUser: httpserver.CurrentUser{ID: uuid.New(), TwitterName: "foo", TwitterUsername: "Foo Bar"},
+			wantBody:    "Welcome to your dashboard",
+		},
+	}
 
-	handler := httpserver.NewHandler(
-		config.Config{},
-		&mocks.Store{},
-		func(*http.Client) httpserver.TwitterAPIClient { return &mocks.TwitterAPIClient{} },
-		&mocks.SessionStore{},
-		&mockTokenGenerator{},
-		zap.NewNop(),
-	)
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, "/", nil)
+			rec := httptest.NewRecorder()
 
-	handler.ServeHTTP(rec, req)
-	res := rec.Result()
-	defer res.Body.Close()
-	body, err := ioutil.ReadAll(res.Body)
-	require.NoError(t, err)
+			var mockSessionStore mocks.SessionStore
+			sess := sessions.NewSession(&mockSessionStore, "elon_session")
+			sess.Values["current_user"] = tc.currentUser
+			mockSessionStore.On("Get", mock.Anything, "elon_session").Return(sess, nil)
+			mockSessionStore.On("Save", mock.Anything, mock.Anything, sess).Return(nil)
 
-	assert.Equal(t, http.StatusOK, res.StatusCode)
-	assert.Contains(t, string(body), "Sign in with Twitter")
+			handler := httpserver.NewHandler(
+				config.Config{},
+				&mocks.Store{},
+				func(*http.Client) httpserver.TwitterAPIClient { return &mocks.TwitterAPIClient{} },
+				&mockSessionStore,
+				&mockTokenGenerator{},
+				zap.NewNop(),
+			)
+
+			handler.ServeHTTP(rec, req)
+			res := rec.Result()
+			defer res.Body.Close()
+			body, err := ioutil.ReadAll(res.Body)
+			require.NoError(t, err)
+
+			assert.Equal(t, http.StatusOK, res.StatusCode)
+			assert.Contains(t, string(body), tc.wantBody)
+		})
+	}
 }
 
-func TestLogin(t *testing.T) {
+func TestGetLogin(t *testing.T) {
 	testCases := []struct {
 		name             string
 		sessionSaveError error
@@ -122,7 +150,7 @@ func TestLogin(t *testing.T) {
 	}
 }
 
-func TestCallback(t *testing.T) {
+func TestGetCallback(t *testing.T) {
 	testCases := []struct {
 		name                string
 		state               string
@@ -133,7 +161,9 @@ func TestCallback(t *testing.T) {
 		oauth2StatusCode    int
 		getTwitterUserError error
 		createUserError     error
+		sessionSaveError    error
 		wantStatusCode      int
+		wantLocation        string
 		wantError           string
 	}{
 		{
@@ -205,6 +235,17 @@ func TestCallback(t *testing.T) {
 			wantStatusCode:      http.StatusInternalServerError,
 			wantError:           "error saving user",
 		},
+		{
+			name:                "error saving session",
+			state:               "mystate",
+			sessionState:        "mystate",
+			code:                "mycode",
+			sessionPkceVerifier: "mypkceverifier",
+			oauth2StatusCode:    http.StatusOK,
+			sessionSaveError:    errors.New("foo"),
+			wantStatusCode:      http.StatusInternalServerError,
+			wantError:           "error saving user",
+		},
 		{
 			name:                "successful exchange",
 			state:               "mystate",
@@ -212,7 +253,8 @@ func TestCallback(t *testing.T) {
 			code:                "mycode",
 			sessionPkceVerifier: "mypkceverifier",
 			oauth2StatusCode:    http.StatusOK,
-			wantStatusCode:      http.StatusOK,
+			wantStatusCode:      http.StatusFound,
+			wantLocation:        "/",
 		},
 	}
 
@@ -223,6 +265,7 @@ func TestCallback(t *testing.T) {
 			sess.Values["state"] = tc.sessionState
 			sess.Values["pkce_verifier"] = tc.sessionPkceVerifier
 			mockSessionStore.On("Get", mock.Anything, "elon_session").Return(sess, tc.sessionReadError)
+			mockSessionStore.On("Save", mock.Anything, mock.Anything, sess).Return(tc.sessionSaveError)
 
 			var mockTwitterClient mocks.TwitterAPIClient
 			mockTwitterClient.On("GetMe").Return(&twitter.User{ID: "1", Name: "foo", Username: "Foo Bar"}, tc.getTwitterUserError)
@@ -283,3 +326,31 @@ func TestCallback(t *testing.T) {
 		})
 	}
 }
+
+func TestPostLogout(t *testing.T) {
+	var mockSessionStore mocks.SessionStore
+	sess := sessions.NewSession(&mockSessionStore, "elon_session")
+	mockSessionStore.On("Get", mock.Anything, "elon_session").Return(sess, nil)
+	mockSessionStore.On("Save", mock.Anything, mock.Anything, mock.MatchedBy(func(s *sessions.Session) bool {
+		_, ok := s.Values["current_user"]
+		return !ok
+	})).Return(nil)
+
+	handler := httpserver.NewHandler(
+		config.Config{},
+		&mocks.Store{},
+		func(*http.Client) httpserver.TwitterAPIClient { return &mocks.TwitterAPIClient{} },
+		&mockSessionStore,
+		nil,
+		zap.NewNop(),
+	)
+
+	req := httptest.NewRequest(http.MethodPost, "/logout", nil)
+	rec := httptest.NewRecorder()
+	handler.ServeHTTP(rec, req)
+	res := rec.Result()
+	defer res.Body.Close()
+
+	assert.Equal(t, http.StatusFound, res.StatusCode)
+	assert.Equal(t, "/", res.Header.Get("Location"))
+}

httpserver/middleware.go

@@ -5,15 +5,22 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/middleware"
+	"github.com/gorilla/sessions"
 	"go.uber.org/zap"
 )
 
-func loggerMiddleware(l *zap.Logger) func(next http.Handler) http.Handler {
+func loggerMiddleware(l *zap.Logger, sessionStore sessions.Store) func(next http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		fn := func(w http.ResponseWriter, r *http.Request) {
 			ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
-
 			t1 := time.Now()
+
+			cu, ok := getCurrentUser(r, sessionStore)
+			var userID string
+			if ok {
+				userID = cu.ID.String()
+			}
+
 			defer func() {
 				l.Info("HTTP",
 					zap.String("proto", r.Proto),
@@ -22,7 +29,10 @@ func loggerMiddleware(l *zap.Logger) func(next http.Handler) http.Handler {
 					zap.Duration("dur", time.Since(t1)),
 					zap.Int("status", ww.Status()),
 					zap.Int("size", ww.BytesWritten()),
-					zap.String("reqId", middleware.GetReqID(r.Context())))
+					zap.String("ip", r.RemoteAddr),
+					zap.String("reqId", middleware.GetReqID(r.Context())),
+					zap.String("userID", userID),
+					zap.String("username", cu.TwitterUsername))
 			}()
 
 			next.ServeHTTP(ww, r)

templates/templates.go

@@ -3,18 +3,36 @@ package templates
 import (
 	"embed"
 	"html/template"
-	"io"
+	"net/http"
+
+	"go.uber.org/zap"
 )
 
 //go:embed views/*.html
 var tmplFS embed.FS
 
-var templatesMap *template.Template
+var (
+	Index     = parse("views/index.html")
+	Dashboard = parse("views/dashboard.html")
+)
 
-func init() {
-	templatesMap = template.Must(template.ParseFS(tmplFS, "views/*.html"))
+func parse(file string) *template.Template {
+	return template.Must(template.New("base.html").ParseFS(tmplFS, "views/base.html", file))
 }
 
-func Execute(w io.Writer, name string, data any) error {
-	return templatesMap.ExecuteTemplate(w, name, data)
+// Renderer renders HTML templates, and logs any errors.
+type Renderer struct {
+	logger *zap.SugaredLogger
+}
+
+func NewRenderer(logger *zap.SugaredLogger) *Renderer {
+	return &Renderer{logger: logger}
+}
+
+// Render renders an HTML template to an http.ResponseWriter.
+func (r *Renderer) Render(w http.ResponseWriter, template *template.Template, data any) {
+	if err := template.Execute(w, data); err != nil {
+		r.logger.With("err", err).Error("error rendering template")
+		http.Error(w, "error rendering template", http.StatusInternalServerError)
+	}
 }

templates/views/base.html

@@ -1,9 +1,18 @@
 <!DOCTYPE html>
 <html>
   <head>
-    <title>Elon Eats My Tweets</title>
+    <title>{{block "title" .}}Elon Eats My Tweets{{end}}</title>
   </head>
   <body>
-    {{block "content" .}}{{end}}
+    <h1>Elon eats my tweets</h1>
+    {{if not .CurrentUser.IsNil}}
+    <p>
+      Logged in as @{{.CurrentUser.TwitterUsername}}
+      <form id="logout_form" action="/logout" method="post"></form>
+      <a href="/logout" onclick="document.getElementById('logout_form').submit(); return false;">Log out</a>
+    </p>
+    {{end}}
+
+    {{template "content" .}}
   </body>
 </html>

templates/views/dashboard.html

@@ -0,0 +1,7 @@
+{{template "base.html" .}}
+
+{{define "title"}}Elon Eats My Tweets | Dashboard{{end}}
+
+{{define "content"}}
+Welcome to your dashboard.
+{{end}}

templates/views/index.html

@@ -1,8 +1,6 @@
 {{template "base.html" .}}
 
 {{define "content"}}
-<h1>Elon eats my tweets<h1>
-
 <p>Sick of Elon? Tired of Twitter? Have Elon Musk delete your tweets for you.</p>
 
 <a href="/login">Sign in with Twitter</a>