Initial commit: Custom Start Page application with authentication and DynamoDB storage

internal/handlers/auth_handler.go

@@ -0,0 +1,170 @@
+package handlers
+
+import (
+	"html/template"
+	"log"
+	"net/http"
+	"path/filepath"
+
+	"custom-start-page/internal/auth"
+)
+
+// AuthHandler handles authentication-related HTTP requests
+type AuthHandler struct {
+	oauthService *auth.OAuthService
+	userService  *auth.UserService
+	sessionStore SessionStore
+	templates    *template.Template
+}
+
+// SessionStore manages user sessions
+type SessionStore interface {
+	CreateSession(w http.ResponseWriter, r *http.Request, userID string) error
+	GetUserID(r *http.Request) (string, error)
+	DestroySession(w http.ResponseWriter, r *http.Request) error
+}
+
+// NewAuthHandler creates a new auth handler
+func NewAuthHandler(oauthService *auth.OAuthService, userService *auth.UserService, sessionStore SessionStore) *AuthHandler {
+	return NewAuthHandlerWithTemplates(oauthService, userService, sessionStore, nil)
+}
+
+// NewAuthHandlerWithTemplates creates a new auth handler with custom templates
+func NewAuthHandlerWithTemplates(oauthService *auth.OAuthService, userService *auth.UserService, sessionStore SessionStore, templates *template.Template) *AuthHandler {
+	if templates == nil {
+		// Parse templates
+		templates = template.Must(template.ParseGlob(filepath.Join("templates", "*.html")))
+		template.Must(templates.ParseGlob(filepath.Join("templates", "layouts", "*.html")))
+	}
+	
+	return &AuthHandler{
+		oauthService: oauthService,
+		userService:  userService,
+		sessionStore: sessionStore,
+		templates:    templates,
+	}
+}
+
+// HandleOAuthInitiate initiates the OAuth flow
+// GET /auth/oauth/:provider
+func (h *AuthHandler) HandleOAuthInitiate(w http.ResponseWriter, r *http.Request) {
+	// Extract provider from URL path
+	provider := r.PathValue("provider")
+	if provider == "" {
+		http.Error(w, "Provider not specified", http.StatusBadRequest)
+		return
+	}
+
+	// Generate OAuth redirect URL
+	redirectURL, err := h.oauthService.InitiateOAuth(provider)
+	if err != nil {
+		log.Printf("Failed to initiate OAuth: %v", err)
+		http.Error(w, "Failed to initiate OAuth", http.StatusInternalServerError)
+		return
+	}
+
+	// Redirect to OAuth provider
+	http.Redirect(w, r, redirectURL, http.StatusTemporaryRedirect)
+}
+
+// HandleOAuthCallback handles the OAuth callback
+// GET /auth/callback/:provider
+func (h *AuthHandler) HandleOAuthCallback(w http.ResponseWriter, r *http.Request) {
+	// Extract provider from URL path
+	provider := r.PathValue("provider")
+	if provider == "" {
+		http.Error(w, "Provider not specified", http.StatusBadRequest)
+		return
+	}
+
+	// Get code and state from query parameters
+	code := r.URL.Query().Get("code")
+	state := r.URL.Query().Get("state")
+
+	if code == "" {
+		// Check for error from OAuth provider
+		if errMsg := r.URL.Query().Get("error"); errMsg != "" {
+			log.Printf("OAuth error: %s", errMsg)
+			http.Redirect(w, r, "/login?error=oauth_failed", http.StatusTemporaryRedirect)
+			return
+		}
+		http.Error(w, "Authorization code not provided", http.StatusBadRequest)
+		return
+	}
+
+	if state == "" {
+		http.Error(w, "State parameter not provided", http.StatusBadRequest)
+		return
+	}
+
+	// Exchange code for token
+	token, err := h.oauthService.HandleOAuthCallback(r.Context(), provider, code, state)
+	if err != nil {
+		log.Printf("Failed to handle OAuth callback: %v", err)
+		http.Redirect(w, r, "/login?error=oauth_failed", http.StatusTemporaryRedirect)
+		return
+	}
+
+	// Get or create user from OAuth provider
+	user, err := h.userService.GetOrCreateUserFromGoogle(r.Context(), token, h.oauthService.GetGoogleConfig())
+	if err != nil {
+		log.Printf("Failed to get or create user: %v", err)
+		http.Redirect(w, r, "/login?error=user_creation_failed", http.StatusTemporaryRedirect)
+		return
+	}
+
+	// Create session
+	if err := h.sessionStore.CreateSession(w, r, user.ID); err != nil {
+		log.Printf("Failed to create session: %v", err)
+		http.Error(w, "Failed to create session", http.StatusInternalServerError)
+		return
+	}
+
+	// Redirect to dashboard
+	http.Redirect(w, r, "/dashboard", http.StatusTemporaryRedirect)
+}
+
+// HandleLogout logs out the user
+// POST /logout
+func (h *AuthHandler) HandleLogout(w http.ResponseWriter, r *http.Request) {
+	if err := h.sessionStore.DestroySession(w, r); err != nil {
+		log.Printf("Failed to destroy session: %v", err)
+	}
+
+	// Redirect to login page
+	http.Redirect(w, r, "/login", http.StatusTemporaryRedirect)
+}
+
+// HandleLogin displays the login page
+// GET /login
+func (h *AuthHandler) HandleLogin(w http.ResponseWriter, r *http.Request) {
+	// Check if user is already logged in
+	if userID, err := h.sessionStore.GetUserID(r); err == nil && userID != "" {
+		http.Redirect(w, r, "/dashboard", http.StatusTemporaryRedirect)
+		return
+	}
+
+	// Get error message if any
+	errorMsg := ""
+	if errParam := r.URL.Query().Get("error"); errParam != "" {
+		switch errParam {
+		case "oauth_failed":
+			errorMsg = "Authentication failed. Please try again."
+		case "user_creation_failed":
+			errorMsg = "Failed to create user account. Please try again."
+		default:
+			errorMsg = "An error occurred. Please try again."
+		}
+	}
+
+	// Render login template
+	data := map[string]interface{}{
+		"Error":          errorMsg,
+		"OAuthProviders": []map[string]string{}, // Empty for now, can be extended
+	}
+
+	if err := h.templates.ExecuteTemplate(w, "login.html", data); err != nil {
+		log.Printf("Failed to render login template: %v", err)
+		http.Error(w, "Internal server error", http.StatusInternalServerError)
+	}
+}