feat: add Google Sign-In with JWT auth and Neon DB persistence

internal/auth/handler.go

@@ -0,0 +1,35 @@
+package auth
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+func (s *Service) RegisterRoutes(mux *http.ServeMux) {
+	mux.HandleFunc("/api/v1/auth/google", s.handleGoogleLogin)
+}
+
+func (s *Service) handleGoogleLogin(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		writeError(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	var req GoogleLoginRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, "invalid request", http.StatusBadRequest)
+		return
+	}
+	resp, err := s.HandleGoogleLogin(r.Context(), req)
+	if err != nil {
+		writeError(w, err.Error(), http.StatusUnauthorized)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(resp)
+}
+
+func writeError(w http.ResponseWriter, message string, code int) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(code)
+	json.NewEncoder(w).Encode(map[string]string{"error": message})
+}