Assignment 4: add unit, integration, and e2e tests; refactor for testability

internal/handler/snippet_handler.go

@@ -9,15 +9,15 @@ import (
 	"5803025015/w04/internal/middleware"
 	"5803025015/w04/internal/models"
 	"5803025015/w04/internal/store"
+
 	"github.com/google/uuid"
-	"github.com/jackc/pgx/v5"
 )
 
 type SnippetHandler struct {
-	snippetStore *store.SnippetStore
+	snippetStore SnippetStore
 }
 
-func NewSnippetHandler(snippetStore *store.SnippetStore) *SnippetHandler {
+func NewSnippetHandler(snippetStore SnippetStore) *SnippetHandler {
 	return &SnippetHandler{snippetStore: snippetStore}
 }
 
@@ -26,6 +26,16 @@ type snippetRequest struct {
 	Content string `json:"content"`
 }
 
+type snippetResponse struct {
+	ID      string `json:"id"`
+	Title   string `json:"title"`
+	Content string `json:"content"`
+}
+
+func toSnippetResponse(s *models.Snippet) snippetResponse {
+	return snippetResponse{ID: s.ID, Title: s.Title, Content: s.Content}
+}
+
 func (h *SnippetHandler) Snippets(w http.ResponseWriter, r *http.Request) {
 	switch r.Method {
 	case http.MethodGet:
@@ -33,7 +43,7 @@ func (h *SnippetHandler) Snippets(w http.ResponseWriter, r *http.Request) {
 	case http.MethodPost:
 		h.Create(w, r)
 	default:
-		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
 	}
 }
 
@@ -44,32 +54,27 @@ func (h *SnippetHandler) SnippetByID(w http.ResponseWriter, r *http.Request) {
 	case http.MethodDelete:
 		h.Delete(w, r)
 	default:
-		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
 	}
 }
 
 func (h *SnippetHandler) Create(w http.ResponseWriter, r *http.Request) {
-	if r.Method != http.MethodPost {
-		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
-		return
-	}
-
 	userID := middleware.GetUserID(r.Context())
 	if userID == "" {
-		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+		writeError(w, http.StatusUnauthorized, "unauthorized")
 		return
 	}
 
 	var req snippetRequest
 	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
-		http.Error(w, "Bad Request", http.StatusBadRequest)
+		writeError(w, http.StatusBadRequest, "invalid request body")
 		return
 	}
 
 	req.Title = strings.TrimSpace(req.Title)
 	req.Content = strings.TrimSpace(req.Content)
 	if req.Title == "" || req.Content == "" {
-		http.Error(w, "Title and content are required", http.StatusBadRequest)
+		writeError(w, http.StatusBadRequest, "title and content are required")
 		return
 	}
 
@@ -81,85 +86,99 @@ func (h *SnippetHandler) Create(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := h.snippetStore.Create(r.Context(), snippet); err != nil {
-		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		writeError(w, http.StatusInternalServerError, "internal error")
 		return
 	}
 
-	w.Header().Set("Content-Type", "application/json")
-	w.WriteHeader(http.StatusCreated)
-	_ = json.NewEncoder(w).Encode(snippet)
+	writeJSON(w, http.StatusCreated, toSnippetResponse(snippet))
 }
 
 func (h *SnippetHandler) List(w http.ResponseWriter, r *http.Request) {
-	if r.Method != http.MethodGet {
-		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+	userID := middleware.GetUserID(r.Context())
+	if userID == "" {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
 		return
 	}
 
-	snippets, err := h.snippetStore.GetAll(r.Context())
+	snippets, err := h.snippetStore.ListByOwner(r.Context(), userID)
 	if err != nil {
-		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		writeError(w, http.StatusInternalServerError, "internal error")
 		return
 	}
 
-	w.Header().Set("Content-Type", "application/json")
-	w.WriteHeader(http.StatusOK)
-	_ = json.NewEncoder(w).Encode(snippets)
+	out := make([]snippetResponse, 0, len(snippets))
+	for _, s := range snippets {
+		out = append(out, toSnippetResponse(s))
+	}
+
+	writeJSON(w, http.StatusOK, out)
 }
 
 func (h *SnippetHandler) Get(w http.ResponseWriter, r *http.Request) {
-	if r.Method != http.MethodGet {
-		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
-		return
-	}
-
-	id := r.PathValue("id")
+	id := extractID(r)
 	if id == "" {
-		path := strings.TrimPrefix(r.URL.Path, "/snippets/")
-		id = strings.TrimSuffix(path, "/")
-	}
-
-	if id == "" {
-		http.Error(w, "Bad Request", http.StatusBadRequest)
+		writeError(w, http.StatusBadRequest, "missing id")
 		return
 	}
 
 	snippet, err := h.snippetStore.GetByID(r.Context(), id)
 	if err != nil {
-		if errors.Is(err, pgx.ErrNoRows) {
-			http.Error(w, "Snippet not found", http.StatusNotFound)
+		if errors.Is(err, store.ErrNotFound) {
+			writeError(w, http.StatusNotFound, "snippet not found")
 			return
 		}
-		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		writeError(w, http.StatusInternalServerError, "internal error")
 		return
 	}
 
-	w.Header().Set("Content-Type", "application/json")
-	w.WriteHeader(http.StatusOK)
-	_ = json.NewEncoder(w).Encode(snippet)
+	writeJSON(w, http.StatusOK, toSnippetResponse(snippet))
 }
 
 func (h *SnippetHandler) Delete(w http.ResponseWriter, r *http.Request) {
-	if r.Method != http.MethodDelete {
-		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+	userID := middleware.GetUserID(r.Context())
+	if userID == "" {
+		writeError(w, http.StatusUnauthorized, "unauthorized")
 		return
 	}
 
-	id := r.PathValue("id")
+	id := extractID(r)
 	if id == "" {
-		path := strings.TrimPrefix(r.URL.Path, "/snippets/")
-		id = strings.TrimSuffix(path, "/")
+		writeError(w, http.StatusBadRequest, "missing id")
+		return
 	}
 
-	if id == "" {
-		http.Error(w, "Bad Request", http.StatusBadRequest)
+	snippet, err := h.snippetStore.GetByID(r.Context(), id)
+	if err != nil {
+		if errors.Is(err, store.ErrNotFound) {
+			writeError(w, http.StatusNotFound, "snippet not found")
+			return
+		}
+		writeError(w, http.StatusInternalServerError, "internal error")
+		return
+	}
+
+	if snippet.UserID != userID {
+		writeError(w, http.StatusForbidden, "forbidden")
 		return
 	}
 
 	if err := h.snippetStore.Delete(r.Context(), id); err != nil {
-		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		if errors.Is(err, store.ErrNotFound) {
+			writeError(w, http.StatusNotFound, "snippet not found")
+			return
+		}
+		writeError(w, http.StatusInternalServerError, "internal error")
 		return
 	}
 
 	w.WriteHeader(http.StatusNoContent)
 }
+
+func extractID(r *http.Request) string {
+	if id := r.PathValue("id"); id != "" {
+		return id
+	}
+	path := strings.TrimPrefix(r.URL.Path, "/snippets/")
+	path = strings.TrimSuffix(path, "/")
+	return path
+}