feat(story-2.1): add feed model and add-feed-by-url API

internal/service/feed.go

@@ -0,0 +1,130 @@
+package service
+
+import (
+	"errors"
+	"fmt"
+	"net/url"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/michael/flowreader/internal/domain"
+)
+
+// Feed service errors
+var (
+	ErrInvalidURL   = errors.New("invalid feed URL")
+	ErrFeedExists   = errors.New("feed already exists")
+	ErrFeedNotFound = errors.New("feed not found")
+	ErrUnauthorized = errors.New("unauthorized access")
+)
+
+// FeedService handles feed-related business logic.
+type FeedService struct {
+	feedRepo domain.FeedRepository
+}
+
+// NewFeedService creates a new feed service.
+func NewFeedService(feedRepo domain.FeedRepository) *FeedService {
+	return &FeedService{feedRepo: feedRepo}
+}
+
+// AddFeedRequest contains the data needed to add a new feed.
+type AddFeedRequest struct {
+	URL    string    `json:"url"`
+	UserID uuid.UUID `json:"-"`
+}
+
+// AddFeedResponse contains the created feed data.
+type AddFeedResponse struct {
+	ID        uuid.UUID `json:"id"`
+	URL       string    `json:"url"`
+	Title     string    `json:"title"`
+	CreatedAt time.Time `json:"created_at"`
+}
+
+// AddFeed creates a new feed subscription.
+func (s *FeedService) AddFeed(req AddFeedRequest) (*AddFeedResponse, error) {
+	// Validate URL
+	parsedURL, err := url.ParseRequestURI(req.URL)
+	if err != nil || (parsedURL.Scheme != "http" && parsedURL.Scheme != "https") {
+		return nil, ErrInvalidURL
+	}
+
+	// Normalize URL
+	normalizedURL := parsedURL.String()
+
+	// Check if feed already exists for this user
+	existing, err := s.feedRepo.GetByURL(req.UserID, normalizedURL)
+	if err != nil {
+		return nil, fmt.Errorf("checking existing feed: %w", err)
+	}
+	if existing != nil {
+		return nil, ErrFeedExists
+	}
+
+	// Create feed (title will be updated after first fetch)
+	now := time.Now()
+	feed := &domain.Feed{
+		ID:        uuid.New(),
+		UserID:    req.UserID,
+		URL:       normalizedURL,
+		Title:     normalizedURL, // Temporary title until fetched
+		CreatedAt: now,
+		UpdatedAt: now,
+	}
+
+	if err := s.feedRepo.Create(feed); err != nil {
+		return nil, fmt.Errorf("creating feed: %w", err)
+	}
+
+	return &AddFeedResponse{
+		ID:        feed.ID,
+		URL:       feed.URL,
+		Title:     feed.Title,
+		CreatedAt: feed.CreatedAt,
+	}, nil
+}
+
+// GetUserFeeds returns all feeds for a user.
+func (s *FeedService) GetUserFeeds(userID uuid.UUID) ([]*domain.Feed, error) {
+	feeds, err := s.feedRepo.GetByUserID(userID)
+	if err != nil {
+		return nil, fmt.Errorf("getting user feeds: %w", err)
+	}
+	return feeds, nil
+}
+
+// GetFeed returns a single feed by ID, verifying ownership.
+func (s *FeedService) GetFeed(feedID, userID uuid.UUID) (*domain.Feed, error) {
+	feed, err := s.feedRepo.GetByID(feedID)
+	if err != nil {
+		return nil, fmt.Errorf("getting feed: %w", err)
+	}
+	if feed == nil {
+		return nil, ErrFeedNotFound
+	}
+	if feed.UserID != userID {
+		return nil, ErrUnauthorized
+	}
+	return feed, nil
+}
+
+// DeleteFeed removes a feed subscription.
+func (s *FeedService) DeleteFeed(feedID, userID uuid.UUID) error {
+	feed, err := s.feedRepo.GetByID(feedID)
+	if err != nil {
+		return fmt.Errorf("getting feed: %w", err)
+	}
+	if feed == nil {
+		return ErrFeedNotFound
+	}
+	if feed.UserID != userID {
+		return ErrUnauthorized
+	}
+
+	if err := s.feedRepo.Delete(feedID); err != nil {
+		return fmt.Errorf("deleting feed: %w", err)
+	}
+
+	return nil
+}