sneak
2cbafe374c
Introduces Fetcher interface, mock implementation for testing, and ApplyMigrations helper for test database setup.
116 lines
2.6 KiB
Go
116 lines
2.6 KiB
Go
package imgcache
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import (
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"context"
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"errors"
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"fmt"
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"io"
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"io/fs"
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"net/http"
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"strings"
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)
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// MockFetcher implements the Fetcher interface using an embedded filesystem.
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// Files are organized as: hostname/path/to/file.ext
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// URLs like https://example.com/images/photo.jpg map to example.com/images/photo.jpg
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type MockFetcher struct {
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fs fs.FS
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}
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// NewMockFetcher creates a new mock fetcher backed by the given filesystem.
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func NewMockFetcher(fsys fs.FS) *MockFetcher {
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return &MockFetcher{fs: fsys}
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}
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// Fetch retrieves content from the mock filesystem.
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func (m *MockFetcher) Fetch(ctx context.Context, url string) (*FetchResult, error) {
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// Check context cancellation
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select {
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case <-ctx.Done():
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return nil, ctx.Err()
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default:
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}
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// Parse URL to get filesystem path
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path, err := urlToFSPath(url)
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if err != nil {
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return nil, err
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}
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// Open the file
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f, err := m.fs.Open(path)
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if err != nil {
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if errors.Is(err, fs.ErrNotExist) {
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return nil, fmt.Errorf("%w: status 404", ErrUpstreamError)
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}
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return nil, fmt.Errorf("failed to open mock file: %w", err)
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}
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// Get file info for content length
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stat, err := f.Stat()
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if err != nil {
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_ = f.Close()
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return nil, fmt.Errorf("failed to stat mock file: %w", err)
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}
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// Detect content type from extension
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contentType := detectContentTypeFromPath(path)
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return &FetchResult{
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Content: f.(io.ReadCloser),
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ContentLength: stat.Size(),
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ContentType: contentType,
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Headers: make(http.Header),
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}, nil
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}
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// urlToFSPath converts a URL to a filesystem path.
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// https://example.com/images/photo.jpg -> example.com/images/photo.jpg
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func urlToFSPath(rawURL string) (string, error) {
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// Strip scheme
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url := rawURL
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if idx := strings.Index(url, "://"); idx != -1 {
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url = url[idx+3:]
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}
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// Remove query string
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if idx := strings.Index(url, "?"); idx != -1 {
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url = url[:idx]
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}
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// Remove fragment
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if idx := strings.Index(url, "#"); idx != -1 {
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url = url[:idx]
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}
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if url == "" {
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return "", errors.New("empty URL path")
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}
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return url, nil
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}
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// detectContentTypeFromPath returns the MIME type based on file extension.
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func detectContentTypeFromPath(path string) string {
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path = strings.ToLower(path)
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switch {
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case strings.HasSuffix(path, ".jpg"), strings.HasSuffix(path, ".jpeg"):
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return "image/jpeg"
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case strings.HasSuffix(path, ".png"):
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return "image/png"
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case strings.HasSuffix(path, ".gif"):
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return "image/gif"
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case strings.HasSuffix(path, ".webp"):
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return "image/webp"
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case strings.HasSuffix(path, ".avif"):
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return "image/avif"
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case strings.HasSuffix(path, ".svg"):
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return "image/svg+xml"
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default:
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return "application/octet-stream"
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}
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}
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