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pixa/internal/httpfetcher/mock.go
clawbot b6e9ac2a93
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refactor: extract httpfetcher package from imgcache (#43)
Extracts the HTTP fetcher concern out of `internal/imgcache/` into its own `internal/httpfetcher/` package, per the plan in [issue #39](#39).

This is one of four planned extractions; only the fetcher is moved here so the diff stays reviewable. The remaining three (signature, magic, urlparser) will land in separate PRs.

## What moved

From `internal/imgcache/fetcher.go` and `internal/imgcache/mock_fetcher.go` into `internal/httpfetcher/`:

- `HTTPFetcher` type, its `New` constructor, and `Config` (formerly `FetcherConfig`) with `DefaultConfig`
- SSRF-safe dialer, `validateURL`, `isPrivateIP`, `isLocalhost`, `extractHost`
- Per-host connection semaphore (rate limiting) and `limitedReader`
- Content-type validation (`isAllowedContentType`, `detectContentTypeFromPath`)
- All related error values (`ErrSSRFBlocked`, `ErrUpstreamError`, `ErrUpstreamTimeout`, `ErrPayloadTooLarge`, `ErrDisallowedContentType`)
- All related constants (`DefaultFetchTimeout`, `DefaultMaxPayloadBytes`, `DefaultMaxConnectionsPerHost`, etc.)
- The `Fetcher` interface and `FetchResult` type (moved here to keep the import edge one-way: `imgcache` depends on `httpfetcher`, never the reverse)
- `MockFetcher` test helper

## Renames (no stuttering)

- `NewHTTPFetcher` → `httpfetcher.New`
- `FetcherConfig` → `httpfetcher.Config`
- `DefaultFetcherConfig` → `httpfetcher.DefaultConfig`
- `NewMockFetcher` → `httpfetcher.NewMock`

The `ServiceConfig.FetcherConfig` field name is retained — it describes what kind of config the field holds (not a stutter).

## Behavior

Pure refactor. No behavior changes. All existing tests pass; unit tests for the new package are included.

`docker build .` passes (fmt-check, lint, test, build).

refs #39

Co-authored-by: clawbot <clawbot@eeqj.de>
Co-authored-by: Jeffrey Paul <sneak@noreply.example.org>
Reviewed-on: #43
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>
2026-07-25 12:26:18 +02:00

116 lines
2.6 KiB
Go

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