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|
package image
import (
"context"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"golang.org/x/sys/unix"
)
// DownloadOptions configures image download behavior.
type DownloadOptions struct {
OutputDir string
OverwriteExisting bool
CreateDir bool
FileNamePattern string
MaxSizeBytes int64
}
// DefaultDownloadOptions returns sensible defaults for image downloads.
func DefaultDownloadOptions() *DownloadOptions {
return &DownloadOptions{
OutputDir: "./images",
OverwriteExisting: false,
CreateDir: true,
FileNamePattern: "{word}_{source}",
MaxSizeBytes: 10 * 1024 * 1024,
}
}
// Downloader handles image downloads from search results.
type Downloader struct {
provider ImageProvider
options *DownloadOptions
}
// NewDownloader creates a new image downloader.
func NewDownloader(provider ImageProvider, options *DownloadOptions) *Downloader {
if options == nil {
options = DefaultDownloadOptions()
}
return &Downloader{
provider: provider,
options: options,
}
}
// DownloadImage downloads a single image to the specified path.
func (d *Downloader) DownloadImage(ctx context.Context, result *SearchResult, outputPath string) (err error) {
if d == nil || d.provider == nil {
return fmt.Errorf("image provider is required")
}
if result == nil {
return fmt.Errorf("search result is required")
}
reader, err := d.provider.Download(ctx, result.URL)
if err != nil {
return fmt.Errorf("download %q: %w", result.URL, err)
}
defer func() {
_ = reader.Close()
}()
store := newSecureOutputStore(d.options)
file, parentFD, finalName, err := store.openSecureOutputFile(outputPath)
if err != nil {
return fmt.Errorf("create output file %q: %w", outputPath, err)
}
defer func() {
_ = unix.Close(parentFD)
}()
defer func() {
if closeErr := file.Close(); err == nil && closeErr != nil {
err = fmt.Errorf("close output file %q: %w", outputPath, closeErr)
}
}()
if d.options != nil && d.options.MaxSizeBytes > 0 {
written, copyErr := io.CopyN(file, reader, d.options.MaxSizeBytes)
if copyErr != nil && copyErr != io.EOF {
_ = unix.Unlinkat(parentFD, finalName, 0)
return fmt.Errorf("write output file %q: %w", outputPath, copyErr)
}
if written == d.options.MaxSizeBytes {
var probe [1]byte
if n, probeErr := reader.Read(probe[:]); n > 0 || probeErr != io.EOF {
_ = unix.Unlinkat(parentFD, finalName, 0)
return fmt.Errorf("image exceeds max size %d bytes", d.options.MaxSizeBytes)
}
}
} else {
if _, err = io.Copy(file, reader); err != nil {
_ = unix.Unlinkat(parentFD, finalName, 0)
return fmt.Errorf("write output file %q: %w", outputPath, err)
}
}
if err := file.Sync(); err != nil {
return fmt.Errorf("sync output file %q: %w", outputPath, err)
}
if attribution := strings.TrimSpace(result.Attribution); attribution != "" {
attrRelPath := strings.TrimSuffix(finalName, filepath.Ext(finalName)) + "_attribution.txt"
if err := store.writeSecureRelativeFile(outputPath, attrRelPath, []byte(attribution), 0o644); err != nil {
fmt.Fprintf(os.Stderr, "Warning: failed to save attribution: %v\n", err)
}
}
return nil
}
// DownloadBestMatch downloads the best matching image for a query.
func (d *Downloader) DownloadBestMatch(ctx context.Context, query string) (*SearchResult, string, error) {
opts := DefaultSearchOptions(query)
opts.PerPage = 5
return d.DownloadBestMatchWithOptions(ctx, opts)
}
// DownloadBestMatchWithOptions downloads the best matching image for given search options.
func (d *Downloader) DownloadBestMatchWithOptions(ctx context.Context, opts *SearchOptions) (*SearchResult, string, error) {
if d == nil || d.provider == nil {
return nil, "", fmt.Errorf("image provider is required")
}
if opts == nil {
return nil, "", fmt.Errorf("search options are required")
}
searchOpts := *opts
searchOpts.PerPage = 5
results, err := d.provider.Search(ctx, &searchOpts)
if err != nil {
return nil, "", fmt.Errorf("search images: %w", err)
}
if len(results) == 0 {
return nil, "", fmt.Errorf("no images found for %q", opts.Query)
}
policy := newDownloadPathPolicy(d.options)
for i, result := range results {
filename := policy.generateFileName(opts.Query, &result, i)
outputPath, err := policy.resolveOutputPath(filename)
if err != nil {
fmt.Fprintf(os.Stderr, "Warning: refusing unsafe output path %q: %v\n", filename, err)
continue
}
if err := d.DownloadImage(ctx, &result, outputPath); err == nil {
return &result, outputPath, nil
} else {
fmt.Fprintf(os.Stderr, "Warning: failed to download image %d: %v\n", i+1, err)
}
}
return nil, "", fmt.Errorf("no downloadable images found for %q", opts.Query)
}
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