mvp implementation

clients/go/officeconvertclient/download.go

@@ -0,0 +1,84 @@
+package officeconvertclient
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+
+	officeconvertapiv1 "github.com/end/officeconvert/gen/go/officeconvertapi/v1"
+)
+
+// DownloadedArtifact records a downloaded slide image destination path.
+type DownloadedArtifact struct {
+	SlideIndex int32
+	LocalPath  string
+}
+
+// DownloadArtifacts fetches all slide image URLs from a slide deck into outputDir.
+func (c *Client) DownloadArtifacts(
+	ctx context.Context,
+	slideDeck *officeconvertapiv1.SlideDeck,
+	outputDir string,
+) ([]DownloadedArtifact, error) {
+	if slideDeck == nil {
+		return nil, fmt.Errorf("slide deck is nil")
+	}
+	if err := os.MkdirAll(outputDir, 0o755); err != nil {
+		return nil, fmt.Errorf("create output directory: %w", err)
+	}
+
+	downloaded := make([]DownloadedArtifact, 0, len(slideDeck.Slides))
+	for _, slide := range slideDeck.Slides {
+		localPath := filepath.Join(outputDir, fmt.Sprintf("slide-%04d%s", slide.Index, inferImageExt(slide.ImageUrl)))
+		if err := c.downloadFile(ctx, slide.ImageUrl, localPath); err != nil {
+			return nil, err
+		}
+		downloaded = append(downloaded, DownloadedArtifact{
+			SlideIndex: slide.Index,
+			LocalPath:  localPath,
+		})
+	}
+
+	return downloaded, nil
+}
+
+func (c *Client) downloadFile(ctx context.Context, sourceURL string, destinationPath string) error {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, sourceURL, nil)
+	if err != nil {
+		return fmt.Errorf("build download request: %w", err)
+	}
+	res, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("download artifact: %w", err)
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode < 200 || res.StatusCode >= 300 {
+		return fmt.Errorf("download failed with status %d", res.StatusCode)
+	}
+	file, err := os.Create(destinationPath)
+	if err != nil {
+		return fmt.Errorf("create artifact file: %w", err)
+	}
+	defer file.Close()
+
+	if _, err := io.Copy(file, res.Body); err != nil {
+		return fmt.Errorf("write artifact file: %w", err)
+	}
+	return nil
+}
+
+func inferImageExt(imageURL string) string {
+	switch {
+	case strings.Contains(imageURL, ".jpeg") || strings.Contains(imageURL, ".jpg"):
+		return ".jpg"
+	case strings.Contains(imageURL, ".webp"):
+		return ".webp"
+	default:
+		return ".png"
+	}
+}