1 files changed, 129 insertions, 0 deletions
diff --git a/src/cmd/export/assets.go b/src/cmd/export/assets.go
new file mode 100644
index 0000000..2e62cbd
--- /dev/null
+++ b/src/cmd/export/assets.go
@@ -0,0 +1,129 @@
+package main
+
+import (
+	"bytes"
+	"compress/gzip"
+	"context"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"dev.mediocregopher.com/mediocre-blog.git/src/post/asset"
+	"dev.mediocregopher.com/mediocre-go-lib.git/mctx"
+	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
+	"github.com/nlepage/go-tarfs"
+)
+
+func writeArchiveAsset(
+	assetStore asset.Store,
+	assetsDirPath string,
+	id string,
+) error {
+	buf := new(bytes.Buffer)
+	if err := assetStore.Get(id, buf); err != nil {
+		return fmt.Errorf("loading into buffer: %w", err)
+	}
+
+	gzipR, err := gzip.NewReader(buf)
+	if err != nil {
+		return fmt.Errorf("decompressing as gzip: %w", err)
+	}
+
+	tarFS, err := tarfs.New(gzipR)
+	if err != nil {
+		return fmt.Errorf("parsing as tar: %w", err)
+	}
+
+	return fs.WalkDir(tarFS, ".", func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return fmt.Errorf("walking path %q: %w", path, err)
+		} else if d.IsDir() {
+			return nil
+		}
+
+		var (
+			dirPath = filepath.Join(assetsDirPath, id, filepath.Dir(path))
+			dstPath = filepath.Join(dirPath, d.Name())
+			srcPath = path
+		)
+
+		if err := os.MkdirAll(dirPath, 0755); err != nil {
+			return fmt.Errorf("creating directory %q: %w", dirPath, err)
+		}
+
+		dstF, err := os.Create(dstPath)
+		if err != nil {
+			return fmt.Errorf("opening dst path %q: %w", dstPath, err)
+		}
+		defer dstF.Close()
+
+		srcF, err := tarFS.Open(srcPath)
+		if err != nil {
+			return fmt.Errorf("opening path %q within the tar: %w", srcPath, err)
+		}
+		defer srcF.Close()
+
+		if _, err = io.Copy(dstF, srcF); err != nil {
+			return fmt.Errorf("copying %q into %q: %w", srcPath, dstPath, err)
+		}
+
+		return nil
+	})
+}
+
+func writeAsset(
+	assetStore asset.Store,
+	assetsDirPath string,
+	id string,
+) error {
+	if strings.HasSuffix(id, ".tgz") {
+		return writeArchiveAsset(assetStore, assetsDirPath, id)
+	}
+
+	assetPath := filepath.Join(assetsDirPath, id)
+
+	f, err := os.Create(assetPath)
+	if err != nil {
+		return fmt.Errorf("creating file %q: %w", assetPath, err)
+	}
+	defer func() { _ = f.Close() }()
+
+	if err := assetStore.Get(id, f); err != nil {
+		return fmt.Errorf("writing asset to %q: %w", assetPath, err)
+	}
+
+	return nil
+}
+
+func exportAssets(
+	ctx context.Context,
+	logger *mlog.Logger,
+	assetStore asset.Store,
+	exportDirPath string,
+) error {
+	var (
+		assetsDirPath = filepath.Join(exportDirPath, "assets")
+	)
+
+	if err := os.MkdirAll(assetsDirPath, 0755); err != nil {
+		return fmt.Errorf("creating asset dir %q: %w", assetsDirPath, err)
+	}
+
+	logger.Info(ctx, "Listing assets")
+	assets, err := assetStore.List()
+	if err != nil {
+		return fmt.Errorf("listing assets: %w", err)
+	}
+
+	for _, id := range assets {
+		logger.Info(mctx.Annotate(ctx, "assetID", id), "Writing asset")
+		if err := writeAsset(assetStore, assetsDirPath, id); err != nil {
+			return fmt.Errorf("writing asset %q: %w", id, err)
+		}
+	}
+
+	return nil
+}