object/fetch: Finish blob

1 files changed, 97 insertions, 0 deletions

diff --git a/object/fetch/blob.go b/object/fetch/blob.go
new file mode 100644
index 00000000..ee5bae1c
--- /dev/null
+++ b/object/fetch/blob.go
@@ -0,0 +1,97 @@
+package fetch
+
+import (
+	"io"
+
+	"lindenii.org/go/furgit/errs"
+	"lindenii.org/go/furgit/object/blob"
+	oid "lindenii.org/go/furgit/object/id"
+	"lindenii.org/go/furgit/object/stored"
+	"lindenii.org/go/furgit/object/tag"
+	"lindenii.org/go/furgit/object/typ"
+)
+
+// ExactBlob reads, parses, and wraps the blob at id.
+//
+// Labels: Life-Parent.
+func (r *Fetcher) ExactBlob(id oid.ObjectID) (*stored.Stored[*blob.Blob], error) {
+	parsed, err := r.parseObject(id)
+	if err != nil {
+		return nil, err
+	}
+
+	blob, ok := parsed.(*blob.Blob)
+	if !ok {
+		return nil, &errs.ObjectTypeError{OID: id, Got: parsed.ObjectType(), Want: typ.TypeBlob}
+	}
+
+	return stored.New(id, blob), nil
+}
+
+// ExactBlobReader returns a reader for the content of the blob at id,
+// together with its content size in bytes.
+//
+// Labels: Life-Parent, Close-Caller.
+func (r *Fetcher) ExactBlobReader(id oid.ObjectID) (io.ReadCloser, int64, error) {
+	return r.exactReader(id, typ.TypeBlob)
+}
+
+// PeelToBlob peels tags until it reaches a blob.
+//
+// Labels: Life-Parent.
+func (r *Fetcher) PeelToBlob(id oid.ObjectID) (*stored.Stored[*blob.Blob], error) {
+	for {
+		obj, err := r.ExactObject(id)
+		if err != nil {
+			return nil, err
+		}
+
+		switch parsed := obj.Object().(type) {
+		case *blob.Blob:
+			return stored.New(id, parsed), nil
+		case *tag.Tag:
+			id = parsed.TargetID
+		default:
+			return nil, &errs.ObjectTypeError{OID: id, Got: parsed.ObjectType(), Want: typ.TypeBlob}
+		}
+	}
+}
+
+// PeelToBlobID peels tags until it reaches a blob object ID.
+func (r *Fetcher) PeelToBlobID(id oid.ObjectID) (oid.ObjectID, error) {
+	for {
+		ty, _, err := r.Header(id)
+		if err != nil {
+			return oid.ObjectID{}, err
+		}
+
+		switch ty {
+		case typ.TypeBlob:
+			return id, nil
+		case typ.TypeTag:
+			tag, err := r.ExactTag(id)
+			if err != nil {
+				return oid.ObjectID{}, err
+			}
+
+			id = tag.Object().TargetID
+		case typ.TypeUnknown, typ.TypeCommit, typ.TypeTree:
+			return oid.ObjectID{}, &errs.ObjectTypeError{OID: id, Got: ty, Want: typ.TypeBlob}
+		default:
+			return oid.ObjectID{}, &errs.ObjectTypeError{OID: id, Got: ty, Want: typ.TypeBlob}
+		}
+	}
+}
+
+// PeelToBlobReader returns a reader for the content of the peeled blob at id,
+// together with its content size in bytes.
+//
+// Labels: Life-Parent, Close-Caller.
+func (r *Fetcher) PeelToBlobReader(id oid.ObjectID) (io.ReadCloser, int64, error) {
+	blobID, err := r.PeelToBlobID(id)
+	if err != nil {
+		return nil, 0, err
+	}
+
+	return r.ExactBlobReader(blobID)
+}