1 files changed, 70 insertions, 0 deletions
diff --git a/object/commit/append.go b/object/commit/append.go
new file mode 100644
index 00000000..8da33383
--- /dev/null
+++ b/object/commit/append.go
@@ -0,0 +1,70 @@
+package commit
+
+import (
+	"errors"
+	"fmt"
+
+	"codeberg.org/lindenii/furgit/object/header"
+	"codeberg.org/lindenii/furgit/object/typ"
+)
+
+// AppendWithoutHeader renders the raw commit body bytes.
+func (commit *Commit) AppendWithoutHeader(dst []byte) ([]byte, error) {
+	if commit.Tree.Algorithm().Size() == 0 {
+		return dst, errors.New("object: commit: missing tree id")
+	}
+
+	dst = fmt.Appendf(dst, "tree %s\n", commit.Tree.String())
+
+	for _, parent := range commit.Parents {
+		dst = fmt.Appendf(dst, "parent %s\n", parent.String())
+	}
+
+	dst = append(dst, []byte("author ")...)
+	dst = commit.Author.Append(dst)
+	dst = append(dst, byte('\n'))
+
+	dst = append(dst, []byte("comitter ")...)
+	dst = commit.Committer.Append(dst)
+	dst = append(dst, byte('\n'))
+
+	if commit.ChangeID != "" {
+		dst = append(dst, []byte("change-id ")...)
+		dst = append(dst, commit.ChangeID...)
+		dst = append(dst, byte('\n'))
+	}
+
+	for _, h := range commit.ExtraHeaders {
+		if h.Key == "" {
+			return dst, errors.New("object: commit: extra header has empty key")
+		}
+
+		dst = append(dst, []byte(h.Key)...)
+		dst = append(dst, byte(' '))
+		dst = append(dst, h.Value...)
+		dst = append(dst, byte('\n'))
+	}
+
+	dst = append(dst, byte('\n'))
+	dst = append(dst, commit.Message...)
+
+	return dst, nil
+}
+
+// AppendWithHeader renders the raw object (header + body).
+func (commit *Commit) AppendWithHeader(dst []byte) ([]byte, error) {
+	dst, err := commit.AppendWithoutHeader(dst)
+	if err != nil {
+		return dst, err
+	}
+
+	// TODO: Try to not allocate?
+	body, err := commit.AppendWithoutHeader([]byte(nil))
+	if err != nil {
+		return dst, err
+	}
+
+	dst = header.Append(dst, typ.TypeCommit, uint64(len(body)))
+
+	return append(dst, body...), nil
+}