Refactor, add Object and Snapshot

object.go

@@ -0,0 +1,119 @@
+package khepri
+
+import "os"
+
+type Object struct {
+	repo *Repository
+
+	id  ID
+	tpe Type
+
+	hw   HashingWriter
+	file *os.File
+}
+
+func (repo *Repository) NewObject(t Type) (*Object, error) {
+	obj := &Object{
+		repo: repo,
+		tpe:  t,
+	}
+
+	return obj, obj.open()
+}
+
+func (obj *Object) open() error {
+	if obj.isFinal() {
+		panic("object is finalized")
+	}
+
+	if obj.isOpen() {
+		panic("object already open")
+	}
+
+	// create tempfile in repository
+	if obj.hw == nil {
+		// save contents to tempfile, hash while writing
+		var err error
+		obj.file, err = obj.repo.tempFile()
+		if err != nil {
+			return err
+		}
+
+		// create hashing writer
+		obj.hw = NewHashingWriter(obj.file, obj.repo.hash)
+	}
+
+	return nil
+}
+
+func (obj *Object) isOpen() bool {
+	return obj.file != nil && obj.hw != nil
+}
+
+func (obj *Object) isFinal() bool {
+	return obj.id != nil
+}
+
+func (obj *Object) Write(data []byte) (int, error) {
+	if !obj.isOpen() {
+		panic("object not open")
+	}
+
+	return obj.hw.Write(data)
+}
+
+func (obj *Object) Close() error {
+	if obj.file == nil || obj.hw == nil {
+		panic("object is not open")
+	}
+
+	obj.file.Close()
+
+	hash := obj.hw.Hash()
+
+	// move file to final name using hash of contents
+	id := ID(hash)
+	err := obj.repo.renameFile(obj.file, obj.tpe, id)
+	if err != nil {
+		return err
+	}
+
+	obj.hw = nil
+	obj.file = nil
+
+	obj.id = id
+	return nil
+}
+
+func (obj *Object) ID() ID {
+	if !obj.isFinal() {
+		panic("object not finalized")
+	}
+
+	return obj.id
+}
+
+func (obj *Object) Type() Type {
+	return obj.tpe
+}
+
+func (obj *Object) Remove() error {
+	if obj.id != nil {
+		return obj.repo.Remove(obj.tpe, obj.id)
+	}
+
+	if obj.file != nil {
+		file := obj.file
+		obj.hw = nil
+		obj.file = nil
+
+		err := file.Close()
+		if err != nil {
+			return err
+		}
+
+		return os.Remove(file.Name())
+	}
+
+	return nil
+}