Create fs.Directory interface and use it everywhere

fs/object.go

@@ -0,0 +1,50 @@
+package fs
+
+import "time"
+
+// NewStaticObjectInfo returns a static ObjectInfo
+// If hashes is nil and fs is not nil, the hash map will be replaced with
+// empty hashes of the types supported by the fs.
+func NewStaticObjectInfo(remote string, modTime time.Time, size int64, storable bool, hashes map[HashType]string, fs Info) ObjectInfo {
+	info := &staticObjectInfo{
+		remote:   remote,
+		modTime:  modTime,
+		size:     size,
+		storable: storable,
+		hashes:   hashes,
+		fs:       fs,
+	}
+	if fs != nil && hashes == nil {
+		set := fs.Hashes().Array()
+		info.hashes = make(map[HashType]string)
+		for _, ht := range set {
+			info.hashes[ht] = ""
+		}
+	}
+	return info
+}
+
+type staticObjectInfo struct {
+	remote   string
+	modTime  time.Time
+	size     int64
+	storable bool
+	hashes   map[HashType]string
+	fs       Info
+}
+
+func (i *staticObjectInfo) Fs() Info           { return i.fs }
+func (i *staticObjectInfo) Remote() string     { return i.remote }
+func (i *staticObjectInfo) String() string     { return i.remote }
+func (i *staticObjectInfo) ModTime() time.Time { return i.modTime }
+func (i *staticObjectInfo) Size() int64        { return i.size }
+func (i *staticObjectInfo) Storable() bool     { return i.storable }
+func (i *staticObjectInfo) Hash(h HashType) (string, error) {
+	if len(i.hashes) == 0 {
+		return "", ErrHashUnsupported
+	}
+	if hash, ok := i.hashes[h]; ok {
+		return hash, nil
+	}
+	return "", ErrHashUnsupported
+}