streamdata: path helper

This prints ident string joined with base directory pathname.

Signed-off-by: Yonah <contrib@gensokyo.uk>

streamdata.go

@@ -202,6 +202,15 @@ func (c *Channel) Add(ident *Ident, f func(v *VOD, w io.Writer) error) error {
 	return nil
 }
 
+// Path returns a pathname by [Ident].
+func (c *Channel) Path(ident *Ident) string {
+	return path.Join(
+		c.root.Name(),
+		channelPathVOD,
+		ident.String()+ChannelVODSuffix,
+	)
+}
+
 // All returns an iterator over all known [Ident] in the on-disk representation.
 // Iteration stops when encountering the first non-nil error, and its value is
 // saved to the value pointed to by errP.