refactor: Decompose index func

pkg/recovery/fetch.go

@@ -0,0 +1,19 @@
+package recovery
+
+import (
+	"github.com/pojntfx/stfs/pkg/config"
+)
+
+func Fetch(
+	state config.StateConfig,
+	pipes config.PipeConfig,
+	crypto config.CryptoConfig,
+
+	recordSize int,
+	record int,
+	block int,
+	to string,
+	preview string,
+) error {
+	return nil
+}