ref: Create a storage interface

This `Storage` interface will define all the interactions with the
storage system. For now I plan to support native file system through
go's standard library and Nextcloud through *webdav*. So this is the
first step in that direction.

1 files changed, 36 insertions, 10 deletions

diff --git a/fileop/fileop.go b/fileop/fileop.go
index d08cb82..1be3f2e 100644
--- a/fileop/fileop.go
+++ b/fileop/fileop.go
@@ -8,7 +8,15 @@ import (
 	"path/filepath"
 )
 
-func WalkFolder(folder string) <-chan string {
+type WalkMode int
+
+const (
+	Folder WalkMode = iota
+	File
+	FileFolder
+)
+
+func WalkFolder(folder string, walkMode WalkMode) <-chan string {
 	c := make(chan string)
 
 	go func(folder string, c chan string) {
@@ -16,7 +24,17 @@ func WalkFolder(folder string) <-chan string {
 			file, _ := os.Open(path)
 			defer file.Close()
 			fileInfo, _ := file.Stat()
-			if !fileInfo.IsDir() {
+
+			switch walkMode {
+			case Folder:
+				if fileInfo.IsDir() {
+					c <- path
+				}
+			case File:
+				if !fileInfo.IsDir() {
+					c <- path
+				}
+			case FileFolder:
 				c <- path
 			}
 			return nil
@@ -28,15 +46,9 @@ func WalkFolder(folder string) <-chan string {
 	return c
 }
 
-func CalculateSHA256(file string) (string, error) {
-	f, err := os.Open(file)
-	if err != nil {
-		return "", err
-	}
-	defer f.Close()
-
+func CalculateSHA256(r io.Reader) (string, error) {
 	h := sha256.New()
-	if _, err := io.Copy(h, f); err != nil {
+	if _, err := io.Copy(h, r); err != nil {
 		return "", err
 	}
 
@@ -64,3 +76,17 @@ func Move() chan<- *MoveCommand {
 
 	return c
 }
+
+func IsEmpty(name string) (bool, error) {
+	f, err := os.Open(name)
+	if err != nil {
+		return false, err
+	}
+	defer f.Close()
+
+	_, err = f.Readdirnames(1)
+	if err == io.EOF {
+		return true, nil
+	}
+	return false, err
+}