save: fix saving of multiple files with the same name

When an email has multiple attachments with the same name, aerc
currently only saves one of them. This patch adds a counter to them. the
file has an extension, the counter is added before the extension.

Signed-off-by: Moritz Poldrack <git@moritz.sh>
Acked-by: Koni Marti <koni.marti@gmail.com>

3 files changed, 45 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6291761d..0aecd62d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Fixed
 
 - `:archive` now works on servers using a different delimiter
+- `:save -a` now works with multiple attachments with the same filename
 
 ### Changed
 
diff --git a/commands/msgview/save.go b/commands/msgview/save.go
index 5bd4c188..170ef7c1 100644
--- a/commands/msgview/save.go
+++ b/commands/msgview/save.go
@@ -115,8 +115,9 @@ func (s Save) Execute(aerc *widgets.Aerc, args []string) error {
 			return fmt.Errorf("This message has no attachments")
 		}
 		params.trailingSlash = true
+		names := make(map[string]struct{})
 		for _, pi := range parts {
-			if err := savePart(pi, path, mv, aerc, &params); err != nil {
+			if err := savePart(pi, path, mv, aerc, &params, names); err != nil {
 				return err
 			}
 		}
@@ -124,7 +125,7 @@ func (s Save) Execute(aerc *widgets.Aerc, args []string) error {
 	}
 
 	pi := mv.SelectedMessagePart()
-	return savePart(pi, path, mv, aerc, &params)
+	return savePart(pi, path, mv, aerc, &params, make(map[string]struct{}))
 }
 
 func savePart(
@@ -133,6 +134,7 @@ func savePart(
 	mv *widgets.MessageViewer,
 	aerc *widgets.Aerc,
 	params *saveParams,
+	names map[string]struct{},
 ) error {
 	if params.trailingSlash || isDirExists(path) {
 		filename := generateFilename(pi.Part)
@@ -147,6 +149,9 @@ func savePart(
 		}
 	}
 
+	path = getCollisionlessFilename(path, names)
+	names[path] = struct{}{}
+
 	if pathExists(path) && !params.force {
 		return fmt.Errorf("%q already exists and -f not given", path)
 	}
@@ -181,6 +186,19 @@ func savePart(
 	return nil
 }
 
+func getCollisionlessFilename(path string, existing map[string]struct{}) string {
+	ext := filepath.Ext(path)
+	name := strings.TrimSuffix(path, ext)
+	_, exists := existing[path]
+	counter := 1
+	for exists {
+		path = fmt.Sprintf("%s_%d%s", name, counter, ext)
+		counter++
+		_, exists = existing[path]
+	}
+	return path
+}
+
 // isDir returns true if path is a directory and exists
 func isDirExists(path string) bool {
 	pathinfo, err := os.Stat(path)
diff --git a/commands/msgview/save_test.go b/commands/msgview/save_test.go
new file mode 100644
index 00000000..d6b7e757
--- /dev/null
+++ b/commands/msgview/save_test.go
@@ -0,0 +1,24 @@
+package msgview
+
+import "testing"
+
+func TestGetCollisionlessFilename(t *testing.T) {
+	tests := []struct {
+		originalFilename string
+		expectedNewName  string
+		existingFiles    map[string]struct{}
+	}{
+		{"test", "test", map[string]struct{}{}},
+		{"test", "test", map[string]struct{}{"other-file": {}}},
+		{"test.txt", "test.txt", map[string]struct{}{"test.log": {}}},
+		{"test.txt", "test_1.txt", map[string]struct{}{"test.txt": {}}},
+		{"test.txt", "test_2.txt", map[string]struct{}{"test.txt": {}, "test_1.txt": {}}},
+		{"test.txt", "test_1.txt", map[string]struct{}{"test.txt": {}, "test_2.txt": {}}},
+	}
+	for _, tt := range tests {
+		actual := getCollisionlessFilename(tt.originalFilename, tt.existingFiles)
+		if actual != tt.expectedNewName {
+			t.Errorf("expected %s, actual %s", tt.expectedNewName, actual)
+		}
+	}
+}