trash: Use non-existing name when restoring image

We usually use the original path of the image.
For the rare case the original file name exists we create
one that is not used yet.

Closes #66

Part-of: <https://gitlab.gnome.org/Incubator/loupe/-/merge_requests/130>

src/util.rs

@@ -1,7 +1,7 @@
 use crate::deps::*;
 use crate::i18n::*;
 
-use anyhow::{anyhow, Context};
+use anyhow::{anyhow, bail, Context};
 use gio::prelude::*;
 use once_cell::sync::Lazy;
 
@@ -96,15 +96,42 @@ pub async fn untrash(path: &Path) -> anyhow::Result<()> {
         if original_path == path {
             let trash_file = trash.child(file_info.name());
             let original_file = gio::File::for_path(original_path);
+            let mut target_file = original_file.clone();
+
+            // Find available filename if original is used
+            for i in 1.. {
+                if !target_file.query_exists(gio::Cancellable::NONE) {
+                    break;
+                }
+
+                // Construct new name of the form "<filename> (i).<ext>"
+                let Some(path) = original_file.path() else { bail!("File without path") };
+                let mut name = path
+                    .file_stem()
+                    .map(|x| x.to_os_string())
+                    .unwrap_or_default();
+                name.push(format!(" ({i})"));
+
+                // Construct new path
+                let mut new_path = path.clone();
+                new_path.set_file_name(name);
+                if let Some(ext) = path.extension() {
+                    new_path.set_extension(ext);
+                }
+
+                target_file = gio::File::for_path(new_path);
+            }
+
             error = trash_file
                 .move_future(
-                    &original_file,
+                    &target_file,
                     gio::FileCopyFlags::NOFOLLOW_SYMLINKS,
                     glib::Priority::default(),
                 )
                 .0
                 .await
                 .context(i18n("Failed to restore image from trash"));
+
             break;
         }
     }