project panel: Copy dragged entry when opt is pressed (#12348)

Partially fixes #5119 
TODO:
- [ ] Change cursor style to Copy when dragging an entry with opt
pressed.

Release Notes:

- Drag-and-dropping a project panel entry with opt modifier pressed now
copies the entry instead of moving it.

crates/project_panel/src/project_panel.rs

@@ -74,6 +74,15 @@ struct DraggedSelection {
     marked_selections: Arc<BTreeSet<SelectedEntry>>,
 }
 
+impl DraggedSelection {
+    fn items<'a>(&'a self) -> Box<dyn Iterator<Item = &'a SelectedEntry> + 'a> {
+        if self.marked_selections.contains(&self.active_selection) {
+            Box::new(self.marked_selections.iter())
+        } else {
+            Box::new(std::iter::once(&self.active_selection))
+        }
+    }
+}
 #[derive(Clone, Debug)]
 struct EditState {
     worktree_id: WorktreeId,
@@ -1202,39 +1211,27 @@ impl ProjectPanel {
         }
     }
 
-    fn paste(&mut self, _: &Paste, cx: &mut ViewContext<Self>) {
-        maybe!({
-            let (worktree, entry) = self.selected_entry_handle(cx)?;
-            let entry = entry.clone();
-            let worktree_id = worktree.read(cx).id();
-            let clipboard_entries = self
-                .clipboard
-                .as_ref()
-                .filter(|clipboard| !clipboard.items().is_empty())?;
-
-            for clipboard_entry in clipboard_entries.items() {
-                if clipboard_entry.worktree_id != worktree_id {
-                    return None;
+    fn create_paste_path(
+        &self,
+        source: &SelectedEntry,
+        (worktree, target_entry): (Model<Worktree>, &Entry),
+        cx: &AppContext,
+    ) -> Option<PathBuf> {
+        let mut new_path = target_entry.path.to_path_buf();
+        // If we're pasting into a file, or a directory into itself, go up one level.
+        if target_entry.is_file() || (target_entry.is_dir() && target_entry.id == source.entry_id) {
+            new_path.pop();
         }
-
         let clipboard_entry_file_name = self
             .project
             .read(cx)
-                    .path_for_entry(clipboard_entry.entry_id, cx)?
+            .path_for_entry(source.entry_id, cx)?
             .path
             .file_name()?
             .to_os_string();
-
-                let mut new_path = entry.path.to_path_buf();
-                // If we're pasting into a file, or a directory into itself, go up one level.
-                if entry.is_file() || (entry.is_dir() && entry.id == clipboard_entry.entry_id) {
-                    new_path.pop();
-                }
-
         new_path.push(&clipboard_entry_file_name);
         let extension = new_path.extension().map(|e| e.to_os_string());
-                let file_name_without_extension =
-                    Path::new(&clipboard_entry_file_name).file_stem()?;
+        let file_name_without_extension = Path::new(&clipboard_entry_file_name).file_stem()?;
         let mut ix = 0;
         {
             let worktree = worktree.read(cx);
@@ -1255,7 +1252,25 @@ impl ProjectPanel {
                 ix += 1;
             }
         }
+        Some(new_path)
+    }
 
+    fn paste(&mut self, _: &Paste, cx: &mut ViewContext<Self>) {
+        maybe!({
+            let (worktree, entry) = self.selected_entry_handle(cx)?;
+            let entry = entry.clone();
+            let worktree_id = worktree.read(cx).id();
+            let clipboard_entries = self
+                .clipboard
+                .as_ref()
+                .filter(|clipboard| !clipboard.items().is_empty())?;
+
+            for clipboard_entry in clipboard_entries.items() {
+                if clipboard_entry.worktree_id != worktree_id {
+                    return None;
+                }
+                let new_path =
+                    self.create_paste_path(clipboard_entry, self.selected_entry_handle(cx)?, cx)?;
                 if clipboard_entries.is_cut() {
                     self.project
                         .update(cx, |project, cx| {
@@ -1686,24 +1701,38 @@ impl ProjectPanel {
     fn drag_onto(
         &mut self,
         selections: &DraggedSelection,
-        dragged_entry_id: ProjectEntryId,
+        target_entry_id: ProjectEntryId,
         is_file: bool,
         cx: &mut ViewContext<Self>,
     ) {
-        if selections
-            .marked_selections
-            .contains(&selections.active_selection)
-        {
-            for selection in selections.marked_selections.iter() {
-                self.move_entry(selection.entry_id, dragged_entry_id, is_file, cx);
-            }
-        } else {
-            self.move_entry(
-                selections.active_selection.entry_id,
-                dragged_entry_id,
-                is_file,
+        let should_copy = cx.modifiers().alt;
+        if should_copy {
+            let _ = maybe!({
+                let project = self.project.read(cx);
+                let target_worktree = project.worktree_for_entry(target_entry_id, cx)?;
+                let target_entry = target_worktree
+                    .read(cx)
+                    .entry_for_id(target_entry_id)?
+                    .clone();
+                for selection in selections.items() {
+                    let new_path = self.create_paste_path(
+                        &selection,
+                        (target_worktree.clone(), &target_entry),
                         cx,
-            );
+                    )?;
+                    self.project
+                        .update(cx, |project, cx| {
+                            project.copy_entry(selection.entry_id, new_path, cx)
+                        })
+                        .detach_and_log_err(cx)
+                }
+
+                Some(())
+            });
+        } else {
+            for selection in selections.items() {
+                self.move_entry(selection.entry_id, target_entry_id, is_file, cx);
+            }
         }
     }