project panel: Support dropping files from finder (#12880)

Partially addresses #7386 



https://github.com/zed-industries/zed/assets/53836821/fc2e9864-40a8-4ada-ac95-a76a31c44437



Release Notes:

- Added support for dropping files from the finder onto the project
panel

crates/worktree/src/worktree.rs

@@ -838,6 +838,23 @@ impl Worktree {
         }
     }
 
+    pub fn copy_external_entries(
+        &mut self,
+        target_directory: PathBuf,
+        paths: Vec<Arc<Path>>,
+        overwrite_existing_files: bool,
+        cx: &mut ModelContext<Worktree>,
+    ) -> Task<Result<Vec<ProjectEntryId>>> {
+        match self {
+            Worktree::Local(this) => {
+                this.copy_external_entries(target_directory, paths, overwrite_existing_files, cx)
+            }
+            _ => Task::ready(Err(anyhow!(
+                "Copying external entries is not supported for remote worktrees"
+            ))),
+        }
+    }
+
     pub fn expand_entry(
         &mut self,
         entry_id: ProjectEntryId,
@@ -1579,6 +1596,87 @@ impl LocalWorktree {
         })
     }
 
+    pub fn copy_external_entries(
+        &mut self,
+        target_directory: PathBuf,
+        paths: Vec<Arc<Path>>,
+        overwrite_existing_files: bool,
+        cx: &mut ModelContext<Worktree>,
+    ) -> Task<Result<Vec<ProjectEntryId>>> {
+        let worktree_path = self.abs_path().clone();
+        let fs = self.fs.clone();
+        let paths = paths
+            .into_iter()
+            .filter_map(|source| {
+                let file_name = source.file_name()?;
+                let mut target = target_directory.clone();
+                target.push(file_name);
+
+                // Do not allow copying the same file to itself.
+                if source.as_ref() != target.as_path() {
+                    Some((source, target))
+                } else {
+                    None
+                }
+            })
+            .collect::<Vec<_>>();
+
+        let paths_to_refresh = paths
+            .iter()
+            .filter_map(|(_, target)| Some(target.strip_prefix(&worktree_path).ok()?.into()))
+            .collect::<Vec<_>>();
+
+        cx.spawn(|this, cx| async move {
+            cx.background_executor()
+                .spawn(async move {
+                    for (source, target) in paths {
+                        copy_recursive(
+                            fs.as_ref(),
+                            &source,
+                            &target,
+                            fs::CopyOptions {
+                                overwrite: overwrite_existing_files,
+                                ..Default::default()
+                            },
+                        )
+                        .await
+                        .with_context(|| {
+                            anyhow!("Failed to copy file from {source:?} to {target:?}")
+                        })?;
+                    }
+                    Ok::<(), anyhow::Error>(())
+                })
+                .await
+                .log_err();
+            let mut refresh = cx.read_model(
+                &this.upgrade().with_context(|| "Dropped worktree")?,
+                |this, _| {
+                    Ok::<postage::barrier::Receiver, anyhow::Error>(
+                        this.as_local()
+                            .with_context(|| "Worktree is not local")?
+                            .refresh_entries_for_paths(paths_to_refresh.clone()),
+                    )
+                },
+            )??;
+
+            cx.background_executor()
+                .spawn(async move {
+                    refresh.next().await;
+                    Ok::<(), anyhow::Error>(())
+                })
+                .await
+                .log_err();
+
+            let this = this.upgrade().with_context(|| "Dropped worktree")?;
+            cx.read_model(&this, |this, _| {
+                paths_to_refresh
+                    .iter()
+                    .filter_map(|path| Some(this.entry_for_path(path)?.id))
+                    .collect()
+            })
+        })
+    }
+
     fn expand_entry(
         &mut self,
         entry_id: ProjectEntryId,