refactor: stop blocking UI when collecting files

random_file_picker/tui.py

@@ -9,12 +9,14 @@ Here's an example usage:
 
 import pathlib
 import random
-from typing import override
+from typing import cast, override
 
 import typed_argparse as tap
+from textual import work
 from textual.app import App, ComposeResult
 from textual.binding import BindingType
 from textual.widgets import Footer, Header, Label
+from textual.worker import Worker, WorkerState
 
 from random_file_picker.core import IMG_EXTENSIONS, collect_files, move_file_to_move_folder, trash_file, upload_file
 from random_file_picker.openers import (
@@ -69,6 +71,7 @@ class MenuApp(App[None]):
         self.usable_files: list[pathlib.Path] = []
         self.current_index: int = 0
         self.current_file: pathlib.Path | None = None
+        self.is_loading: bool = False
 
     @override
     def compose(self) -> ComposeResult:
@@ -78,11 +81,78 @@ class MenuApp(App[None]):
         yield Footer()
 
     def on_mount(self) -> None:
-        self.gather_files()
-        if self.usable_files:
+        self.start_gathering_files()
+
+    @override
+    def check_action(self, action: str, parameters: tuple[object, ...]) -> bool | None:
+        """Disable every action except quit while files are being gathered."""
+        if self.is_loading and action != "quit":
+            return None
+        return True
+
+    def start_gathering_files(self) -> None:
+        """Start file collection in a background worker so the UI stays responsive."""
+        if not self.directory.exists() or not self.directory.is_dir():
+            self.query_one("#status", Label).update(f"❌ Directory '{self.directory}' not found")
+            return
+
+        self.is_loading = True
+        self.refresh_bindings()
+
+        self.query_one("#current-file", Label).update(f"🔍 Scanning '{self.directory}' for files, please wait...")
+        status = self.query_one("#status", Label)
+        status.update("")
+        status.loading = True
+        _ = self.gather_files_worker(
+            self.directory, self.file_limit, self.blacklist_patterns, self.whitelist_patterns,
+            recurse=self.recurse,
+        )
+
+    @work(thread=True, exclusive=True)
+    def gather_files_worker(
+        self,
+        directory: pathlib.Path,
+        file_limit: int,
+        blacklist_patterns: list[str],
+        whitelist_patterns: list[str],
+        *,
+        recurse: bool,
+    ) -> list[pathlib.Path]:
+        """Run file collection in a worker thread so a large/recursive scan doesn't block the UI."""
+        return collect_files(
+            search_path=directory,
+            search_subdirectories=recurse,
+            file_size_limit=file_limit,
+            blacklist_patterns=blacklist_patterns,
+            whitelist_patterns=whitelist_patterns,
+        )
+
+    def on_worker_state_changed(self, event: Worker.StateChanged) -> None:
+        """Handle the completion of the background file scan, updating the UI with results or errors."""
+        worker = cast("Worker[list[pathlib.Path]]", event.worker)
+        if worker.name != "gather_files_worker":
+            return
+
+        status = self.query_one("#status", Label)
+        self.is_loading = False
+        status.loading = False
+        self.refresh_bindings()
+
+        if event.state == WorkerState.SUCCESS:
+            files = worker.result or []
+            self.usable_files = list(files)
+            random.shuffle(self.usable_files)
+
+            if not self.usable_files:
+                status.update("❌ No usable files found")
+            else:
+                status.update(f"✅ Found {len(self.usable_files)} files")
                 self.current_index = 0
                 self.display_current_file()
 
+        elif event.state == WorkerState.ERROR:
+            status.update(f"❌ Failed to scan directory: {worker.error}")
+
     def assert_current_file_exists(self) -> bool:
         """Check if the current file exists and update the status label accordingly."""
         if not self.current_file or not self.current_file.exists():
@@ -102,28 +172,6 @@ class MenuApp(App[None]):
         self.query_one("#current-file", Label).update(f"📄 {self.current_file} {file_count_str}")
         self.open_file()
 
-    def gather_files(self) -> None:
-        """Collect files from the directory based on filters."""
-        self.usable_files = []
-
-        if not self.directory.exists() or not self.directory.is_dir():
-            self.query_one("#status", Label).update(f"❌ Directory '{self.directory}' not found")
-            return
-
-        self.usable_files = collect_files(
-            search_path=self.directory,
-            search_subdirectories=self.recurse,
-            file_size_limit=self.file_limit,
-            blacklist_patterns=self.blacklist_patterns,
-            whitelist_patterns=self.whitelist_patterns,
-        )
-
-        if not self.usable_files:
-            self.query_one("#status", Label).update("❌ No usable files found")
-        else:
-            self.query_one("#status", Label).update(f"✅ Found {len(self.usable_files)} files")
-        random.shuffle(self.usable_files)
-
     def open_file(self) -> None:
         """Open the current file - display images in terminal, play others externally."""
         if not self.current_file:
@@ -159,7 +207,7 @@ class MenuApp(App[None]):
             self.query_one("#status", Label).update(f"❌ Upload failed: {str(e)}")
 
     def delete_file(self) -> None:
-        """Delete the current file."""
+        """Delete the current file (move to trash if enabled)."""
         if not self.current_file or self.current_index >= len(self.usable_files):
             return
 
@@ -210,7 +258,7 @@ class MenuApp(App[None]):
             self.query_one("#status", Label).update(f"❌ Move failed: {str(e)}")
 
     def open_in_folder(self) -> None:
-        """Open the file's folder in file manager."""
+        """Open the current file's folder in the file manager."""
         if not self.current_file:
             return
 
@@ -221,30 +269,37 @@ class MenuApp(App[None]):
         self.query_one("#status", Label).update("📂 Opened file in folder")
 
     def action_upload(self) -> None:
+        """Upload the current file to Discord webhook."""
         self.send_file()
 
     def action_delete(self) -> None:
+        """Delete the current file (move to trash if enabled)."""
         self.delete_file()
 
     def action_move_to_folder(self) -> None:
+        """Move the current file to the move folder."""
         self.move_to_move_folder()
 
     def action_open_folder(self) -> None:
+        """Open the current file's folder in the file manager."""
         self.open_in_folder()
 
     def action_next_file(self) -> None:
+        """Display the next file."""
         if not self.usable_files:
             return
         self.current_index = (self.current_index + 1) % len(self.usable_files)
         self.display_current_file()
 
     def action_prev_file(self) -> None:
+        """Display the previous file."""
         if not self.usable_files:
             return
         self.current_index = (self.current_index - 1) % len(self.usable_files)
         self.display_current_file()
 
     def action_reopen_file(self) -> None:
+        """Reopen the current file."""
         if not self.current_file:
             return
         self.open_file()