enh: display object count and size in tree views

CHANGELOG

@@ -4,6 +4,7 @@
  - enh: handle PermissionError when building directory tree
  - enh: identify existing target paths based on size quicker
  - enh: correct progress display and remove unused code
+ - enh: display object count and size in tree views
  - ref: migrate from pkg_resources to importlib.resources
  - ref: unify input and output tree widget with one base class
 0.5.2

mpl_data_cast/gui/main.py

@@ -173,6 +173,8 @@ def on_recipe_changed(self):
         rec_cls = self.current_recipe
         doc = rec_cls.__doc__.split("\n")[0]
         self.label_recipe_descr.setText(f"*{doc}*")
+        self.widget_input.recipe = rec_cls
+        self.widget_output.recipe = rec_cls
 
 
 class Callback:

mpl_data_cast/gui/widget_tree.py

@@ -1,24 +1,117 @@
-from PyQt6 import QtWidgets, QtCore, uic
 from importlib import resources
 import pathlib
+import time
+import threading
+from typing import Literal
+
+from PyQt6 import QtWidgets, QtCore, uic
 
 from ..path_tree import PathTree, list_items_in_tree
+from ..recipe import map_recipe_name_to_class
 from ..util import is_dir_writable
 
 
+class TreeObjectCounter(threading.Thread):
+    """Thread running in the background, counting objects and their size"""
+    def __init__(self, *args, **kwargs):
+        super(TreeObjectCounter, self).__init__(*args, **kwargs)
+        self.daemon = True
+        self.recipe = None
+        self.path = None
+        self.num_objects = 0
+        self.size_objects = 0
+        self.must_break = False
+        self.is_counting = False
+
+    def run(self):
+        recipe = self.recipe
+        path = self.path
+        while True:
+            if self.must_break:
+                # user requested we quit
+                break
+            elif recipe is None or path is None:
+                # not initialized yet
+                recipe = self.recipe
+                path = self.path
+            elif (self.recipe is None
+                  or self.path is None
+                  or self.recipe != recipe
+                    or self.path != path):
+                # reset
+                self.num_objects = 0
+                self.size_objects = 0
+                recipe = self.recipe
+                path = self.path
+            elif self.num_objects:
+                # already counted
+                pass
+            else:
+                # start crawling the directory tree
+                self.is_counting = True
+                try:
+                    rcp = recipe(path, path)
+                except BaseException:
+                    pass
+                else:
+                    tree_iterator = rcp.get_raw_data_iterator()
+                    while True:
+                        # check whether we have to abort
+                        if (self.must_break
+                                or recipe != self.recipe or path != self.path):
+                            self.num_objects = 0
+                            break
+                        try:
+                            item = next(tree_iterator)
+                        except StopIteration:
+                            break
+                        except BaseException:
+                            # Windows might encounter PermissionError.
+                            pass
+                        else:
+                            self.num_objects += 1
+                            try:
+                                self.size_objects += sum(
+                                    [it.stat().st_size for it in item])
+                            except BaseException:
+                                pass
+                self.is_counting = False
+            time.sleep(0.5)
+
+
 class TreeWidget(QtWidgets.QWidget):
-    def __init__(self, which="tree", *args, **kwargs):
+    def __init__(self,
+                 which: Literal["input", "output"] = "input",
+                 *args,
+                 **kwargs):
         """Widget handling tree views for directories"""
         super(TreeWidget, self).__init__(*args, **kwargs)
         ref_ui = resources.files("mpl_data_cast.gui") / "widget_tree.ui"
         with resources.as_file(ref_ui) as path_ui:
             uic.loadUi(path_ui, self)
 
+        #: keep track of recipe
+        self._recipe = map_recipe_name_to_class("CatchAll")
+        #: whether we are "output" or "input"
         self.which = which
+        #: whether the directory tree should be read-only
+        self.readonly = which == "input"
+        #: path of current working directory
+        self._path = None
+        #: tree data structure
+        self.p_tree = None
+
+        # tree spider counter daemon
+        self.tree_counter = TreeObjectCounter()
+        self.tree_counter.start()
+
+        # UI update function
+        self.tree_label_timer = QtCore.QTimer(self)
+        self.tree_label_timer.timeout.connect(self.on_update_object_count)
+        self.tree_label_timer.start(300)
+
         self.groupBox.setTitle(self.which.capitalize())
         self.pushButton_dir.setText(f"Select {self.which} directory")
-        self.path = None
-        self.p_tree = None
         self.settings = QtCore.QSettings()
         self.tree_depth_limit = int(self.settings.value(
             "main/tree_depth_limit", 3))
@@ -29,6 +122,25 @@ def __init__(self, which="tree", *args, **kwargs):
         self.lineEdit_dir.editingFinished.connect(
             self.update_tree_dir_from_lineedit)
 
+    @property
+    def path(self):
+        return self._path
+
+    @path.setter
+    def path(self, path):
+        self._path = path
+        self.tree_counter.path = path
+
+    @property
+    def recipe(self):
+        """The current recipe we are working with"""
+        return self._recipe
+
+    @recipe.setter
+    def recipe(self, recipe):
+        self._recipe = recipe
+        self.tree_counter.recipe = recipe
+
     @QtCore.pyqtSlot()
     def on_task_select_tree_dir(self) -> None:
         p = QtWidgets.QFileDialog.getExistingDirectory(
@@ -38,13 +150,26 @@ def on_task_select_tree_dir(self) -> None:
         if p:
             self.update_tree_dir(p)
 
+    @QtCore.pyqtSlot()
+    def on_update_object_count(self):
+        objects = self.tree_counter.num_objects
+        size = self.tree_counter.size_objects
+        size_str = human_size(size)
+        if self.tree_counter.is_counting:
+            label = f"counting {objects} objects ({size_str})"
+        else:
+            label = f"{objects} objects ({size_str})"
+        self.label_objects.setText(label)
+
+    @QtCore.pyqtSlot(object)
     def dragEnterEvent(self, e) -> None:
         """Whether files are accepted"""
         if e.mimeData().hasUrls():
             e.accept()
         else:
             e.ignore()
 
+    @QtCore.pyqtSlot(object)
     def dropEvent(self, e) -> None:
         """Add dropped directory to treeview and lineedit."""
         urls = e.mimeData().urls()
@@ -54,7 +179,6 @@ def dropEvent(self, e) -> None:
             path_tree = pp
         else:
             path_tree = pp.parent
-
         self.update_tree_dir(path_tree)
 
     @QtCore.pyqtSlot()
@@ -64,6 +188,11 @@ def update_tree_dir_from_lineedit(self) -> None:
         if tree_dir:
             self.update_tree_dir(tree_dir)
 
+    @QtCore.pyqtSlot()
+    def update_object_count(self) -> None:
+        """Update `self.label_objects` with the counted events"""
+
+    @QtCore.pyqtSlot()
     def update_tree_dir(self, tree_dir: str | pathlib.Path) -> None:
         """Checks if the tree directory as given by the user exists and
         updates the lineEdit widget accordingly.
@@ -73,20 +202,21 @@ def update_tree_dir(self, tree_dir: str | pathlib.Path) -> None:
         tree_dir: str or pathlib.Path
             The directory for the tree.
         """
-        if is_dir_writable(tree_dir):
-            tree_dir = pathlib.Path(tree_dir)
-            self.path = tree_dir
-            self.lineEdit_dir.setText(str(tree_dir))
-            self.update_tree()
-        else:
+        if not self.readonly and not is_dir_writable(tree_dir):
             msg_txt = f"The {self.which} directory '{tree_dir}' is not " \
-                      f"valid. Please select a different directory."
+                      f"writable. Please select a different directory."
             msg = QtWidgets.QMessageBox(self)
             msg.setIcon(QtWidgets.QMessageBox.Icon.Warning)
             msg.setText(msg_txt)
             msg.setWindowTitle(f"{self.which.capitalize()} directory invalid")
             msg.exec()
+        else:
+            tree_dir = pathlib.Path(tree_dir)
+            self.path = tree_dir
+            self.lineEdit_dir.setText(str(tree_dir))
+            self.update_tree()
 
+    @QtCore.pyqtSlot()
     def update_tree(self) -> None:
         """Update the `PathTree` object based on the current root path in
         `self.path` and update the GUI to show the new tree."""
@@ -101,3 +231,10 @@ def update_tree(self) -> None:
 
         QtWidgets.QApplication.processEvents(
             QtCore.QEventLoop.ProcessEventsFlag.AllEvents, 300)
+
+
+def human_size(bt, units=None):
+    """Return a human-eadable string representation of bytes """
+    if units is None:
+        units = [' bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB']
+    return str(bt) + units[0] if bt < 1024 else human_size(bt >> 10, units[1:])