Refactor Cart into checkerboard table

Closes: #173 (closed)

Removes clear all feature from: #233

This one improves focus behavior in the cart, moving cart items and deleting items from the cart.

clive/__private/ui/operations/cart.py

 from __future__ import annotations
 
+import contextlib
 from typing import TYPE_CHECKING, Sequence
 
 from textual import on
 from textual.binding import Binding
 from textual.containers import Horizontal
+from textual.css.query import NoMatches
 from textual.message import Message
 from textual.reactive import reactive
 from textual.widgets import Static
+from typing_extensions import Self
 
 from clive.__private.core.formatters.humanize import humanize_operation_details, humanize_operation_name
 from clive.__private.ui.get_css import get_relative_css_path
@@ -68,18 +71,16 @@ class CartItem(CliveCheckerboardTableRow, CliveWidget):
             super().__init__()
 
     class Move(Message):
-        def __init__(self, from_idx: int, to_idx: int, button_to_focus: str | None) -> None:
+        def __init__(self, from_idx: int, to_idx: int) -> None:
             self.from_idx = from_idx
             self.to_idx = to_idx
-            self.button_to_focus = button_to_focus
             super().__init__()
 
     class Focus(Message):
         """Message sent when other CartItem should be focused."""
 
-        def __init__(self, target_idx: int, button_to_focus: str | None) -> None:
+        def __init__(self, target_idx: int) -> None:
             self.target_idx = target_idx
-            self.button_to_focus = button_to_focus
             super().__init__()
 
     def __init__(self, operation_idx: int) -> None:
@@ -90,15 +91,17 @@ class CartItem(CliveCheckerboardTableRow, CliveWidget):
         to remove an operation and there are a large number of operations in the shopping basket."""
 
         assert self.is_valid(self._idx), "During construction, index has to be valid"
+        self._button_move_up = ButtonMoveUp(disabled=self._is_first)
+        self._button_move_down = ButtonMoveDown(disabled=self._is_last)
+        self._button_delete = ButtonDelete()
         self._index_cell = CliveCheckerBoardTableCell(self.get_operation_index(), classes="index")
+        self._horizontal_with_buttons = Horizontal(self._button_move_up, self._button_move_down, self._button_delete)
         super().__init__(
             self._index_cell,
             CliveCheckerBoardTableCell(self.get_operation_name(), classes="operation-type"),
             CliveCheckerBoardTableCell(self.get_operation_details(), classes="operation-details"),
             CliveCheckerBoardTableCell(
-                Horizontal(
-                    ButtonMoveUp(disabled=self._is_first), ButtonMoveDown(disabled=self._is_last), ButtonDelete()
-                ),
+                self._horizontal_with_buttons,
                 classes="actions",
             ),
         )
@@ -128,22 +131,40 @@ class CartItem(CliveCheckerboardTableRow, CliveWidget):
         return humanize_operation_name(self.operation) if self.is_valid(self._idx) else "?"
 
     def action_select_previous(self) -> None:
-        focused = self.get_focused_button_or_none()
-        self.post_message(self.Focus(target_idx=self._idx - 1, button_to_focus=focused))
+        self.post_message(self.Focus(target_idx=self._idx - 1))
 
     def action_select_next(self) -> None:
-        focused = self.get_focused_button_or_none()
-        self.post_message(self.Focus(target_idx=self._idx + 1, button_to_focus=focused))
+        self.post_message(self.Focus(target_idx=self._idx + 1))
 
     def get_operation_details(self) -> str:
         return humanize_operation_details(self.operation) if self.is_valid(self._idx) else "?"
 
-    def get_focused_button_or_none(self) -> str | None:
-        buttons = self.query(CliveButton)
-        for button in buttons:
-            if button.has_focus:
-                return button.id
-        return None
+    def focus(self, _: bool = True) -> Self:  # noqa: FBT001, FBT002
+        if focused := self.app.focused:  # Focus the corresponding button as it was before
+            assert focused.id, "Previously focused widget has no id!"
+            with contextlib.suppress(NoMatches):
+                previous = self._horizontal_with_buttons.get_child_by_id(focused.id)
+                if previous.focusable:
+                    previous.focus()
+                    return self
+
+        for button in reversed(self._horizontal_with_buttons.children):  # Focus first focusable
+            if button.focusable:
+                button.focus()
+
+        return self
+
+    @property
+    def button_move_up(self) -> ButtonMoveUp:
+        return self._button_move_up
+
+    @property
+    def button_move_down(self) -> ButtonMoveDown:
+        return self._button_move_down
+
+    @property
+    def button_delete(self) -> ButtonDelete:
+        return self._button_delete
 
     @property
     def operation(self) -> OperationBase:
@@ -164,13 +185,11 @@ class CartItem(CliveCheckerboardTableRow, CliveWidget):
 
     @on(CliveButton.Pressed, "#move-up-button")
     def move_up(self) -> None:
-        focused = self.get_focused_button_or_none()
-        self.post_message(self.Move(from_idx=self._idx, to_idx=self._idx - 1, button_to_focus=focused))
+        self.post_message(self.Move(from_idx=self._idx, to_idx=self._idx - 1))
 
     @on(CliveButton.Pressed, "#move-down-button")
     def move_down(self) -> None:
-        focused = self.get_focused_button_or_none()
-        self.post_message(self.Move(from_idx=self._idx, to_idx=self._idx + 1, button_to_focus=focused))
+        self.post_message(self.Move(from_idx=self._idx, to_idx=self._idx + 1))
 
     @on(CliveButton.Pressed, "#delete-button")
     def delete(self) -> None:
@@ -211,18 +230,13 @@ class CartTable(CliveCheckerboardTable):
         ]
         return self._rows
 
-    @staticmethod
-    def _create_widget_id_to_focus(event: CartItem.Focus | CartItem.Move) -> str:
-        assert event.button_to_focus is not None, "Button to focus has to be passed to get it's id."
-        return f"#{event.button_to_focus}"
-
     def _disable_appropriate_button(self, widget: CartItem) -> None:
         if len(self.app.world.profile.cart) > 0 and widget.reactive_idx == 0:
-            # disable first ButtomMoveUp if first element was removed
-            self.query(ButtonMoveUp)[0].disabled = True
+            # disable ButtomMoveUp if first element was removed
+            self._rows[0].button_move_up.disabled = True
         if 0 < len(self.app.world.profile.cart) == widget.reactive_idx:
-            # disable last ButtonMoveDown if only last element was removed
-            self.query(ButtonMoveDown)[-1].disabled = True
+            # disable ButtonMoveDown if only last element was removed
+            self._rows[-1].button_move_down.disabled = True
 
     def _handle_remove_event(self, triggering_widget: CartItem) -> None:
         def devalue_indexes(rows: Sequence[CartItem]) -> None:
@@ -270,49 +284,34 @@ class CartTable(CliveCheckerboardTable):
         self.profile.cart.swap(event.from_idx, event.to_idx)
         self.app.trigger_profile_watchers()
         self._update_values_of_swapped_rows(from_index=event.from_idx, to_index=event.to_idx)
-        # focus item that was moved
+
         for cart_item in self._rows:
             if event.to_idx == cart_item.reactive_idx:
-                self.app.set_focus(cart_item)
-                if event.button_to_focus:
-                    button_id = self._create_widget_id_to_focus(event)
-                    cart_item.query_one(button_id).focus()
+                cart_item.focus()
 
     @on(CartItem.Focus)
     def focus_item(self, event: CartItem.Focus) -> None:
         for cart_item in self._rows:
             if event.target_idx == cart_item.reactive_idx:
-                self.app.set_focus(cart_item)
-                if event.button_to_focus:
-                    button_id = self._create_widget_id_to_focus(event)
-                    cart_item.query_one(button_id).focus()
+                cart_item.focus()
 
 
 class Cart(BaseScreen):
     CSS_PATH = [get_relative_css_path(__file__)]
     BINDINGS = [
         Binding("escape", "app.pop_screen", "Back"),
-        Binding("f9", "clear_all", "Clear all"),
         Binding("f6", "summary", "Summary"),
     ]
     BIG_TITLE = "operations cart"
 
     def __init__(self) -> None:
         super().__init__()
-        self.__scrollable_part = ScrollablePart()
+        self._scrollable_part = ScrollablePart()
         self._cart_table = CartTable()
 
     def create_main_panel(self) -> ComposeResult:
-        with self.__scrollable_part:
+        with self._scrollable_part:
             yield self._cart_table
 
-    async def __rebuild_items(self, from_index: int = 0, to_index: int | None = None) -> None:
-        await self._cart_table.rebuild(starting_from_element=from_index, ending_with_element=to_index)
-
     def action_summary(self) -> None:
         self.app.push_screen(TransactionSummaryFromCart())
-
-    async def action_clear_all(self) -> None:
-        self.profile.cart.clear()
-        self.app.trigger_profile_watchers()
-        await self.__rebuild_items()