LED-mapper/canvas.py

from __future__ import annotations

import math
from pathlib import Path

from PySide6.QtCore import QPointF, QRectF, QSize, Qt, Signal
from PySide6.QtGui import QColor, QBrush, QImageReader, QPainter, QPainterPath, QPen, QPixmap, QTransform
from PySide6.QtWidgets import (
    QGraphicsEllipseItem,
    QGraphicsItem,
    QGraphicsLineItem,
    QGraphicsPathItem,
    QGraphicsPixmapItem,
    QGraphicsRectItem,
    QGraphicsScene,
    QGraphicsSimpleTextItem,
    QGraphicsView,
    QMenu,
    QScrollBar,
)
from shiboken6 import isValid

try:
    from .models import BackgroundImage, LedLine, LedPoint, MappingDocument, coordinate_display_scale
except ImportError:
    from models import BackgroundImage, LedLine, LedPoint, MappingDocument, coordinate_display_scale


MAX_BACKGROUND_PIXMAP_SIDE = 8192


class LedItem(QGraphicsEllipseItem):
    def __init__(self, point: LedPoint, radius: float) -> None:
        super().__init__(-radius, -radius, radius * 2, radius * 2)
        self.point_id = point.uid
        self.setFlag(QGraphicsEllipseItem.ItemIsSelectable, True)
        self.setToolTip(self._tooltip(point))
        self.setZValue(10)

    @staticmethod
    def _tooltip(point: LedPoint) -> str:
        line = "-" if point.line_id is None else str(point.line_id)
        block = "-" if point.block_id is None else str(point.block_id)
        line_index = "-" if point.line_id is None or point.line_index is None else f"Л{point.line_id}: {point.line_index}"
        block_index = "-" if point.block_index is None else str(point.block_index)
        return (
            f"Источник: {point.source_id}\n"
            f"Сетка: ряд {point.row}, колонка {point.col}\n"
            f"Линия: {line}, блок: {block}\n"
            f"Индекс в линии: {line_index}\n"
            f"Индекс в блоке: {block_index}"
        )


class LedCanvas(QGraphicsView):
    selectionChanged = Signal(list)
    deleteSelectionRequested = Signal()
    deletePointsRequested = Signal()
    autoBlockFromPointRequested = Signal(int)
    brushStrokeStarted = Signal(bool)
    brushPointTouched = Signal(int)
    brushStrokeFinished = Signal()
    addLedRequested = Signal(float, float)
    backgroundEditStarted = Signal()
    backgroundChanged = Signal()
    backgroundEditFinished = Signal(bool)

    def __init__(self) -> None:
        super().__init__()
        self.setScene(QGraphicsScene(self))
        self.setRenderHint(QPainter.Antialiasing)
        self.setRenderHint(QPainter.SmoothPixmapTransform)
        self.setMouseTracking(True)
        self.viewport().setMouseTracking(True)
        self.setDragMode(QGraphicsView.RubberBandDrag)
        self.setTransformationAnchor(QGraphicsView.AnchorUnderMouse)
        self.setResizeAnchor(QGraphicsView.AnchorUnderMouse)
        self.document: MappingDocument | None = None
        self.active_line_id: int | None = None
        self.items_by_id: dict[int, LedItem] = {}
        self.grid_items: list[QGraphicsLineItem] = []
        self.connection_items: list[QGraphicsPathItem] = []
        self.line_index_label_items: dict[int, QGraphicsSimpleTextItem] = {}
        self._background_item: QGraphicsPixmapItem | None = None
        self._background_outline: QGraphicsRectItem | None = None
        self._background_handles: dict[str, QGraphicsRectItem] = {}
        self._background_edit_mode = False
        self._background_drag: dict | None = None
        self._background_pixmap_cache_key: tuple[str, int | None] | None = None
        self._background_pixmap_cache: QPixmap | None = None
        self._background_loaded = False
        self._direction_arrows_visible = True
        self._line_index_labels_visible = True
        self._point_radius = 4.5
        self._brush_radius = 18.0
        self._zoom_focus_pull = 0.35
        self._brush_zone_item: QGraphicsEllipseItem | None = None
        self._grid_visible = False
        self._grid_step = 34.0
        self._raw_bounds: tuple[float, float, float, float] | None = None
        self._content_scene_rect: QRectF | None = None
        self._display_scale = 1.0
        self._margin = 40.0
        self._theme = "dark"
        self._pan_mode = "middle_space"
        self._instant_space_pan = False
        self._space_pressed = False
        self._is_panning = False
        self._last_pan_pos = None
        self._last_mouse_pos = None
        self._brush_enabled = False
        self._add_led_enabled = False
        self._is_brush_stroke = False
        self._brush_touched_ids: set[int] = set()
        self._brush_preview_ids: set[int] = set()
        self._brush_excluded_point_ids: set[int] = set()
        self._last_brush_viewport_pos = None
        self._last_selected_ids: set[int] = set()
        self.scene().setBackgroundBrush(QBrush(QColor("#2b2b2b")))
        self.scene().selectionChanged.connect(self._emit_selection)
        self.setToolTip("Выделение рамкой: перетащите мышью. Масштаб: колесо. Del: снять фиксацию выбранных LED.")

    def set_document(self, document: MappingDocument, *, reset_view: bool = True) -> None:
        self.document = document
        self.rebuild(reset_view=reset_view)

    def set_active_line(self, line_id: int | None) -> None:
        if self.active_line_id == line_id:
            return
        self.active_line_id = line_id
        self.refresh_styles(redraw_connections=False)

    def set_grid_visible(self, visible: bool) -> None:
        self._grid_visible = visible
        self._refresh_grid()

    def set_direction_arrows_visible(self, visible: bool) -> None:
        if self._direction_arrows_visible == visible:
            return
        self._direction_arrows_visible = visible
        self.refresh_styles(redraw_connections=True)

    def direction_arrows_visible(self) -> bool:
        return self._direction_arrows_visible

    def set_line_index_labels_visible(self, visible: bool) -> None:
        if self._line_index_labels_visible == visible:
            return
        self._line_index_labels_visible = visible
        self._refresh_line_index_labels()

    def line_index_labels_visible(self) -> bool:
        return self._line_index_labels_visible

    def set_brush_radius(self, radius: int) -> None:
        self._brush_radius = float(max(4, min(80, radius)))
        if self._brush_zone_item is not None and isValid(self._brush_zone_item):
            self.scene().removeItem(self._brush_zone_item)
            self._brush_zone_item = None
        if self._brush_enabled:
            self._ensure_brush_zone()
            if self._last_brush_viewport_pos is not None:
                self._update_brush_zone(self._last_brush_viewport_pos)

    def set_zoom_focus_pull(self, percent: int) -> None:
        self._zoom_focus_pull = max(0.0, min(1.0, percent / 100.0))

    def set_pan_mode(self, mode: str) -> None:
        self._pan_mode = mode if mode in {"middle", "space", "middle_space"} else "middle_space"
        if self._pan_mode == "middle" and self._space_pressed:
            self._space_pressed = False
            self._apply_default_cursor()

    def set_instant_space_pan(self, enabled: bool) -> None:
        self._instant_space_pan = enabled
        if not enabled and self._is_panning and self._space_pressed:
            self._finish_pan()

    def set_theme(self, theme: str) -> None:
        next_theme = "dark" if theme == "dark" else "light"
        if self._theme == next_theme:
            return
        self._theme = next_theme
        background = "#2b2b2b" if self._theme == "dark" else "#ffffff"
        self.scene().setBackgroundBrush(QBrush(QColor(background)))
        self._refresh_grid()
        self.refresh_styles(redraw_connections=True)

    def set_brush_enabled(self, enabled: bool) -> None:
        self._brush_enabled = enabled
        if enabled:
            self._add_led_enabled = False
        self._is_brush_stroke = False
        self._clear_brush_state()
        self.setDragMode(QGraphicsView.NoDrag if enabled else QGraphicsView.RubberBandDrag)
        if enabled:
            self._ensure_brush_zone()
        else:
            self._hide_brush_zone()
        self._apply_default_cursor()

    def set_add_led_enabled(self, enabled: bool) -> None:
        self._add_led_enabled = enabled
        if enabled:
            self.set_brush_enabled(False)
            self.set_background_edit_mode(False)
        self._apply_default_cursor()

    def add_led_enabled(self) -> bool:
        return self._add_led_enabled

    def set_brush_excluded_point_ids(self, point_ids: set[int] | list[int]) -> None:
        self._brush_excluded_point_ids = set(point_ids)
        changed_ids = self._brush_preview_ids | self._brush_touched_ids
        self._brush_preview_ids.difference_update(self._brush_excluded_point_ids)
        self._refresh_brush_preview_styles(changed_ids)

    def set_background_edit_mode(self, enabled: bool) -> None:
        self._background_edit_mode = enabled
        if enabled:
            self._add_led_enabled = False
        if enabled and self._brush_enabled:
            self.set_brush_enabled(False)
        if not enabled:
            self._background_drag = None
        self._update_background_handles()
        self._apply_default_cursor()

    def background_edit_mode(self) -> bool:
        return self._background_edit_mode

    def background_loaded(self) -> bool:
        return self._background_loaded

    def set_background(self, background: BackgroundImage) -> None:
        if self.document is None:
            return
        view_state = self._capture_view_state()
        self.document.background = background
        self._refresh_background()
        self._update_scene_rect()
        self._restore_view_state(view_state)

    def clear_background(self) -> None:
        if self.document is None:
            return
        view_state = self._capture_view_state()
        self.document.background = BackgroundImage()
        self._refresh_background()
        self._update_scene_rect()
        self._restore_view_state(view_state)

    def reset_background_scale(self) -> None:
        if self.document is None:
            return
        view_state = self._capture_view_state()
        self.document.background.scale_x_percent = 100.0
        self.document.background.scale_y_percent = 100.0
        self._apply_background_geometry()
        self._restore_view_state(view_state)
        self.backgroundChanged.emit()

    def set_background_visible(self, visible: bool) -> None:
        if self.document is None or not self.document.background.is_enabled():
            return
        view_state = self._capture_view_state()
        self.document.background.visible = visible
        self._apply_background_geometry()
        self._restore_view_state(view_state)
        self.backgroundChanged.emit()

    def rebuild(self, *, reset_view: bool = True) -> None:
        old_transform = self.transform()
        old_center = self.mapToScene(self.viewport().rect().center())
        scene = self.scene()
        scene.blockSignals(True)
        self.setUpdatesEnabled(False)
        try:
            self.items_by_id.clear()
            self.grid_items.clear()
            self.connection_items.clear()
            self.line_index_label_items.clear()
            self._background_item = None
            self._background_outline = None
            self._background_handles.clear()
            self._background_drag = None
            self._brush_zone_item = None
            self._brush_preview_ids.clear()
            self._brush_touched_ids.clear()
            self._last_selected_ids.clear()
            scene.clear()
        finally:
            scene.blockSignals(False)
            self.setUpdatesEnabled(True)
        self._raw_bounds = None
        self._content_scene_rect = None
        if self.document is None or not self.document.points:
            self._refresh_background()
            self._update_scene_rect()
            return

        self._display_scale = coordinate_display_scale(self.document.points)
        xs = [point.x * self._display_scale for point in self.document.points]
        ys = [point.y * self._display_scale for point in self.document.points]
        min_x, max_x = min(xs), max(xs)
        min_y, max_y = min(ys), max(ys)
        self._raw_bounds = (min_x, max_x, min_y, max_y)
        self._margin = max(self._point_radius * 4, 40)

        for point in self.document.points:
            item = LedItem(point, self._point_radius)
            item.setPos(self._to_scene_point(point.x, point.y))
            self.items_by_id[point.uid] = item
            self.scene().addItem(item)

        self._content_scene_rect = QRectF(
            0,
            0,
            max(max_x - min_x, 1.0) + self._margin * 2,
            max(max_y - min_y, 1.0) + self._margin * 2,
        )
        self._refresh_background()
        self._update_scene_rect()
        self._refresh_grid()
        self.refresh_styles()
        if reset_view:
            self.fit_to_content()
        else:
            self.setTransform(old_transform)
            self.centerOn(old_center)

    def refresh_styles(self, redraw_connections: bool = True) -> None:
        if self.document is None:
            return
        if redraw_connections:
            self._clear_connections()
            self._connection_segments: list[tuple[QPointF, QPointF]] = []
            self._connection_segment_buckets: dict[tuple[int, int], list[tuple[QPointF, QPointF]]] = {}
        line_by_id = {line.id: line for line in self.document.lines}
        for point in self.document.points:
            item = self.items_by_id.get(point.uid)
            if item is None or not isValid(item):
                continue
            color = QColor("#94a3b8")
            if point.line_id in line_by_id:
                color = QColor(line_by_id[point.line_id].color)
                if self.active_line_id is not None and point.line_id != self.active_line_id:
                    color.setAlphaF(0.45)
            item.setBrush(color)
            is_active_line_point = self.active_line_id is not None and point.line_id == self.active_line_id
            try:
                pen_color = QColor("#111827") if item.isSelected() else QColor("#ffffff")
                item.setPen(QPen(pen_color, 2.0 if is_active_line_point else 1.2))
                item.setToolTip(LedItem._tooltip(point))
            except RuntimeError:
                continue
        self._last_selected_ids = {
            item.point_id
            for item in self.scene().selectedItems()
            if isinstance(item, LedItem) and isValid(item)
        }
        if redraw_connections:
            for line in self.document.lines:
                self._draw_line_connections(line)
        else:
            self._restyle_connection_items()
        self._refresh_brush_preview_styles(self._brush_preview_ids | self._brush_touched_ids)
        self._refresh_line_index_labels()

    def selected_point_ids(self) -> list[int]:
        return sorted(
            item.point_id
            for item in self.scene().selectedItems()
            if isinstance(item, LedItem) and isValid(item)
        )

    def select_points(self, point_ids: list[int]) -> None:
        target_ids = set(point_ids)
        if target_ids == self._last_selected_ids:
            return
        changed_ids = target_ids ^ self._last_selected_ids
        scene = self.scene()
        scene.blockSignals(True)
        self.setUpdatesEnabled(False)
        try:
            for point_id in changed_ids:
                item = self.items_by_id.get(point_id)
                if not isValid(item):
                    continue
                should_select = item.point_id in target_ids
                if item.isSelected() != should_select:
                    item.setSelected(should_select)
        finally:
            self.setUpdatesEnabled(True)
            scene.blockSignals(False)
        self._emit_selection()

    def _refresh_background(self) -> None:
        self._remove_background_items()
        if self.document is None or not self.document.background.is_enabled():
            return
        image_path = Path(self.document.background.path)
        if not image_path.is_absolute() and self.document.path is not None:
            image_path = self.document.path.parent / image_path
        pixmap = self._load_background_pixmap(image_path)
        if pixmap.isNull():
            self._background_loaded = False
            return
        self._background_loaded = True
        self._background_item = self.scene().addPixmap(pixmap)
        self._background_item.setTransformationMode(Qt.SmoothTransformation)
        self._background_item.setZValue(-30)
        self._background_item.setAcceptedMouseButtons(Qt.NoButton)
        self._apply_background_geometry()

    def _remove_background_items(self) -> None:
        for item in [self._background_item, self._background_outline, *self._background_handles.values()]:
            if item is not None and isValid(item):
                self.scene().removeItem(item)
        self._background_item = None
        self._background_outline = None
        self._background_handles.clear()
        self._background_loaded = False

    def _load_background_pixmap(self, path: Path) -> QPixmap:
        cache_key = (str(path), path.stat().st_mtime_ns if path.exists() else None)
        if self._background_pixmap_cache_key == cache_key and self._background_pixmap_cache is not None:
            return self._background_pixmap_cache
        reader = QImageReader(str(path))
        size = reader.size()
        if size.isValid() and max(size.width(), size.height()) > MAX_BACKGROUND_PIXMAP_SIDE:
            factor = MAX_BACKGROUND_PIXMAP_SIDE / max(size.width(), size.height())
            reader.setScaledSize(QSize(max(1, int(size.width() * factor)), max(1, int(size.height() * factor))))
        image = reader.read()
        pixmap = QPixmap.fromImage(image) if not image.isNull() else QPixmap()
        self._background_pixmap_cache_key = cache_key
        self._background_pixmap_cache = pixmap
        return pixmap

    def _apply_background_geometry(self) -> None:
        if self.document is None or self._background_item is None or not isValid(self._background_item):
            self._update_background_handles()
            return
        view_state = self._capture_view_state()
        background = self.document.background
        origin = self._background_origin_scene_point()
        scale_x = max(1.0, background.scale_x_percent) / 100.0
        scale_y = max(1.0, background.scale_y_percent) / 100.0
        source_rect = self._background_item.boundingRect()
        center_x = origin.x() + background.offset_x
        center_y = origin.y() + background.offset_y
        self._background_item.setVisible(background.visible)
        self._background_item.setOpacity(max(0.0, min(1.0, background.opacity_percent / 100.0)))
        self._background_item.setPos(
            center_x - source_rect.width() * scale_x / 2.0,
            center_y - source_rect.height() * scale_y / 2.0,
        )
        self._background_item.setScale(1.0)
        self._background_item.setTransformOriginPoint(0, 0)
        self._background_item.setTransform(
            QTransform.fromScale(
                scale_x,
                scale_y,
            )
        )
        self._update_background_handles()
        self._update_scene_rect()
        self._restore_view_state(view_state)

    def _background_scene_rect(self) -> QRectF | None:
        if self._background_item is None or not isValid(self._background_item):
            return None
        if self.document is not None and not self.document.background.visible:
            return None
        return self._background_item.sceneBoundingRect()

    def _update_scene_rect(self) -> None:
        rect = self._content_scene_rect
        background_rect = self._background_scene_rect()
        if rect is None:
            rect = background_rect
        elif background_rect is not None:
            rect = rect.united(background_rect)
        if rect is None:
            rect = QRectF(0, 0, 1, 1)
        self.scene().setSceneRect(rect)

    def _update_background_handles(self) -> None:
        rect = self._background_scene_rect()
        if not self._background_edit_mode or rect is None:
            for item in [self._background_outline, *self._background_handles.values()]:
                if item is not None and isValid(item):
                    self.scene().removeItem(item)
            self._background_outline = None
            self._background_handles.clear()
            return
        pen = QPen(QColor("#fbbf24"), 1.2)
        pen.setCosmetic(True)
        if self._background_outline is None or not isValid(self._background_outline):
            self._background_outline = self.scene().addRect(rect, pen)
            self._background_outline.setZValue(60)
        else:
            self._background_outline.setRect(rect)
            self._background_outline.setPen(pen)
        handle_positions = {
            "nw": rect.topLeft(),
            "n": QPointF(rect.center().x(), rect.top()),
            "ne": rect.topRight(),
            "e": QPointF(rect.right(), rect.center().y()),
            "se": rect.bottomRight(),
            "s": QPointF(rect.center().x(), rect.bottom()),
            "sw": rect.bottomLeft(),
            "w": QPointF(rect.left(), rect.center().y()),
        }
        for name, point in handle_positions.items():
            handle = self._background_handles.get(name)
            if handle is None or not isValid(handle):
                handle = QGraphicsRectItem(-4, -4, 8, 8)
                handle.setBrush(QColor("#fbbf24"))
                handle.setPen(QPen(QColor("#111827"), 1.0))
                handle.setFlag(QGraphicsItem.ItemIgnoresTransformations, True)
                handle.setZValue(61)
                handle.setAcceptedMouseButtons(Qt.NoButton)
                self.scene().addItem(handle)
                self._background_handles[name] = handle
            handle.setPos(point)

    def fit_to_content(self) -> None:
        self._update_scene_rect()
        if self.scene() is None or self.sceneRect().isEmpty():
            return
        self.fitInView(self.sceneRect(), Qt.KeepAspectRatio)

    def _capture_view_state(self) -> tuple[QTransform, QPointF, QRectF] | None:
        if self.viewport().rect().isEmpty():
            return None
        return (
            self.transform(),
            self.mapToScene(self.viewport().rect().center()),
            self.mapToScene(self.viewport().rect()).boundingRect(),
        )

    def _restore_view_state(self, state: tuple[QTransform, QPointF, QRectF] | None) -> None:
        if state is None:
            return
        transform, center, visible_rect = state
        self.setTransform(transform)
        scene_rect = self.scene().sceneRect()
        if not scene_rect.contains(visible_rect):
            self.scene().setSceneRect(scene_rect.united(visible_rect))
        self.centerOn(center)

    def wheelEvent(self, event) -> None:  # noqa: ANN001
        if self._background_drag is not None:
            event.ignore()
            return
        factor = 1.15 if event.angleDelta().y() > 0 else 1 / 1.15
        viewport_pos = event.position().toPoint() if hasattr(event, "position") else event.pos()
        self._zoom_at_viewport_pos(viewport_pos, factor)
        if self._brush_enabled:
            self._update_brush_zone(viewport_pos)
        self._position_line_index_labels()
        event.accept()

    def _zoom_at_viewport_pos(self, viewport_pos, factor: float) -> None:  # noqa: ANN001
        old_anchor = self.transformationAnchor()
        self.setTransformationAnchor(QGraphicsView.NoAnchor)
        focus_scene_pos = self.mapToScene(viewport_pos)
        current_center = self.mapToScene(self.viewport().rect().center())
        self.scale(factor, factor)
        self._ensure_zoom_padding()
        pull_strength = self._zoom_focus_pull
        target_center = QPointF(
            current_center.x() + (focus_scene_pos.x() - current_center.x()) * pull_strength,
            current_center.y() + (focus_scene_pos.y() - current_center.y()) * pull_strength,
        )
        self.centerOn(target_center)
        self.setTransformationAnchor(old_anchor)

    def _ensure_zoom_padding(self) -> None:
        if self.viewport().rect().isEmpty():
            return
        self._update_scene_rect()
        base_rect = self.scene().sceneRect()
        visible_scene_rect = self.mapToScene(self.viewport().rect()).boundingRect()
        pad_x = visible_scene_rect.width() * 0.5
        pad_y = visible_scene_rect.height() * 0.5
        self.scene().setSceneRect(base_rect.adjusted(-pad_x, -pad_y, pad_x, pad_y))

    def keyPressEvent(self, event) -> None:  # noqa: ANN001
        if event.key() == Qt.Key_Delete:
            self.deleteSelectionRequested.emit()
            event.accept()
            return
        if event.key() == Qt.Key_Space and not event.isAutoRepeat() and self._can_pan_with_space():
            self._space_pressed = True
            if self._instant_space_pan and self._last_mouse_pos is not None:
                self._start_pan(self._last_mouse_pos)
            self._apply_default_cursor()
            event.accept()
            return
        super().keyPressEvent(event)

    def keyReleaseEvent(self, event) -> None:  # noqa: ANN001
        if event.key() == Qt.Key_Space and not event.isAutoRepeat():
            self._space_pressed = False
            if self._is_panning:
                self._is_panning = False
                self._last_pan_pos = None
            self._apply_default_cursor()
            event.accept()
            return
        super().keyReleaseEvent(event)

    def mousePressEvent(self, event) -> None:  # noqa: ANN001
        self._last_mouse_pos = event.pos()
        if event.button() == Qt.RightButton:
            event.accept()
            return
        if self._should_start_pan(event.button()):
            self._start_pan(event.pos())
            event.accept()
            return
        if self._background_edit_mode and event.button() == Qt.LeftButton and self._start_background_edit(event.pos()):
            event.accept()
            return
        if self._add_led_enabled and event.button() == Qt.LeftButton:
            point = self._document_point_from_scene(self.mapToScene(event.pos()))
            self.addLedRequested.emit(point.x(), point.y())
            event.accept()
            return
        if self._brush_enabled and event.button() == Qt.LeftButton:
            self._is_brush_stroke = True
            self._brush_touched_ids.clear()
            self.brushStrokeStarted.emit(bool(event.modifiers() & Qt.ShiftModifier))
            self._update_brush_zone(event.pos())
            self._touch_brush_point(event.pos())
            event.accept()
            return
        super().mousePressEvent(event)

    def mouseMoveEvent(self, event) -> None:  # noqa: ANN001
        previous_mouse_pos = self._last_mouse_pos
        self._last_mouse_pos = event.pos()
        if (
            self._instant_space_pan
            and self._space_pressed
            and self._can_pan_with_space()
            and not self._is_panning
            and previous_mouse_pos is not None
        ):
            self._start_pan(previous_mouse_pos)
        if self._is_panning and self._last_pan_pos is not None:
            delta = event.pos() - self._last_pan_pos
            self._last_pan_pos = event.pos()
            self._move_scrollbar(self.horizontalScrollBar(), delta.x())
            self._move_scrollbar(self.verticalScrollBar(), delta.y())
            event.accept()
            return
        if self._background_drag is not None:
            self._move_background_edit(event.pos())
            event.accept()
            return
        if self._brush_enabled and self._is_brush_stroke:
            self._update_brush_zone(event.pos())
            self._touch_brush_point(event.pos())
            event.accept()
            return
        if self._brush_enabled:
            self._update_brush_zone(event.pos())
            event.accept()
            return
        super().mouseMoveEvent(event)

    def mouseReleaseEvent(self, event) -> None:  # noqa: ANN001
        self._last_mouse_pos = event.pos()
        if event.button() == Qt.RightButton:
            event.accept()
            return
        if self._should_finish_pan(event.button()):
            self._finish_pan()
            event.accept()
            return
        if event.button() == Qt.LeftButton and self._background_drag is not None:
            self._finish_background_edit()
            event.accept()
            return
        if self._brush_enabled and event.button() == Qt.LeftButton and self._is_brush_stroke:
            self._update_brush_zone(event.pos())
            self._touch_brush_point(event.pos())
            self._is_brush_stroke = False
            self._clear_brush_state()
            self.brushStrokeFinished.emit()
            event.accept()
            return
        super().mouseReleaseEvent(event)

    def _start_background_edit(self, viewport_pos) -> bool:  # noqa: ANN001
        if self.document is None or self._background_item is None or not isValid(self._background_item):
            return False
        if not self.document.background.visible:
            return False
        scene_pos = self.mapToScene(viewport_pos)
        rect = self._background_scene_rect()
        if rect is None:
            return False
        handle_name = self._background_handle_at(viewport_pos)
        if handle_name is None and not rect.contains(scene_pos):
            return False
        start_payload = self.document.background.to_payload()
        self._background_drag = {
            "mode": "resize" if handle_name else "move",
            "handle": handle_name,
            "start_pos": scene_pos,
            "start_rect": QRectF(rect),
            "start_background": BackgroundImage(
                path=self.document.background.path,
                offset_x=self.document.background.offset_x,
                offset_y=self.document.background.offset_y,
                scale_x_percent=self.document.background.scale_x_percent,
                scale_y_percent=self.document.background.scale_y_percent,
                opacity_percent=self.document.background.opacity_percent,
                visible=self.document.background.visible,
            ),
            "start_payload": start_payload,
            "undo_emitted": False,
            "changed": False,
        }
        self._apply_default_cursor()
        return True

    def _move_background_edit(self, viewport_pos) -> None:  # noqa: ANN001
        if self.document is None or self._background_drag is None:
            return
        scene_pos = self.mapToScene(viewport_pos)
        start_pos: QPointF = self._background_drag["start_pos"]
        delta = scene_pos - start_pos
        if abs(delta.x()) < 0.001 and abs(delta.y()) < 0.001:
            return
        if not self._background_drag.get("undo_emitted"):
            self.backgroundEditStarted.emit()
            self._background_drag["undo_emitted"] = True
        self._background_drag["changed"] = True
        start_rect: QRectF = self._background_drag["start_rect"]
        start_background: BackgroundImage = self._background_drag["start_background"]
        if self._background_drag["mode"] == "move":
            self.document.background.offset_x = start_background.offset_x + delta.x()
            self.document.background.offset_y = start_background.offset_y + delta.y()
        else:
            handle = str(self._background_drag["handle"])
            rect = QRectF(start_rect)
            if "w" in handle:
                rect.setLeft(min(rect.right() - 8.0, rect.left() + delta.x()))
            if "e" in handle:
                rect.setRight(max(rect.left() + 8.0, rect.right() + delta.x()))
            if "n" in handle:
                rect.setTop(min(rect.bottom() - 8.0, rect.top() + delta.y()))
            if "s" in handle:
                rect.setBottom(max(rect.top() + 8.0, rect.bottom() + delta.y()))
            self._apply_background_rect(rect, start_background, start_rect)
        self._apply_background_geometry()

    def _finish_background_edit(self) -> None:
        changed = bool(self._background_drag and self._background_drag.get("changed"))
        start_payload = self._background_drag.get("start_payload") if self._background_drag else None
        self._background_drag = None
        self._apply_default_cursor()
        payload_changed = changed and self.document is not None and self.document.background.to_payload() != start_payload
        if payload_changed:
            self._update_scene_rect()
            self.backgroundChanged.emit()
        self.backgroundEditFinished.emit(bool(payload_changed))

    def _background_handle_at(self, viewport_pos) -> str | None:  # noqa: ANN001
        for name, handle in self._background_handles.items():
            if handle is not None and isValid(handle):
                handle_pos = self.mapFromScene(handle.scenePos())
                if abs(handle_pos.x() - viewport_pos.x()) <= 8 and abs(handle_pos.y() - viewport_pos.y()) <= 8:
                    return name
        return None

    def _apply_background_rect(
        self,
        rect: QRectF,
        start_background: BackgroundImage,
        start_rect: QRectF,
    ) -> None:
        if self.document is None:
            return
        origin = self._background_origin_scene_point()
        self.document.background.offset_x = rect.center().x() - origin.x()
        self.document.background.offset_y = rect.center().y() - origin.y()
        if start_rect.width() > 0:
            self.document.background.scale_x_percent = max(
                1.0,
                start_background.scale_x_percent * rect.width() / start_rect.width(),
            )
        if start_rect.height() > 0:
            self.document.background.scale_y_percent = max(
                1.0,
                start_background.scale_y_percent * rect.height() / start_rect.height(),
            )

    def enterEvent(self, event) -> None:  # noqa: ANN001
        self._apply_default_cursor()
        super().enterEvent(event)

    def leaveEvent(self, event) -> None:  # noqa: ANN001
        self._hide_brush_zone()
        self._clear_brush_preview()
        super().leaveEvent(event)

    def _apply_default_cursor(self) -> None:
        if self._is_panning:
            cursor_shape = Qt.ClosedHandCursor
        elif self._background_drag is not None:
            cursor_shape = Qt.ClosedHandCursor if self._background_drag.get("mode") == "move" else Qt.SizeAllCursor
        elif self._space_pressed and self._can_pan_with_space():
            cursor_shape = Qt.OpenHandCursor
        elif self._brush_enabled or self._add_led_enabled:
            cursor_shape = Qt.CrossCursor
        else:
            cursor_shape = Qt.ArrowCursor
        self.setCursor(cursor_shape)
        self.viewport().setCursor(cursor_shape)

    def _can_pan_with_middle(self) -> bool:
        return self._pan_mode in {"middle", "middle_space"}

    def _can_pan_with_space(self) -> bool:
        return self._pan_mode in {"space", "middle_space"}

    def _should_start_pan(self, button: Qt.MouseButton) -> bool:
        return (button == Qt.MiddleButton and self._can_pan_with_middle()) or (
            button == Qt.LeftButton and self._space_pressed and self._can_pan_with_space()
        )

    def _should_finish_pan(self, button: Qt.MouseButton) -> bool:
        return self._is_panning and (
            (button == Qt.MiddleButton and self._can_pan_with_middle())
            or (button == Qt.LeftButton and self._space_pressed and self._can_pan_with_space())
        )

    def _start_pan(self, pos) -> None:  # noqa: ANN001
        self._is_panning = True
        self._last_pan_pos = pos
        self._apply_default_cursor()

    def _finish_pan(self) -> None:
        self._is_panning = False
        self._last_pan_pos = None
        self._apply_default_cursor()

    def contextMenuEvent(self, event) -> None:  # noqa: ANN001
        item = self.itemAt(event.pos())
        point_id = item.point_id if isinstance(item, LedItem) and isValid(item) else self._single_selected_point_id()

        menu = QMenu(self)
        delete_action = menu.addAction("Удалить фиксацию выбранных LED")
        delete_action.setEnabled(self._selection_has_assignment())
        delete_points_action = menu.addAction("Удалить выбранные точки")
        delete_points_action.setEnabled(bool(self.selected_point_ids()))
        clear_selection_action = menu.addAction("Очистить выбор")
        clear_selection_action.setEnabled(bool(self.selected_point_ids()))
        auto_block_action = menu.addAction("Автоматически добавить блок")
        auto_block_action.setEnabled(point_id is not None)
        fit_action = menu.addAction("Показать все точки")
        fit_action.setEnabled(self.document is not None and bool(self.document.points))
        chosen = menu.exec(event.globalPos())
        if chosen == delete_action:
            self.deleteSelectionRequested.emit()
        elif chosen == delete_points_action:
            self.deletePointsRequested.emit()
        elif chosen == clear_selection_action:
            self.select_points([])
        elif chosen == auto_block_action and point_id is not None:
            self.autoBlockFromPointRequested.emit(point_id)
        elif chosen == fit_action:
            self.fit_to_content()

    def _emit_selection(self) -> None:
        selected_ids = {
            item.point_id
            for item in self.scene().selectedItems()
            if isinstance(item, LedItem) and isValid(item)
        }
        if selected_ids == self._last_selected_ids:
            return
        self._refresh_selection_pens(selected_ids ^ self._last_selected_ids)
        self._last_selected_ids = selected_ids
        self._refresh_line_index_labels()
        self.selectionChanged.emit(sorted(selected_ids))

    def _refresh_selection_pens(self, point_ids: set[int]) -> None:
        if self.document is None:
            return
        for point_id in point_ids:
            item = self.items_by_id.get(point_id)
            if item is None or not isValid(item):
                continue
            point = self.document.get_point(point_id)
            is_active_line_point = self.active_line_id is not None and point.line_id == self.active_line_id
            try:
                pen_color = QColor("#111827") if item.isSelected() else QColor("#ffffff")
                item.setPen(QPen(pen_color, 2.0 if is_active_line_point else 1.2))
            except RuntimeError:
                continue

    def _refresh_line_index_labels(self) -> None:
        self._clear_line_index_labels()
        if self.document is None or not self._line_index_labels_visible:
            return
        for point_id in sorted(self._last_selected_ids):
            point = self.document.get_point(point_id)
            if point.line_id is None or point.line_index is None:
                continue
            item = self.items_by_id.get(point_id)
            if item is None or not isValid(item):
                continue
            label = QGraphicsSimpleTextItem(str(point.line_index))
            label.setBrush(QColor("#f8fafc" if self._theme == "dark" else "#111827"))
            label.setZValue(40)
            label.setFlag(QGraphicsItem.ItemIgnoresTransformations, True)
            label.setAcceptedMouseButtons(Qt.NoButton)
            self.scene().addItem(label)
            self.line_index_label_items[point_id] = label
        self._position_line_index_labels()

    def _position_line_index_labels(self) -> None:
        if not self.line_index_label_items:
            return
        scale = max(abs(self.transform().m11()), 0.001)
        scene_gap = 6.0 / scale
        scene_radius = self._point_radius / scale
        for point_id, label in list(self.line_index_label_items.items()):
            item = self.items_by_id.get(point_id)
            if item is None or not isValid(item) or not isValid(label):
                continue
            label_rect = label.boundingRect()
            label.setPos(
                item.pos().x() - label_rect.width() / 2.0,
                item.pos().y() - scene_radius - scene_gap,
            )

    def _clear_line_index_labels(self) -> None:
        for label in self.line_index_label_items.values():
            if isValid(label):
                self.scene().removeItem(label)
        self.line_index_label_items.clear()

    def _touch_brush_point(self, viewport_pos) -> None:  # noqa: ANN001
        touched = self._brush_candidate_ids(viewport_pos)
        for point_id in sorted(touched):
            self._brush_touched_ids.add(point_id)
            self.brushPointTouched.emit(point_id)
        self._update_brush_preview(viewport_pos)

    def _brush_candidate_ids(self, viewport_pos) -> list[int]:  # noqa: ANN001
        return [
            item.point_id
            for item in self.items_by_id.values()
            if isValid(item)
            and item.point_id not in self._brush_touched_ids
            and item.point_id not in self._brush_excluded_point_ids
            and self._is_inside_brush_zone(viewport_pos, item)
        ]

    def _is_inside_brush_zone(self, viewport_center, item: LedItem) -> bool:  # noqa: ANN001
        point_viewport = self.mapFromScene(item.pos())
        radius = self._brush_radius + self._point_radius
        dx = viewport_center.x() - point_viewport.x()
        dy = viewport_center.y() - point_viewport.y()
        return dx * dx + dy * dy <= radius * radius

    def _ensure_brush_zone(self) -> QGraphicsEllipseItem | None:
        if self.scene() is None:
            return None
        if self._brush_zone_item is not None and isValid(self._brush_zone_item):
            return self._brush_zone_item
        item = QGraphicsEllipseItem(-self._brush_radius, -self._brush_radius, self._brush_radius * 2, self._brush_radius * 2)
        pen = QPen(QColor("#f43f5e"), 1.4)
        pen.setCosmetic(True)
        item.setPen(pen)
        item.setBrush(QBrush(QColor(244, 63, 94, 32)))
        item.setZValue(40)
        item.setFlag(QGraphicsItem.ItemIgnoresTransformations, True)
        item.setAcceptedMouseButtons(Qt.NoButton)
        item.setVisible(False)
        self.scene().addItem(item)
        self._brush_zone_item = item
        return item

    def _update_brush_zone(self, viewport_pos) -> None:  # noqa: ANN001
        if not self._brush_enabled:
            return
        item = self._ensure_brush_zone()
        if item is None:
            return
        self._last_brush_viewport_pos = viewport_pos
        item.setPos(self.mapToScene(viewport_pos))
        item.setVisible(True)
        self._update_brush_preview(viewport_pos)

    def _hide_brush_zone(self) -> None:
        if self._brush_zone_item is not None and isValid(self._brush_zone_item):
            self._brush_zone_item.setVisible(False)

    def _update_brush_preview(self, viewport_pos) -> None:  # noqa: ANN001
        if not self._brush_enabled:
            self._clear_brush_preview()
            return
        next_preview_ids = set(self._brush_candidate_ids(viewport_pos))
        changed_ids = self._brush_preview_ids ^ next_preview_ids
        self._brush_preview_ids = next_preview_ids
        self._refresh_brush_preview_styles(changed_ids | self._brush_touched_ids)

    def _clear_brush_preview(self) -> None:
        changed_ids = self._brush_preview_ids | self._brush_touched_ids
        self._brush_preview_ids.clear()
        self._refresh_brush_preview_styles(changed_ids)

    def _clear_brush_state(self) -> None:
        changed_ids = self._brush_preview_ids | self._brush_touched_ids
        self._brush_preview_ids.clear()
        self._brush_touched_ids.clear()
        self._refresh_brush_preview_styles(changed_ids)

    def _refresh_brush_preview_styles(self, point_ids: set[int]) -> None:
        if self.document is None:
            return
        line_by_id = {line.id: line for line in self.document.lines}
        for point_id in point_ids:
            item = self.items_by_id.get(point_id)
            if item is None or not isValid(item):
                continue
            try:
                if point_id in self._brush_touched_ids:
                    item.setBrush(QColor("#f43f5e"))
                    item.setPen(QPen(QColor("#ffffff"), 2.4))
                    continue
                if point_id in self._brush_preview_ids:
                    item.setBrush(QColor("#fbbf24"))
                    item.setPen(QPen(QColor("#111827"), 2.4))
                    continue
                point = self.document.get_point(point_id)
                color = QColor("#94a3b8")
                if point.line_id in line_by_id:
                    color = QColor(line_by_id[point.line_id].color)
                    if self.active_line_id is not None and point.line_id != self.active_line_id:
                        color.setAlphaF(0.45)
                is_active_line_point = self.active_line_id is not None and point.line_id == self.active_line_id
                pen_color = QColor("#111827") if item.isSelected() else QColor("#ffffff")
                item.setBrush(color)
                item.setPen(QPen(pen_color, 2.0 if is_active_line_point else 1.2))
            except RuntimeError:
                continue

    def _clear_connections(self) -> None:
        for item in self.connection_items:
            if not isValid(item):
                continue
            self.scene().removeItem(item)
        self.connection_items.clear()

    def _refresh_grid(self) -> None:
        for item in self.grid_items:
            if not isValid(item):
                continue
            self.scene().removeItem(item)
        self.grid_items.clear()
        if not self._grid_visible or self._raw_bounds is None:
            return

        if self.document is None or not self.document.points:
            return
        min_x, max_x, min_y, max_y = self._raw_bounds
        origin_x, origin_y = self._grid_origin_scene_units()
        left_x = min_x - self._margin
        right_x = max_x + self._margin
        bottom_y = min_y - self._margin
        top_y = max_y + self._margin
        scene_rect = self.scene().sceneRect()
        left_x = min(left_x, scene_rect.left() + min_x - self._margin)
        right_x = max(right_x, scene_rect.right() + min_x - self._margin)
        top_y = max(top_y, max_y + self._margin - scene_rect.top())
        bottom_y = min(bottom_y, max_y + self._margin - scene_rect.bottom())
        first_col = math.floor((left_x - origin_x) / self._grid_step)
        last_col = math.ceil((right_x - origin_x) / self._grid_step)
        first_row = math.floor((bottom_y - origin_y) / self._grid_step)
        last_row = math.ceil((top_y - origin_y) / self._grid_step)
        grid_span = (last_col - first_col) + (last_row - first_row)
        step_multiplier = max(1, math.ceil(grid_span / 800))
        pen = QPen(QColor("#334155" if self._theme == "dark" else "#d1d5db"), 0.6)
        pen.setCosmetic(True)

        for col in range(first_col, last_col + 1, step_multiplier):
            x = origin_x + col * self._grid_step
            top = self._scene_point_from_display_units(x, top_y)
            bottom = self._scene_point_from_display_units(x, bottom_y)
            item = self.scene().addLine(top.x(), top.y(), bottom.x(), bottom.y(), pen)
            item.setZValue(-20)
            self.grid_items.append(item)

        for row in range(first_row, last_row + 1, step_multiplier):
            y = origin_y + row * self._grid_step
            left = self._scene_point_from_display_units(left_x, y)
            right = self._scene_point_from_display_units(right_x, y)
            item = self.scene().addLine(left.x(), left.y(), right.x(), right.y(), pen)
            item.setZValue(-20)
            self.grid_items.append(item)

    def _draw_line_connections(self, line: LedLine) -> None:
        is_active = self.active_line_id is None or line.id == self.active_line_id
        inner_width = 2.8 if is_active else 1.2
        inner_alpha = 0.9 if is_active else 0.25
        bridge_width = 1.9 if is_active else 1.0
        bridge_alpha = 0.65 if is_active else 0.18
        arrow_width = 1.8 if is_active else 1.0
        arrow_alpha = 0.95 if is_active else 0.28
        inner_path = QPainterPath()
        inner_arrows = QPainterPath()
        for block in line.blocks:
            ordered_items = [self.items_by_id[point_id] for point_id in block.point_ids if point_id in self.items_by_id]
            for first, second in zip(ordered_items, ordered_items[1:]):
                start = first.pos()
                end = second.pos()
                control = self._append_connection(inner_path, start, end)
                if self._direction_arrows_visible:
                    self._append_arrow_marker(inner_arrows, start, end, control)
        self._add_connection_path(inner_path, line.color, inner_width, inner_alpha, line_id=line.id, connection_kind="inner")
        if self._direction_arrows_visible:
            self._add_connection_path(
                inner_arrows,
                line.color,
                arrow_width,
                arrow_alpha,
                z_value=2,
                line_id=line.id,
                connection_kind="arrow",
            )

        previous_block_end = None
        bridge_path = QPainterPath()
        bridge_arrows = QPainterPath()
        for block in line.blocks:
            if not block.point_ids:
                continue
            block_start = self.items_by_id.get(block.point_ids[0])
            block_end = self.items_by_id.get(block.point_ids[-1])
            if block_start is not None and previous_block_end is not None:
                start = previous_block_end.pos()
                end = block_start.pos()
                control = self._append_connection(bridge_path, start, end)
                if self._direction_arrows_visible:
                    self._append_arrow_marker(bridge_arrows, start, end, control)
            if block_end is not None:
                previous_block_end = block_end
        self._add_connection_path(bridge_path, line.color, bridge_width, bridge_alpha, line_id=line.id, connection_kind="bridge")
        if self._direction_arrows_visible:
            self._add_connection_path(
                bridge_arrows,
                line.color,
                arrow_width,
                bridge_alpha,
                z_value=2,
                line_id=line.id,
                connection_kind="bridge_arrow",
            )

    def _append_connection(self, path: QPainterPath, start: QPointF, end: QPointF) -> QPointF | None:
        path.moveTo(start)
        control = self._overlap_control_point(start, end)
        if control is None:
            path.lineTo(end)
        else:
            path.quadTo(control, end)
        return control

    @staticmethod
    def _append_arrow_marker(path: QPainterPath, start: QPointF, end: QPointF, control: QPointF | None = None) -> None:
        dx = end.x() - start.x()
        dy = end.y() - start.y()
        length = math.hypot(dx, dy)
        if length < 8.0:
            return
        if control is None:
            unit_x = dx / length
            unit_y = dy / length
            mid_x = start.x() + dx * 0.55
            mid_y = start.y() + dy * 0.55
        else:
            t = 0.55
            inv_t = 1.0 - t
            mid_x = inv_t * inv_t * start.x() + 2.0 * inv_t * t * control.x() + t * t * end.x()
            mid_y = inv_t * inv_t * start.y() + 2.0 * inv_t * t * control.y() + t * t * end.y()
            tangent_x = 2.0 * inv_t * (control.x() - start.x()) + 2.0 * t * (end.x() - control.x())
            tangent_y = 2.0 * inv_t * (control.y() - start.y()) + 2.0 * t * (end.y() - control.y())
            tangent_length = math.hypot(tangent_x, tangent_y)
            if tangent_length < 0.001:
                return
            unit_x = tangent_x / tangent_length
            unit_y = tangent_y / tangent_length
        arrow_length = min(7.0, length * 0.28)
        arrow_width = arrow_length * 0.55
        base_x = mid_x - unit_x * arrow_length
        base_y = mid_y - unit_y * arrow_length
        perp_x = -unit_y
        perp_y = unit_x
        left = QPointF(base_x + perp_x * arrow_width, base_y + perp_y * arrow_width)
        right = QPointF(base_x - perp_x * arrow_width, base_y - perp_y * arrow_width)
        tip = QPointF(mid_x, mid_y)
        path.moveTo(left)
        path.lineTo(tip)
        path.lineTo(right)

    def _overlap_control_point(self, start: QPointF, end: QPointF) -> QPointF | None:
        segments = getattr(self, "_connection_segments", None)
        if segments is None:
            return None
        candidates = self._overlap_candidates(start, end)
        previous_count = sum(
            1
            for previous_start, previous_end in candidates
            if self._segments_visually_overlap(start, end, previous_start, previous_end)
        )
        segments.append((QPointF(start), QPointF(end)))
        buckets = getattr(self, "_connection_segment_buckets", None)
        if buckets is not None:
            segment = (QPointF(start), QPointF(end))
            for bucket in self._segment_buckets(start, end):
                buckets.setdefault(bucket, []).append(segment)
        if previous_count == 0:
            return None
        dx = end.x() - start.x()
        dy = end.y() - start.y()
        length = math.hypot(dx, dy)
        if length < 0.001:
            return None
        bend = min(16.0, max(7.0, length * 0.24))
        side = 1.0 if previous_count % 2 == 1 else -1.0
        layer = 1.0 + (previous_count - 1) // 2
        offset = side * bend * layer
        perp_x = -dy / length
        perp_y = dx / length
        return QPointF(
            (start.x() + end.x()) / 2.0 + perp_x * offset,
            (start.y() + end.y()) / 2.0 + perp_y * offset,
        )

    def _overlap_candidates(self, start: QPointF, end: QPointF) -> list[tuple[QPointF, QPointF]]:
        buckets = getattr(self, "_connection_segment_buckets", None)
        if not buckets:
            return getattr(self, "_connection_segments", [])
        candidates: list[tuple[QPointF, QPointF]] = []
        seen: set[int] = set()
        for bucket in self._segment_buckets(start, end):
            for segment in buckets.get(bucket, []):
                marker = id(segment)
                if marker not in seen:
                    seen.add(marker)
                    candidates.append(segment)
        return candidates

    @staticmethod
    def _segment_buckets(start: QPointF, end: QPointF) -> set[tuple[int, int]]:
        bucket_size = 96.0
        left = math.floor(min(start.x(), end.x()) / bucket_size)
        right = math.floor(max(start.x(), end.x()) / bucket_size)
        top = math.floor(min(start.y(), end.y()) / bucket_size)
        bottom = math.floor(max(start.y(), end.y()) / bucket_size)
        return {
            (x_bucket, y_bucket)
            for x_bucket in range(left, right + 1)
            for y_bucket in range(top, bottom + 1)
        }

    @staticmethod
    def _segments_visually_overlap(a_start: QPointF, a_end: QPointF, b_start: QPointF, b_end: QPointF) -> bool:
        ax = a_end.x() - a_start.x()
        ay = a_end.y() - a_start.y()
        bx = b_end.x() - b_start.x()
        by = b_end.y() - b_start.y()
        a_length = math.hypot(ax, ay)
        b_length = math.hypot(bx, by)
        if a_length < 0.001 or b_length < 0.001:
            return False

        unit_ax = ax / a_length
        unit_ay = ay / a_length
        unit_bx = bx / b_length
        unit_by = by / b_length
        parallel_score = abs(unit_ax * unit_bx + unit_ay * unit_by)
        if parallel_score < 0.985:
            return False

        def distance_to_a_line(point: QPointF) -> float:
            return abs((point.x() - a_start.x()) * unit_ay - (point.y() - a_start.y()) * unit_ax)

        if max(distance_to_a_line(b_start), distance_to_a_line(b_end)) > 5.0:
            return False

        b0 = (b_start.x() - a_start.x()) * unit_ax + (b_start.y() - a_start.y()) * unit_ay
        b1 = (b_end.x() - a_start.x()) * unit_ax + (b_end.y() - a_start.y()) * unit_ay
        overlap_start = max(0.0, min(b0, b1))
        overlap_end = min(a_length, max(b0, b1))
        return (overlap_end - overlap_start) >= min(10.0, min(a_length, b_length) * 0.35)

    def _add_connection_path(
        self,
        path: QPainterPath,
        color: str,
        width: float,
        alpha: float,
        *,
        z_value: float = 1,
        line_id: int | None = None,
        connection_kind: str = "inner",
    ) -> None:
        if path.isEmpty():
            return
        item = self.scene().addPath(path)
        item.setData(0, line_id)
        item.setData(1, connection_kind)
        item.setData(2, color)
        item.setZValue(z_value)
        self._apply_connection_item_style(item)
        self.connection_items.append(item)

    def _restyle_connection_items(self) -> None:
        for item in self.connection_items:
            if isValid(item):
                self._apply_connection_item_style(item)

    def _apply_connection_item_style(self, item: QGraphicsPathItem) -> None:
        line_id = item.data(0)
        kind = str(item.data(1) or "inner")
        color = str(item.data(2) or "#e11d48")
        is_active = self.active_line_id is None or line_id == self.active_line_id
        if kind == "inner":
            width = 2.8 if is_active else 1.2
            alpha = 0.9 if is_active else 0.25
        elif kind == "bridge":
            width = 1.9 if is_active else 1.0
            alpha = 0.65 if is_active else 0.18
        elif kind == "arrow":
            width = 1.8 if is_active else 1.0
            alpha = 0.95 if is_active else 0.28
        else:
            width = 1.8 if is_active else 1.0
            alpha = 0.65 if is_active else 0.18
        pen_color = QColor(color)
        pen_color.setAlphaF(alpha)
        item.setPen(QPen(pen_color, width))

    def _selection_has_assignment(self) -> bool:
        if self.document is None:
            return False
        for point_id in self.selected_point_ids():
            point = self.document.get_point(point_id)
            if point.line_id is not None or point.block_id is not None:
                return True
        return False

    def _single_selected_point_id(self) -> int | None:
        point_ids = self.selected_point_ids()
        return point_ids[0] if len(point_ids) == 1 else None

    def _to_scene_point(self, x: float, y: float) -> QPointF:
        if self._raw_bounds is None:
            return QPointF(x, y)
        x *= self._display_scale
        y *= self._display_scale
        min_x, _max_x, _min_y, max_y = self._raw_bounds
        return QPointF((x - min_x) + self._margin, (max_y - y) + self._margin)

    def _background_origin_scene_point(self) -> QPointF:
        if self._raw_bounds is not None:
            min_x, max_x, min_y, max_y = self._raw_bounds
            return self._scene_point_from_display_units((min_x + max_x) / 2.0, (min_y + max_y) / 2.0)
        if self._content_scene_rect is not None:
            return self._content_scene_rect.center()
        return QPointF(0.0, 0.0)

    def _grid_origin_scene_units(self) -> tuple[float, float]:
        if self.document is None or not self.document.points:
            return 0.0, 0.0
        points = [point for point in self.document.points if not point.manual] or self.document.points
        min_row = min(point.row for point in points)
        min_col = min(point.col for point in points)
        anchor = min(points, key=lambda point: (point.y * self._display_scale, point.x * self._display_scale, point.uid))
        anchor_x = anchor.x * self._display_scale
        anchor_y = anchor.y * self._display_scale
        origin_x = anchor_x - (anchor.col - min_col + 0.5) * self._grid_step
        origin_y = anchor_y - (anchor.row - min_row + 0.5) * self._grid_step
        return origin_x, origin_y

    def _scene_point_from_display_units(self, x: float, y: float) -> QPointF:
        if self._raw_bounds is None:
            return QPointF(x, y)
        min_x, _max_x, _min_y, max_y = self._raw_bounds
        return QPointF((x - min_x) + self._margin, (max_y - y) + self._margin)

    def _document_point_from_scene(self, scene_pos: QPointF) -> QPointF:
        if self._raw_bounds is None:
            return QPointF(scene_pos.x(), scene_pos.y())
        min_x, _max_x, _min_y, max_y = self._raw_bounds
        display_x = scene_pos.x() - self._margin + min_x
        display_y = max_y - (scene_pos.y() - self._margin)
        scale = self._display_scale or 1.0
        return QPointF(display_x / scale, display_y / scale)

    @staticmethod
    def _move_scrollbar(scrollbar: QScrollBar, delta: int) -> None:
        scrollbar.setValue(scrollbar.value() - delta)