"""Các phần tử vẽ của đồ thị: node, cạnh, khung nhìn — R08-T14.

Thuần đồ hoạ Qt, không biết gì về GraphRAG hay agent. Tách riêng vì đây là
chỗ duy nhất cần mở khi chỉnh cách đồ thị trông ra sao — màu, hình mũi tên,
cách kéo thả và phóng to.
"""
from __future__ import annotations

import re
from pathlib import Path
from PySide6.QtCore import QObject, QPointF, Qt, Slot
from PySide6.QtGui import QBrush, QColor, QFont, QPen
from PySide6.QtWidgets import QGraphicsEllipseItem, QGraphicsLineItem, QGraphicsSimpleTextItem, QGraphicsView
from ...core.structure_graph import EDGE_KIND_COLORS, NODE_KIND_COLORS
from ...theme import current_palette
from ...i18n import tr
from ...ui.osutil import open_folder, open_location


class _Bridge(QObject):
    """Exposed to the D3 page so a Shift+click on a node can open its
    storage folder/link (local path or URL — see osutil.open_location)."""

    @Slot(str)
    def openPath(self, path: str) -> None:  # noqa: N802 - JS-facing name
        if path:
            open_location(path)

class _Edge(QGraphicsLineItem):
    def __init__(self, a: "_Node", b: "_Node", type_: str = ""):
        super().__init__()
        self.a, self.b = a, b
        self.type = type_
        # Colour the edge by its RELATIONSHIP type (contains/defines/method/…),
        # so the graph shows what each connection MEANS — falling back to the
        # source node's tint for any untyped edge.
        color = QColor(EDGE_KIND_COLORS.get(type_, "")) if type_ else QColor()
        if not color.isValid():
            color = a.brush().color().lighter(130)
        self._color = color
        self.setPen(QPen(color, 1.4))
        self.setZValue(-1)
        # A small label naming the relationship, shown at the edge midpoint.
        self._label = None
        if type_:
            self._label = QGraphicsSimpleTextItem(type_, self)
            self._label.setBrush(QBrush(color.lighter(140)))
            f = QFont()
            f.setPointSize(7)
            self._label.setFont(f)
            self._label.setZValue(0)
        a.edges.append(self)
        b.edges.append(self)
        self.adjust()

    def adjust(self) -> None:
        pa, pb = self.a.scenePos(), self.b.scenePos()
        self.setLine(pa.x(), pa.y(), pb.x(), pb.y())
        if self._label is not None:
            br = self._label.boundingRect()
            self._label.setPos((pa.x() + pb.x()) / 2 - br.width() / 2,
                                (pa.y() + pb.y()) / 2 - br.height() / 2)

class _Node(QGraphicsEllipseItem):
    def __init__(self, data, radius: int):
        super().__init__(-radius, -radius, 2 * radius, 2 * radius)
        self.data = data
        self.edges = []
        tok = current_palette()
        # NODE_KIND_COLORS is a categorical data encoding (one hue per node
        # kind), not UI chrome — it stays fixed across themes on purpose so a
        # given kind is always the same colour. Only the chrome follows tokens.
        color = QColor(NODE_KIND_COLORS.get(data.kind, tok.text_muted))
        self.setBrush(QBrush(color))
        self.setPen(QPen(color.darker(160), 1.5))
        self.setFlags(
            QGraphicsEllipseItem.ItemIsMovable
            | QGraphicsEllipseItem.ItemIsSelectable
            | QGraphicsEllipseItem.ItemSendsGeometryChanges
        )
        self.setZValue(1)
        label = QGraphicsSimpleTextItem(data.label, self)
        label.setBrush(QBrush(QColor(tok.text)))
        label.setPos(radius + 3, -8)

    def itemChange(self, change, value):  # noqa: N802
        if change == QGraphicsEllipseItem.ItemPositionHasChanged:
            for edge in self.edges:
                edge.adjust()
        return super().itemChange(change, value)

class _GraphView(QGraphicsView):
    def __init__(self, scene):
        super().__init__(scene)
        self.setDragMode(QGraphicsView.NoDrag)
        self._panning = False
        self._pan_start = QPointF()

    def wheelEvent(self, e):  # noqa: N802
        self.scale(1.15 if e.angleDelta().y() > 0 else 1 / 1.15,
                   1.15 if e.angleDelta().y() > 0 else 1 / 1.15)

    def mousePressEvent(self, e):  # noqa: N802
        if e.button() == Qt.LeftButton and self.itemAt(e.pos()) is None:
            self._panning = True
            self._pan_start = e.position()
            self.setCursor(Qt.ClosedHandCursor)
            e.accept()
            return
        super().mousePressEvent(e)

    def mouseMoveEvent(self, e):  # noqa: N802
        if self._panning:
            delta = e.position() - self._pan_start
            self._pan_start = e.position()
            self.horizontalScrollBar().setValue(int(self.horizontalScrollBar().value() - delta.x()))
            self.verticalScrollBar().setValue(int(self.verticalScrollBar().value() - delta.y()))
            e.accept()
            return
        super().mouseMoveEvent(e)

    def mouseReleaseEvent(self, e):  # noqa: N802
        if self._panning:
            self._panning = False
            self.setCursor(Qt.ArrowCursor)
            e.accept()
            return
        super().mouseReleaseEvent(e)

    def mouseDoubleClickEvent(self, e):  # noqa: N802
        """Double-click or Ctrl+click on a node opens its storage folder."""
        item = self.itemAt(e.pos())
        if isinstance(item, _Node) and getattr(item.data, "path", ""):
            open_folder(item.data.path)
            e.accept()
            return
        super().mouseDoubleClickEvent(e)