"""NodeItem: renders a node's SVG symbol, title and ports; draggable/selectable."""
from __future__ import annotations

from PyQt6.QtCore import QRectF, Qt, QPointF
from PyQt6.QtGui import QColor, QFont, QPen
from PyQt6.QtWidgets import QGraphicsObject, QGraphicsItem, QStyle

from ..model.node import NodeModel
from . import svg_cache
from .port_item import PortItem

LABEL_HEIGHT = 18.0


class NodeItem(QGraphicsObject):
    """Graphics item bound to a :class:`NodeModel`."""

    def __init__(self, scene_ref, node: NodeModel) -> None:
        super().__init__()
        self._scene = scene_ref
        self.node = node
        self.setFlags(
            QGraphicsItem.GraphicsItemFlag.ItemIsMovable
            | QGraphicsItem.GraphicsItemFlag.ItemIsSelectable
            | QGraphicsItem.GraphicsItemFlag.ItemSendsGeometryChanges
        )
        self.setAcceptHoverEvents(True)
        self.setZValue(1)
        self.setPos(node.x, node.y)
        self._renderer = svg_cache.renderer(node.svg_name)
        self._port_items: dict[str, PortItem] = {}
        self._press_pos: QPointF | None = None
        self._build_ports()

    # -- helpers used by children ----------------------------------------
    def scene_relations(self):
        return getattr(self._scene, "document", None) and self._scene.document.relations

    def port_item(self, port_id: str) -> PortItem | None:
        return self._port_items.get(port_id)

    def port_items(self):
        return self._port_items.values()

    def _build_ports(self) -> None:
        for p in self.node.ports:
            self._port_items[p.port_id] = PortItem(self, p)

    def refresh_ports(self) -> None:
        for pi in self._port_items.values():
            pi.update_position()

    # -- geometry ---------------------------------------------------------
    def body_rect(self) -> QRectF:
        return QRectF(0, 0, self.node.width, self.node.height)

    def boundingRect(self) -> QRectF:
        m = 6
        return QRectF(-m, -m, self.node.width + 2 * m,
                      self.node.height + LABEL_HEIGHT + 2 * m)

    def set_model_size(self, w: float, h: float) -> None:
        self.prepareGeometryChange()
        self.node.width = w
        self.node.height = h
        self.refresh_ports()
        self.update()

    # -- interaction ------------------------------------------------------
    def mousePressEvent(self, event):
        self._press_pos = self.pos()
        super().mousePressEvent(event)

    def mouseReleaseEvent(self, event):
        super().mouseReleaseEvent(event)
        if self._press_pos is not None and self.pos() != self._press_pos:
            old = (self._press_pos.x(), self._press_pos.y())
            new = (self.pos().x(), self.pos().y())
            self._scene.on_node_move_finished(self.node.node_id, old, new)
        self._press_pos = None

    def itemChange(self, change, value):
        if change == QGraphicsItem.GraphicsItemChange.ItemPositionChange and self.scene():
            cfg = getattr(self._scene, "config", None)
            if cfg is not None and cfg.snap_to_grid:
                value = QPointF(cfg.snap(value.x()), cfg.snap(value.y()))
            return value
        if change == QGraphicsItem.GraphicsItemChange.ItemPositionHasChanged:
            self.node.x = self.pos().x()
            self.node.y = self.pos().y()
            self._scene.reroute_edges_for_node(self.node.node_id)
        if change == QGraphicsItem.GraphicsItemChange.ItemSelectedHasChanged:
            self.update()
        return super().itemChange(change, value)

    # -- painting ---------------------------------------------------------
    def paint(self, painter, option, widget=None):
        painter.setRenderHint(painter.RenderHint.Antialiasing, True)
        body = self.body_rect()
        selected = bool(option.state & QStyle.StateFlag.State_Selected)

        if selected:
            pen = QPen(QColor("#1976d2"), 1.5, Qt.PenStyle.DashLine)
            painter.setPen(pen)
            painter.setBrush(QColor(25, 118, 210, 30))
            painter.drawRoundedRect(body.adjusted(-3, -3, 3, 3), 4, 4)

        if self._renderer is not None:
            self._renderer.render(painter, body)
        else:
            painter.setPen(QPen(QColor("#555"), 2))
            painter.setBrush(QColor("#eceff1"))
            painter.drawRoundedRect(body, 6, 6)

        # title label
        title = self.node.title
        if title:
            painter.setPen(QColor("#263238"))
            f = QFont()
            f.setPointSizeF(8.5)
            painter.setFont(f)
            rect = QRectF(-10, self.node.height + 2, self.node.width + 20, LABEL_HEIGHT)
            painter.drawText(rect, Qt.AlignmentFlag.AlignHCenter | Qt.AlignmentFlag.AlignTop, title)