src/eric7/Graphics/AssociationItem.py

# -*- coding: utf-8 -*-

# Copyright (c) 2004 - 2025 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing a graphics item for an association between two items.
"""

import enum

from PyQt6.QtCore import QLineF, QPointF, QRectF
from PyQt6.QtWidgets import QGraphicsItem

from eric7 import EricUtilities
from eric7.EricGraphics.EricArrowItem import EricArrowItem, EricArrowType


class AssociationType(enum.Enum):
    """
    Class defining the association types.
    """

    NORMAL = 0
    GENERALISATION = 1
    IMPORTS = 2


class AssociationPointRegion(enum.Enum):
    """
    Class defining the regions for an association end point.
    """

    NO_REGION = 0
    WEST = 1
    NORTH = 2
    EAST = 3
    SOUTH = 4
    NORTH_WEST = 5
    NORTH_EAST = 6
    SOUTH_EAST = 7
    SOUTH_WEST = 8
    CENTER = 9


class AssociationItem(EricArrowItem):
    """
    Class implementing a graphics item for an association between two items.

    The association is drawn as an arrow starting at the first items and
    ending at the second.
    """

    def __init__(
        self,
        itemA,
        itemB,
        assocType=AssociationType.NORMAL,
        topToBottom=False,
        colors=None,
        parent=None,
    ):
        """
        Constructor

        @param itemA first widget of the association
        @type UMLItem
        @param itemB second widget of the association
        @type UMLItem
        @param assocType type of the association
        @type AssociationType
        @param topToBottom flag indicating to draw the association
            from item A top to item B bottom
        @type bool
        @param colors tuple containing the foreground and background colors
        @type tuple of (QColor, QColor)
        @param parent reference to the parent object
        @type QGraphicsItem
        """
        if assocType in (AssociationType.NORMAL, AssociationType.IMPORTS):
            arrowType = EricArrowType.NORMAL
            arrowFilled = True
        elif assocType == AssociationType.GENERALISATION:
            arrowType = EricArrowType.WIDE
            arrowFilled = False

        EricArrowItem.__init__(
            self,
            QPointF(0, 0),
            QPointF(100, 100),
            arrowFilled,
            arrowType,
            colors,
            parent,
        )

        self.setFlag(QGraphicsItem.GraphicsItemFlag.ItemIsMovable, False)
        self.setFlag(QGraphicsItem.GraphicsItemFlag.ItemIsSelectable, False)

        if topToBottom:
            self.calculateEndingPoints = self.__calculateEndingPoints_topToBottom
        else:
            # - self.calculateEndingPoints = self.__calculateEndingPoints_center
            self.calculateEndingPoints = self.__calculateEndingPoints_rectangle

        self.itemA = itemA
        self.itemB = itemB
        self.assocType = assocType
        self.topToBottom = topToBottom

        self.regionA = AssociationPointRegion.NO_REGION
        self.regionB = AssociationPointRegion.NO_REGION

        self.calculateEndingPoints()

        self.itemA.addAssociation(self)
        self.itemB.addAssociation(self)

    def __mapRectFromItem(self, item):
        """
        Private method to map item's rectangle to this item's coordinate
        system.

        @param item reference to the item to be mapped
        @type QGraphicsRectItem
        @return item's rectangle in local coordinates
        @rtype QRectF
        """
        rect = item.rect()
        tl = self.mapFromItem(item, rect.topLeft())
        return QRectF(tl.x(), tl.y(), rect.width(), rect.height())

    def __calculateEndingPoints_topToBottom(self):
        """
        Private method to calculate the ending points of the association item.

        The ending points are calculated from the top center of the lower item
        to the bottom center of the upper item.
        """
        if self.itemA is None or self.itemB is None:
            return

        self.prepareGeometryChange()

        rectA = self.__mapRectFromItem(self.itemA)
        rectB = self.__mapRectFromItem(self.itemB)
        midA = QPointF(
            rectA.x() + rectA.width() / 2.0, rectA.y() + rectA.height() / 2.0
        )
        midB = QPointF(
            rectB.x() + rectB.width() / 2.0, rectB.y() + rectB.height() / 2.0
        )
        if midA.y() > midB.y():
            startP = QPointF(rectA.x() + rectA.width() / 2.0, rectA.y())
            endP = QPointF(rectB.x() + rectB.width() / 2.0, rectB.y() + rectB.height())
        else:
            startP = QPointF(
                rectA.x() + rectA.width() / 2.0, rectA.y() + rectA.height()
            )
            endP = QPointF(rectB.x() + rectB.width() / 2.0, rectB.y())
        self.setPoints(startP.x(), startP.y(), endP.x(), endP.y())

    def __calculateEndingPoints_center(self):
        """
        Private method to calculate the ending points of the association item.

        The ending points are calculated from the centers of the
        two associated items.
        """
        if self.itemA is None or self.itemB is None:
            return

        self.prepareGeometryChange()

        rectA = self.__mapRectFromItem(self.itemA)
        rectB = self.__mapRectFromItem(self.itemB)
        midA = QPointF(
            rectA.x() + rectA.width() / 2.0, rectA.y() + rectA.height() / 2.0
        )
        midB = QPointF(
            rectB.x() + rectB.width() / 2.0, rectB.y() + rectB.height() / 2.0
        )
        startP = self.__findRectIntersectionPoint(self.itemA, midA, midB)
        endP = self.__findRectIntersectionPoint(self.itemB, midB, midA)

        if startP.x() != -1 and startP.y() != -1 and endP.x() != -1 and endP.y() != -1:
            # __IGNORE_WARNING_C-111__
            self.setPoints(startP.x(), startP.y(), endP.x(), endP.y())

    def __calculateEndingPoints_rectangle(self):
        r"""
        Private method to calculate the ending points of the association item.

        The ending points are calculated by the following method.

        For each item the diagram is divided in four Regions by its diagonals
        as indicated below
        <pre>
            +------------------------------+
            |        \  Region 2  /        |
            |         \          /         |
            |          |--------|          |
            |          | \    / |          |
            |          |  \  /  |          |
            |          |   \/   |          |
            | Region 1 |   /\   | Region 3 |
            |          |  /  \  |          |
            |          | /    \ |          |
            |          |--------|          |
            |         /          \         |
            |        /  Region 4  \        |
            +------------------------------+
        </pre>

        Each diagonal is defined by two corners of the bounding rectangle.

        To calculate the start point  we have to find out in which
        region (defined by itemA's diagonals) is itemB's TopLeft corner
        (lets call it region M). After that the start point will be
        the middle point of rectangle's side contained in region M.

        To calculate the end point we repeat the above but in the opposite
        direction (from itemB to itemA)
        """
        if self.itemA is None or self.itemB is None:
            return

        self.prepareGeometryChange()

        rectA = self.__mapRectFromItem(self.itemA)
        rectB = self.__mapRectFromItem(self.itemB)

        xA = rectA.x() + rectA.width() / 2.0
        yA = rectA.y() + rectA.height() / 2.0
        xB = rectB.x() + rectB.width() / 2.0
        yB = rectB.y() + rectB.height() / 2.0

        # find itemA region
        rc = QRectF(xA, yA, rectA.width(), rectA.height())
        self.regionA = self.__findPointRegion(rc, xB, yB)
        # move some regions to the standard ones
        if self.regionA == AssociationPointRegion.NORTH_WEST:
            self.regionA = AssociationPointRegion.NORTH
        elif self.regionA == AssociationPointRegion.NORTH_EAST:
            self.regionA = AssociationPointRegion.EAST
        elif self.regionA == AssociationPointRegion.SOUTH_EAST:
            self.regionA = AssociationPointRegion.SOUTH
        elif self.regionA in (
            AssociationPointRegion.SOUTH_WEST,
            AssociationPointRegion.CENTER,
        ):
            self.regionA = AssociationPointRegion.WEST

        self.__updateEndPoint(self.regionA, True)

        # now do the same for itemB
        rc = QRectF(xB, yB, rectB.width(), rectB.height())
        self.regionB = self.__findPointRegion(rc, xA, yA)
        # move some regions to the standard ones
        if self.regionB == AssociationPointRegion.NORTH_WEST:
            self.regionB = AssociationPointRegion.NORTH
        elif self.regionB == AssociationPointRegion.NORTH_EAST:
            self.regionB = AssociationPointRegion.EAST
        elif self.regionB == AssociationPointRegion.SOUTH_EAST:
            self.regionB = AssociationPointRegion.SOUTH
        elif self.regionB in (
            AssociationPointRegion.SOUTH_WEST,
            AssociationPointRegion.CENTER,
        ):
            self.regionB = AssociationPointRegion.WEST

        self.__updateEndPoint(self.regionB, False)

    def __findPointRegion(self, rect, posX, posY):
        """
        Private method to find out, which region of rectangle rect contains
        the point (PosX, PosY) and returns the region number.

        @param rect rectangle to calculate the region for
        @type QRectF
        @param posX x position of point
        @type float
        @param posY y position of point
        @type float
        @return the calculated region number<br />
            West = Region 1<br />
            North = Region 2<br />
            East = Region 3<br />
            South = Region 4<br />
            NorthWest = On diagonal 2 between Region 1 and 2<br />
            NorthEast = On diagonal 1 between Region 2 and 3<br />
            SouthEast = On diagonal 2 between Region 3 and 4<br />
            SouthWest = On diagonal 1 between Region4 and 1<br />
            Center = On diagonal 1 and On diagonal 2 (the center)<br />
        @rtype AssociationPointRegion
        """
        w = rect.width()
        h = rect.height()
        x = rect.x()
        y = rect.y()
        slope2 = w / h
        slope1 = -slope2
        b1 = x + w / 2.0 - y * slope1
        b2 = x + w / 2.0 - y * slope2

        eval1 = slope1 * posY + b1
        eval2 = slope2 * posY + b2

        result = AssociationPointRegion.NO_REGION

        # inside region 1
        if eval1 > posX and eval2 > posX:
            result = AssociationPointRegion.WEST

        # inside region 2
        elif eval1 > posX and eval2 < posX:
            result = AssociationPointRegion.NORTH

        # inside region 3
        elif eval1 < posX and eval2 < posX:
            result = AssociationPointRegion.EAST

        # inside region 4
        elif eval1 < posX and eval2 > posX:
            result = AssociationPointRegion.SOUTH

        # inside region 5
        elif eval1 == posX and eval2 < posX:
            result = AssociationPointRegion.NORTH_WEST

        # inside region 6
        elif eval1 < posX and eval2 == posX:
            result = AssociationPointRegion.NORTH_EAST

        # inside region 7
        elif eval1 == posX and eval2 > posX:
            result = AssociationPointRegion.SOUTH_EAST

        # inside region 8
        elif eval1 > posX and eval2 == posX:
            result = AssociationPointRegion.SOUTH_WEST

        # inside region 9
        elif eval1 == posX and eval2 == posX:
            result = AssociationPointRegion.CENTER

        return result

    def __updateEndPoint(self, region, isWidgetA):
        """
        Private method to update an endpoint.

        @param region the region for the endpoint
        @type AssociationPointRegion
        @param isWidgetA flag indicating update for itemA is done
        @type bool
        """
        if region == AssociationPointRegion.NO_REGION:
            return

        rect = (
            self.__mapRectFromItem(self.itemA)
            if isWidgetA
            else self.__mapRectFromItem(self.itemB)
        )
        x = rect.x()
        y = rect.y()
        ww = rect.width()
        wh = rect.height()
        ch = wh / 2.0
        cw = ww / 2.0

        if region == AssociationPointRegion.WEST:
            px = x
            py = y + ch
        elif region == AssociationPointRegion.NORTH:
            px = x + cw
            py = y
        elif region == AssociationPointRegion.EAST:
            px = x + ww
            py = y + ch
        elif region in (AssociationPointRegion.SOUTH, AssociationPointRegion.CENTER):
            px = x + cw
            py = y + wh

        if isWidgetA:
            self.setStartPoint(px, py)
        else:
            self.setEndPoint(px, py)

    def __findRectIntersectionPoint(self, item, p1, p2):
        """
        Private method to find the intersection point of a line with a
        rectangle.

        @param item item to check against
        @type UMLItem
        @param p1 first point of the line
        @type QPointF
        @param p2 second point of the line
        @type QPointF
        @return the intersection point
        @rtype QPointF
        """
        rect = self.__mapRectFromItem(item)
        lines = [
            QLineF(rect.topLeft(), rect.topRight()),
            QLineF(rect.topLeft(), rect.bottomLeft()),
            QLineF(rect.bottomRight(), rect.bottomLeft()),
            QLineF(rect.bottomRight(), rect.topRight()),
        ]
        intersectLine = QLineF(p1, p2)
        intersectPoint = QPointF(0, 0)
        for line in lines:
            if (
                intersectLine.intersect(line, intersectPoint)
                == QLineF.IntersectType.BoundedIntersection
            ):
                return intersectPoint
        return QPointF(-1.0, -1.0)

    def __findIntersection(self, p1, p2, p3, p4):
        """
        Private method to calculate the intersection point of two lines.

        The first line is determined by the points p1 and p2, the second
        line by p3 and p4. If the intersection point is not contained in
        the segment p1p2, then it returns (-1.0, -1.0).

        For the function's internal calculations remember:<br />
        QT coordinates start with the point (0,0) as the topleft corner
        and x-values increase from left to right and y-values increase
        from top to bottom; it means the visible area is quadrant I in
        the regular XY coordinate system

        <pre>
            Quadrant II     |   Quadrant I
           -----------------|-----------------
            Quadrant III    |   Quadrant IV
        </pre>

        In order for the linear function calculations to work in this method
        we must switch x and y values (x values become y values and viceversa)

        @param p1 first point of first line
        @type QPointF
        @param p2 second point of first line
        @type QPointF
        @param p3 first point of second line
        @type QPointF
        @param p4 second point of second line
        @type QPointF
        @return the intersection point
        @rtype QPointF
        """
        x1 = p1.y()
        y1 = p1.x()
        x2 = p2.y()
        y2 = p2.x()
        x3 = p3.y()
        y3 = p3.x()
        x4 = p4.y()
        y4 = p4.x()

        # line 1 is the line between (x1, y1) and (x2, y2)
        # line 2 is the line between (x3, y3) and (x4, y4)
        no_line1 = True  # it is false, if line 1 is a linear function
        no_line2 = True  # it is false, if line 2 is a linear function
        slope1 = 0.0
        slope2 = 0.0
        b1 = 0.0
        b2 = 0.0

        if x2 != x1:
            slope1 = (y2 - y1) / (x2 - x1)
            b1 = y1 - slope1 * x1
            no_line1 = False
        if x4 != x3:
            slope2 = (y4 - y3) / (x4 - x3)
            b2 = y3 - slope2 * x3
            no_line2 = False

        pt = QPointF()
        # if either line is not a function
        if no_line1 and no_line2:
            # if the lines are not the same one
            if x1 != x3:
                return QPointF(-1.0, -1.0)
            # if the lines are the same ones
            if y3 <= y4:
                if y3 <= y1 and y1 <= y4:
                    return QPointF(y1, x1)
                else:
                    return QPointF(y2, x2)
            else:
                if y4 <= y1 and y1 <= y3:
                    return QPointF(y1, x1)
                else:
                    return QPointF(y2, x2)
        elif no_line1:
            pt.setX(slope2 * x1 + b2)
            pt.setY(x1)
            if y1 >= y2:
                if not (y2 <= pt.x() and pt.x() <= y1):
                    pt.setX(-1.0)
                    pt.setY(-1.0)
            else:
                if not (y1 <= pt.x() and pt.x() <= y2):
                    pt.setX(-1.0)
                    pt.setY(-1.0)
            return pt
        elif no_line2:
            pt.setX(slope1 * x3 + b1)
            pt.setY(x3)
            if y3 >= y4:
                if not (y4 <= pt.x() and pt.x() <= y3):
                    pt.setX(-1.0)
                    pt.setY(-1.0)
            else:
                if not (y3 <= pt.x() and pt.x() <= y4):
                    pt.setX(-1.0)
                    pt.setY(-1.0)
            return pt

        if slope1 == slope2:
            pt.setX(-1.0)
            pt.setY(-1.0)
            return pt

        pt.setY((b2 - b1) / (slope1 - slope2))
        pt.setX(slope1 * pt.y() + b1)
        # the intersection point must be inside the segment (x1, y1) (x2, y2)
        if x2 >= x1 and y2 >= y1:
            if not (
                (x1 <= pt.y() and pt.y() <= x2) and (y1 <= pt.x() and pt.x() <= y2)
            ):
                pt.setX(-1.0)
                pt.setY(-1.0)
        elif x2 < x1 and y2 >= y1:
            if not (
                (x2 <= pt.y() and pt.y() <= x1) and (y1 <= pt.x() and pt.x() <= y2)
            ):
                pt.setX(-1.0)
                pt.setY(-1.0)
        elif x2 >= x1 and y2 < y1:
            if not (
                (x1 <= pt.y() and pt.y() <= x2) and (y2 <= pt.x() and pt.x() <= y1)
            ):
                pt.setX(-1.0)
                pt.setY(-1.0)
        else:
            if not (
                (x2 <= pt.y() and pt.y() <= x1) and (y2 <= pt.x() and pt.x() <= y1)
            ):
                pt.setX(-1.0)
                pt.setY(-1.0)

        return pt

    def widgetMoved(self):
        """
        Public method to recalculate the association after a widget was moved.
        """
        self.calculateEndingPoints()

    def unassociate(self):
        """
        Public method to unassociate from the widgets.
        """
        self.itemA.removeAssociation(self)
        self.itemB.removeAssociation(self)

    @classmethod
    def parseAssociationItemDataString(cls, data):
        """
        Class method to parse the given persistence data.

        @param data persisted data to be parsed
        @type str
        @return tuple with the IDs of the source and destination items,
            the association type and a flag indicating to associate from top
            to bottom
        @rtype tuple of (int, int, int, bool)
        """
        src = -1
        dst = -1
        assocType = AssociationType.NORMAL
        topToBottom = False
        for entry in data.split(", "):
            if "=" in entry:
                key, value = entry.split("=", 1)
                if key == "src":
                    src = int(value)
                elif key == "dst":
                    dst = int(value)
                elif key == "type":
                    assocType = AssociationType(int(value))
                elif key == "topToBottom":
                    topToBottom = EricUtilities.toBool(value)

        return src, dst, assocType, topToBottom

    def toDict(self):
        """
        Public method to collect data to be persisted.

        @return dictionary containing data to be persisted
        @rtype dict
        """
        return {
            "src": self.itemA.getId(),
            "dst": self.itemB.getId(),
            "type": self.assocType.value,
            "topToBottom": self.topToBottom,
        }

    @classmethod
    def fromDict(cls, data, umlItems, colors=None):
        """
        Class method to create an association item from persisted data.

        @param data dictionary containing the persisted data as generated
            by toDict()
        @type dict
        @param umlItems list of UML items
        @type list of UMLItem
        @param colors tuple containing the foreground and background colors
        @type tuple of (QColor, QColor)
        @return created association item
        @rtype AssociationItem
        """
        try:
            return cls(
                umlItems[data["src"]],
                umlItems[data["dst"]],
                assocType=AssociationType(data["type"]),
                topToBottom=data["topToBottom"],
                colors=colors,
            )
        except (KeyError, ValueError):
            return None