__all__ = ["Terminal", "TerminalGraphicsItem"]

import weakref

from .. import functions as fn
from ..graphicsItems.GraphicsObject import GraphicsObject
from ..Point import Point
from ..Qt import QtCore, QtGui, QtWidgets

translate = QtCore.QCoreApplication.translate

class Terminal(object):
    def __init__(self, node, name, io, optional=False, multi=False, pos=None, renamable=False, removable=False, multiable=False, bypass=None):
        """
        Construct a new terminal. 
        
        ==============  =================================================================================
        **Arguments:**
        node            the node to which this terminal belongs
        name            string, the name of the terminal
        io              'in' or 'out'
        optional        bool, whether the node may process without connection to this terminal
        multi           bool, for inputs: whether this terminal may make multiple connections
                        for outputs: whether this terminal creates a different value for each connection
        pos             [x, y], the position of the terminal within its node's boundaries
        renamable       (bool) Whether the terminal can be renamed by the user
        removable       (bool) Whether the terminal can be removed by the user
        multiable       (bool) Whether the user may toggle the *multi* option for this terminal
        bypass          (str) Name of the terminal from which this terminal's value is derived
                        when the Node is in bypass mode.
        ==============  =================================================================================
        """
        self._io = io
        self._optional = optional
        self._multi = multi
        self._node = weakref.ref(node)
        self._name = name
        self._renamable = renamable
        self._removable = removable
        self._multiable = multiable
        self._connections = {}
        self._graphicsItem = TerminalGraphicsItem(self, parent=self._node().graphicsItem())
        self._bypass = bypass
        
        if multi:
            self._value = {}  ## dictionary of terminal:value pairs.
        else:
            self._value = None  
        
        self.valueOk = None
        self.recolor()
        
    def value(self, term=None):
        """Return the value this terminal provides for the connected terminal"""
        if term is None:
            return self._value
            
        if self.isMultiValue():
            return self._value.get(term, None)
        else:
            return self._value

    def bypassValue(self):
        return self._bypass

    def setValue(self, val, process=True):
        """If this is a single-value terminal, val should be a single value.
        If this is a multi-value terminal, val should be a dict of terminal:value pairs"""
        if not self.isMultiValue():
            if fn.eq(val, self._value):
                return
            self._value = val
        else:
            if not isinstance(self._value, dict):
                self._value = {}
            if val is not None:
                self._value.update(val)
            
        self.setValueAcceptable(None)  ## by default, input values are 'unchecked' until Node.update(). 
        if self.isInput() and process:
            self.node().update()
            
        self.recolor()
        
    def setOpts(self, **opts):
        self._renamable = opts.get('renamable', self._renamable)
        self._removable = opts.get('removable', self._removable)
        self._multiable = opts.get('multiable', self._multiable)
        if 'multi' in opts:
            self.setMultiValue(opts['multi'])

    def connected(self, term):
        """Called whenever this terminal has been connected to another. (note--this function is called on both terminals)"""
        if self.isInput() and term.isOutput():
            self.inputChanged(term)
        if self.isOutput() and self.isMultiValue():
            self.node().update()
        self.node().connected(self, term)
        
    def disconnected(self, term):
        """Called whenever this terminal has been disconnected from another. (note--this function is called on both terminals)"""
        if self.isMultiValue() and term in self._value:
            del self._value[term]
            self.node().update()
        else:
            if self.isInput():
                self.setValue(None)
        self.node().disconnected(self, term)

    def inputChanged(self, term, process=True):
        """Called whenever there is a change to the input value to this terminal.
        It may often be useful to override this function."""
        if self.isMultiValue():
            self.setValue({term: term.value(self)}, process=process)
        else:
            self.setValue(term.value(self), process=process)
            
    def valueIsAcceptable(self):
        """Returns True->acceptable  None->unknown  False->Unacceptable"""
        return self.valueOk
        
    def setValueAcceptable(self, v=True):
        self.valueOk = v
        self.recolor()
        
    def connections(self):
        return self._connections
        
    def node(self):
        return self._node()
        
    def isInput(self):
        return self._io == 'in'
    
    def isMultiValue(self):
        return self._multi
    
    def setMultiValue(self, multi):
        """Set whether this is a multi-value terminal."""
        self._multi = multi
        if not multi and len(self.inputTerminals()) > 1:
            self.disconnectAll()
            
        for term in self.inputTerminals():
            self.inputChanged(term)

    def isOutput(self):
        return self._io == 'out'
        
    def isRenamable(self):
        return self._renamable

    def isRemovable(self):
        return self._removable

    def isMultiable(self):
        return self._multiable

    def name(self):
        return self._name
        
    def graphicsItem(self):
        return self._graphicsItem
        
    def isConnected(self):
        return len(self.connections()) > 0
        
    def connectedTo(self, term):
        return term in self.connections()
        
    def hasInput(self):
        for t in self.connections():
            if t.isOutput():
                return True
        return False        
        
    def inputTerminals(self):
        """Return the terminal(s) that give input to this one."""
        return [t for t in self.connections() if t.isOutput()]
        
    def dependentNodes(self):
        """Return the list of nodes which receive input from this terminal."""
        return set([t.node() for t in self.connections() if t.isInput()])
        
    def connectTo(self, term, connectionItem=None):
        try:
            if self.connectedTo(term):
                raise Exception('Already connected')
            if term is self:
                raise Exception('Not connecting terminal to self')
            if term.node() is self.node():
                raise Exception("Can't connect to terminal on same node.")
            for t in [self, term]:
                if t.isInput() and not t._multi and len(t.connections()) > 0:
                    raise Exception("Cannot connect %s <-> %s: Terminal %s is already connected to %s (and does not allow multiple connections)" % (self, term, t, list(t.connections().keys())))
        except:
            if connectionItem is not None:
                connectionItem.close()
            raise
            
        if connectionItem is None:
            connectionItem = ConnectionItem(self.graphicsItem(), term.graphicsItem())
            self.graphicsItem().getViewBox().addItem(connectionItem)
        self._connections[term] = connectionItem
        term._connections[self] = connectionItem
        
        self.recolor()
        
        self.connected(term)
        term.connected(self)
        
        return connectionItem
        
    def disconnectFrom(self, term):
        if not self.connectedTo(term):
            return
        item = self._connections[term]
        item.close()
        del self._connections[term]
        del term._connections[self]
        self.recolor()
        term.recolor()
        
        self.disconnected(term)
        term.disconnected(self)
            
        
    def disconnectAll(self):
        for t in list(self._connections.keys()):
            self.disconnectFrom(t)
        
    def recolor(self, color=None, recurse=True):
        if color is None:
            if not self.isConnected():       ## disconnected terminals are black
                color = QtGui.QColor(0,0,0)
            elif self.isInput() and not self.hasInput():   ## input terminal with no connected output terminals 
                color = QtGui.QColor(200,200,0)
            elif self._value is None or fn.eq(self._value, {}):  ## terminal is connected but has no data (possibly due to processing error) 
                color = QtGui.QColor(255,255,255)
            elif self.valueIsAcceptable() is None:   ## terminal has data, but it is unknown if the data is ok
                color = QtGui.QColor(200, 200, 0)
            elif self.valueIsAcceptable() is True:   ## terminal has good input, all ok
                color = QtGui.QColor(0, 200, 0)
            else:                                    ## terminal has bad input
                color = QtGui.QColor(200, 0, 0)
        self.graphicsItem().setBrush(QtGui.QBrush(color))
        
        if recurse:
            for t in self.connections():
                t.recolor(color, recurse=False)
        
    def rename(self, name):
        oldName = self._name
        self._name = name
        self.node().terminalRenamed(self, oldName)
        self.graphicsItem().termRenamed(name)
        
    def __repr__(self):
        return "<Terminal %s.%s>" % (str(self.node().name()), str(self.name()))
        
    def __hash__(self):
        return id(self)

    def close(self):
        self.disconnectAll()
        item = self.graphicsItem()
        if item.scene() is not None:
            item.scene().removeItem(item)
        
    def saveState(self):
        return {'io': self._io, 'multi': self._multi, 'optional': self._optional, 'renamable': self._renamable, 'removable': self._removable, 'multiable': self._multiable}

    def __lt__(self, other):
        """When the terminal is multi value, the data passed to the DatTreeWidget for each input or output, is {Terminal: value}.
        To make this sortable, we provide the < operator.
        """
        return self._name < other._name


class TextItem(QtWidgets.QGraphicsTextItem):
    def __init__(self, text, parent, on_update):
        super().__init__(text, parent)
        self.on_update = on_update

    def focusOutEvent(self, ev):
        super().focusOutEvent(ev)
        if self.on_update is not None:
            self.on_update()

    def keyPressEvent(self, ev):
        if ev.key() == QtCore.Qt.Key.Key_Enter or ev.key() == QtCore.Qt.Key.Key_Return:
            if self.on_update is not None:
                self.on_update()
                return
        super().keyPressEvent(ev)


class TerminalGraphicsItem(GraphicsObject):
    
    def __init__(self, term, parent=None):
        self.term = term
        GraphicsObject.__init__(self, parent)
        self.brush = fn.mkBrush(0,0,0)
        self.box = QtWidgets.QGraphicsRectItem(0, 0, 10, 10, self)
        on_update = self.labelChanged if self.term.isRenamable() else None
        self.label = TextItem(self.term.name(), self, on_update)
        self.label.setScale(0.7)
        self.newConnection = None
        self.setFiltersChildEvents(True)  ## to pick up mouse events on the rectitem
        if self.term.isRenamable():
            self.label.setTextInteractionFlags(QtCore.Qt.TextInteractionFlag.TextEditorInteraction)
        self.setZValue(1)
        self.menu = None

    def labelChanged(self):
        newName = self.label.toPlainText()
        if newName != self.term.name():
            self.term.rename(newName)

    def termRenamed(self, name):
        self.label.setPlainText(name)

    def setBrush(self, brush):
        self.brush = brush
        self.box.setBrush(brush)

    def disconnect(self, target):
        self.term.disconnectFrom(target.term)

    def boundingRect(self):
        br = self.box.mapRectToParent(self.box.boundingRect())
        lr = self.label.mapRectToParent(self.label.boundingRect())
        return br | lr
        
    def paint(self, p, *args):
        pass
        
    def setAnchor(self, x, y):
        pos = QtCore.QPointF(x, y)
        self.anchorPos = pos
        br = self.box.mapRectToParent(self.box.boundingRect())
        lr = self.label.mapRectToParent(self.label.boundingRect())
        
        
        if self.term.isInput():
            self.box.setPos(pos.x(), pos.y()-br.height()/2.)
            self.label.setPos(pos.x() + br.width(), pos.y() - lr.height()/2.)
        else:
            self.box.setPos(pos.x()-br.width(), pos.y()-br.height()/2.)
            self.label.setPos(pos.x()-br.width()-lr.width(), pos.y()-lr.height()/2.)
        self.updateConnections()
        
    def updateConnections(self):
        for t, c in self.term.connections().items():
            c.updateLine()
            
    def mousePressEvent(self, ev):
        #ev.accept()
        ev.ignore() ## necessary to allow click/drag events to process correctly

    def mouseClickEvent(self, ev):
        if ev.button() == QtCore.Qt.MouseButton.LeftButton:
            ev.accept()
            self.label.setFocus(QtCore.Qt.FocusReason.MouseFocusReason)
        elif ev.button() == QtCore.Qt.MouseButton.RightButton:
            ev.accept()
            self.raiseContextMenu(ev)
            
    def raiseContextMenu(self, ev):
        ## only raise menu if this terminal is removable
        menu = self.getMenu()
        menu = self.scene().addParentContextMenus(self, menu, ev)
        pos = ev.screenPos()
        menu.popup(QtCore.QPoint(pos.x(), pos.y()))
        
    def getMenu(self):
        if self.menu is None:
            self.menu = QtWidgets.QMenu()
            self.menu.setTitle(translate("Context Menu", "Terminal"))
            remAct = QtGui.QAction(translate("Context Menu", "Remove terminal"), self.menu)
            remAct.triggered.connect(self.removeSelf)
            self.menu.addAction(remAct)
            self.menu.remAct = remAct
            if not self.term.isRemovable():
                remAct.setEnabled(False)
            multiAct = QtGui.QAction(translate("Context Menu", "Multi-value"), self.menu)
            multiAct.setCheckable(True)
            multiAct.setChecked(self.term.isMultiValue())
            multiAct.setEnabled(self.term.isMultiable())
            
            multiAct.triggered.connect(self.toggleMulti)
            self.menu.addAction(multiAct)
            self.menu.multiAct = multiAct
            if self.term.isMultiable():
                multiAct.setEnabled = False
        return self.menu

    def toggleMulti(self):
        multi = self.menu.multiAct.isChecked()
        self.term.setMultiValue(multi)
    
    def removeSelf(self):
        self.term.node().removeTerminal(self.term)
        
    def mouseDragEvent(self, ev):
        if ev.button() != QtCore.Qt.MouseButton.LeftButton:
            ev.ignore()
            return
        
        ev.accept()
        if ev.isStart():
            if self.newConnection is None:
                self.newConnection = ConnectionItem(self)
                #self.scene().addItem(self.newConnection)
                self.getViewBox().addItem(self.newConnection)
                #self.newConnection.setParentItem(self.parent().parent())

            self.newConnection.setTarget(self.mapToView(ev.pos()))
        elif ev.isFinish():
            if self.newConnection is not None:
                items = self.scene().items(ev.scenePos())
                gotTarget = False
                for i in items:
                    if isinstance(i, TerminalGraphicsItem):
                        self.newConnection.setTarget(i)
                        try:
                            self.term.connectTo(i.term, self.newConnection)
                            gotTarget = True
                        except:
                            self.scene().removeItem(self.newConnection)
                            self.newConnection = None
                            raise
                        break
                
                if not gotTarget:
                    self.newConnection.close()
                self.newConnection = None
        else:
            if self.newConnection is not None:
                self.newConnection.setTarget(self.mapToView(ev.pos()))
        
    def hoverEvent(self, ev):
        if not ev.isExit() and ev.acceptDrags(QtCore.Qt.MouseButton.LeftButton):
            ev.acceptClicks(QtCore.Qt.MouseButton.LeftButton) ## we don't use the click, but we also don't want anyone else to use it.
            ev.acceptClicks(QtCore.Qt.MouseButton.RightButton)
            self.box.setBrush(fn.mkBrush('w'))
        else:
            self.box.setBrush(self.brush)
        self.update()
        
    def connectPoint(self):
        ## return the connect position of this terminal in view coords
        return self.mapToView(self.mapFromItem(self.box, self.box.boundingRect().center()))

    def nodeMoved(self):
        for t, item in self.term.connections().items():
            item.updateLine()


class ConnectionItem(GraphicsObject):
    
    def __init__(self, source, target=None):
        GraphicsObject.__init__(self)
        self.setFlags(
            self.GraphicsItemFlag.ItemIsSelectable | 
            self.GraphicsItemFlag.ItemIsFocusable
        )
        self.source = source
        self.target = target
        self.length = 0
        self.hovered = False
        self.path = None
        self.shapePath = None
        self.style = {
            'shape': 'line',
            'color': (100, 100, 250),
            'width': 1.0,
            'hoverColor': (150, 150, 250),
            'hoverWidth': 1.0,
            'selectedColor': (200, 200, 0),
            'selectedWidth': 3.0,
            }
        self.source.getViewBox().addItem(self)
        self.updateLine()
        self.setZValue(0)
        
    def close(self):
        if self.scene() is not None:
            self.scene().removeItem(self)
        
    def setTarget(self, target):
        self.target = target
        self.updateLine()
    
    def setStyle(self, **kwds):
        self.style.update(kwds)
        if 'shape' in kwds:
            self.updateLine()
        else:
            self.update()
    
    def updateLine(self):
        start = Point(self.source.connectPoint())
        if isinstance(self.target, TerminalGraphicsItem):
            stop = Point(self.target.connectPoint())
        elif isinstance(self.target, QtCore.QPointF):
            stop = Point(self.target)
        else:
            return
        self.prepareGeometryChange()
        
        self.path = self.generatePath(start, stop)
        self.shapePath = None
        self.update()
        
    def generatePath(self, start, stop):
        path = QtGui.QPainterPath()
        path.moveTo(start)
        if self.style['shape'] == 'line':
            path.lineTo(stop)
        elif self.style['shape'] == 'cubic':
            path.cubicTo(Point(stop.x(), start.y()), Point(start.x(), stop.y()), Point(stop.x(), stop.y()))
        else:
            raise Exception('Invalid shape "%s"; options are "line" or "cubic"' % self.style['shape'])
        return path

    def keyPressEvent(self, ev):
        if not self.isSelected():
            ev.ignore()
            return
        
        if ev.key() == QtCore.Qt.Key.Key_Delete or ev.key() == QtCore.Qt.Key.Key_Backspace:
            self.source.disconnect(self.target)
            ev.accept()
        else:
            ev.ignore()
    
    def mousePressEvent(self, ev):
        ev.ignore()
        
    def mouseClickEvent(self, ev):
        if ev.button() == QtCore.Qt.MouseButton.LeftButton:
            ev.accept()
            sel = self.isSelected()
            self.setSelected(True)
            self.setFocus()
            if not sel and self.isSelected():
                self.update()
                
    def hoverEvent(self, ev):
        if (not ev.isExit()) and ev.acceptClicks(QtCore.Qt.MouseButton.LeftButton):
            self.hovered = True
        else:
            self.hovered = False
        self.update()
            
    def boundingRect(self):
        return self.shape().boundingRect()

    def viewRangeChanged(self):
        self.shapePath = None
        self.prepareGeometryChange()
        
    def shape(self):
        if self.shapePath is None:
            if self.path is None:
                return QtGui.QPainterPath()
            stroker = QtGui.QPainterPathStroker()
            px = self.pixelWidth()
            stroker.setWidth(px*8)
            self.shapePath = stroker.createStroke(self.path)
        return self.shapePath
        
    def paint(self, p, *args):
        if self.isSelected():
            p.setPen(fn.mkPen(self.style['selectedColor'], width=self.style['selectedWidth']))
        else:
            if self.hovered:
                p.setPen(fn.mkPen(self.style['hoverColor'], width=self.style['hoverWidth']))
            else:
                p.setPen(fn.mkPen(self.style['color'], width=self.style['width']))
        
        p.drawPath(self.path)
