#!/usr/bin/python

from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys, xml
import xml.dom.minidom as md

"""
 Author: Windel Bouwman
 Year: 2012
 Description: This script implements a diagram editor.
 run with python 3.x as:
  $ python [thisfile.py]
"""

def buildPath(pts):
   path = QPainterPath(pts[0])
   for pt in pts[1:]:
      path.lineTo(pt)
   return path

class Connection(QGraphicsPathItem):
   """ Implementation of a connection between blocks """
   def __init__(self, fromPort, toPort):
      super(Connection, self).__init__()
      self.pos1, self.pos2 = None, None
      self.fromPort, self.toPort = None, None
      self.setFlag(self.ItemIsSelectable, True)
      self.setFlag(self.ItemClipsToShape, True)
      pen = QPen(Qt.blue, 2)
      pen.setCapStyle(Qt.RoundCap)
      self.setPen(pen)
      self.arrowhead = QGraphicsPathItem(self)
      self.arrowhead.setPath(buildPath([QPointF(0.0, 0.0), QPointF(-6.0, 10.0), QPointF(6.0, 10.0), QPointF(0.0, 0.0)]))
      self.arrowhead.setPen(pen)
      self.arrowhead.setBrush(QBrush(pen.color()))
      self.vias = []
      self.setFromPort(fromPort)
      self.setToPort(toPort)
   def mouseDoubleClickEvent(self, event):
      pos = event.scenePos()
      pts = [self.pos1] + [v.pos() for v in self.vias] + [self.pos2]
      idx = 0
      tidx = 0
      for p1, p2 in zip(pts[0:-1], pts[1:]):
         l1 = QLineF(p1, p2)
         l2 = QLineF(p1, pos)
         l3 = QLineF(pos, p2)
         d = l2.length() + l3.length() - l1.length()
         if d < 5:
            tidx = idx
         idx += 1
      self.addHandle(pos, tidx)
      
   def addHandle(self, pos, idx=None):
      hi = HandleItem(self)
      if idx:
         self.vias.insert(idx, hi)
      else:
         self.vias.append(hi)
      def callback(p):
         self.updateLineStukken()
         return p
      hi.posChangeCallbacks.append(callback)
      hi.setPos(pos)
      self.updateLineStukken()
   def myDelete(self):
      scene = self.scene()
      if scene:
         self.setFromPort(None)
         self.setToPort(None)
         scene.removeItem(self)
      
   def setFromPort(self, fromPort):
      if self.fromPort:
         self.fromPort.posCallbacks.remove(self.setBeginPos)
         self.fromPort.connection = None
      self.fromPort = fromPort
      if self.fromPort:
         self.fromPort.connection = self
         self.setBeginPos(fromPort.scenePos())
         self.fromPort.posCallbacks.append(self.setBeginPos)
   def setToPort(self, toPort):
      if self.toPort:
         self.toPort.posCallbacks.remove(self.setEndPos)
         self.toPort.connection = None
      self.toPort = toPort
      if self.toPort:
         self.setEndPos(toPort.scenePos())
         self.toPort.connection = self
         self.toPort.posCallbacks.append(self.setEndPos)
   def setBeginPos(self, pos1):
      self.pos1 = pos1
      self.updateLineStukken()
   def setEndPos(self, endpos):
      self.pos2 = endpos
      self.updateLineStukken()
   def itemChange(self, change, value):
      if change == self.ItemSelectedHasChanged:
         for via in self.vias:
            via.setVisible(value)
      return super(Connection, self).itemChange(change, value)
   def shape(self):
      return self.myshape
   def updateLineStukken(self):
      """
         This algorithm determines the optimal routing of all signals.
         TODO: implement nice automatic line router
      """
      if self.pos1 is None or self.pos2 is None:
         return
      pts = [self.pos1] + [v.pos() for v in self.vias] + [self.pos2]
      self.arrowhead.setPos(self.pos2)
      if pts[-1].x() < pts[-2].x():
         self.arrowhead.setRotation(-90)
      else:
         self.arrowhead.setRotation(90)
      self.setPath(buildPath(pts))
      """ Create a shape outline using the path stroker """
      s = super(Connection, self).shape()
      pps = QPainterPathStroker()
      pps.setWidth(10)
      self.myshape = pps.createStroke(s).simplified()

class ParameterDialog(QDialog):
   def __init__(self, block, parent = None):
      super(ParameterDialog, self).__init__(parent)
      self.block = block
      self.button = QPushButton('Ok', self)
      l = QGridLayout(self)
      l.addWidget(QLabel('Name:', self), 0, 0)
      self.nameEdit = QLineEdit(self.block.name)
      l.addWidget(self.nameEdit, 0, 1)
      l.addWidget(QLabel('Code:', self), 1, 0)
      self.codeEdit = QTextEdit(self)
      self.codeEdit.setPlainText(self.block.code)
      l.addWidget(self.codeEdit, 1, 1)
      l.addWidget(self.button, 2, 0, 1, 2)
      self.button.clicked.connect(self.OK)
   def OK(self):
      self.block.setName(self.nameEdit.text())
      self.block.code = self.codeEdit.toPlainText()
      self.close()

class PortItem(QGraphicsPathItem):
   """ Represents a port to a subsystem """
   def __init__(self, name, block, direction):
      super(PortItem, self).__init__(block)
      self.connection = None
      path = QPainterPath()
      d = 10.0
      if direction == 'input':
         path.moveTo(-d, -d)
         path.lineTo(0.0, 0.0)
         path.lineTo(-d, d)
      else:
         path.moveTo(0.0, -d)
         path.lineTo(d, 0.0)
         path.lineTo(0.0, d)
      self.setPath(path)
      self.direction = direction
      self.block = block
      self.setCursor(QCursor(Qt.CrossCursor))
      pen = QPen(Qt.blue, 2)
      pen.setCapStyle(Qt.RoundCap)
      self.setPen(pen)
      self.name = name
      self.textItem = QGraphicsTextItem(name, self)
      self.setName(name)
      self.posCallbacks = []
      self.setFlag(self.ItemSendsScenePositionChanges, True)
   def setName(self, name):
      self.name = name
      self.textItem.setPlainText(name)
      rect = self.textItem.boundingRect()
      lw, lh = rect.width(), rect.height()
      if self.direction == 'input':
         lx = 3
      else:
         lx = -3 - lw
      self.textItem.setPos(lx, -lh / 2)
   def itemChange(self, change, value):
      if change == self.ItemScenePositionHasChanged:
         for cb in self.posCallbacks:
            cb(value)
         return value
      return super(PortItem, self).itemChange(change, value)
   def mousePressEvent(self, event):
      if self.direction == 'output':
         self.scene().startConnection(self)

class OutputPort(PortItem):
   # TODO: create a subclass OR make a member porttype
   pass

# Block part:
class HandleItem(QGraphicsEllipseItem):
   """ A handle that can be moved by the mouse """
   def __init__(self, parent=None):
      dx = 13.0
      super(HandleItem, self).__init__(QRectF(-0.5*dx,-0.5*dx,dx,dx), parent)
      self.posChangeCallbacks = []
      self.setBrush(QBrush(Qt.white))
      self.setFlag(self.ItemSendsScenePositionChanges, True)
      self.setFlag(self.ItemIsMovable, True)
      self.setVisible(False)
      self.setCursor(QCursor(Qt.SizeFDiagCursor))
   def mouseMoveEvent(self, event):
      """ Move function without moving the other selected elements """
      p = self.mapToParent(event.pos())
      self.setPos(p)
   def mySetPos(self, p):
      # TODO: use this instead of itemChange?
      self.setPos(p)
   def itemChange(self, change, value):
      if change == self.ItemPositionChange:
         for cb in self.posChangeCallbacks:
            res = cb(value)
            if res:
               value = res
         return value
      # Call superclass method:
      return super(HandleItem, self).itemChange(change, value)

def uniqify(name, names):
   newname = name
   i = 1
   while newname in names:
      newname = name + str(i)
      i += 1
   return newname

class BlockItem(QGraphicsRectItem):
   """ 
      Represents a block in the diagram
      Has an x and y and width and height
      width and height can only be adjusted with a tip in the lower right corner.

      - in and output ports
      - parameters
      - description
   """
   def __init__(self, name='Untitled', parent=None):
      super(BlockItem, self).__init__(parent)
      # Properties of the rectangle:
      self.setPen(QPen(Qt.blue, 2))
      self.setBrush(QBrush(Qt.lightGray))
      self.setFlags(self.ItemIsSelectable | self.ItemIsMovable)
      self.setFlag(self.ItemSendsScenePositionChanges, True)
      self.setCursor(QCursor(Qt.PointingHandCursor))
      self.label = QGraphicsTextItem(name, self)
      self.name = name
      self.code = ''
      # Create corner for resize:
      self.sizer = HandleItem(self)
      self.sizer.posChangeCallbacks.append(self.changeSize) # Connect the callback
      button = QPushButton('+in')
      button.clicked.connect(self.newInputPort)
      self.buttonItemAddInput = QGraphicsProxyWidget(self)
      self.buttonItemAddInput.setWidget(button)
      self.buttonItemAddInput.setVisible(False)
      button = QPushButton('+out')
      button.clicked.connect(self.newOutputPort)
      self.buttonItemAddOutput = QGraphicsProxyWidget(self)
      self.buttonItemAddOutput.setWidget(button)
      self.buttonItemAddOutput.setVisible(False)

      # Inputs and outputs of the block:
      self.inputs = []
      self.outputs = []
      # Update size:
      self.sizer.mySetPos(QPointF(60, 40)) # This is a better resize function
   def editParameters(self):
      pd = ParameterDialog(self, self.window())
      pd.exec_()
   def mouseDoubleClickEvent(self, event):
      self.editParameters()
   def newInputPort(self):
      names = [i.name for i in self.inputs + self.outputs]
      self.addInput(PortItem(uniqify('in', names), self, 'input'))
   def newOutputPort(self):
      names = [i.name for i in self.inputs + self.outputs]
      self.addOutput(PortItem(uniqify('out', names), self, 'output'))
   def setName(self, name):
      self.name = name
      self.label.setPlainText(name)
   def addInput(self, i):
      self.inputs.append(i)
      self.updateSize()
   def addOutput(self, o):
      self.outputs.append(o)
      self.updateSize()

   def contextMenuEvent(self, event):
      menu = QMenu()
      pa = menu.addAction('Parameters')
      pa.triggered.connect(self.editParameters)
      menu.exec_(event.screenPos())
   def itemChange(self, change, value):
      if change == self.ItemSelectedHasChanged:
         for child in [self.sizer, self.buttonItemAddInput, self.buttonItemAddOutput]:
            child.setVisible(value)
      return super(BlockItem, self).itemChange(change, value)
   def myDelete(self):
         # TODO: move the below to blockitem:
         scene = self.scene()
         if scene:
            for p in self.inputs + self.outputs:
               if p.connection:
                  p.connection.myDelete()
            scene.removeItem(self)

   def updateSize(self):
      rect = self.rect()
      h, w = rect.height(), rect.width()
      self.buttonItemAddInput.setPos(0, h + 4)
      self.buttonItemAddOutput.setPos(w+10, h+4)
      for inp in self.inputs:
         inp.setX(0.0)
      for inp in self.outputs:
         inp.setX(w)
      if len(self.inputs) == 1:
         self.inputs[0].setPos(0.0, h / 2)
      elif len(self.inputs) > 1:
         y = 15
         dy = (h - 30) / (len(self.inputs) - 1)
         for inp in self.inputs:
            inp.setPos(0.0, y)
            y += dy
      if len(self.outputs) == 1:
         self.outputs[0].setPos(w, h / 2)
      elif len(self.outputs) > 1:
         y = 15
         dy = (h - 30) / (len(self.outputs) - 1)
         for outp in self.outputs:
            outp.setPos(w, y)
            y += dy
      
   def changeSize(self, p):
      """ Resize block function """
      w, h = p.x(), p.y()
      # Limit the block size:
      h = 20 if h < 20 else h
      w = 40 if w < 40 else w
      self.setRect(0.0, 0.0, w, h)
      # center label:
      rect = self.label.boundingRect()
      lw, lh = rect.width(), rect.height()
      lx = (w - lw) / 2
      ly = (h - lh) / 2
      self.label.setPos(lx, ly)
      # Update port positions:
      self.updateSize()
      return QPointF(w, h)

class EditorGraphicsView(QGraphicsView):
   def __init__(self, parent=None):
      QGraphicsView.__init__(self, parent)
      scene = DiagramScene(self)
      self.diagramScene = scene
      self.setScene(scene)
      self.setDragMode(QGraphicsView.RubberBandDrag)
      testShortcut = QShortcut(QKeySequence("F12"), self)
      testShortcut.activated.connect(self.test)
      delShort = QShortcut(QKeySequence.Delete, self)
      delShort.activated.connect(scene.deleteItems)
      self.loadDiagram = scene.loadDiagram
   def save(self):
      self.diagramScene.saveDiagram('diagram2.usd')
   def load(self):
      filename = QFileDialog.getOpenFileName(self)
      self.diagramScene.loadDiagram(filename)
   def zoomAll(self):
      """ zoom to fit all items """
      rect = self.diagramScene.itemsBoundingRect()
      self.fitInView(rect, Qt.KeepAspectRatio)
   def test(self):
      self.rotate(30)
      self.zoomAll()

   def wheelEvent(self, event):
      pos = event.pos()
      posbefore = self.mapToScene(pos)
      degrees = event.delta() / 8.0
      sx = (100.0 + degrees) / 100.0
      self.scale(sx, sx)
      event.accept()
   def dragEnterEvent(self, event):
      if event.mimeData().hasFormat('component/name'):
         event.accept()
   def dragMoveEvent(self, event):
      if event.mimeData().hasFormat('component/name'):
         event.accept()
   def dropEvent(self, event):
      if event.mimeData().hasFormat('component/name'):
         name = bytes(event.mimeData().data('component/name')).decode()
         pos = self.mapToScene(event.pos())
         self.scene().addNewBlock(pos, name)

class LibraryModel(QStandardItemModel):
   def __init__(self, parent=None):
      QStandardItemModel.__init__(self, parent)
   def mimeTypes(self):
      return ['component/name']
   def mimeData(self, idxs):
      mimedata = QMimeData()
      for idx in idxs:
         if idx.isValid():
            txt = self.data(idx, Qt.DisplayRole) # python 3
            mimedata.setData('component/name', txt)
      return mimedata

class DiagramScene(QGraphicsScene):
   """ Save and load and deletion of item"""
   def __init__(self, parent=None):
      super(DiagramScene, self).__init__(parent)
      self.startedConnection = None

   def saveDiagram(self, filename):
      items = self.items()
      blocks = [item for item in items if type(item) is BlockItem]
      connections = [item for item in items if type(item) is Connection]

      doc = md.Document()
      modelElement = doc.createElement('system')
      doc.appendChild(modelElement)
      for block in blocks:
         blockElement = doc.createElement("block")
         x, y = block.scenePos().x(), block.scenePos().y()
         rect = block.rect()
         w, h = rect.width(), rect.height()
         blockElement.setAttribute("name", block.name)
         blockElement.setAttribute("x", str(int(x)))
         blockElement.setAttribute("y", str(int(y)))
         blockElement.setAttribute("width", str(int(w)))
         blockElement.setAttribute("height", str(int(h)))
         codeNode = doc.createCDATASection(block.code)
         codeElement = doc.createElement('code')
         codeElement.appendChild(codeNode)
         blockElement.appendChild(codeElement)
         for inp in block.inputs:
            portElement = doc.createElement("input")
            portElement.setAttribute("name", inp.name)
            blockElement.appendChild(portElement)
         for outp in block.outputs:
            portElement = doc.createElement("output")
            portElement.setAttribute("name", outp.name)
            blockElement.appendChild(portElement)
         modelElement.appendChild(blockElement)
      for connection in connections:
         connectionElement = doc.createElement("connection")
         fromPort = connection.fromPort.name
         toPort = connection.toPort.name
         fromBlock = connection.fromPort.block.name
         toBlock = connection.toPort.block.name
         connectionElement.setAttribute("fromBlock", fromBlock)
         connectionElement.setAttribute("fromPort", fromPort)
         connectionElement.setAttribute("toBlock", toBlock)
         connectionElement.setAttribute("toPort", toPort)
         for via in connection.vias:
            viaElement = doc.createElement('via')
            viaElement.setAttribute('x', str(int(via.x())))
            viaElement.setAttribute('y', str(int(via.y())))
            connectionElement.appendChild(viaElement)
         modelElement.appendChild(connectionElement)
      with open(filename, 'w') as f:
         f.write(doc.toprettyxml())
         
   def loadDiagram(self, filename):
      try:
         doc = md.parse(filename)
      except IOError as e:
         print('{0} not found'.format(filename))
         return
      except xml.parsers.expat.ExpatError as e:
         print('{0}'.format(e))
         return
      sysElements = doc.getElementsByTagName('system')
      blockElements = doc.getElementsByTagName('block')
      for sysElement in sysElements:
         blockElements = sysElement.getElementsByTagName('block')
         for blockElement in blockElements:
            x = float(blockElement.getAttribute('x'))
            y = float(blockElement.getAttribute('y'))
            w = float(blockElement.getAttribute('width'))
            h = float(blockElement.getAttribute('height'))
            name = blockElement.getAttribute('name')
            block = BlockItem(name)
            self.addItem(block)
            block.setPos(x, y)
            block.sizer.setPos(w, h)
            codeElements = blockElement.getElementsByTagName('code')
            if codeElements:
               cn = codeElements[0].childNodes
               cdatas = [cd for cd in cn if type(cd) is md.CDATASection]
               if len(cdatas) > 0:
                  block.code = cdatas[0].data
            # Load ports:
            portElements = blockElement.getElementsByTagName('input')
            for portElement in portElements:
               name = portElement.getAttribute('name')
               inp = PortItem(name, block, 'input')
               block.addInput(inp)
            portElements = blockElement.getElementsByTagName('output')
            for portElement in portElements:
               name = portElement.getAttribute('name')
               outp = PortItem(name, block, 'output')
               block.addOutput(outp)
         connectionElements = sysElement.getElementsByTagName('connection')
         for connectionElement in connectionElements:
            fromBlock = connectionElement.getAttribute('fromBlock')
            fromPort = connectionElement.getAttribute('fromPort')
            toBlock = connectionElement.getAttribute('toBlock')
            toPort = connectionElement.getAttribute('toPort')
            viaElements = connectionElement.getElementsByTagName('via')
            fromPort = self.findPort(fromBlock, fromPort)
            toPort = self.findPort(toBlock, toPort)
            connection = Connection(fromPort, toPort)
            for viaElement in viaElements:
               x = int(viaElement.getAttribute('x'))
               y = int(viaElement.getAttribute('y'))
               connection.addHandle(QPointF(x, y))
            self.addItem(connection)
   def findPort(self, blockname, portname):
      items = self.items()
      blocks = [item for item in items if type(item) is BlockItem]
      for block in [b for b in blocks if b.name == blockname]:
         for port in block.inputs + block.outputs:
            if port.name == portname:
               return port
   def addNewBlock(self, pos, name):
      blocknames = [item.name for item in self.items() if type(item) is BlockItem]
      b1 = BlockItem(uniqify(name, blocknames))
      b1.setPos(pos)
      self.addItem(b1)
   def mouseMoveEvent(self, event):
      if self.startedConnection:
         pos = event.scenePos()
         self.startedConnection.setEndPos(pos)
      super(DiagramScene, self).mouseMoveEvent(event)
   def mouseReleaseEvent(self, event):
      if self.startedConnection:
         items = self.items(event.scenePos())
         for item in items:
            if type(item) is PortItem:
               self.startedConnection.setToPort(item)
               self.startedConnection = None
               return
         self.startedConnection.myDelete()
         self.startedConnection = None
      super(DiagramScene, self).mouseReleaseEvent(event)
   def startConnection(self, port):
      self.startedConnection = Connection(port, None)
      pos = port.scenePos()
      self.startedConnection.setEndPos(pos)
      self.addItem(self.startedConnection)
   def deleteItems(self):
      # Try to delete all currently selected items:
      for item in list(self.selectedItems()):
         item.myDelete()

class LibraryWidget(QListView):
   def __init__(self):
      super(LibraryWidget, self).__init__(None)
      self.libraryModel = LibraryModel(self)
      self.libraryModel.setColumnCount(1)
      # Create an icon with an icon:
      pixmap = QPixmap(60, 60)
      pixmap.fill()
      painter = QPainter(pixmap)
      painter.fillRect(10, 10, 40, 40, Qt.blue)
      painter.setBrush(Qt.yellow)
      painter.drawEllipse(20, 20, 20, 20)
      painter.end()

      # Fill library:
      self.libItems = []
      self.libItems.append( QStandardItem(QIcon(pixmap), 'Block') )
      self.libItems.append( QStandardItem(QIcon(pixmap), 'Uber Unit') )
      self.libItems.append( QStandardItem(QIcon(pixmap), 'Device') )
      for i in self.libItems:
         self.libraryModel.appendRow(i)
      self.setModel(self.libraryModel)
      self.setViewMode(self.IconMode)
      self.setDragDropMode(self.DragOnly)

class Main(QMainWindow):
   def __init__(self):
      super(Main, self).__init__(None)
      self.editor = EditorGraphicsView()
      self.setCentralWidget(self.editor)
      self.setWindowTitle("Diagram editor")
      toolbar = self.addToolBar('Tools')
      def act(name, shortcut, callback):
         a = QAction(name, self)
         a.setShortcuts(shortcut)
         a.triggered.connect(callback)
         toolbar.addAction(a)
      act('Save', QKeySequence.Save, self.editor.save)
      act('Load', QKeySequence.Open, self.editor.load)
      act('Full screen', QKeySequence("F11"), self.toggleFullScreen)
      act('Fit in view', QKeySequence("F8"), self.editor.zoomAll)

      self.library = LibraryWidget() 
      libraryDock = QDockWidget('Library', self)
      libraryDock.setWidget(self.library)
      self.addDockWidget(Qt.LeftDockWidgetArea, libraryDock)

      self.editor.loadDiagram('diagram2.usd')

   def toggleFullScreen(self):
      self.setWindowState(self.windowState() ^ Qt.WindowFullScreen)
      self.editor.zoomAll()

if __name__ == '__main__':
   if sys.version_info.major != 3:
      print('Please use python 3.x')
      sys.exit(1)

   app = QApplication(sys.argv)
   main = Main()
   main.show()
   main.resize(700, 500)
   main.editor.zoomAll()
   app.exec_()