from workspaceStructure import WorkspaceStructure
from slipnet import slipnet
from workspace import workspace

class Bond(WorkspaceStructure):
	def __init__(self,source, destination, bondCategory, bondFacet, sourceDescriptor, destinationDescriptor):
		WorkspaceStructure.__init__(self)
		self.source = source
		self.string = self.source.string
		self.destination = destination
		self.leftObject = self.source
		self.rightObject = self.destination
		self.directionCategory = slipnet.right
		if self.source.leftStringPosition > self.destination.rightStringPosition:
			self.leftObject = self.destination
			self.rightObject = self.source
			self.directionCategory = slipnet.left
		self.facet = bondFacet
		self.sourceDescriptor = sourceDescriptor
		self.destinationDescriptor = destinationDescriptor
		self.category = bondCategory

		self.destinationIsOnRight = self.destination == self.rightObject
		self.bidirectional = self.sourceDescriptor == self.destinationDescriptor
		if self.bidirectional:
			self.directionCategory = None

	def flippedVersion(self):
		"""

		"""
		return Bond(
				self.destination, self.get_source(), self.category.getRelatedNode(slipnet.opposite),
				self.facet, self.destinationDescriptor, self.sourceDescriptor
		)

	def __repr__(self):
		return '<Bond: %s>' % self.__str__()

	def __str__(self):
		return '%s bond between %s and %s' % ( self.category.name, self.leftObject, self.rightObject)

	def buildBond(self):
		workspace.structures += [ self ]
		self.string.bonds += [ self ]
		self.category.buffer = 100.0
		if self.directionCategory:
				self.directionCategory.buffer = 100.0
		self.leftObject.rightBond = self
		self.rightObject.leftBond = self
		self.leftObject.bonds += [ self ]
		self.rightObject.bonds += [ self ]

	def break_the_structure(self):
		self.breakBond()

	def breakBond(self):
		if self in workspace.structures:
			workspace.structures.remove(self)
		if self in self.string.bonds:
			self.string.bonds.remove(self)
		self.leftObject.rightBond = None
		self.rightObject.leftBond = None
		if self in self.leftObject.bonds:
			self.leftObject.bonds.remove(self)
		if self in self.rightObject.bonds:
			self.rightObject.bonds.remove(self)

	def getIncompatibleCorrespondences(self):
		# returns a list of correspondences that are incompatible with
		# self bond
		incompatibles = []
		if self.leftObject.leftmost and self.leftObject.correspondence:
			correspondence = self.leftObject.correspondence
			if self.string == workspace.initial:
				objekt = self.leftObject.correspondence.objectFromTarget
			else:
				objekt = self.leftObject.correspondence.objectFromInitial
			if objekt.leftmost and objekt.rightBond:
				if objekt.rightBond.directionCategory and objekt.rightBond.directionCategory != self.directionCategory:
					incompatibles += [ correspondence ]
		if self.rightObject.rightmost and self.rightObject.correspondence:
			correspondence = self.rightObject.correspondence
			if self.string == workspace.initial:
				objekt = self.rightObject.correspondence.objectFromTarget
			else:
				objekt = self.rightObject.correspondence.objectFromInitial
			if objekt.rightmost and objekt.leftBond:
				if objekt.leftBond.directionCategory and objekt.leftBond.directionCategory != self.directionCategory:
					incompatibles += [ correspondence ]
		return incompatibles

	def updateInternalStrength(self):
		# bonds between objects of same type(ie. letter or group) are
		# stronger than bonds between different types
		sourceGap = self.get_source().leftStringPosition != self.get_source().rightStringPosition
		destinationGap = self.destination.leftStringPosition != self.destination.rightStringPosition
		if sourceGap == destinationGap:
			memberCompatibility = 1.0
		else:
			memberCompatibility = 0.7
		# letter category bonds are stronger
		if self.facet == slipnet.letterCategory:
			facetFactor = 1.0
		else:
			facetFactor = 0.7
		strength = min(100.0,memberCompatibility * facetFactor * self.category.bondDegreeOfAssociation())
		self.internalStrength = strength

	def updateExternalStrength(self):
		self.externalStrength = 0.0
		supporters = self.numberOfLocalSupportingBonds()
		if supporters > 0.0:
			density = self.localDensity() / 100.0
			density = density ** 0.5 * 100.0
			supportFactor = 0.6 ** (1.0 / supporters ** 3)
			supportFactor = max(1.0,supportFactor)
			strength = supportFactor * density
			self.externalStrength = strength

	def numberOfLocalSupportingBonds(self):
		return len([ b for b in self.string.bonds if b.string == self.get_source().string and
			self.leftObject.letterDistance(b.leftObject) != 0 and
			self.rightObject.letterDistance(b.rightObject) != 0 and
			self.category == b.category and
			self.directionCategory == b.directionCategory ])

	def sameCategories(self,other):
		return self.category == other.category and self.directionCategory == other.directionCategory

	def myEnds(self,object1,object2):
		if self.get_source() == object1 and self.destination == object2:
			return True
		return self.get_source() == object2 and self.destination == object1

	def localDensity(self):
		# returns a rough measure of the density in the string
		# of the same bond-category and the direction-category of
		# the given bond
		slotSum = supportSum = 0.0
		for object1 in workspace.objects:
			if object1.string == self.string:
				for object2 in workspace.objects:
					if object1.beside(object2):
						slotSum += 1.0
						for bond in self.string.bonds:
							if bond != self and self.sameCategories(bond) and self.myEnds(object1,object2):
									supportSum += 1.0
		if slotSum == 0.0:
				return 0.0
		return 100.0 * supportSum / slotSum

	def sameNeighbours(self,other):
		if self.leftObject == other.leftObject:
			return True
		return self.rightObject == other.rightObject

	def getIncompatibleBonds(self):
		return [ b for b in self.string.bonds if self.sameNeighbours(b) ]

	def get_source(self):
		return self.source

	def set_source(self, value):
		self.source = value

def possibleGroupBonds(bondCategory, directionCategory, bondFacet, bonds):
	result = []
	for bond in bonds:
		if bond.category == bondCategory and bond.directionCategory == directionCategory:
			result += [ bond ]
		else:
			# a modified bond might be made
			if bondCategory == slipnet.sameness:
				return None # a different bond cannot be made here
			if bond.category == bondCategory or bond.directionCategory == directionCategory:
				return None # a different bond cannot be made here
			if bond.category == slipnet.sameness:
				return None
			bond = Bond(bond.destination, bond.get_source(), bondCategory, bondFacet, bond.destinationDescriptor, bond.sourceDescriptor)
			result += [ bond ]
	return result