import random

class TreeNode:
    def __init__(self,key,val,left=None,right=None,parent=None):
        self.key = key
        self.payload = val
        self.leftChild = left
        self.rightChild = right
        self.parent = parent

    def hasLeftChild(self):
        return self.leftChild

    def hasRightChild(self):
        return self.rightChild

    def isLeftChild(self):
        return self.parent and self.parent.leftChild == self

    def isRightChild(self):
        return self.parent and self.parent.rightChild == self

    def isRoot(self):
        return not self.parent

    def isLeaf(self):
        return not (self.rightChild or self.leftChild)

    def hasAnyChildren(self):
        return self.rightChild or self.leftChild

    def hasBothChildren(self):
        return self.rightChild and self.leftChild

    def replaceNodeData(self,key,value,lc,rc):
        self.key = key
        self.payload = value
        self.leftChild = lc
        self.rightChild = rc
        if self.hasLeftChild():
            self.leftChild.parent = self
        if self.hasRightChild():
            self.rightChild.parent = self


class BinarySearchTree:

    def __init__(self):
        self.root = None

    def length(self):
        return self.size

    def __len__(self):
        return self.size

    def put(self,key,val):
        if self.root:
            self._put(key,val,self.root)
        else:
            self.root = TreeNode(key,val)

    def _put(self,key,val,currentNode):
        if key < currentNode.key:
            if currentNode.hasLeftChild():
                self._put(key,val,currentNode.leftChild)
            else:
                currentNode.leftChild = TreeNode(key,val,None,None,currentNode)
        else:
            if currentNode.hasRightChild():
                self._put(key,val,currentNode.rightChild)
            else:
                currentNode.rightChild = TreeNode(key,val,None,None,currentNode)

    def __setitem__(self,k,v):
        self.put(k,v)

    def get(self,key):
        if self.root:
            res = self._get(key,self.root)
            if res:
                return res.payload
            else:
                return None
        else:
            return None

    def _get(self,key,currentNode):
        if not currentNode:
            return None
        elif currentNode.key == key:
            return currentNode
        elif key < currentNode.key:
            return self._get(key,currentNode.leftChild)
        else:
            return self._get(key,currentNode.rightChild)

    def __getitem__(self,key):
        return self.get(key)

    def __contains__(self,key):
        if self._get(key,self.root):
            return True
        else:
            return False

    def delete(self,key):
        if self.root and self.root.hasAnyChildren():
            nodeToRemove = self._get(key,self.root)
            if nodeToRemove:
                self.remove(nodeToRemove)
            else:
                raise KeyError('Error, key not in tree')
        elif self.root and self.root.isLeaf() and self.root.key == key:
            self.root = None
        else:
            raise KeyError('Error, key not in tree')

    def __delitem__(self,key):
        self.delete(key)

    def spliceOut(self,currentNode):
        if currentNode.isLeaf():
            if currentNode.isLeftChild():
                currentNode.parent.leftChild = None
            else:
                currentNode.parent.rightChild = None
        elif currentNode.hasAnyChildren():
            if currentNode.hasLeftChild():
                if currentNode.isLeftChild():
                    currentNode.parent.leftChild = currentNode.leftChild
                else:
                    currentNode.parent.rightChild = currentNode.leftChild
                currentNode.leftChild.parent = currentNode.parent
            else:
                if currentNode.isLeftChild():
                    currentNode.parent.leftChild = currentNode.rightChild
                else:
                    currentNode.parent.rightChild = currentNode.rightChild
                currentNode.rightChild.parent = currentNode.parent

    def findSuccessor(self,currentNode):
        succ = None
        if currentNode.hasRightChild():
            succ = self.findMin(currentNode.rightChild)
        else:
            if currentNode.parent:
                if currentNode.isLeftChild():
                    succ = currentNode.parent
                else:
                    currentNode.parent.rightChild = None
                    succ = currentNode.parent.findSuccessor()
                    currentNode.parent.rightChild = currentNode
        return succ

    def findMin(self, currentNode): #returns a node with lowest key from subtree starting at currentNode
        while currentNode.hasLeftChild():
            currentNode = currentNode.leftChild
        return currentNode

    def remove(self,currentNode):
        if currentNode.isLeaf(): #leaf
            if currentNode == currentNode.parent.leftChild:
                currentNode.parent.leftChild = None
            else:
                currentNode.parent.rightChild = None
        elif currentNode.hasBothChildren(): #interior
            succ = self.findSuccessor(currentNode)
            self.spliceOut(succ)
            currentNode.key = succ.key
            currentNode.payload = succ.payload

        else: # this node has one child
            if currentNode.hasLeftChild():
                if currentNode.isLeftChild():
                    currentNode.leftChild.parent = currentNode.parent
                    currentNode.parent.leftChild = currentNode.leftChild
                elif currentNode.isRightChild():
                    currentNode.leftChild.parent = currentNode.parent
                    currentNode.parent.rightChild = currentNode.leftChild
                else:
                    currentNode.replaceNodeData(currentNode.leftChild.key,
                                    currentNode.leftChild.payload,
                                    currentNode.leftChild.leftChild,
                                    currentNode.leftChild.rightChild)
            else:
                if currentNode.isLeftChild():
                    currentNode.rightChild.parent = currentNode.parent
                    currentNode.parent.leftChild = currentNode.rightChild
                elif currentNode.isRightChild():
                    currentNode.rightChild.parent = currentNode.parent
                    currentNode.parent.rightChild = currentNode.rightChild
                else:
                    currentNode.replaceNodeData(currentNode.rightChild.key,
                                    currentNode.rightChild.payload,
                                    currentNode.rightChild.leftChild,
                                    currentNode.rightChild.rightChild)




#Demonstrating how it works:
mytree = BinarySearchTree()
mytree[3]="red"
mytree[4]="blue"
mytree[6]="yellow"
mytree[2]="green"
del mytree[3]

print(mytree[6])
print(mytree[2])