# Cmput 455 sample code
# Written by Martin Mueller
# Creates the sample tree of 
# https://en.wikipedia.org/wiki/Alpha–beta_pruning 
# returns dictionary with the tree in adjacency list form
# In the names, children of the root are labeled a, b, c.
# Below that level, 'l' stands for left-most child,
# 'r' for right-most child, and
# 'm' for middle child when there are three children.

from minimax_sample_tree_data import generateSampleTree

def opponent(player):
    if player == 'MIN':
        return 'MAX'
    else:
        return 'MIN'

class SampleTree(object):

    def __init__(self):
        self._tree, self._score = generateSampleTree()
        self.resetGame()

    def resetGame(self):
        self.toPlay = 'MAX'
        self.current = 'root'
        self.moves = []

    def switchToPlay(self):
        self.toPlay = opponent(self.toPlay)

    def play(self, location):
        assert not self.endOfGame()
        assert location in self._tree[self.current]
        self.moves.append(self.current)
        self.current = location
        self.switchToPlay()

    def undoMove(self):
        location = self.moves.pop()
        self.current = location
        self.switchToPlay()

    def staticallyEvaluate(self):
        assert self.endOfGame()
        return self._score[self.current]
        
    def staticallyEvaluateForToPlay(self):
        score = self.staticallyEvaluate()
        if 'MIN' == self.toPlay:
            return -score
        return score
    
    def endOfGame(self):
        return self._tree[self.current] == []

    def legalMoves(self):
        return self._tree[self.current]