#include <iostream>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <limits.h>
#include "Engine.h"

Engine::Engine(){
	Board* brd = new Board();
	b = brd;
}

void Engine::startGame(){
	cout<<"WELCOME\n";
	
	cout<<"1. Play against AI?\n";
	cout<<"2. Play against a human?\n";
	cout<<"Enter choice: \n";

	int choice = -1;
	cin >> choice;
	cout << "OK" << endl;

	string move;

	bool gameOver = false; 
	vector<Board> record;
	b->snapshot(record, *b);

	while (gameOver != true){
		gameOver = b->isGameOver();
		
		while(b->getTurn() == 'O' && !b->isValid()){
			b->displayBoard();
			cout<<"\nEnter command: ";
			cin>>move;
			cout << "\n";
			b->interpret(move, *b);
			
			if(b->isValid()){
				b->changeTurns();
				b->setValidFalse();
			}
		}
		
		while(b->getTurn() == 'X' ){
			//easyAI();
			AI(3);
		}
		
		gameOver = b->isGameOver();
		b->setValidFalse();
		
		b->snapshot(record, *b);
	}
}

void Engine::easyAI(){
	vector<moves> listOfMoves = b->viewPossibleMoves();
	
	srand(time(NULL));
	int randomChoice = rand() % (listOfMoves.size()-1) - 0;
	
	b->move(listOfMoves[randomChoice]);
	b->changeTurns();
}

void Engine::AI(int depth){
	Board* state = new Board(*b);
	moves m;
	MNode* root = new MNode(*state, m, 0);	
	createMMTree(root, depth);
	m = evaluateMMTree(root);

	/*
	printTree(0, root);
	cout << "\n";
	cout << "AI move: (" << m.row << ", " << m.column << "): " << m.moveType << "\n";
	*/

	b->move(m);
	b->changeTurns();
	b->displayBoard();
}

void Engine::createMMTree(MNode* node, int depth){
	MNode* temp;
	Board current = node->getState();
	vector<moves> listOfMoves = current.viewPossibleMoves();
	
	if (depth >= 0){
		for (int i = 0; i < listOfMoves.size(); ++i){
			if(current.getPiece(8 - listOfMoves[i].row, listOfMoves[i].column)->getType() == 
								current.getTurn() && current.isThisMovePossible(8 - listOfMoves[i].row, 
																				listOfMoves[i].column, 
																				listOfMoves[i].moveType)){
				current = current.move(listOfMoves[i]);
				current.changeTurns();
				temp = new MNode(current, listOfMoves[i], current.evaluate('X'));
				node->addChild(temp);
				createMMTree(temp, --depth);
				current.changeTurns();
			}
		}
	}

	return;
}

moves Engine::evaluateMMTree(MNode* node){
	//returns the move from children that maximizes evaluate()
	MNode* temp;
	moves m;
	int max = INT_MIN;
	int val;
	vector<MNode*> children = node->getChildren();
	
	for (auto &c : children){
		val = evaluateMMBranch(c, 0);
		if(val > max){
			temp = c;
			max = val;
		}
	}

	return temp->getMove();
}

//return sum of eval values
//pass in each child of root and 0
int Engine::evaluateMMBranch(MNode* node, int sum){
	sum += node->getMMVal();
	vector<MNode*> children = node->getChildren();
	
	for (auto &c : children){
		sum += evaluateMMBranch(c, sum);
	}
	
	return sum;
}