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

Engine::Engine(){
	Board* brd = new Board();
	b = brd;
	alpha = INT_MIN;
	beta = INT_MAX;
}

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

	int choice = -1;
	cin >> choice;
	cout<<"Enter AI difficulty: \n";
	int difficulty;
	cin >> difficulty;
	
	cout << "OK" << endl;

	if (choice == 1)
		userGame(difficulty);
	else if (choice == 2)
		AIGame(difficulty);
	else {
		cout << "Please enter a valid choice.\n";
		startGame();
	}
}

void Engine::userGame(int difficulty){
	string move;

	bool gameOver = false; 
	vector<Board> record;
	b->snapshot(record, *b);
	cin.ignore();
	cin.clear();
	
	while (gameOver != true){
		gameOver = b->isGameOver();
		
		while(b->getTurn() == 'O' && !b->isValid()){
			b->displayBoard();
			cout<<"\nEnter command: ";
			cin.clear();
			getline(cin, move);
			cout << "\n";
			parse(move, *b);
			
			if(b->isValid()){
				b->changeTurns();
				b->resetTaken();
				b->setValidFalse();
			}
			b->displayBoard();
		}
		
		while(b->getTurn() == 'X' ){
			AI(difficulty);
		
			gameOver = b->isGameOver();
			b->setValidFalse();
			b->snapshot(record, *b);
			b->displayBoard();
		}
	}
	
	string s = "";
	s += b->getTurn();
	cout << "Game over. " + s + " wins!\n\n";
}

void Engine::AIGame(int difficulty){
	bool gameOver = false;

	while (gameOver != true){
		gameOver = b->isGameOver();
		
		while(b->getTurn() == 'O'){
			AI(difficulty);
		}
		
		b->displayBoard();
		sleep(1);
		
		while(b->getTurn() == 'X' ){
			AI(difficulty);
		}
		
		b->displayBoard();
		sleep(1);
		gameOver = b->isGameOver();
	}
	
	string s = "";
	s += b->getTurn();
	cout << "Game over. " + s + " wins!\n\n";
}

void Engine::AI(int depth){
	if (depth == -1)
		depth = INT_MAX;
	
	Board* state = new Board(*b);
	moves m;
	MNode* root = new MNode(*state, m, 0);
	this->resetAB();
	createMMTree(root, depth, 1);
	m = evaluateMMTree(root);
	
	b->move(m);
	b->changeTurns();
	b->resetTaken();
}

void Engine::createMMTree(MNode* node, int depth, int alt){
	MNode* temp;
	char max, min;
	bool cond = true;
	Board current = node->getState();
	vector<moves> listOfMoves = current.viewPossibleMoves();
	
	if (node->getType() == "max"){
		if (node->getMMVal() <= alpha){
			cond = false;
		}
	}
	
	else if (node->getType() == "min"){
		if (node->getMMVal() >= beta){
			cond = false;
		}
	}
	
	if (depth >= 0){
		for (int i = 0; i < listOfMoves.size(); ++i){
			if(current.getPiece(listOfMoves[i].row, listOfMoves[i].column)->getType() == 
								current.getTurn() && current.isThisMovePossible(listOfMoves[i].row, 
																				listOfMoves[i].column, 
																				listOfMoves[i].moveType)){
				if (cond){
					current.resetTaken();
					current = current.move(listOfMoves[i]);
					max = current.getTurn();
					current.changeTurns();
					min = current.getTurn();
					
					temp = new MNode(current, listOfMoves[i], current.evaluate(max, min));
					
					if (alt == 1)
						temp->setType("max");
					else if (alt == -1)
						temp->setType("min");
					
					current.resetTaken();
					node->addChild(temp);
					
					alt = alt * -1;
					createMMTree(temp, --depth, alt);
					
					current.changeTurns();
				}
			}
		}
	}
	
	else {
		if (node->getType() == "max"){
			if (node->getMMVal() > alpha){
				alpha = node->getMMVal();
			}
		}
		
		else if (node->getType() == "min"){
			if (node->getMMVal() < beta){
				beta = node->getMMVal();
			}
		}
	}
	
	return;
}

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

int Engine::evaluateMMBranch(MNode* node, int max, int min){
	vector<MNode*> children = node->getChildren();
	
	for (auto &c : children){
		evaluateMMBranch(c, max, min);
	}
	
	if (node->getMMVal() > max)
		max = node->getMMVal();
	
	if (node->getMMVal() < min)
		min = node->getMMVal();
	
	return max;
}

void Engine::resetAB(){
	alpha = INT_MIN;
	beta = INT_MAX;
}