/************************************************************************************* 
* Filename:   A3Part3.cpp                                            Scott O'Brien   *           
* Login:   sob401                                                                    * 
* LAB: A                                                                             * 
* Assignment: 3, Q3                                                                  * 
* File Description:  Connect 4 game                                                  * 
*                                                                                    * 
*                                                                                    * 
*                                                                                    * 
* Date Last Modified: 09/05/2007                                                     * 
*************************************************************************************/ 

#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;

const int COL = 8;
const int ROW = 6;

struct GameState
{
	char board[ROW][COL];
	char symbol;
	char nextTurn;
};

void drawHeader();
char chooseOption();
void initialiseBoard(GameState &);
void drawBoard(GameState);
int playMove(GameState &);
void computerMove(GameState &);
bool makeMove(GameState &, int);
int checkWinner(GameState &);
bool saveGame(GameState, char[255]);
bool loadGame(GameState &, char[255]);
bool checkDraw(GameState);

int main () 
{
	//Set up the game board
	drawHeader();
	char option = chooseOption();
	GameState game;
	initialiseBoard(game);
	
	int MoveResult;
	int winner;
	char playAgain;
	char inputResult;
					
	do
	{
		switch(option)
		{
			case 'a':
				cout << "\nPlaying against computer, good luck!\n";
				do
				{
					drawBoard(game);
					if(checkDraw(game))
					{
						cout << "\nDRAW! No more moves possible, game over!";
						option = chooseOption();
					}
					else
					{
						MoveResult = playMove(game);
						winner = checkWinner(game);
						if(MoveResult && !winner && !checkDraw(game))
						{
							drawBoard(game);
							computerMove(game);
							winner = checkWinner(game);
						}
					}
				} while(MoveResult && !winner && !checkDraw(game));
				if(MoveResult)
					switch(winner)
					{
						case 0:
							cout << "\n\nDRAW! No more moves possible, game over!\n";
							break;
						case 1:
							cout << "\n\nCongratulations, you have beaten the computer!\n\n";
							break;
						case 2:
							drawBoard(game);
							cout << "\n\nBad luck, the computer beat you.\n\n";
					}
				if(MoveResult)
				{
					cout << "Do you want to start a new game (y/n)?: ";
					cin >> playAgain; cin.clear(); //Clear the input stream inclase more then one input was entered
					playAgain = tolower(playAgain);
					if(playAgain == 'n')
						option = 'd';
				}
				else
				{
					cout << "Do you want to save the game? :";
					cin >> inputResult; cin.clear(); // Clear the input stream in case more then one input character was sent.
					inputResult = tolower(inputResult);
					if(inputResult == 'y')
					{
						cout << "Enter name of file to save as: ";
						char fileName[255];
						cin >> fileName;
						if(saveGame(game, fileName))
							cout << "\nGame saved!\n";
					}
				}
				initialiseBoard(game);
				option = chooseOption();
				break;
			case 'b':
				bool isDraw;
				do
				{
					winner = checkWinner(game);
					isDraw = checkDraw(game);
					drawBoard(game);
					switch(winner)
					{
						case 0:
							if(!isDraw)
								MoveResult = playMove(game);
							else
								cout << "\nDRAW! No more moves possible, game over!\n";
							break;
						case 1:
							cout << "\nPlayer 1 is the winner\n";
							break;
						case 2:
							cout << "\nPlayer 2 is the winner\n";
					}
				} while(MoveResult && !winner && !isDraw);
								
				//Ask the user if they wish to save the game if there is no result
				if(!winner && !isDraw)
				{
					cout << "Do you want to save the game? :";
					cin >> inputResult; cin.clear(); //Clear the input stream inclase more then one input was entered
					inputResult = tolower(inputResult);
					if(inputResult == 'y')
					{
						cout << "Enter name of file to save as: ";
						char fileName[255];
						cin >> fileName;
						if(saveGame(game, fileName))
							cout << "\nGame saved!\n";
					}
					else {
						cout << "Do you want to start a new game (y/n)?: ";
						cin >> inputResult; cin.clear(); //Clear the input stream inclase more then one input was entered
						inputResult = tolower(inputResult);
					}
				}
				else
					inputResult = 'y';
				initialiseBoard(game);
				if(inputResult == 'n')
					option = 'd';
				else
					option = chooseOption();
				break;
			case 'c':
				char fileName[255];
				cout << "Enter name of game to load: ";
				cin >> fileName;
				loadGame(game, fileName);
				option = chooseOption();
				break;
		}
	} while(option != 'd');
	cout << "\nThanks for playing Connect Four, the game of the clever people!";
	return 0;
}

void drawHeader()
{
	cout << "*********************************************************\n"
	<< "*                  Connect Four                         *\n"
	<< "*********************************************************\n"
	<< "Welcome to the Connect Four computer game. You can choose\n"
	<< "to play against another player or against the computer\n"
	<< "(not implemented in this version).\n"
	<< "In this game the first player to position four of his/her\n"
	<< "pieces on a line will win. The line can be horizontal,\n"
	<< "vertical or at an angle, but the 4 pieces must be next to\n"
	<< "each other.\n"
	<< "*********************************************************\n";
}

char chooseOption()
{
	char choice;
	//Options is in a loop to make sure a valid option gets entered.
	do {
		cout << "*************************************\n"
		<< "*          Choose an Option         *\n"
		<< "*************************************\n"
		<< "* a) Play against the computer      *\n"
		<< "* b) Play against another player    *\n"
		<< "* c) Load game                      *\n"
		<< "* d) Quit                           *\n"
		<< "*************************************\n"
		<< "Enter your choice: ";
		cin >> choice; cin.clear();
		choice = tolower(choice);
		if(choice < 'a' || choice > 'd')
			cout << "Invalid input!\n\n";
	} while(choice < 'a' || choice > 'd');
	return choice;
}

void initialiseBoard(GameState &game)
{
	for(int rowLoop=0; rowLoop < ROW; rowLoop++)
		for(int colLoop=0; colLoop < COL; colLoop++)
			game.board[rowLoop][colLoop] = '.';
	game.nextTurn = '1';
	game.symbol = 'O';
}

void drawBoard(GameState game)
{
	for(int rowLoop=0; rowLoop < ROW; rowLoop++)
	{
		for(int colLoop=0; colLoop < COL; colLoop++)
			cout << ' ' << game.board[rowLoop][colLoop];
		cout << endl;
	}
	for(int i=1; i <= COL; i++)
		cout << ' ' << i;
	cout << endl;
}

int playMove(GameState &game)
{
	//Gets a number from the user, and loops untill a valid number (between 1-COL) has been chosen
	//And there is room for the user to move in this column.
	int choice;
	cout << "Player " << game.nextTurn << " move (1-" << COL << ", 0 to quit): ";
	cin >> choice;
	while(cin.fail()) //in case characters are entered
	{
		cout << "\nInvalid input!\n";
		cin.clear();			//clear flag so that input can be read
		cin.ignore(200,'\n');  //flush the input buffer	  
		cout << "Player " << game.nextTurn << " move (1-" << COL << ", 0 to quit): ";
		cin >> choice;
	}
	while((choice < 0 || choice > COL) || (choice != 0 && makeMove(game, choice-1) == false))
	{
		if(choice >= 0 && choice <= COL)
			cout << "\nSorry no more room in this column...\n\n";
		else
			cout << "\nInvalid input!\n";
		cout << "Player " << game.nextTurn << " move (1-" << COL << ", 0 to quit): ";
		cin >> choice;
		while(cin.fail()) //in case characters are entered
		{
			cout << "\nInvalid input!\n";
			cin.clear();			//clear flag so that input can be read
			cin.ignore(200,'\n');  //flush the input buffer	  
			cout << "Player " << game.nextTurn << " move (1-" << COL << ", 0 to quit): ";
			cin >> choice;
		}
	}
	if(!choice)
		return 0;
//	makeMove(game, choice-1);
	return choice;
}

void computerMove(GameState &game)
{
	srand(time(0));
	int move;
	do 
		move = rand() % 8;
	while (!makeMove(game, move));
	cout << "Computer move: " << move + 1 << endl;
	
}

bool makeMove(GameState &game, int slot)
{
	/*
	 The purpose of this function is to simulate a 'drop' of a piece in a column.
	 This function will return false if the move can't be made, or True if the move
	 can be made, and will adjust the GameState to reflect the desired move
	 */
	if(game.board[0][slot] != '.')
		return false;
	bool done = false;
	for(int i=ROW-1; i >= 0 && !done; i--)
		if(game.board[i][slot] == '.')
		{
			game.board[i][slot] = game.symbol;
			game.symbol = (game.symbol == 'X' ? 'O' : 'X');
			game.nextTurn = (game.nextTurn == '1' ? '2' : '1');
			done = true;
		}
	return true;
}

int checkWinner(GameState &game)
{
	//Check the rows
	char lastChr;
	int counter;
	for(int row = ROW; row >= 0; row--)
	{
		lastChr = '.';
		counter = 1;
		for(int col = 0; col < COL; col++)
			if(lastChr != '.' && game.board[row][col] == lastChr)
			{
				if(++counter == 4)
					return (lastChr == 'O' ? 1 : 2);
			}
			else
			{
				counter = 1;
				lastChr = game.board[row][col];
			}
	}
	for(int col = 0; col < COL; col++)
	{
		lastChr = '.';
		counter = 1;
		for(int row = 0; row < ROW; row++)
			if(lastChr != '.' && game.board[row][col] == lastChr)
			{
				if(++counter == 4)
					return (lastChr == 'O' ? 1 : 2);
			}
			else
			{
				counter = 1;
				lastChr = game.board[row][col];
			}
	}
	//Check diagonals
	for(int row = 2; row >= 0; row--)
	{
		lastChr = '.';
		counter = 1;
		for(int col = 0; col < COL - row - 2; col++)
			if(lastChr != '.' && game.board[row+col][col] == lastChr)
			{
				if(++counter == 4)
					return (lastChr == 'O' ? 1 : 2);
			}
			else
			{
				counter = 1;
				lastChr = game.board[row+col][col];
			}
	}
	lastChr = '.';
	counter = 1;
	for(int i=0; i< 6; i++)
		if(lastChr != '.' && game.board[i][i+1] == lastChr)
		{
			if(++counter == 4)
				return (lastChr == 'O' ? 1 : 2);
		}
		else
		{
			counter = 1;
			lastChr = game.board[i][i+1];
		}

	for(int col = 2; col < COL - 3; col++)
	{
		lastChr = '.';
		counter = 1;
		for(int row = 0; row < ROW -col +2; row++)
			if(lastChr != '.' && game.board[row][col+row] == lastChr)
			{
				if(++counter == 4)
					return (lastChr == 'O' ? 1 : 2);
			}
			else
			{
				counter = 1;
				lastChr = game.board[row][col+row];
			}
	}
	
	for(int row=3; row < 6; row++)
	{
		lastChr = '.';
		counter = 1;
		for(int col=0; col < row + 1; col++)
			if(lastChr != '.' && game.board[row-col][col] == lastChr)
			{
				if(++counter == 4)
					return (lastChr == 'O' ? 1 : 2);
			}
			else
			{
				counter = 1;
				lastChr = game.board[row-col][col];
			}
	}
	lastChr = '.';
	counter = 1;
	for(int i=0; i < 6; i++)
		if(lastChr != '.' && game.board[5-i][i+1] == lastChr)
		{
			if(++counter == 4)
				return (lastChr == 'O' ? 1 : 2);
		}
		else
		{
			counter = 1;
			lastChr = game.board[5-i][i+1];
		}

	for(int col=0; col < 3; col++)
	{
		lastChr = '.';
		counter = 1;
		for(int row=col; row < 6; row++)
			if(lastChr != '.' && game.board[5-row+col][row+2] == lastChr)
			{
				if(++counter == 4)
					return (lastChr == 'O' ? 1 : 2);
			}
			else
			{
				counter = 1;
				lastChr = game.board[5-row+col][row+2];
			}
	}

//	}
	return 0;
}

bool saveGame(GameState game, char fileName[255])
{
	ofstream saveFile(fileName, ios::out);
	
	if(!saveFile)
	{
		cout << "Error opening file.  The game could not be saved!\n";
		return false;
	}
	for(int rowLoop=0; rowLoop < ROW; rowLoop++)
	{
		for(int colLoop=0; colLoop < COL; colLoop++)
			saveFile.put(game.board[rowLoop][colLoop]);
		if(rowLoop < ROW -1)
			saveFile.put('#');
	}
	saveFile.put(game.symbol);
	saveFile.put(game.nextTurn);
	saveFile.close();
	return true;
}

bool loadGame(GameState &game, char fileName[255])
{
	ifstream loadFile;
	loadFile.open(fileName);
	if(!loadFile)
	{
		cout << "Error opening the file.  The game could not be loaded!\n";
		return false;
	}
	for(int rowLoop=0; rowLoop < ROW && !loadFile.fail(); rowLoop++)
	{
		for(int colLoop=0; colLoop < COL; colLoop++)
			loadFile.get(game.board[rowLoop][colLoop]);
		if(rowLoop < ROW -1)
			loadFile.get();
	}
	loadFile.get(game.symbol);
	loadFile.get(game.nextTurn);
	if(loadFile.fail())
	{
		cout << "Error reading from the file.  The game could not be loaded!\n";
		return false;
	}
	cout << "\nGame loaded!\n\n";
	loadFile.close();
	return true;
}

bool checkDraw(GameState game)
{
	bool isDraw = true;
	for(int col = 0; col < COL && isDraw; col++)
		if(game.board[0][col] == '.')
			isDraw = false;
	return isDraw;
}