/*
 * Hw01_121044046.cpp
 *
 *  Created on: 23 Eyl 2014
 *      Author: Yakup TURKAN
 *
 *      Project Name : The Game of Life
 *      Purpose : Implementing game of life(Von
 */

#include <iostream>
#include <cstdlib>
#include <cstdio>

using namespace std;

#define FILLER "-"

#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif

//Prototypes
struct cell_s {
	int isAlive; //1 = Alive 0 = Dead
};

struct board_s {
	int rowc;
	int colc;
	struct cell_s *cells;
};

struct event_s {
	struct cell_s *cell;
	struct event_s *nextEvent;
};

struct board_s *initBoard(char *filename);
void nextStep(struct board_s *board);
void printBoard(struct board_s *board);
void printBoard(struct board_s *board, char *filename);
struct cell_s *getCell(struct board_s *board, int x, int y);
struct event_s *addEvent(struct event_s *eventc, struct cell_s *cell);
struct event_s *queEvents(struct board_s *board);
void pollEvents(struct event_s *eventh);

int main(int argc, char **argv) {
	char filename[FILENAME_MAX];
	struct board_s *board;
	int stepc;

	cout << "Please enter the file name : ";
	cin >> filename;

	cout << "Initial form of file : " << endl;
	board = initBoard(filename);
	printBoard(board);

	cout << "How many steps you want to see ? : ";
	cin >> stepc;

	while (cin.get() != '\n');

	for (int i = 0; i < stepc; ++i) {
		cout << "Step " << i + 1 << " : " << endl;
		nextStep(board);
		printBoard(board);
		while (cin.get() != '\n')
			;
	}

	cout << "Please enter the output file name : ";
	cin >> filename;

	printBoard(board, filename);

	free(board->cells);
	return 0;
}

struct board_s *initBoard(char *filename) {
	FILE *file;
	static struct board_s board;
	int rowc, colc;
	char c;

	file = fopen(filename, "r");

	if (file != NULL) {
		fscanf(file, "%d %d%c", &rowc, &colc,&c);

		if (c == '\r')
			fscanf(file, "%c", &c);

		board.rowc = rowc;
		board.colc = colc;
		board.cells = (struct cell_s *) malloc(
				sizeof(struct cell_s) * rowc * colc);

		for (int i = 0; i < rowc; ++i) {
			for (int j = 0; j < colc; ++j) {
				fscanf(file, "%c", &c);

				if (c == 'X' || c == 'x')
					board.cells[i * colc + j].isAlive = TRUE;
				else
					board.cells[i * colc + j].isAlive = FALSE;
			}
			fscanf(file, "%c", &c);

			if (c == '\r')
				fscanf(file, "%c", &c);
		}
	} else
		cout << "Error occurred : Cannot read file." << endl
		<< "Please make sure file exists."
		<< " If error persists contact with writer." << endl;

	fclose(file);
	return &board;
}

void nextStep(struct board_s *board) {
	pollEvents(queEvents(board));
}

void printBoard(struct board_s *board) {
	struct cell_s *cells = board->cells;
	int rowc = board->rowc, colc = board->colc;

	for (int i = 0; i < rowc; ++i) {
		for (int j = 0; j < colc; ++j)
			if (cells[i * colc + j].isAlive)
				cout << 'X';
			else
				cout << FILLER;
		cout << endl;
	}
}

void printBoard(struct board_s *board, char *filename) {
	struct cell_s *cells = board->cells;
	int rowc = board->rowc, colc = board->colc;
	FILE *outp;

	outp = fopen(filename, "w");

	if (outp == NULL) {
		cout << "An error occurred : Cannot write to file!" << endl
				<< "Please contact with writer." << endl;
	} else {
		for (int i = 0; i < rowc; ++i) {
			for (int j = 0; j < colc; ++j)
				if (cells[i * colc + j].isAlive)
					fprintf(outp, "X");
				else
					fprintf(outp, FILLER);
			fprintf(outp, "\n");
		}
		fclose(outp);
	}
}

struct cell_s *getCell(struct board_s *board, int x, int y) {
	if (x >= 0 && x < board->colc)
		if (y >= 0 && y < board->rowc)
			return &(board->cells[y * board->colc + x]);

	return NULL;
}

struct event_s *addEvent(struct event_s *eventc, struct cell_s *cell) {
	struct event_s *eventn;

	eventn = (struct event_s *) malloc(sizeof(struct event_s));
	eventn->cell = cell;
	eventn->nextEvent = NULL;

	if (eventc != NULL)
		eventc->nextEvent = eventn;

	return eventn;
}

struct event_s *queEvents(struct board_s *board) {
	struct cell_s *cellc, *celln;
	struct event_s *eventh = NULL, *eventc = NULL;
	int ans,	//Alive Neighbor Count
	shouldAdd;

	for (int row = 0; row < board->rowc; ++row) {
		for (int col = 0; col < board->colc; ++col) {
			ans = 0;
			shouldAdd = TRUE;
			cellc = getCell(board, col, row);

			for (int distx = -1; distx < 2; ++distx) {
				for (int disty = -1; disty < 2; ++disty) {
					celln = getCell(board, distx + col, row + disty);
					if (celln != NULL && celln->isAlive)
						++ans;
				}
			}

			if (cellc->isAlive) {
				if (ans == 3 || ans == 4)
					shouldAdd = FALSE;
			} else if (ans != 3)
				shouldAdd = FALSE;

			if (shouldAdd) {
				if (eventh == NULL) {
					eventh = addEvent(eventh, cellc);
					eventc = eventh;
				} else
					eventc = addEvent(eventc, cellc);
			}
		}
	}

	return eventh;
}

void pollEvents(struct event_s *eventh) {
	struct cell_s *cell;

	if (eventh != NULL) {
		cell = eventh->cell;

		//Births
		if (!cell->isAlive)
			cell->isAlive = TRUE;
		//Deaths
		else if (cell->isAlive)
			cell->isAlive = FALSE;

		pollEvents(eventh->nextEvent);
		free(eventh);
	}
}