path: root/main.c

/*	Terrible winnable tic-tac-toe against the computer.
	Copyright (C) 2021, 2022 Gentoo-libre Install

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or (at
	your option) any later version.

	This program is distributed in the hope that it will be useful, but
	WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
	General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <time.h>

#define clear() printf("\033[H\033[J")
/* the board as a 1D array. It's global due to the want to easily access in from any function. */
char board[] ={"|---|---|---|\n| - | - | - |\n|---|---|---|\n| - | - | - |\n|---|---|---|\n| - | - | - |\n|---|---|---|\n"};
struct termios oldt,newt;//the struct used by the terminal mode changer. Global due to want of easy access from any function.
int pos[3][3] =
		{
		{16,20,24},
		{44,48,52},
		{72,76,80}
		}; //each number matches up to the position where the pieces should go on the board

int moves = 0; //the amount of moves done by the computer.

void checkWin(void)//check if the board is currently in a winning state
{
//leftright
int x;
int y;
int Xcount = 0;
int Ocount = 0;
for (x=0;x<3;++x)
	{
	for (y=0;y<3;++y)
		{
		if(board[pos[x][y]] == 'X'){++Xcount;}
		if(board[pos[x][y]] == 'O'){++Ocount;}
		if (Xcount == 3){goto Xwin;}
		if (Ocount == 3){goto Owin;}
		}
	Xcount = 0;
	Ocount = 0;
	}

//up/down
for (x=0;x<3;++x)
	{
	for (y=0;y<3;++y)
		{
		if(board[pos[y][x]] == 'X'){++Xcount;}
		if(board[pos[y][x]] == 'O'){++Ocount;}
		if (Xcount == 3){goto Xwin;}
		if (Ocount == 3){goto Owin;}
		}
	Xcount = 0;
	Ocount = 0;
	}

/* across topleft-bottomright */
if ((board[pos[0][0]] == 'X') && (board[pos[1][1]] == 'X') && (board[pos[2][2]] == 'X') ){goto Xwin;}
if ((board[pos[0][0]] == 'O') && (board[pos[1][1]] == 'O') && (board[pos[2][2]] == 'O') ){goto Owin;}

/* across bottomleft-topright */
if ((board[pos[2][0]] == 'X') && (board[pos[1][1]] == 'X') && (board[pos[0][2]] == 'X') ){goto Xwin;}
if ((board[pos[2][0]] == 'O') && (board[pos[1][1]] == 'O') && (board[pos[0][2]] == 'O') ){goto Owin;}





goto skip;//Skip over the winning exit code

/* exit here due to lack of want to exit 2(?) layers deep of loops */
Xwin: printf("Pathetic.\n"); tcsetattr( STDIN_FILENO, TCSANOW, &oldt ); exit(0); //return the terminal back to it's old state and exit
Owin: printf("You win! (Good job)\n"); tcsetattr( STDIN_FILENO, TCSANOW, &oldt ); exit(0); //return the terminal back to it's old state and exit

skip:;
}





void otherPlayer(void)//The other player takes a move when this function is called.
{
int x;
int y;
bool tie = true;
for (x=0;x<3;++x)
	{
	for (y=0;y<3;++y)
		{
		if (board[pos[x][y]] == '-'){tie = false;}
		}
	}

if (tie){printf("It's a tie. \n"); tcsetattr(STDIN_FILENO,TCSANOW,&oldt); exit(0);}

//if it's the second turn, there are a limited amount of moves to make
if (!moves)
	{
	if (board[pos[1][1]] == 'O')//if first move was center, a move in the 4 non-diaginal places should be made
		{
		int randNum = rand() % 4;//generate a pseudorandom number from 0 to 3.
		switch(randNum)
			{
			case 0:
				board[pos[0][0]] = 'X';
				goto skip;
			case 1:
				board[pos[2][0]] = 'X';
				goto skip;
			case 2:
				board[pos[0][2]] = 'X';
				goto skip;
			case 3:
				board[pos[2][2]] = 'X';
				goto skip;
			}
		}

	//if the player placed anywhere else, place in the center
	board[pos[1][1]] = 'X';
	goto skip;

	}


//leftright
int Xcount = 0;
for (x=0;x<3;++x)
	{
	for (y=0;y<3;++y)
		{
		if(board[pos[x][y]] == 'X'){++Xcount;}
		if ((Xcount == 2)&&(board[pos[x][y+1]] == '-')){board[pos[x][y+1]] = 'X'; goto skip;}
		}
	Xcount = 0;
	}

//up/down
for (x=0;x<3;++x)
	{
	for (y=0;y<3;++y)
		{
		if(board[pos[y][x]] == 'X'){++Xcount;}
		if ((Xcount == 2)&&(board[pos[x+1][y]] == '-')){board[pos[x+1][y]] = 'X'; goto skip;}
		}
	Xcount = 0;
	}

//across topleft-bottomright
if ((board[pos[0][0]] == 'X') && (board[pos[1][1]] == 'X') && (board[pos[2][2]] == '-') ){board[pos[2][2]] = 'X'; goto skip;}
if ((board[pos[0][0]] == '-') && (board[pos[1][1]] == 'X') && (board[pos[2][2]] == 'X') ){board[pos[0][0]] = 'X'; goto skip;}

//across bottomleft-topright
if ((board[pos[2][0]] == '-') && (board[pos[1][1]] == 'X') && (board[pos[0][2]] == 'X') ){board[pos[2][0]] = 'X'; goto skip;}
if ((board[pos[2][0]] == 'X') && (board[pos[1][1]] == 'X') && (board[pos[0][2]] == '-') ){board[pos[0][2]] = 'X'; goto skip;}



//copy the position of O's into an array for later processing
bool Ostate[3][3];
for (x=0;x<3;++x)
	{
	for (y=0;y<3;++y)
		{
		if (board[pos[x][y]] == 'O'){Ostate[x][y] = true;}
		else {Ostate[x][y] = false;}
		}
	}

bool Nstate[3][3]; //state is empty
for (x=0;x<3;++x)
	{
	for (y=0;y<3;++y)
		{
		if (board[pos[x][y]] == '-'){Nstate[x][y] = true;}
		else {Nstate[x][y] = false;}
		}
	}



//check for double moves including the center piece
if (Ostate[1][1])
	{
	int x;
	int y;
	int newx;
	int newy;
	for (x=0;x<3;++x)
		{
		for (y=0;y<3;++y)
			{
			if (Ostate[x][y])
				{
				//calculate move by applying these rules; if (x == 0){x=2;} if (x == 1){x=1;} if (x == 2){x=0;}
				if (!x){newx=2;}
				if (x==1){newx=1;}
				if (x==2){newx=0;}
				if (!y){newy=2;}
				if (y==1){newy=1;}
				if (y==2){newy=0;}
				if (board[pos[newx][newy]] == '-'){board[pos[newx][newy]] = 'X'; goto skip;}
				}
			}
		}

	}

//check for double moves including gap in space
if ((Ostate[0][0])&&(Ostate[0][2])&&(Nstate[0][1])){board[pos[0][1]] = 'X'; goto skip;}
if ((Ostate[0][2])&&(Ostate[2][2])&&(Nstate[1][2])){board[pos[1][2]] = 'X'; goto skip;}
if ((Ostate[2][2])&&(Ostate[2][0])&&(Nstate[2][1])){board[pos[2][1]] = 'X'; goto skip;}
if ((Ostate[2][0])&&(Ostate[0][0])&&(Nstate[1][0])){board[pos[1][0]] = 'X'; goto skip;}

//check for double moves not including center diagonally and vertically
//top row
if ((Ostate[0][0])&&(Ostate[0][1])&&(Nstate[0][2])){board[pos[0][2]] = 'X'; goto skip;}
if ((Ostate[0][2])&&(Ostate[0][1])&&(Nstate[0][0])){board[pos[0][0]] = 'X'; goto skip;}

//right down
if ((Ostate[0][2])&&(Ostate[1][2])&&(Nstate[2][2])){board[pos[2][2]] = 'X'; goto skip;}
if ((Ostate[2][2])&&(Ostate[1][2])&&(Nstate[0][2])){board[pos[0][2]] = 'X'; goto skip;}

//bottom row
if ((Ostate[2][0])&&(Ostate[2][1])&&(Nstate[2][2])){board[pos[2][2]] = 'X'; goto skip;}
if ((Ostate[2][2])&&(Ostate[2][1])&&(Nstate[2][0])){board[pos[2][0]] = 'X'; goto skip;}

//left down
if ((Ostate[2][0])&&(Ostate[1][0])&&(Nstate[0][0])){board[pos[0][0]] = 'X'; goto skip;}
if ((Ostate[0][0])&&(Ostate[1][0])&&(Nstate[2][0])){board[pos[2][0]] = 'X'; goto skip;}

//if all above was passed, just peform a random move
redo: x = rand() % 4;//generate a pseudorandom number from 0 to 3.
y = rand() % 4;//ditto
if (board[pos[x][y]] == '-'){board[pos[x][y]] = 'X';}
else{goto redo;}//generate random numbers again if the space wasn't free

skip:	clear();//clear the terminal
	printf("%s", board);//print the new board
	++moves;

}




int main(int argc, char *argv[])
{
if (argc > 1)
	{
	printf("Usage: %s\n\n\
	Controls:\nArrow keys to move cursor.\nPress any other key to take a move.\n\n\
	This in intentionally badly written.\n", argv[0]);
	exit(0);
	}

srand(time(NULL));//seed a srandom number generator very poorly with the time(should only be done once)
//modified is simply a copy of the board with the cursor written on it
char modified[] =
{
"|---|---|---|\n| - | - | - |\n|---|---|---|\n| - | - | - |\n|---|---|---|\n| - | - | - |\n|---|---|---|\n"
};

char c;//char used to recieve user input
tcgetattr(STDIN_FILENO, &oldt);//get the current state of the terminal
newt = oldt;//set the new state to the old state
newt.c_lflag &= ~( ICANON | ECHO );//disable ICANON and ECHO
tcsetattr(STDIN_FILENO,TCSANOW,&newt);//set the terminal to the new state

int cursor = 48;//the position of the cursor on the board(default is the center)
modified[cursor] = '#'; //Write the marker char to the current location of the cursor

clear(); //clear the screen ready for the board
printf("%s", modified);//print board with marker on it

while(1)//loop until a win or tie
{
if (getchar() == '\033')//ingnore escape char in front the symbol used to carry arrow key presses
	{
	getchar();//ignore '['
	c = getchar();//Get th arrow state.
	switch(c)//an arrow is pressed if 'A', 'B', 'C' or 'D' is recieved.
	{
	case 'A':
		if (cursor-14 < 0){break;}//Don't try to go up if we are on the first row
		cursor-=14;//move cursor to previous row
		memcpy(modified,board,strlen(board)+1);//refresh modified with board
		modified[cursor]='#';//write a marking char to the position of cursor
		clear();//clear the screen
		printf("%s", modified);//print the modified board
		//printf("Up arrow\n");
		break;

	case 'B':
		if (cursor+14 >= strlen(board)){break;}//If we are on the last row, don't increment further
		cursor+=14;//move x to next row
		memcpy(modified,board,strlen(board)+1);//refresh bord with a blank one
		modified[cursor]='#';//write a marking char to the position
		clear();//clear the screen
		printf("%s", modified);//print the modified board
		//printf("Down arrow\n");
		break;
	case 'C':
		if (cursor==(strlen(board+1))){break;}//don't go past the end of the board
		++cursor;//move cursor right
		if ((board[cursor]) == '\n'){--cursor; break;}//If going right will lead to a newline, don't
		memcpy(modified,board,strlen(board)+1);//refresh board with the default
		modified[cursor]='#';//write a marking char to the position
		clear();//clear the screen
		printf("%s", modified);//print the modified board
		//printf("Right arrow\n");
		break;
	case 'D':
		if (cursor-1<0){break;}//don't attempt to go to -1 in board
		--cursor;//move cursor left
		if ((board[cursor]) == '\n'){++cursor; break;}//If going left will lead to a newline, don't
		memcpy(modified,board,strlen(board)+1);//refresh board with the default
		modified[cursor]='#';//write a marking char to the position
		clear();//clear the screen
		printf("%s", modified);//print the modified board
		//printf("Left arrow\n");
		break;
	default:
		clear(); //to correct an issue where is seems that any key resulted in the last pressed arrow key direction, the board is cleared and reset.
		printf("%s", modified);
		break;
	}
	}
else //if any other key than an arrow key was pressed, we end up here
	{
	int x;//x cord.
	int y;//y cord.
	for(x=0;x<3;++x)
		{
		for(y=0;y<3;++y)
			{
			if (pos[x][y] == cursor){goto checkBoard;}//If cursor is the position of a valid move place, keep the value of x and y
			}
		}
	goto noMove; //if the above goto doesn't trigger, cursor is not in a valid move place

	checkBoard: if (board[pos[x][y]] != '-'){goto noMove;}//move has already been made

	board[pos[x][y]] = 'O';//write an 'O' to the board.
	modified[pos[x][y]] = 'O';//write that to the modified board too.
	clear();//clear the terminal
	printf("%s", modified);//print the modified board
	checkWin();//check if the move made was a winning move.
	otherPlayer();//make the CPU take a move
	checkWin();//check if the CPU move made was a winning one.
	noMove: ;
	}
}


tcsetattr(STDIN_FILENO,TCSANOW,&oldt);//return the terminal back to it's old state, this should never be reached though.
return 1;//if we exit here, something has gone wrong
}