#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void draw_board(int boardState[3][3]) {
	for(int r = 0; r < 3; r++) {
		char* line = calloc(3, 1);
		for(int c = 0; c < 3; c++) {
			if(boardState[c][r] == 0) {
				line[c] = '-';
			}
			else if(boardState[c][r] == 1) {
				line[c] = 'x';
			}
			else if(boardState[c][r] == 2) {
				line[c] = 'o';
			}
			else {
				line[c] = 'E';
			}
		}
		printf(line);
		printf("\n");
		free(line);
	}
}
int check_dir(int sx, int sy, int dx, int dy, int boardState[3][3]) {
	int sv = boardState[sx][sy];
	if(sv != 0) {
		for(int i = 0; i < 2; i++) {
			sx += dx;
			sy += dy;
			if(boardState[sx][sy] != sv) {
				return 0;
			}
		}
		return sv;
	}
	return 0;
}
//return 0 if no win, 1 if x win, 2 if o win
int check_win(int boardState[3][3]) {
	if(boardState[1][1] != 0) {
		int c = check_dir(1, 0, 0, 1, boardState);
		if(c != 0) {
			return c;
		}
		c = check_dir(0, 0, 1, 1, boardState);
		if(c != 0) {
			return c;
		} 
		c = check_dir(0, 1, 1, 0, boardState);
		if(c != 0) {
			return c;
		} 
		c = check_dir(0, 2, 1, -1, boardState);
		if(c != 0) {
			return c;
		} 
	}
	if(boardState[0][0] != 0) {
		int c = check_dir(0, 0, 1, 0, boardState);
		if(c != 0) {
			return c;
		}
		c = check_dir(0, 0, 0, 1, boardState);
		if(c != 0) {
			return c;
		}
	}
	if(boardState[2][2] != 0) {
		int c = check_dir(2, 2, -1, 0, boardState);
		if(c != 0) {
			return c;
		}
		c = check_dir(2, 2, 0, -1, boardState);
		if(c != 0) {
			return c;
		}
	}
	return 0;
}
int is_full(int boardState[3][3]) {
	//if all squares full, return 1
	//else return 0
	for(int r = 0; r < 3; r++) {
		for(int c = 0; c < 3; c++) {
			if(boardState[c][r] == 0) {
				return 0;
			}
		}
	}
	return 1;
}
int get_game_state(int boardState[3][3]) {
	//0 if game in progress, 1 if x win, 2 if o win, 3 if drawn
	int w = check_win(boardState);
	if(w == 1 || w == 2) {
		return w;
	}
	else if(is_full(boardState)) {
		return 3;
	}
	else {
		return 0;
	}
}
int* user_input_pos(int boardState[3][3], int turn) {
	int* ip = malloc(2 * sizeof(int));
	printf("Enter X coordinate");
	scanf("%d", &ip[0]); 
	printf("Enter Y coordinate");
	scanf("%d", &ip[1]); 
	return ip;
}
struct PosInfo {
	int* pos;
	int eval;
};
struct PosInfo minimax(int boardState[3][3], int turn) {
	int eval;
	int bestMove[2] = { -1, -1 }; 
	int s = get_game_state(boardState);
	if(s == 1) {
		eval = 10;
	}
	else if(s == 2) {
		eval = -10;
	}
	else if(s == 3) {
		eval = 0;
	}
	else {
		eval = -999;
		for(int r = 0; r < 3; r++) {
			for(int c = 0; c < 3; c++) {
				if(boardState[c][r] == 0) {
					int simBoard[3][3];
					//deep copy boardState to simBoard
					for(int i = 0; i < 9; i++) {
						simBoard[i % 3][i / 3] = boardState[i % 3][i / 3];
					} 
					simBoard[c][r] = turn + 1;
					struct PosInfo mr = minimax(simBoard, !turn);
					if((turn == 0 && mr.eval > eval) || (turn == 1 && mr.eval < eval) || eval == -999) {
						eval = mr.eval;
						bestMove[0] = c;
						bestMove[1] = r;
					}
				}
			}
		}
	}
	//don't forget to clean up bestmove pointers
	struct PosInfo posInfo;
	posInfo.eval = eval;
	posInfo.pos = bestMove; 
	return posInfo;
}
int* ai_input_pos(int boardState[3][3], int turn) {
	struct PosInfo i = minimax(boardState, turn);
	int* nPos = malloc(2 * sizeof(int));
	nPos[0] = i.pos[0];
	nPos[1] = i.pos[1];
	return nPos;
}
void clear_screen() {
    system("@cls||clear");
}
int main() {
	int board[3][3] = { { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 } };
	int turn = 0;
	int* (*get_move_ptrs[2])(int[3][3], int) = { &user_input_pos, &ai_input_pos };
	while(1) {
		clear_screen();
		draw_board(board);
		int* tl = get_move_ptrs[turn](board, turn);
		board[tl[0]][tl[1]] = turn + 1;
		free(tl);
		int s = get_game_state(board);
		if(s == 1 || s == 2) {
			clear_screen();
			draw_board(board);
			printf("Someone won!");
			printf("\n");
			break;
		}
		if(s == 3) {
			printf("Game is drawn!");
			printf("\n");
			break;
		}
		turn = !turn;
	}
	return 0;
}