path: root/chess.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "vector.h"
#include "console.h"
#include "chesshelpers.h"

vectorp_t get_pawn_moves(int** board, vector_t position, int color) {
	vector_t* moves = malloc(6 * sizeof(vector_t));
	int moveCount = 0;
	int forwardDir = (color == 0 ? -1 : 1);
	vector_t move1 = init_vector(position.mx, position.my + forwardDir);
	if(in_board(move1) && is_empty(board, move1)) {
		moves[moveCount] = move1;
		moveCount++;
		if(position.my == (color == 0 ? 6 : 1)) {
			vector_t move2 = init_vector(position.mx, position.my + (forwardDir * 2));
			if(is_empty(board, move2)) {
				moves[moveCount] = move2;
				moveCount++;
			}
		}
	}
	vector_t captureL = init_vector(position.mx - 1, position.my + forwardDir);
	if(in_board(captureL) && is_color(board, captureL, !color)) {
		moves[moveCount] = captureL;
		moveCount++;
	}
	vector_t captureR = init_vector(position.mx + 1, position.my + forwardDir);
	if(in_board(captureR) && is_color(board, captureR, !color)) {
		moves[moveCount] = captureR;
		moveCount++;
	}
	return init_vectorp(moves, moveCount);
}
vectorp_t get_knight_moves(int** board, vector_t position, int color) {
	vector_t* moves = malloc(8 * sizeof(vector_t));
	int moveCount = 0;
	for(int i = 0; i < 8; i++) {
		int h = ((i == 0 || i == 1) ? 2 : (i == 2 || i == 3) ? -2 : (i == 4 || i == 5) ? 1 : -1);
		int v = ((i == 0 || i == 2) ? -1 : (i == 1 || i == 3) ? 1 : (i == 4 || i == 6) ? 2 : -2);
		vector_t move = init_vector(position.mx + h, position.my + v);
		if(in_board(move) && (is_empty(board, move) || is_color(board, move, !color))) {
			moves[moveCount] = move;
			moveCount++;
		}
	}
	return init_vectorp(moves, moveCount);
}
vectorp_t get_bishop_moves(int** board, vector_t position, int color) {
	vector_t* moves = malloc(14 * sizeof(vector_t));
	int moveCount = 0;
	for(int i = 0; i < 4; i++) {
		int h = i < 2 ? 1 : -1;
		int v = (i == 0 || i == 2) ? 1 : -1;
		vector_t checkPos = init_vector(position.mx, position.my);
		for(int d = 0; d < 7; d++) {
			checkPos.mx += h;
			checkPos.my += v;
			if(in_board(checkPos)) {
				if(is_empty(board, checkPos)) {
					moves[moveCount] = init_vector(checkPos.mx, checkPos.my);
					moveCount++;
				}
				else if(is_color(board, checkPos, !color)) {
					moves[moveCount] = init_vector(checkPos.mx, checkPos.my);
					moveCount++;
					break;
				}
				else {
					break;
				}
			}
			else {
				break;
			}
		}
	}
	return init_vectorp(moves, moveCount);
}
vectorp_t get_rook_moves(int** board, vector_t position, int color) {
	vector_t* moves = malloc(14 * sizeof(vector_t));
	int moveCount = 0;
	for(int i = 0; i < 4; i++) {
		int h = (i == 0 || i == 2) ? 0 : i == 1 ? 1 : -1;
		int v = (i == 1 || i == 3) ? 0 : i == 2 ? 1 : -1;
		vector_t checkPos = init_vector(position.mx, position.my);
		for(int d = 0; d < 7; d++) {
			checkPos.mx += h;
			checkPos.my += v;
			if(in_board(checkPos)) {
				if(is_empty(board, checkPos)) {
					moves[moveCount] = init_vector(checkPos.mx, checkPos.my);
					moveCount++;
				}
				else if(is_color(board, checkPos, !color)) {
					moves[moveCount] = init_vector(checkPos.mx, checkPos.my);
					moveCount++;
					break;
				}
				else {
					break;
				}
			}
			else {
				break;
			}
		}
	}
	return init_vectorp(moves, moveCount);
}
vectorp_t get_queen_moves(int** board, vector_t position, int color) {
	vector_t* moves = malloc(28 * sizeof(vector_t));
	int moveCount = 0;
	for(int i = 0; i < 8; i++) {
		int h;
		int v;
		//diagonal moves
		if(i < 4) {
			h = i < 2 ? 1 : -1;
			v = (i == 0 || i == 2) ? 1 : -1;
		}
		//straight moves
		else {
			h = (i == 4 || i == 6) ? 0 : i == 5 ? 1 : -1;
			v = (i == 5 || i == 7) ? 0 : i == 6 ? 1 : -1;
		}
		vector_t checkPos = init_vector(position.mx, position.my);
		for(int d = 0; d < 7; d++) {
			checkPos.mx += h;
			checkPos.my += v;
			if(in_board(checkPos)) {
				if(is_empty(board, checkPos)) {
					moves[moveCount] = init_vector(checkPos.mx, checkPos.my);
					moveCount++;
				}
				else if(is_color(board, checkPos, !color)) {
					moves[moveCount] = init_vector(checkPos.mx, checkPos.my);
					moveCount++;
					break;
				}
				else {
					break;
				}
			}
			else {
				break;
			}
		}
	}
	return init_vectorp(moves, moveCount);
}
//this function returns moves that will place the player in check!
vectorp_t get_moves(int** board, vector_t position, piece_t piece) {
	int color = 0;
	if(piece > 6) {
		color = 1;
		piece -= 6;
	}
	if(piece == pawn) {
		return get_pawn_moves(board, position, color);
	}
	else if(piece == knight) {
		return get_knight_moves(board, position, color);
	}
	else if(piece == bishop) {
		return get_bishop_moves(board, position, color);
	}
	else if(piece == rook) {
		return get_rook_moves(board, position, color);
	}
	else if(piece == queen) {
		return get_queen_moves(board, position, color);
	}
	else {
		return init_vectorp(0, 0);
	}
}
//array of arrays representing all the moves each piece of color can make
vectorpp_t get_all_moves(int** board, int color) {
	vectorp_t* allMoves = malloc(16 * sizeof(vectorp_t));
	int pieceCount = 0;
	for(int r = 0; r < 8; r++) {
		for(int c = 0; c < 8; c++) {
			vector_t v = init_vector(c, r);
			if(is_color(board, v, color)) {
				allMoves[pieceCount] = get_moves(board, v, board[c][r]);
				pieceCount++;
			}
		}
	}
	allMoves = realloc(allMoves, pieceCount * sizeof(vectorp_t));
	return init_vectorpp(allMoves, pieceCount);
}
//returns the position of color's king
vector_t get_king_position(int** board, int color) {
	for(int r = 0; r < 8; r++) {
		for(int c = 0; c < 8; c++) {
			if(board[c][r] == (king + color * 6)) {
				return init_vector(c, r);
			}
		}
	}
}
//returns true if the player of color is currently in check
int is_in_check(int** board, int color) {
	int returnV = 0;
	vector_t kingPos = get_king_position(board, color);
	//get all the moves for the opponent
	vectorpp_t allMoves = get_all_moves(board, !color);
	for(int i = 0; i < allMoves.length; i++) {
		vectorp_t moves = allMoves.vectorps[i];
		for(int j = 0; j < moves.length; j++) {
			if(moves.vectors[j].mx == kingPos.mx && moves.vectors[j].my == kingPos.my) {
				returnV = 1;
			}
		}
		free(moves.vectors);
	}
	free(allMoves.vectorps);
	return returnV;
}
//this function removes moves that place you in check
vectorp_t get_moves_final(int** board, vector_t position, piece_t piece) {
	int color = 0;
	if(piece > 6) {
		color = 1;
	}
	vectorp_t moves = get_moves(board, position, piece);
	//try making that move, see if it puts the player in check
	int* invalidMoves = malloc(moves.length * sizeof(int));
	int invalidMovesCount = 0;
	for(int i = 0; i < moves.length; i++) {
		int** tempBoard = clone_board(board);
		tempBoard[moves.vectors[i].mx][moves.vectors[i].my] = piece;
		//remove the piece from where it was
		tempBoard[position.mx][position.my] = 0;
		if(is_in_check(tempBoard, color)) {
			invalidMoves[invalidMovesCount];
			invalidMovesCount++;
		}
		free(tempBoard);
	}
	vectorp_t finalMoves = remove_vectors(moves, invalidMoves, invalidMovesCount);
	free(invalidMoves);
	free(moves.vectors);
	return finalMoves;
}
int main() {
	//set up the board
	int boardA[8][8] = { 
		{ rook + 6, pawn + 6, 0, 0, 0, 0, pawn, rook }, 
		{ knight + 6, pawn + 6, 0, 0, 0, 0, pawn, knight },
		{ bishop + 6, pawn + 6, 0, 0, 0, 0, pawn, bishop },
		{ queen + 6, pawn + 6, 0, 0, 0, 0, pawn, queen },
		{ king + 6, pawn + 6, 0, 0, 0, 0, pawn, king },
		{ bishop + 6, pawn + 6, 0, 0, 0, 0, pawn, bishop },
		{ knight + 6, pawn + 6, 0, 0, 0, 0, pawn, knight },
		{ rook + 6, pawn + 6, 0, 0, 0, 0, pawn, rook }
	}; 
	//convert the array to pointers
	int** board = malloc(8 * sizeof(int*));
	for(int r = 0; r < 8; r++) {
		board[r] = malloc(8 * sizeof(int));
		for(int c = 0; c < 8; c++) {
			board[r][c] = boardA[r][c];
		}
	}
	int turn = 0;
	while(1) {
		//draw the board, write some info
		clear_screen();
		draw_board(board);
		printf(turn == 0 ? "\nWhite's turn\n" : "\nBlack's turn\n");
		if(is_in_check(board, turn)) {
			printf("You're in check!\n");
		}
		printf("Enter the coordinates of the piece you want to move\n");
		//get the selection for the piece to be moved
		vector_t selection = user_input_pos();
		int selectedPiece = board[selection.mx][selection.my];
		//check if the piece is of the right colour, and that there is a piece there
		if(selectedPiece == 0 || (selectedPiece > 6 && turn == 0) || (selectedPiece <= 6 && turn == 1)) {
			warn_user("Invalid selection!");
			continue;
		}
		printf("Selected piece: ");
		printf("%d", selectedPiece);
		printf("\n");
		vectorp_t moves = get_moves_final(board, selection, selectedPiece);
		if(moves.length == 0) {
			warn_user("That piece has no valid moves!");
			continue;
		}
		printf("Valid moves: ");
		//write all the valid moves
		for(int i = 0; i < moves.length; i++) {
			char* readable_coords = get_move_name(board, selection, moves.vectors[i]);
			printf(readable_coords);
			free(readable_coords);
			printf("; ");
		}
		printf("\nEnter the coordinates you would like to move that piece to, or enter < to go back\n");
		//get the selection for the location to move the piece to
		vector_t target = user_input_pos();
		if(target.mx == -1) {
			continue;
		}
		//check if target is in list of valid moves
		int match = 0;
		for(int i = 0; i < moves.length; i++) {
			if(moves.vectors[i].mx == target.mx && moves.vectors[i].my == target.my) {
				match = 1;
				break;
			}
		}
		if(!match) {
			warn_user("Invalid move");
			continue;
		}
		board[selection.mx][selection.my] = 0;
		board[target.mx][target.my] = selectedPiece;
		printf("\n");
		turn = !turn;
	}	
	return 0;
}