/*  DreamChess
**
**  DreamChess is the legal property of its developers, whose names are too
**  numerous to list here. Please refer to the AUTHORS.txt file distributed
**  with this source distribution.
**
**  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 <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "commands.h"
#include "dreamer.h"
#include "e_comm.h"
#include "git_rev.h"
#include "history.h"
#include "move.h"
#include "repetition.h"
#include "san.h"
#include "search.h"
#include "timer.h"
#include "transposition.h"

static int is_coord_move(char *ms) {
	int len = strlen(ms);
	/* Check format. */
	if ((len < 4) || (len > 5))
		return 0;
	if ((ms[0] < 'a') || (ms[0] > 'h') || (ms[1] < '1') || (ms[1] > '8') || (ms[2] < 'a') || (ms[2] > 'h') ||
		(ms[3] < '1') || (ms[3] > '8'))
		return 0;

	if (len == 5)
		switch (ms[4]) {
		case 'q':
		case 'r':
		case 'n':
		case 'b':
			return 1;
		default:
			return 0;
		}

	return 1;
}

static int convert_piece(int san_piece) {
	switch (san_piece) {
	case SAN_KING:
		return KING;
	case SAN_QUEEN:
		return QUEEN;
	case SAN_ROOK:
		return ROOK;
	case SAN_KNIGHT:
		return KNIGHT;
	case SAN_BISHOP:
		return BISHOP;
	case SAN_PAWN:
		return PAWN;
	}

	/* We should never get here */
	assert(0);
}

static int san_piece(int piece) {
	switch (piece) {
	case KING:
		return SAN_KING;
	case QUEEN:
		return SAN_QUEEN;
	case ROOK:
		return SAN_ROOK;
	case KNIGHT:
		return SAN_KNIGHT;
	case BISHOP:
		return SAN_BISHOP;
	case PAWN:
		return SAN_PAWN;
	}

	/* We should never get here */
	assert(0);
}

static move_t get_san_move(board_t *board, int ply, san_move_t *san) {
	move_t move;
	int piece;
	bitboard_t en_passant = board->en_passant;
	int castle_flags = board->castle_flags;
	int fifty_moves = board->fifty_moves;
	int found = 0;
	move_t found_move;

	if (san->type == SAN_QUEENSIDE_CASTLE) {
		san->source_file = 4;
		san->source_rank = (board->current_player == SIDE_WHITE ? 0 : 7);
		san->destination = (board->current_player == SIDE_WHITE ? 2 : 58);
		piece = KING + board->current_player;
	} else if (san->type == SAN_KINGSIDE_CASTLE) {
		san->source_file = 4;
		san->source_rank = (board->current_player == SIDE_WHITE ? 0 : 7);
		san->destination = (board->current_player == SIDE_WHITE ? 6 : 62);
		piece = KING + board->current_player;
	} else
		piece = convert_piece(san->piece) + board->current_player;

	compute_legal_moves(board, ply);

	/* Look for move in list. */
	while ((move = move_next(board, ply)) != NO_MOVE) {
		int move_piece;

		if (MOVE_GET(move, DEST) != san->destination)
			continue;

		if (board->current_player == SIDE_WHITE)
			move_piece = find_white_piece(board, MOVE_GET(move, SOURCE));
		else
			move_piece = find_black_piece(board, MOVE_GET(move, SOURCE));

		if (move_piece != piece)
			continue;

		if (san->source_file != SAN_NOT_SPECIFIED)
			if (san->source_file != MOVE_GET(move, SOURCE) % 8)
				continue;

		if (san->source_rank != SAN_NOT_SPECIFIED)
			if (san->source_rank != MOVE_GET(move, SOURCE) / 8)
				continue;

		if (san->type == SAN_CAPTURE) {
			/* TODO verify en passant capture? */
			if (!(move & (CAPTURE_MOVE_EN_PASSANT | CAPTURE_MOVE)))
				continue;
		}

		if ((move & PROMOTION_MOVE_QUEEN) && (san->promotion_piece != SAN_QUEEN))
			continue;
		if ((move & PROMOTION_MOVE_ROOK) && (san->promotion_piece != SAN_ROOK))
			continue;
		if ((move & PROMOTION_MOVE_BISHOP) && (san->promotion_piece != SAN_BISHOP))
			continue;
		if ((move & PROMOTION_MOVE_KNIGHT) && (san->promotion_piece != SAN_KNIGHT))
			continue;
		if (!(move & MOVE_PROMOTION_MASK) && (san->promotion_piece != SAN_NOT_SPECIFIED))
			continue;

		/* TODO verify check and checkmate flags? */

		execute_move(board, move);
		board->current_player = OPPONENT(board->current_player);
		if (!is_check(board, ply + 1)) {
			found++;
			found_move = move;
		}

		board->current_player = OPPONENT(board->current_player);
		unmake_move(board, move, en_passant, castle_flags, fifty_moves);
	}

	if (found != 1)
		return NO_MOVE;

	return found_move;
}

static move_t get_coord_move(board_t *board, int ply, char *ms) {
	int source, dest;
	move_t move;

	source = (ms[0] - 'a') + 8 * (ms[1] - '1');
	dest = (ms[2] - 'a') + 8 * (ms[3] - '1');

	compute_legal_moves(board, ply);

	/* Look for move in list. */
	while ((move = move_next(board, ply)) != NO_MOVE) {
		if ((MOVE_GET(move, SOURCE) == source) && (MOVE_GET(move, DEST) == dest)) {
			bitboard_t en_passant = board->en_passant;
			int castle_flags = board->castle_flags;
			int fifty_moves = board->fifty_moves;

			/* Move found. */
			execute_move(board, move);
			board->current_player = OPPONENT(board->current_player);
			if (!is_check(board, ply + 1)) {
				board->current_player = OPPONENT(board->current_player);
				unmake_move(board, move, en_passant, castle_flags, fifty_moves);
				break;
			}
			board->current_player = OPPONENT(board->current_player);
			unmake_move(board, move, en_passant, castle_flags, fifty_moves);
		}
	}
	if (move != NO_MOVE) {
		if (move & MOVE_PROMOTION_MASK) {
			/* Set correct promotion piece. */
			move &= ~MOVE_PROMOTION_MASK;
			if (strlen(ms) == 5)
				switch (ms[4]) {
				case 'q':
					move |= PROMOTION_MOVE_QUEEN;
					break;
				case 'r':
					move |= PROMOTION_MOVE_ROOK;
					break;
				case 'n':
					move |= PROMOTION_MOVE_KNIGHT;
					break;
				case 'b':
					move |= PROMOTION_MOVE_BISHOP;
				}
			else {
				/* No promotion piece specified. */
				return NO_MOVE;
			}
			return move;
		}
		if (strlen(ms) == 4)
			return move;
	}
	return NO_MOVE;
}

char *coord_move_str(move_t move) {
	char *ret = malloc(6);
	ret[5] = '\0';
	ret[0] = 'a' + MOVE_GET(move, SOURCE) % 8;
	ret[1] = '1' + MOVE_GET(move, SOURCE) / 8;
	ret[2] = 'a' + MOVE_GET(move, DEST) % 8;
	ret[3] = '1' + MOVE_GET(move, DEST) / 8;
	switch (move & MOVE_PROMOTION_MASK) {
	case PROMOTION_MOVE_QUEEN:
		ret[4] = 'q';
		break;
	case PROMOTION_MOVE_BISHOP:
		ret[4] = 'b';
		break;
	case PROMOTION_MOVE_KNIGHT:
		ret[4] = 'n';
		break;
	case PROMOTION_MOVE_ROOK:
		ret[4] = 'r';
		break;
	default:
		ret[4] = '\0';
	}
	return ret;
}

char *san_move_str(board_t *board, int ply, move_t move) {
	san_move_t san_move;
	int state;
	int move_piece;
	bitboard_t en_passant = board->en_passant;
	int castle_flags = board->castle_flags;
	int fifty_moves = board->fifty_moves;

	execute_move(board, move);
	state = check_game_state(board, ply);
	unmake_move(board, move, en_passant, castle_flags, fifty_moves);

	switch (state) {
	case STATE_CHECK:
		san_move.state = SAN_STATE_CHECK;
		break;
	case STATE_MATE:
		san_move.state = SAN_STATE_CHECKMATE;
		break;
	default:
		san_move.state = SAN_STATE_NORMAL;
	}

	switch (MOVE_GET(move, TYPE)) {
	case CASTLING_MOVE_QUEENSIDE:
		san_move.type = SAN_QUEENSIDE_CASTLE;
		return san_string(&san_move);
	case CASTLING_MOVE_KINGSIDE:
		san_move.type = SAN_KINGSIDE_CASTLE;
		return san_string(&san_move);
	case CAPTURE_MOVE:
	case CAPTURE_MOVE_EN_PASSANT:
		san_move.type = SAN_CAPTURE;
		break;
	default:
		san_move.type = SAN_NORMAL;
	}

	if (board->current_player == SIDE_WHITE)
		move_piece = find_white_piece(board, MOVE_GET(move, SOURCE)) & PIECE_MASK;
	else
		move_piece = find_black_piece(board, MOVE_GET(move, SOURCE)) & PIECE_MASK;

	san_move.piece = san_piece(move_piece);

	if (MOVE_GET(move, TYPE) & MOVE_PROMOTION_MASK)
		san_move.promotion_piece = san_piece(MOVE_GET(move, CAPTURED) & PIECE_MASK);
	else
		san_move.promotion_piece = SAN_NOT_SPECIFIED;

	san_move.source_file = SAN_NOT_SPECIFIED;
	san_move.source_rank = SAN_NOT_SPECIFIED;
	san_move.destination = MOVE_GET(move, DEST);

	if (san_move.piece == SAN_PAWN) {
		if (MOVE_GET(move, SOURCE) % 8 != MOVE_GET(move, DEST) % 8)
			san_move.source_file = MOVE_GET(move, SOURCE) % 8;
	} else {
		move_t u_move;
		u_move = get_san_move(board, ply, &san_move);

		if (u_move == NO_MOVE) {
			san_move.source_file = MOVE_GET(move, SOURCE) % 8;
			u_move = get_san_move(board, ply, &san_move);
			if (u_move == NO_MOVE) {
				san_move.source_file = SAN_NOT_SPECIFIED;
				san_move.source_rank = MOVE_GET(move, SOURCE) / 8;
				u_move = get_san_move(board, ply, &san_move);
				if (u_move == NO_MOVE) {
					san_move.source_file = MOVE_GET(move, SOURCE) % 8;
					u_move = get_san_move(board, ply, &san_move);
					if (!u_move) {
						char *move_s = coord_move_str(move);

						e_comm_send("failed to convert move %s to SAN notation", move_s);

						free(move_s);
						return NULL;
					}
				}
			}
		}
	}

	return san_string(&san_move);
}

static void error(char *type, char *command) {
	e_comm_send("Error (%s): %s\n", type, command);
}

#define NOT_NOW(c) error("command not legal now", c)
#define UNKNOWN(c) error("unknown command", c)
#define BADPARAM(c) error("invalid or missing parameter(s)", c)

static int parse_time_control(state_t *state, char *s) {
	struct time_control t;
	char *end;
	char *semi;

	errno = 0;
	t.mps = strtol(s, &end, 10);

	if (errno || *end != ' ')
		return 1;

	semi = strchr(end + 1, ':');

	if (semi) {
		*semi = ' ';
		t.base = strtol(end + 1, &end, 10) * 60 * 100;
		*semi = ':';

		if (errno || end != semi)
			return 1;

		t.base += strtol(end + 1, &end, 10) * 100;

		if (errno || *end != ' ')
			return 1;
	} else {
		t.base = strtol(end + 1, &end, 10) * 60 * 100;

		if (errno || *end != ' ')
			return 1;
	}

	t.inc = strtol(end + 1, &end, 10) * 100;

	if (errno || *end != 0)
		return 1;

	/* Time control with both mps and inc is invalid */
	if (t.mps != 0 && t.inc != 0)
		return 1;

	state->time = t;
	timer_set(&state->engine_time, t.base);
	return 0;
}

static int command_always(state_t *state, char *command) {
	if (!strcmp(command, "post")) {
		set_option(OPTION_POST, 1);
		return 1;
	}

	if (!strcmp(command, "nopost")) {
		set_option(OPTION_POST, 0);
		return 1;
	}

	if (!strncmp(command, "time ", 5)) {
		int time;
		char *end;
		errno = 0;
		time = strtol(command + 5, &end, 10);
		if (errno || *end != 0)
			BADPARAM(command);
		else
			timer_set(&state->engine_time, time);
		return 1;
	}

	if (!strncmp(command, "otim ", 5))
		return 1;

	return 0;
}

int parse_move(board_t *board, int ply, char *command, move_t *move) {
	san_move_t *san;

	san = san_parse(command);

	if (san) {
		*move = get_san_move(board, ply, san);
		free(san);
		return 0;
	} else if (is_coord_move(command)) {
		*move = get_coord_move(board, ply, command);
		return 0;
	}

	return 1;
}

int command_usermove(state_t *state, char *command) {
	move_t move;

	if (!parse_move(&state->board, 0, command, &move)) {
		if (move == NO_MOVE) {
			e_comm_send("Illegal move: %s\n", command);
			return 0;
		}

		if (my_turn(state)) {
			NOT_NOW(command);
			return 0;
		}

		if (state->mode == MODE_WHITE || state->mode == MODE_BLACK)
			timer_start(&state->engine_time);

		do_move(state, move);
		check_game_end(state);

		if (state->mode == MODE_IDLE)
			state->mode = (state->board.current_player == SIDE_WHITE ? MODE_WHITE : MODE_BLACK);

		if (state->ponder_my_move != NO_MOVE) {
			/* We already have a possible answer to this move from pondering. */
			if (move == state->ponder_opp_move && MOVE_IS_REGULAR(state->ponder_my_move)) {
				/* User made the expected move. */
				send_move(state, state->ponder_my_move);
			}

			state->ponder_my_move = NO_MOVE;
		}

		return 0;
	}

	return 1;
}

void command_handle(state_t *state, char *command) {
	if (command_always(state, command))
		return;

	if (!strcmp(command, "xboard")) {
		/* xboard mode is default. */
		return;
	}

	if (!strncmp(command, "protover ", 9)) {
		char *endptr;
		errno = 0;
		strtol(command + 9, &endptr, 10);

		if (errno || (*endptr != 0))
			BADPARAM(command);

		e_comm_send("feature myname=\"Dreamer %s\"\n", g_version);
		e_comm_send("feature setboard=1\n");
		e_comm_send("feature colors=0\n");
		e_comm_send("feature done=1\n");
		return;
	}

	if (!strncmp(command, "level ", 6)) {
		if (parse_time_control(state, command + 6))
			BADPARAM(command);

		return;
	}

	if (!strncmp(command, "accepted ", 9)) {
		if (!strcmp(command + 9, "setboard") || !strcmp(command + 9, "done") || !strcmp(command + 9, "myname") ||
			!strcmp(command + 9, "colors"))
			return;

		BADPARAM(command);
		return;
	}

	if (!strcmp(command, "new")) {
		setup_board(&state->board);
		forget_history();
		clear_table();
		pv_clear();
		repetition_init(&state->board);
		state->done = 0;
		state->mode = MODE_BLACK;
		state->flags = 0;
		state->depth = MAX_DEPTH;

		if (state->undo_data != NULL)
			free(state->undo_data);
		state->undo_data = NULL;

		state->moves = 0;
		timer_init(&state->engine_time, 1);
		timer_set(&state->engine_time, state->time.base * 60 * 100);
		timer_init(&state->move_time, 1);

		state->hint = NO_MOVE;
		state->ponder_opp_move = NO_MOVE;
		state->ponder_my_move = NO_MOVE;
		state->ponder_actual_move = NO_MOVE;
		return;
	}

	if (!strcmp(command, "quit")) {
		state->mode = MODE_QUIT;
		return;
	}

	if (!strcmp(command, "force")) {
		state->mode = MODE_FORCE;
		return;
	}

	if (!strcmp(command, "white")) {
		if (state->board.current_player != SIDE_WHITE) {
			/* FIXME, we should support this, but right now it would cause
			** severe problems with the undo system.
			*/
			NOT_NOW(command);
			return;
		}
		state->mode = MODE_BLACK;
		return;
	}

	if (!strcmp(command, "black")) {
		if (state->board.current_player != SIDE_BLACK) {
			/* FIXME, see above. */
			NOT_NOW(command);
			return;
		}
		state->mode = MODE_WHITE;
		return;
	}

	if (!strcmp(command, "playother")) {
		if (state->mode != MODE_FORCE) {
			NOT_NOW(command);
			return;
		}

		if (state->board.current_player == SIDE_WHITE)
			state->mode = MODE_BLACK;
		else
			state->mode = MODE_WHITE;
		return;
	}

	if (!strncmp(command, "sd", 2)) {
		char *number = strchr(command, ' ');
		char *end;
		if (number && (*(number + 1) != '\0')) {
			long int val = strtol(number + 1, &end, 10);
			if ((*end == '\0') && (val > 0))
				state->depth = val;
			else
				BADPARAM(command);
		} else
			BADPARAM(command);
		return;
	}

	if (!strcmp(command, "go")) {
		if (state->board.current_player == SIDE_WHITE)
			state->mode = MODE_WHITE;
		else
			state->mode = MODE_BLACK;
		return;
	}

	if (!strcmp(command, "remove")) {
		switch (state->mode) {
		case MODE_WHITE:
			if (state->board.current_player == SIDE_WHITE) {
				NOT_NOW(command);
				return;
			}
			break;
		case MODE_BLACK:
			if (state->board.current_player == SIDE_BLACK) {
				NOT_NOW(command);
				return;
			}
			break;
		case MODE_FORCE:
			break;
		default:
			NOT_NOW(command);
			return;
		}

		if (state->moves < 2)
			NOT_NOW(command);

		undo_move(state);
		undo_move(state);
		state->done = 0;
		return;
	}

	if (!strcmp(command, "?")) {
		NOT_NOW(command);
		return;
	}

	if (!strncmp(command, "setboard ", 9)) {
		board_t board;

		if (state->mode != MODE_FORCE) {
			NOT_NOW(command);
			return;
		}

		if (setup_board_fen(&board, command + 9)) {
			BADPARAM(command);
			return;
		}

		state->board = board;
		forget_history();
		clear_table();
		repetition_init(&state->board);
		state->done = 0;
		return;
	}

	if (!strcmp(command, "noquiesce")) {
		set_option(OPTION_QUIESCE, 0);
		return;
	}

	if (!strcmp(command, "easy")) {
		set_option(OPTION_PONDER, 0);
		state->ponder_my_move = NO_MOVE;
		return;
	}

	if (!strcmp(command, "hard")) {
		set_option(OPTION_PONDER, 1);
		if (state->moves != 0)
			state->flags |= FLAG_PONDER;
		return;
	}

	if (!strcmp(command, "hint")) {
		if (state->hint != NO_MOVE) {
			char *str = coord_move_str(state->hint);
			e_comm_send("Hint: %s\n", str);
			free(str);
		}
		return;
	}

	if (!command_usermove(state, command))
		return;

	UNKNOWN(command);
}

int command_check_abort(state_t *state, int ply, char *command) {
	if (!strcmp(command, "?")) {
		if (my_turn(state))
			return 1;
	}

	if (command_always(state, command))
		return 0;

	if (!strcmp(command, "new")) {
		state->flags = FLAG_NEW_GAME | FLAG_IGNORE_MOVE;
		return 1;
	}

	if (!strcmp(command, "quit") || !strcmp(command, "force")) {
		state->flags = FLAG_IGNORE_MOVE;
		command_handle(state, command);
		return 1;
	}

	if (!strcmp(command, "easy")) {
		if (state->flags & FLAG_PONDER) {
			state->flags = FLAG_IGNORE_MOVE;
			state->ponder_actual_move = NO_MOVE;
		}
		command_handle(state, command);
		return 1;
	}

	if (!strcmp(command, "hint")) {
		if (state->flags & FLAG_PONDER) {
			char *str = coord_move_str(state->ponder_opp_move);
			e_comm_send("Hint: %s\n", str);
			free(str);
			return 0;
		}
	}

	if (state->flags & FLAG_PONDER) {
		move_t move;

		if (!parse_move(&state->root_board, ply, command, &move)) {
			if (move == NO_MOVE) {
				e_comm_send("Illegal move: %s\n", command);
				return 0;
			}

			/* Start our timer */
			timer_start(&state->engine_time);

			if (move == state->ponder_opp_move) {
				/* User made the expected move. */
				state->flags = 0;
				return 0;
			} else {
				/* User made a different move, abort and restart search. */
				state->flags = FLAG_IGNORE_MOVE;
				state->ponder_actual_move = move;
				return 1;
			}
		}
	}

	NOT_NOW(command);
	return 0;
}