/*      $OpenBSD: makemaze.c,v 1.10 2017/01/21 08:22:57 krw Exp $       */
/*      $NetBSD: makemaze.c,v 1.2 1997/10/10 16:33:43 lukem Exp $       */
/*
 * Copyright (c) 1983-2003, Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * + Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * + Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * + Neither the name of the University of California, San Francisco nor
 *   the names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior written
 *   permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/select.h>
#include <string.h>

#include "conf.h"
#include "hunt.h"
#include "server.h"

# define        ISCLEAR(y,x)    (Maze[y][x] == SPACE)
# define        ODD(n)          ((n) & 01)

static  int     candig(int, int);
static  void    dig(int, int);
static  void    dig_maze(int, int);
static  void    remap(void);

void
makemaze(void)
{
        char    *sp;
        int     y, x;

        /*
         * fill maze with walls
         */
        sp = &Maze[0][0];
        while (sp < &Maze[HEIGHT - 1][WIDTH])
                *sp++ = DOOR;

        x = rand_num(WIDTH / 2) * 2 + 1;
        y = rand_num(HEIGHT / 2) * 2 + 1;
        dig_maze(x, y);
        remap();
}

# define        NPERM   24
# define        NDIR    4

int     dirs[NPERM][NDIR] = {
                {0,1,2,3},      {3,0,1,2},      {0,2,3,1},      {0,3,2,1},
                {1,0,2,3},      {2,3,0,1},      {0,2,1,3},      {2,3,1,0},
                {1,0,3,2},      {1,2,0,3},      {3,1,2,0},      {2,0,3,1},
                {1,3,0,2},      {0,3,1,2},      {1,3,2,0},      {2,0,1,3},
                {0,1,3,2},      {3,1,0,2},      {2,1,0,3},      {1,2,3,0},
                {2,1,3,0},      {3,0,2,1},      {3,2,0,1},      {3,2,1,0}
        };

int     incr[NDIR][2] = {
                {0, 1}, {1, 0}, {0, -1}, {-1, 0}
        };

static void
dig(int y, int x)
{
        int     *dp;
        int     *ip;
        int     ny, nx;
        int     *endp;

        Maze[y][x] = SPACE;                     /* Clear this spot */
        dp = dirs[rand_num(NPERM)];
        endp = &dp[NDIR];
        while (dp < endp) {
                ip = &incr[*dp++][0];
                ny = y + *ip++;
                nx = x + *ip;
                if (candig(ny, nx))
                        dig(ny, nx);
        }
}

/*
 * candig:
 *      Is it legal to clear this spot?
 */
static int
candig(int y, int x)
{
        int     i;

        if (ODD(x) && ODD(y))
                return FALSE;           /* can't touch ODD spots */

        if (y < UBOUND || y >= DBOUND)
                return FALSE;           /* Beyond vertical bounds, NO */
        if (x < LBOUND || x >= RBOUND)
                return FALSE;           /* Beyond horizontal bounds, NO */

        if (ISCLEAR(y, x))
                return FALSE;           /* Already clear, NO */

        i = ISCLEAR(y, x + 1);
        i += ISCLEAR(y, x - 1);
        if (i > 1)
                return FALSE;           /* Introduces cycle, NO */
        i += ISCLEAR(y + 1, x);
        if (i > 1)
                return FALSE;           /* Introduces cycle, NO */
        i += ISCLEAR(y - 1, x);
        if (i > 1)
                return FALSE;           /* Introduces cycle, NO */

        return TRUE;                    /* OK */
}

static void
dig_maze(int x, int y)
{
        int     tx, ty;
        int     i, j;
        int     order[4];
#define MNORTH  0x1
#define MSOUTH  0x2
#define MEAST   0x4
#define MWEST   0x8

        tx = ty = 0;
        Maze[y][x] = SPACE;
        order[0] = MNORTH;
        for (i = 1; i < 4; i++) {
                j = rand_num(i + 1);
                order[i] = order[j];
                order[j] = 0x1 << i;
        }
        for (i = 0; i < 4; i++) {
                switch (order[i]) {
                  case MNORTH:
                        tx = x;
                        ty = y - 2;
                        break;
                  case MSOUTH:
                        tx = x;
                        ty = y + 2;
                        break;
                  case MEAST:
                        tx = x + 2;
                        ty = y;
                        break;
                  case MWEST:
                        tx = x - 2;
                        ty = y;
                        break;
                }
                if (tx < 0 || ty < 0 || tx >= WIDTH || ty >= HEIGHT)
                        continue;
                if (Maze[ty][tx] == SPACE)
                        continue;
                Maze[(y + ty) / 2][(x + tx) / 2] = SPACE;
                dig_maze(tx, ty);
        }
}

static void
remap(void)
{
        int     y, x;
        char    *sp;
        int     stat;

        for (y = 0; y < HEIGHT; y++)
                for (x = 0; x < WIDTH; x++) {
                        sp = &Maze[y][x];
                        if (*sp == SPACE)
                                continue;
                        /* Find occupied adjacent cells. */
                        stat = 0;
                        if (y - 1 >= 0 && Maze[y - 1][x] != SPACE)
                                stat |= NORTH;
                        if (y + 1 < HEIGHT && Maze[y + 1][x] != SPACE)
                                stat |= SOUTH;
                        if (x + 1 < WIDTH && Maze[y][x + 1] != SPACE)
                                stat |= EAST;
                        if (x - 1 >= 0 && Maze[y][x - 1] != SPACE)
                                stat |= WEST;
                        switch (stat) {
                          case WEST | EAST:
                          case EAST:
                          case WEST:
                                *sp = WALL1;                       /* - */
                                break;
                          case NORTH | SOUTH:
                          case NORTH:
                          case SOUTH:
                                *sp = WALL2;                       /* | */
                                break;
                          case 0:
                                if (conf_random)
                                        *sp = DOOR;
                                if (conf_reflect)
                                        *sp = rand_num(2) ? WALL4 : WALL5;
                                break;
                          default:
                                *sp = WALL3;                       /* + */
                                break;
                        }
                }
        memcpy(Orig_maze, Maze, sizeof Orig_maze);
}