/*	$NetBSD: worm.c,v 1.31 2015/08/17 17:17:01 dholland Exp $	*/

/*
 * Copyright (c) 1980, 1993
 *	The 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:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. Neither the name of the University 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 REGENTS 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 REGENTS 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/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1980, 1993\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)worm.c	8.1 (Berkeley) 5/31/93";
#else
__RCSID("$NetBSD: worm.c,v 1.31 2015/08/17 17:17:01 dholland Exp $");
#endif
#endif /* not lint */

/*
 * Worm.  Written by Michael Toy
 * UCSC
 */

#include <ctype.h>
#include <curses.h>
#include <err.h>
#include <signal.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>

#define HEAD '@'
#define BODY 'o'
#define LENGTH 7
#define RUNLEN 8
#define CNTRL(p) (p-'A'+1)

struct body {
	int x;
	int y;
	struct body *prev;
	struct body *next;
};

static WINDOW *tv;
static WINDOW *stw;
static struct body *head, *tail, goody;
static int growing = 0;
static int running = 0;
static int slow = 0;
static int score = 0;
static int start_len = LENGTH;
static int visible_len;
static int lastch;
static char outbuf[BUFSIZ];

int	main(int, char **);
static void crash(void) __dead;
static void display(const struct body *, char);
static void leave(int) __dead;
static void life(void);
static void newpos(struct body *);
static void process(int);
static void prize(void);
static int rnd(int);
static void setup(void);
static void wake(int);

static struct body *
newlink(void)
{
	struct body *b;

	b = malloc(sizeof(*b));
	if (b == NULL) {
		err(EXIT_FAILURE, NULL);
	}
	return b;
}

int
main(int argc, char **argv)
{

	/* Revoke setgid privileges */
	setgid(getgid());

	setbuf(stdout, outbuf);
	srand(getpid());
	signal(SIGALRM, wake);
	signal(SIGINT, leave);
	signal(SIGQUIT, leave);
	if (!initscr())
		errx(0, "couldn't initialize screen");
	cbreak();
	noecho();
#ifdef KEY_LEFT
	keypad(stdscr, TRUE);
#endif
	slow = (baudrate() <= 1200);
	clear();
	if (COLS < 18 || LINES < 5) {
		/*
		 * Insufficient room for the line with " Worm" and the
		 * score if fewer than 18 columns; insufficient room for
		 * anything much if fewer than 5 lines.
		 */
		endwin();
		errx(1, "screen too small");
	}
	if (argc == 2)
		start_len = atoi(argv[1]);
	if ((start_len <= 0) || (start_len > ((LINES-3) * (COLS-2)) / 3))
		start_len = LENGTH;
	stw = newwin(1, COLS-1, 0, 0);
	tv = newwin(LINES-1, COLS-1, 1, 0);
	box(tv, '*', '*');
	scrollok(tv, FALSE);
	scrollok(stw, FALSE);
	wmove(stw, 0, 0);
	wprintw(stw, " Worm");
	refresh();
	wrefresh(stw);
	wrefresh(tv);
	life();			/* Create the worm */
	prize();		/* Put up a goal */
	while(1)
	{
		if (running)
		{
			running--;
			process(lastch);
		}
		else
		{
		    fflush(stdout);
		    process(getch());
		}
	}
}

static void
life(void)
{
	struct body *bp, *np;
	int i, j = 1;

	np = NULL;
	head = newlink();
	head->x = start_len % (COLS-5) + 2;
	head->y = LINES / 2;
	head->next = NULL;
	display(head, HEAD);
	for (i = 0, bp = head; i < start_len; i++, bp = np) {
		np = newlink();
		np->next = bp;
		bp->prev = np;
		if (((bp->x <= 2) && (j == 1)) || ((bp->x >= COLS-4) && (j == -1))) {
			j *= -1;
			np->x = bp->x;
			np->y = bp->y + 1;
		} else {
			np->x = bp->x - j;
			np->y = bp->y;
		}
		display(np, BODY);
	}
	tail = np;
	tail->prev = NULL;
	visible_len = start_len + 1;
}

static void
display(const struct body *pos, char chr)
{
	wmove(tv, pos->y, pos->x);
	waddch(tv, chr);
}

static void
leave(int dummy)
{
	endwin();

	if (dummy == 0){	/* called via crash() */
		printf("\nWell, you ran into something and the game is over.\n");
		printf("Your final score was %d\n\n", score);
	}
	exit(0);
}

static void
wake(int dummy)
{
	signal(SIGALRM, wake);
	fflush(stdout);
	process(lastch);
}

static int
rnd(int range)
{
	return abs((rand()>>5)+(rand()>>5)) % range;
}

static void
newpos(struct body *bp)
{
	if (visible_len == (LINES-3) * (COLS-3) - 1) {
		endwin();

		printf("\nYou won!\n");
		printf("Your final score was %d\n\n", score);
		exit(0);
	}
	do {
		bp->y = rnd(LINES-3)+ 1;
		bp->x = rnd(COLS-3) + 1;
		wmove(tv, bp->y, bp->x);
	} while(winch(tv) != ' ');
}

static void
prize(void)
{
	int value;

	value = rnd(9) + 1;
	newpos(&goody);
	waddch(tv, value+'0');
	wrefresh(tv);
}

static void
process(int ch)
{
	int x,y;
	struct body *nh;

	alarm(0);
	x = head->x;
	y = head->y;
	switch(ch)
	{
#ifdef KEY_LEFT
		case KEY_LEFT:
#endif
		case 'h':
			x--; break;

#ifdef KEY_DOWN
		case KEY_DOWN:
#endif
		case 'j':
			y++; break;

#ifdef KEY_UP
		case KEY_UP:
#endif
		case 'k':
			y--; break;

#ifdef KEY_RIGHT
		case KEY_RIGHT:
#endif
		case 'l':
			x++; break;

		case 'H': x--; running = RUNLEN; ch = tolower(ch); break;
		case 'J': y++; running = RUNLEN/2; ch = tolower(ch); break;
		case 'K': y--; running = RUNLEN/2; ch = tolower(ch); break;
		case 'L': x++; running = RUNLEN; ch = tolower(ch); break;
		case '\f': setup(); return;

		case ERR:
		case CNTRL('C'):
		case CNTRL('D'):
			crash();
			return;

		default: if (! running) alarm(1);
			   return;
	}
	lastch = ch;
	if (growing == 0)
	{
		display(tail, ' ');
		tail->next->prev = NULL;
		nh = tail->next;
		free(tail);
		tail = nh;
		visible_len--;
	}
	else growing--;
	display(head, BODY);
	wmove(tv, y, x);
	if (isdigit(ch = winch(tv)))
	{
		growing += ch-'0';
		prize();
		score += growing;
		running = 0;
		wmove(stw, 0, COLS - 12);
		wprintw(stw, "Score: %3d", score);
		wrefresh(stw);
	}
	else if(ch != ' ') crash();
	nh = newlink();
	nh->next = NULL;
	nh->prev = head;
	head->next = nh;
	nh->y = y;
	nh->x = x;
	display(nh, HEAD);
	head = nh;
	visible_len++;
	if (!(slow && running))
	{
		wmove(tv, head->y, head->x);
		wrefresh(tv);
	}
	if (!running)
		alarm(1);
}

static void
crash(void)
{
	leave(0);
}

static void
setup(void)
{
	clear();
	refresh();
	touchwin(stw);
	wrefresh(stw);
	touchwin(tv);
	wrefresh(tv);
	alarm(1);
}