/*      $OpenBSD: worm.c,v 1.39 2018/08/24 11:14:49 mestre 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.
 */

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

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

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

WINDOW *tv;
WINDOW *stw;
struct body {
        int x;
        int y;
        struct body *prev;
        struct body *next;
} *head, *tail, goody;
int growing = 0;
int growthscale = 1;
int running = 0;
int slow = 0;
int score = 0;
int start_len = LENGTH;
int visible_len;
int lastch;
char outbuf[BUFSIZ];

volatile sig_atomic_t wantleave = 0;
volatile sig_atomic_t wantsuspend = 0;

__dead void     crash(void);
void    display(struct body *, char);
void    leave(int);
void    life(void);
void    newpos(struct body *);
struct body     *newlink(void);
int     process(int);
void    prize(void);
int     rnd(int);
void    setup(void);
void    suspend(int);

int
main(int argc, char **argv)
{
        int retval;
        struct pollfd pfd[1];
        const char *errstr;
        struct timespec t, tn, tdiff;

        timespecclear(&t);

        setvbuf(stdout, outbuf, _IOFBF, sizeof outbuf);
        signal(SIGINT, leave);
        signal(SIGQUIT, leave);
        signal(SIGTSTP, suspend);       /* process control signal */
        initscr();

        if (pledge("stdio tty", NULL) == -1)
                err(1, "pledge");

        cbreak();
        noecho();
        keypad(stdscr, TRUE);
        slow = (baudrate() <= 1200);
        clear();
        if (COLS < 18 || LINES < 5) {
                endwin();
                errx(1, "screen too small");
        }
        growthscale = COLS * LINES / 2000;
        if (growthscale == 0)
                growthscale = 1;
        if (argc >= 2) {
                start_len = strtonum(argv[1], 1, ((LINES-3) * (COLS-2)) / 3,
                    &errstr);
                if (errstr) {
                        endwin();
                        errx(1, "length argument is %s.", errstr);
                }
        }
        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 */
        wmove(tv, head->y, head->x);    /* Leave cursor on worm */
        wrefresh(tv);
        while (1) {
                if (wantleave) {
                        endwin();
                        return 0;
                }
                if (wantsuspend) {
                        move(LINES-1, 0);
                        refresh();
                        endwin();
                        fflush(stdout);
                        kill(getpid(), SIGSTOP);
                        signal(SIGTSTP, suspend);
                        cbreak();
                        noecho();
                        setup();
                        wantsuspend = 0;
                }

                if (running) {
                        running--;
                        process(lastch);
                } else {
                        /* Check for timeout. */
                        clock_gettime(CLOCK_MONOTONIC, &tn);
                        if (timespeccmp(&t, &tn, <=)) {
                                t = tn;
                                t.tv_sec += 1;

                                process(lastch);
                                continue;
                        }

                        /* Prepare next read */
                        pfd[0].fd = STDIN_FILENO;
                        pfd[0].events = POLLIN;
                        timespecsub(&t, &tn, &tdiff);
                        retval = ppoll(pfd, 1, &tdiff, NULL);

                        /* Nothing to do if timed out or signal. */
                        if (retval <= 0)
                                continue;

                        /* Only update timer if valid key was pressed. */
                        if (process(getch()) == 0)
                                continue;

                        /* Update using clock_gettime(), tn is too old now. */
                        clock_gettime(CLOCK_MONOTONIC, &t);
                        t.tv_sec += 1;
                }
        }
}

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

        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;
}

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

void
leave(int dummy)
{
        wantleave = 1;
}

int
rnd(int range)
{
        return arc4random_uniform(range);
}

void
newpos(struct body *bp)
{
        if (visible_len == (LINES-3) * (COLS-3) - 1) {
                endwin();
                printf("\nYou won!\nYour 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) != ' ');
}

void
prize(void)
{
        int value;

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

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

        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 (0);
        case CNTRL('Z'):
                suspend(0);
                return (0);
        case CNTRL('C'):
                crash();
                return (0);
        case CNTRL('D'):
                crash();
                return (0);
        case ERR:
                leave(0);
                return (0);
        default:
                return (0);
        }
        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))) {
                int amt = ch - '0';
                growing += amt * growthscale;
                prize();
                score += amt;
                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);
        }
        return (1);
}

struct body *
newlink(void)
{
        struct body *tmp;

        if ((tmp = malloc(sizeof (struct body))) == NULL) {
                endwin();
                errx(1, "out of memory");
        }
        return (tmp);
}

void
crash(void)
{
        sleep(2);
        clear();
        endwin();
        printf("Well, you ran into something and the game is over.\n");
        printf("Your final score was %d\n", score);
        exit(0);  /* leave() calls endwin(), which would hose the printf()'s */
}

void
suspend(int dummy)
{
        wantsuspend = 1;
}

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