/*      $OpenBSD: ex_z.c,v 1.8 2015/03/29 01:04:23 bcallah Exp $        */

/*-
 * Copyright (c) 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1993, 1994, 1995, 1996
 *      Keith Bostic.  All rights reserved.
 *
 * See the LICENSE file for redistribution information.
 */

#include "config.h"

#include <sys/types.h>
#include <sys/queue.h>

#include <bitstring.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "../common/common.h"

/*
 * ex_z -- :[line] z [^-.+=] [count] [flags]
 *      Adjust window.
 *
 * PUBLIC: int ex_z(SCR *, EXCMD *);
 */
int
ex_z(SCR *sp, EXCMD *cmdp)
{
        MARK mark_abs;
        recno_t cnt, equals, lno;
        int eofcheck;

        NEEDFILE(sp, cmdp);

        /*
         * !!!
         * If no count specified, use either two times the size of the
         * scrolling region, or the size of the window option.  POSIX
         * 1003.2 claims that the latter is correct, but historic ex/vi
         * documentation and practice appear to use the scrolling region.
         * I'm using the window size as it means that the entire screen
         * is used instead of losing a line to roundoff.  Note, we drop
         * a line from the cnt if using the window size to leave room for
         * the next ex prompt.
         */
        if (FL_ISSET(cmdp->iflags, E_C_COUNT))
                cnt = cmdp->count;
        else
                cnt = O_VAL(sp, O_WINDOW) - 1;

        equals = 0;
        eofcheck = 0;
        lno = cmdp->addr1.lno;

        switch (FL_ISSET(cmdp->iflags,
            E_C_CARAT | E_C_DASH | E_C_DOT | E_C_EQUAL | E_C_PLUS)) {
        case E_C_CARAT:         /* Display cnt * 2 before the line. */
                eofcheck = 1;
                if (lno > cnt * 2)
                        cmdp->addr1.lno = (lno - cnt * 2) + 1;
                else
                        cmdp->addr1.lno = 1;
                cmdp->addr2.lno = (cmdp->addr1.lno + cnt) - 1;
                break;
        case E_C_DASH:          /* Line goes at the bottom of the screen. */
                cmdp->addr1.lno = lno > cnt ? (lno - cnt) + 1 : 1;
                cmdp->addr2.lno = lno;
                break;
        case E_C_DOT:           /* Line goes in the middle of the screen. */
                /*
                 * !!!
                 * Historically, the "middleness" of the line overrode the
                 * count, so that "3z.19" or "3z.20" would display the first
                 * 12 lines of the file, i.e. (N - 1) / 2 lines before and
                 * after the specified line.
                 */
                eofcheck = 1;
                cnt = (cnt - 1) / 2;
                cmdp->addr1.lno = lno > cnt ? lno - cnt : 1;
                cmdp->addr2.lno = lno + cnt;

                /*
                 * !!!
                 * Historically, z. set the absolute cursor mark.
                 */
                mark_abs.lno = sp->lno;
                mark_abs.cno = sp->cno;
                (void)mark_set(sp, ABSMARK1, &mark_abs, 1);
                break;
        case E_C_EQUAL:         /* Center with hyphens. */
                /*
                 * !!!
                 * Strangeness.  The '=' flag is like the '.' flag (see the
                 * above comment, it applies here as well) but with a special
                 * little hack.  Print out lines of hyphens before and after
                 * the specified line.  Additionally, the cursor remains set
                 * on that line.
                 */
                eofcheck = 1;
                cnt = (cnt - 1) / 2;
                cmdp->addr1.lno = lno > cnt ? lno - cnt : 1;
                cmdp->addr2.lno = lno - 1;
                if (ex_pr(sp, cmdp))
                        return (1);
                (void)ex_puts(sp, "----------------------------------------\n");
                cmdp->addr2.lno = cmdp->addr1.lno = equals = lno;
                if (ex_pr(sp, cmdp))
                        return (1);
                (void)ex_puts(sp, "----------------------------------------\n");
                cmdp->addr1.lno = lno + 1;
                cmdp->addr2.lno = (lno + cnt) - 1;
                break;
        default:
                /* If no line specified, move to the next one. */
                if (F_ISSET(cmdp, E_ADDR_DEF))
                        ++lno;
                /* FALLTHROUGH */
        case E_C_PLUS:          /* Line goes at the top of the screen. */
                eofcheck = 1;
                cmdp->addr1.lno = lno;
                cmdp->addr2.lno = (lno + cnt) - 1;
                break;
        }

        if (eofcheck) {
                if (db_last(sp, &lno))
                        return (1);
                if (cmdp->addr2.lno > lno)
                        cmdp->addr2.lno = lno;
        }

        if (ex_pr(sp, cmdp))
                return (1);
        if (equals)
                sp->lno = equals;
        return (0);
}