/*      @(#)wwscroll.c  8.1 (Berkeley) 6/6/93   */
/*      $NetBSD: wwscroll.c,v 1.7 2003/08/07 11:17:44 agc Exp $ */

/*
 * Copyright (c) 1983, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Edward Wang at The University of California, Berkeley.
 *
 * 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 <stdlib.h>

#include "ww.h"
#include "tt.h"
#include "xx.h"

void
wwscroll(struct ww *w, int n)
{
        int dir;
        int top;

        if (n == 0)
                return;
        dir = n < 0 ? -1 : 1;
        top = w->ww_b.t - n;
        if (top > w->ww_w.t)
                top = w->ww_w.t;
        else if (top + w->ww_b.nr < w->ww_w.b)
                top = w->ww_w.b - w->ww_b.nr;
        n = abs(top - w->ww_b.t);
        if (n < w->ww_i.nr) {
                while (--n >= 0) {
                        (void) wwscroll1(w, w->ww_i.t, w->ww_i.b, dir, 0);
                        w->ww_buf += dir;
                        w->ww_b.t -= dir;
                        w->ww_b.b -= dir;
                }
        } else {
                w->ww_buf -= top - w->ww_b.t;
                w->ww_b.t = top;
                w->ww_b.b = top + w->ww_b.nr;
                wwredrawwin(w);
        }
}

/*
 * Scroll one line, between 'row1' and 'row2', in direction 'dir'.
 * Don't adjust ww_scroll.
 * And don't redraw 'leaveit' lines.
 */
int
wwscroll1(struct ww *w, int row1, int row2, int dir, int leaveit)
{
        int i;
        int row1x, row2x;
        int nvis;
        int nvismax;
        int scrolled = 0;

        /*
         * See how many lines on the screen are affected.
         * And calculate row1x, row2x, and left at the same time.
         */
        for (i = row1; i < row2 && w->ww_nvis[i] == 0; i++)
                ;
        if (i >= row2)                  /* can't do any fancy stuff */
                goto out;
        row1x = i;
        for (i = row2 - 1; i >= row1 && w->ww_nvis[i] == 0; i--)
                ;
        if (i <= row1x)
                goto out;               /* just one line is easy */
        row2x = i + 1;

        /*
         * See how much of this window is visible.
         */
        nvismax = wwncol * (row2x - row1x);
        nvis = 0;
        for (i = row1x; i < row2x; i++)
                nvis += w->ww_nvis[i];

        /*
         * If it's a good idea to scroll and the terminal can, then do it.
         */
        if (nvis < nvismax / 2)
                goto no_scroll;         /* not worth it */
        if ((dir > 0 ? tt.tt_scroll_down == 0 : tt.tt_scroll_up == 0) ||
            ((tt.tt_scroll_top != row1x || tt.tt_scroll_bot != row2x - 1) &&
            tt.tt_setscroll == 0))
                if (tt.tt_delline == 0 || tt.tt_insline == 0)
                        goto no_scroll;
        xxscroll(dir, row1x, row2x);
        scrolled = 1;
        /*
         * Fix up the old screen.
         */
        {
                union ww_char *tmp;
                union ww_char **cpp, **cqq;

                if (dir > 0) {
                        cpp = &wwos[row1x];
                        cqq = cpp + 1;
                        tmp = *cpp;
                        for (i = row2x - row1x; --i > 0;)
                                *cpp++ = *cqq++;
                        *cpp = tmp;
                } else {
                        cpp = &wwos[row2x];
                        cqq = cpp - 1;
                        tmp = *cqq;
                        for (i = row2x - row1x; --i > 0;)
                                *--cpp = *--cqq;
                        *cqq = tmp;
                }
                for (i = wwncol; --i >= 0;)
                        tmp++->c_w = ' ';
        }

no_scroll:
        /*
         * Fix the new screen.
         */
        if (nvis == nvismax) {
                /*
                 * Can shift whole lines.
                 */
                if (dir > 0) {
                        {
                                union ww_char *tmp;
                                union ww_char **cpp, **cqq;

                                cpp = &wwns[row1x];
                                cqq = cpp + 1;
                                tmp = *cpp;
                                for (i = row2x - row1x; --i > 0;)
                                        *cpp++ = *cqq++;
                                *cpp = tmp;
                        }
                        if (scrolled) {
                                char *p, *q;

                                p = &wwtouched[row1x];
                                q = p + 1;
                                for (i = row2x - row1x; --i > 0;)
                                        *p++ = *q++;
                                *p |= WWU_TOUCHED;
                        } else {
                                char *p;

                                p = &wwtouched[row1x];
                                for (i = row2x - row1x; --i >= 0;)
                                        *p++ |= WWU_TOUCHED;
                        }
                        wwredrawwin1(w, row1, row1x, dir);
                        wwredrawwin1(w, row2x - 1, row2 - leaveit, dir);
                } else {
                        {
                                union ww_char *tmp;
                                union ww_char **cpp, **cqq;

                                cpp = &wwns[row2x];
                                cqq = cpp - 1;
                                tmp = *cqq;
                                for (i = row2x - row1x; --i > 0;)
                                        *--cpp = *--cqq;
                                *cqq = tmp;
                        }
                        if (scrolled) {
                                char *p, *q;

                                p = &wwtouched[row2x];
                                q = p - 1;
                                for (i = row2x - row1x; --i > 0;)
                                        *--p = *--q;
                                *q |= WWU_TOUCHED;
                        } else {
                                char *p;

                                p = &wwtouched[row1x];
                                for (i = row2x - row1x; --i >= 0;)
                                        *p++ |= WWU_TOUCHED;
                        }
                        wwredrawwin1(w, row1 + leaveit, row1x + 1, dir);
                        wwredrawwin1(w, row2x, row2, dir);
                }
        } else {
                if (scrolled) {
                        char *p;

                        p = &wwtouched[row1x];
                        for (i = row2x - row1x; --i >= 0;)
                                *p++ |= WWU_TOUCHED;
                }
out:
                if (dir > 0)
                        wwredrawwin1(w, row1, row2 - leaveit, dir);
                else
                        wwredrawwin1(w, row1 + leaveit, row2, dir);
        }
        return scrolled;
}