/*      $OpenBSD: vs_split.c,v 1.16 2016/05/27 09:18:12 martijn 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 <sys/time.h>

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

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

static SCR *vs_getbg(SCR *, char *);

/*
 * vs_split --
 *      Create a new screen.
 *
 * PUBLIC: int vs_split(SCR *, SCR *, int);
 */
int
vs_split(SCR *sp, SCR *new, int ccl)
{
        GS *gp;
        SMAP *smp;
        size_t half;
        int issmallscreen, splitup;

        gp = sp->gp;

        /* Check to see if it's possible. */
        /* XXX: The IS_ONELINE fix will change this, too. */
        if (sp->rows < 4) {
                msgq(sp, M_ERR,
                    "Screen must be larger than %d lines to split", 4 - 1);
                return (1);
        }

        /* Wait for any messages in the screen. */
        vs_resolve(sp, NULL, 1);

        half = sp->rows / 2;
        if (ccl && half > 6)
                half = 6;

        /* Get a new screen map. */
        CALLOC(sp, _HMAP(new), SIZE_HMAP(sp), sizeof(SMAP));
        if (_HMAP(new) == NULL)
                return (1);
        _HMAP(new)->lno = sp->lno;
        _HMAP(new)->coff = 0;
        _HMAP(new)->soff = 1;

        /*
         * Small screens: see vs_refresh.c section 6a.  Set a flag so
         * we know to fix the screen up later.
         */
        issmallscreen = IS_SMALL(sp);

        /* The columns in the screen don't change. */
        new->cols = sp->cols;

        /*
         * Split the screen, and link the screens together.  If creating a
         * screen to edit the colon command line or the cursor is in the top
         * half of the current screen, the new screen goes under the current
         * screen.  Else, it goes above the current screen.
         *
         * Recalculate current cursor position based on sp->lno, we're called
         * with the cursor on the colon command line.  Then split the screen
         * in half and update the shared information.
         */
        splitup =
            !ccl && (vs_sm_cursor(sp, &smp) ? 0 : (smp - HMAP) + 1) >= half;
        if (splitup) {                          /* Old is bottom half. */
                new->rows = sp->rows - half;    /* New. */
                new->woff = sp->woff;
                sp->rows = half;                /* Old. */
                sp->woff += new->rows;
                                                /* Link in before old. */
                TAILQ_INSERT_BEFORE(sp, new, q);

                /*
                 * If the parent is the bottom half of the screen, shift
                 * the map down to match on-screen text.
                 */
                memmove(_HMAP(sp), _HMAP(sp) + new->rows,
                    (sp->t_maxrows - new->rows) * sizeof(SMAP));
        } else {                                /* Old is top half. */
                new->rows = half;               /* New. */
                sp->rows -= half;               /* Old. */
                new->woff = sp->woff + sp->rows;
                                                /* Link in after old. */
                TAILQ_INSERT_AFTER(&gp->dq, sp, new, q);
        }

        /* Adjust maximum text count. */
        sp->t_maxrows = IS_ONELINE(sp) ? 1 : sp->rows - 1;
        new->t_maxrows = IS_ONELINE(new) ? 1 : new->rows - 1;

        /*
         * Small screens: see vs_refresh.c, section 6a.
         *
         * The child may have different screen options sizes than the parent,
         * so use them.  Guarantee that text counts aren't larger than the
         * new screen sizes.
         */
        if (issmallscreen) {
                /* Fix the text line count for the parent. */
                if (splitup)
                        sp->t_rows -= new->rows;

                /* Fix the parent screen. */
                if (sp->t_rows > sp->t_maxrows)
                        sp->t_rows = sp->t_maxrows;
                if (sp->t_minrows > sp->t_maxrows)
                        sp->t_minrows = sp->t_maxrows;

                /* Fix the child screen. */
                new->t_minrows = new->t_rows = O_VAL(sp, O_WINDOW);
                if (new->t_rows > new->t_maxrows)
                        new->t_rows = new->t_maxrows;
                if (new->t_minrows > new->t_maxrows)
                        new->t_minrows = new->t_maxrows;
        } else {
                sp->t_minrows = sp->t_rows = IS_ONELINE(sp) ? 1 : sp->rows - 1;

                /*
                 * The new screen may be a small screen, even if the parent
                 * was not.  Don't complain if O_WINDOW is too large, we're
                 * splitting the screen so the screen is much smaller than
                 * normal.
                 */
                new->t_minrows = new->t_rows = O_VAL(sp, O_WINDOW);
                if (new->t_rows > new->rows - 1)
                        new->t_minrows = new->t_rows =
                            IS_ONELINE(new) ? 1 : new->rows - 1;
        }

        /* Adjust the ends of the new and old maps. */
        _TMAP(sp) = IS_ONELINE(sp) ?
            _HMAP(sp) : _HMAP(sp) + (sp->t_rows - 1);
        _TMAP(new) = IS_ONELINE(new) ?
            _HMAP(new) : _HMAP(new) + (new->t_rows - 1);

        /* Reset the length of the default scroll. */
        if ((sp->defscroll = sp->t_maxrows / 2) == 0)
                sp->defscroll = 1;
        if ((new->defscroll = new->t_maxrows / 2) == 0)
                new->defscroll = 1;

        /*
         * Initialize the screen flags:
         *
         * If we're in vi mode in one screen, we don't have to reinitialize.
         * This isn't just a cosmetic fix.  The path goes like this:
         *
         *      return into vi(), SC_SSWITCH set
         *      call vs_refresh() with SC_STATUS set
         *      call vs_resolve to display the status message
         *      call vs_refresh() because the SC_SCR_VI bit isn't set
         *
         * Things go downhill at this point.
         *
         * Draw the new screen from scratch, and add a status line.
         */
        F_SET(new,
            SC_SCR_REFORMAT | SC_STATUS |
            F_ISSET(sp, SC_EX | SC_VI | SC_SCR_VI | SC_SCR_EX));
        return (0);
}

/*
 * vs_discard --
 *      Discard the screen, folding the real-estate into a related screen,
 *      if one exists, and return that screen.
 *
 * PUBLIC: int vs_discard(SCR *, SCR **);
 */
int
vs_discard(SCR *sp, SCR **spp)
{
        SCR *nsp;
        dir_t dir;

        /*
         * Save the old screen's cursor information.
         *
         * XXX
         * If called after file_end(), and the underlying file was a tmp
         * file, it may have gone away.
         */
        if (sp->frp != NULL) {
                sp->frp->lno = sp->lno;
                sp->frp->cno = sp->cno;
                F_SET(sp->frp, FR_CURSORSET);
        }

        /*
         * Add into a previous screen and then into a subsequent screen, as
         * they're the closest to the current screen.  If that doesn't work,
         * there was no screen to join.
         */
        if ((nsp = TAILQ_PREV(sp, _dqh, q))) {
                nsp->rows += sp->rows;
                sp = nsp;
                dir = FORWARD;
        } else if ((nsp = TAILQ_NEXT(sp, q))) {
                nsp->woff = sp->woff;
                nsp->rows += sp->rows;
                sp = nsp;
                dir = BACKWARD;
        } else {
                sp = NULL;
                dir = 0;        /* unused */
        }

        if (spp != NULL)
                *spp = sp;
        if (sp == NULL)
                return (0);
                
        /*
         * Make no effort to clean up the discarded screen's information.  If
         * it's not exiting, we'll do the work when the user redisplays it.
         *
         * Small screens: see vs_refresh.c section 6a.  Adjust text line info,
         * unless it's a small screen.
         *
         * Reset the length of the default scroll.
         */
        if (!IS_SMALL(sp))
                sp->t_rows = sp->t_minrows = sp->rows - 1;
        sp->t_maxrows = sp->rows - 1;
        sp->defscroll = sp->t_maxrows / 2;
        *(HMAP + (sp->t_rows - 1)) = *TMAP;
        TMAP = HMAP + (sp->t_rows - 1);

        /*
         * Draw the new screen from scratch, and add a status line.
         *
         * XXX
         * We could play games with the map, if this were ever to be a
         * performance problem, but I wrote the code a few times and it
         * was never clean or easy.
         */
        switch (dir) {
        case FORWARD:
                vs_sm_fill(sp, OOBLNO, P_TOP);
                break;
        case BACKWARD:
                vs_sm_fill(sp, OOBLNO, P_BOTTOM);
                break;
        default:
                abort();
        }

        F_SET(sp, SC_STATUS);
        return (0);
}

/*
 * vs_fg --
 *      Background the current screen, and foreground a new one.
 *
 * PUBLIC: int vs_fg(SCR *, SCR **, CHAR_T *, int);
 */
int
vs_fg(SCR *sp, SCR **nspp, CHAR_T *name, int newscreen)
{
        GS *gp;
        SCR *nsp;

        gp = sp->gp;

        if (newscreen)
                /* Get the specified background screen. */
                nsp = vs_getbg(sp, name);
        else
                /* Swap screens. */
                if (vs_swap(sp, &nsp, name))
                        return (1);

        if ((*nspp = nsp) == NULL) {
                msgq_str(sp, M_ERR, name,
                    name == NULL ?
                    "There are no background screens" :
                    "There's no background screen editing a file named %s");
                return (1);
        }

        if (newscreen) {
                /* Remove the new screen from the background queue. */
                TAILQ_REMOVE(&gp->hq, nsp, q);

                /* Split the screen; if we fail, hook the screen back in. */
                if (vs_split(sp, nsp, 0)) {
                        TAILQ_INSERT_TAIL(&gp->hq, nsp, q);
                        return (1);
                }
        } else {
                /* Move the old screen to the background queue. */
                TAILQ_REMOVE(&gp->dq, sp, q);
                TAILQ_INSERT_TAIL(&gp->hq, sp, q);
        }
        return (0);
}

/*
 * vs_bg --
 *      Background the screen, and switch to the next one.
 *
 * PUBLIC: int vs_bg(SCR *);
 */
int
vs_bg(SCR *sp)
{
        GS *gp;
        SCR *nsp;

        gp = sp->gp;

        /* Try and join with another screen. */
        if (vs_discard(sp, &nsp))
                return (1);
        if (nsp == NULL) {
                msgq(sp, M_ERR,
                    "You may not background your only displayed screen");
                return (1);
        }

        /* Move the old screen to the background queue. */
        TAILQ_REMOVE(&gp->dq, sp, q);
        TAILQ_INSERT_TAIL(&gp->hq, sp, q);

        /* Toss the screen map. */
        free(_HMAP(sp));
        _HMAP(sp) = NULL;

        /* Switch screens. */
        sp->nextdisp = nsp;
        F_SET(sp, SC_SSWITCH);

        return (0);
}

/*
 * vs_swap --
 *      Swap the current screen with a backgrounded one.
 *
 * PUBLIC: int vs_swap(SCR *, SCR **, char *);
 */
int
vs_swap(SCR *sp, SCR **nspp, char *name)
{
        GS *gp;
        SCR *nsp;

        gp = sp->gp;

        /* Get the specified background screen. */
        if ((*nspp = nsp = vs_getbg(sp, name)) == NULL)
                return (0);

        /*
         * Save the old screen's cursor information.
         *
         * XXX
         * If called after file_end(), and the underlying file was a tmp
         * file, it may have gone away.
         */
        if (sp->frp != NULL) {
                sp->frp->lno = sp->lno;
                sp->frp->cno = sp->cno;
                F_SET(sp->frp, FR_CURSORSET);
        }

        /* Switch screens. */
        sp->nextdisp = nsp;
        F_SET(sp, SC_SSWITCH);

        /* Initialize terminal information. */
        VIP(nsp)->srows = VIP(sp)->srows;

        /* Initialize screen information. */
        nsp->cols = sp->cols;
        nsp->rows = sp->rows;   /* XXX: Only place in vi that sets rows. */
        nsp->woff = sp->woff;

        /*
         * Small screens: see vs_refresh.c, section 6a.
         *
         * The new screens may have different screen options sizes than the
         * old one, so use them.  Make sure that text counts aren't larger
         * than the new screen sizes.
         */
        if (IS_SMALL(nsp)) {
                nsp->t_minrows = nsp->t_rows = O_VAL(nsp, O_WINDOW);
                if (nsp->t_rows > sp->t_maxrows)
                        nsp->t_rows = nsp->t_maxrows;
                if (nsp->t_minrows > sp->t_maxrows)
                        nsp->t_minrows = nsp->t_maxrows;
        } else
                nsp->t_rows = nsp->t_maxrows = nsp->t_minrows = nsp->rows - 1;

        /* Reset the length of the default scroll. */
        nsp->defscroll = nsp->t_maxrows / 2;

        /* Allocate a new screen map. */
        CALLOC_RET(nsp, _HMAP(nsp), SIZE_HMAP(nsp), sizeof(SMAP));
        _TMAP(nsp) = _HMAP(nsp) + (nsp->t_rows - 1);

        /* Fill the map. */
        if (vs_sm_fill(nsp, nsp->lno, P_FILL))
                return (1);

        /*
         * The new screen replaces the old screen in the parent/child list.
         * We insert the new screen after the old one.  If we're exiting,
         * the exit will delete the old one, if we're foregrounding, the fg
         * code will move the old one to the background queue.
         */
        TAILQ_REMOVE(&gp->hq, nsp, q);
        TAILQ_INSERT_AFTER(&gp->dq, sp, nsp, q);

        /*
         * Don't change the screen's cursor information other than to
         * note that the cursor is wrong.
         */
        F_SET(VIP(nsp), VIP_CUR_INVALID);

        /* Draw the new screen from scratch, and add a status line. */
        F_SET(nsp, SC_SCR_REDRAW | SC_STATUS);
        return (0);
}

/*
 * vs_resize --
 *      Change the absolute size of the current screen.
 *
 * PUBLIC: int vs_resize(SCR *, long, adj_t);
 */
int
vs_resize(SCR *sp, long count, adj_t adj)
{
        GS *gp;
        SCR *g, *s;
        size_t g_off, s_off;

        gp = sp->gp;

        /*
         * Figure out which screens will grow, which will shrink, and
         * make sure it's possible.
         */
        if (count == 0)
                return (0);
        if (adj == A_SET) {
                if (sp->t_maxrows == count)
                        return (0);
                if (sp->t_maxrows > count) {
                        adj = A_DECREASE;
                        count = sp->t_maxrows - count;
                } else {
                        adj = A_INCREASE;
                        count = count - sp->t_maxrows;
                }
        }

        g_off = s_off = 0;
        if (adj == A_DECREASE) {
                if (count < 0)
                        count = -count;
                s = sp;
                if (s->t_maxrows < MINIMUM_SCREEN_ROWS + count)
                        goto toosmall;
                if ((g = TAILQ_PREV(sp, _dqh, q)) == NULL) {
                        if ((g = TAILQ_NEXT(sp, q)) == NULL)
                                goto toobig;
                        g_off = -count;
                } else
                        s_off = count;
        } else {
                g = sp;
                if ((s = TAILQ_NEXT(sp, q)))
                        if (s->t_maxrows < MINIMUM_SCREEN_ROWS + count)
                                s = NULL;
                        else
                                s_off = count;
                else
                        s = NULL;
                if (s == NULL) {
                        if ((s = TAILQ_PREV(sp, _dqh, q)) == NULL) {
toobig:                         msgq(sp, M_BERR, adj == A_DECREASE ?
                                    "The screen cannot shrink" :
                                    "The screen cannot grow");
                                return (1);
                        }
                        if (s->t_maxrows < MINIMUM_SCREEN_ROWS + count) {
toosmall:                       msgq(sp, M_BERR,
                                    "The screen can only shrink to %d rows",
                                    MINIMUM_SCREEN_ROWS);
                                return (1);
                        }
                        g_off = -count;
                }
        }

        /*
         * Fix up the screens; we could optimize the reformatting of the
         * screen, but this isn't likely to be a common enough operation
         * to make it worthwhile.
         */
        s->rows += -count;
        s->woff += s_off;
        g->rows += count;
        g->woff += g_off;

        g->t_rows += count;
        if (g->t_minrows == g->t_maxrows)
                g->t_minrows += count;
        g->t_maxrows += count;
        _TMAP(g) += count;
        F_SET(g, SC_SCR_REFORMAT | SC_STATUS);

        s->t_rows -= count;
        s->t_maxrows -= count;
        if (s->t_minrows > s->t_maxrows)
                s->t_minrows = s->t_maxrows;
        _TMAP(s) -= count;
        F_SET(s, SC_SCR_REFORMAT | SC_STATUS);

        return (0);
}

/*
 * vs_getbg --
 *      Get the specified background screen, or, if name is NULL, the first
 *      background screen.
 */
static SCR *
vs_getbg(SCR *sp, char *name)
{
        GS *gp;
        SCR *nsp;
        char *p;

        gp = sp->gp;

        /* If name is NULL, return the first background screen on the list. */
        if (name == NULL)
                return (TAILQ_FIRST(&gp->hq));

        /* Search for a full match. */
        TAILQ_FOREACH(nsp, &gp->hq, q) {
                if (!strcmp(nsp->frp->name, name))
                        return(nsp);
        }

        /* Search for a last-component match. */
        TAILQ_FOREACH(nsp, &gp->hq, q) {
                if ((p = strrchr(nsp->frp->name, '/')) == NULL)
                        p = nsp->frp->name;
                else
                        ++p;
                if (!strcmp(p, name))
                        return(nsp);
        }

        return (NULL);
}