/*      $OpenBSD: ex_shift.c,v 1.11 2025/07/30 22:19:13 millert Exp $   */

/*-
 * Copyright (c) 1992, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1992, 1993, 1994, 1995, 1996
 *      Keith Bostic.  All rights reserved.
 *
 * See the LICENSE file for redistribution information.
 */

#include "config.h"

#include <sys/queue.h>

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

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

enum which {RETAB, LEFT, RIGHT};
static int shift(SCR *, EXCMD *, enum which);

/*
 * ex_shiftl -- :<[<...]
 *
 *
 * PUBLIC: int ex_shiftl(SCR *, EXCMD *);
 */
int
ex_shiftl(SCR *sp, EXCMD *cmdp)
{
        return (shift(sp, cmdp, LEFT));
}

/*
 * ex_shiftr -- :>[>...]
 *
 * PUBLIC: int ex_shiftr(SCR *, EXCMD *);
 */
int
ex_shiftr(SCR *sp, EXCMD *cmdp)
{
        return (shift(sp, cmdp, RIGHT));
}

/*
 * ex_retab -- Expand tabs (if enabled)
 *
 *
 * PUBLIC: int ex_retab(SCR *, EXCMD *);
 */
int
ex_retab(SCR *sp, EXCMD *cmdp)
{
        return (shift(sp, cmdp, RETAB));
}

/*
 * shift --
 *      Ex shift support.
 */
static int
shift(SCR *sp, EXCMD *cmdp, enum which rl)
{
        recno_t from, to;
        size_t blen, len, newcol, newidx, oldcol, oldidx, sw;
        int curset;
        char *p, *bp, *tbp;

        NEEDFILE(sp, cmdp);

        if (O_VAL(sp, O_SHIFTWIDTH) == 0) {
                msgq(sp, M_INFO, "shiftwidth option set to 0");
                return (0);
        }

        /*
         * When not doing re-expand tabs, copy the lines being shifted into
         * the unnamed buffer.
         */
        if (rl != RETAB &&
            cut(sp, NULL, &cmdp->addr1, &cmdp->addr2, CUT_LINEMODE))
                return (1);

        /*
         * The historic version of vi permitted the user to string any number
         * of '>' or '<' characters together, resulting in an indent of the
         * appropriate levels.  There's a special hack in ex_cmd() so that
         * cmdp->argv[0] points to the string of '>' or '<' characters.
         *
         * Q: What's the difference between the people adding features
         *    to vi and the Girl Scouts?
         * A: The Girl Scouts have mint cookies and adult supervision.
         */
        for (p = cmdp->argv[0]->bp, sw = 0; *p == '>' || *p == '<'; ++p)
                sw += O_VAL(sp, O_SHIFTWIDTH);

        GET_SPACE_RET(sp, bp, blen, 256);

        curset = 0;
        for (from = cmdp->addr1.lno, to = cmdp->addr2.lno; from <= to; ++from) {
                if (db_get(sp, from, DBG_FATAL, &p, &len))
                        goto err;
                if (!len) {
                        if (sp->lno == from)
                                curset = 1;
                        continue;
                }

                /*
                 * Calculate the old indent amount and the number of
                 * characters it used.
                 */
                for (oldidx = 0, oldcol = 0; oldidx < len; ++oldidx)
                        if (p[oldidx] == ' ')
                                ++oldcol;
                        else if (p[oldidx] == '\t')
                                oldcol += O_VAL(sp, O_TABSTOP) -
                                    oldcol % O_VAL(sp, O_TABSTOP);
                        else
                                break;

                /* Calculate the new indent amount. */
                if (rl == RETAB)
                        newcol = oldcol;
                else if (rl == RIGHT)
                        newcol = oldcol + sw;
                else {
                        newcol = oldcol < sw ? 0 : oldcol - sw;
                        if (newcol == oldcol) {
                                if (sp->lno == from)
                                        curset = 1;
                                continue;
                        }
                }

                /* Get a buffer that will hold the new line. */
                ADD_SPACE_RET(sp, bp, blen, newcol + len);

                /*
                 * Build a new indent string and count the number of
                 * characters it uses.
                 */
                tbp = bp;
                newidx = 0;
                if (!O_ISSET(sp, O_EXPANDTAB)) {
                        for (; newcol >= O_VAL(sp, O_TABSTOP); ++newidx) {
                                *tbp++ = '\t';
                                newcol -= O_VAL(sp, O_TABSTOP);
                        }
                }
                for (; newcol > 0; --newcol, ++newidx)
                        *tbp++ = ' ';

                /* Add the original line. */
                memcpy(tbp, p + oldidx, len - oldidx);

                /* Set the replacement line. */
                if (db_set(sp, from, bp, (tbp + (len - oldidx)) - bp)) {
err:                    FREE_SPACE(sp, bp, blen);
                        return (1);
                }

                /*
                 * !!!
                 * The shift command in historic vi had the usual bizarre
                 * collection of cursor semantics.  If called from vi, the
                 * cursor was repositioned to the first non-blank character
                 * of the lowest numbered line shifted.  If called from ex,
                 * the cursor was repositioned to the first non-blank of the
                 * highest numbered line shifted.  Here, if the cursor isn't
                 * part of the set of lines that are moved, move it to the
                 * first non-blank of the last line shifted.  (This makes
                 * ":3>>" in vi work reasonably.)  If the cursor is part of
                 * the shifted lines, it doesn't get moved at all.  This
                 * permits shifting of marked areas, i.e. ">'a." shifts the
                 * marked area twice, something that couldn't be done with
                 * historic vi.
                 */
                if (sp->lno == from) {
                        curset = 1;
                        if (newidx > oldidx)
                                sp->cno += newidx - oldidx;
                        else if (sp->cno >= oldidx - newidx)
                                sp->cno -= oldidx - newidx;
                }
        }
        if (!curset) {
                sp->lno = to;
                sp->cno = 0;
                (void)nonblank(sp, to, &sp->cno);
        }

        FREE_SPACE(sp, bp, blen);

        sp->rptlines[L_SHIFT] += cmdp->addr2.lno - cmdp->addr1.lno + 1;
        return (0);
}