/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1990, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * 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 <sys/types.h>

#include <errno.h>
#include <stdio.h>
#include <string.h>

#include <db.h>
#include "recno.h"

static int rec_rdelete(BTREE *, recno_t);

/*
 * __REC_DELETE -- Delete the item(s) referenced by a key.
 *
 * Parameters:
 *      dbp:    pointer to access method
 *      key:    key to delete
 *      flags:  R_CURSOR if deleting what the cursor references
 *
 * Returns:
 *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 */
int
__rec_delete(const DB *dbp, const DBT *key, u_int flags)
{
        BTREE *t;
        recno_t nrec;
        int status;

        t = dbp->internal;

        /* Toss any page pinned across calls. */
        if (t->bt_pinned != NULL) {
                mpool_put(t->bt_mp, t->bt_pinned, 0);
                t->bt_pinned = NULL;
        }

        switch(flags) {
        case 0:
                if ((nrec = *(recno_t *)key->data) == 0)
                        goto einval;
                if (nrec > t->bt_nrecs)
                        return (RET_SPECIAL);
                --nrec;
                status = rec_rdelete(t, nrec);
                break;
        case R_CURSOR:
                if (!F_ISSET(&t->bt_cursor, CURS_INIT))
                        goto einval;
                if (t->bt_nrecs == 0)
                        return (RET_SPECIAL);
                status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
                if (status == RET_SUCCESS)
                        --t->bt_cursor.rcursor;
                break;
        default:
einval:         errno = EINVAL;
                return (RET_ERROR);
        }

        if (status == RET_SUCCESS)
                F_SET(t, B_MODIFIED | R_MODIFIED);
        return (status);
}

/*
 * REC_RDELETE -- Delete the data matching the specified key.
 *
 * Parameters:
 *      tree:   tree
 *      nrec:   record to delete
 *
 * Returns:
 *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 */
static int
rec_rdelete(BTREE *t, recno_t nrec)
{
        EPG *e;
        PAGE *h;
        int status;

        /* Find the record; __rec_search pins the page. */
        if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
                return (RET_ERROR);

        /* Delete the record. */
        h = e->page;
        status = __rec_dleaf(t, h, e->index);
        if (status != RET_SUCCESS) {
                mpool_put(t->bt_mp, h, 0);
                return (status);
        }
        mpool_put(t->bt_mp, h, MPOOL_DIRTY);
        return (RET_SUCCESS);
}

/*
 * __REC_DLEAF -- Delete a single record from a recno leaf page.
 *
 * Parameters:
 *      t:      tree
 *      idx:    index on current page to delete
 *
 * Returns:
 *      RET_SUCCESS, RET_ERROR.
 */
int
__rec_dleaf(BTREE *t, PAGE *h, u_int32_t idx)
{
        RLEAF *rl;
        indx_t *ip, cnt, offset;
        u_int32_t nbytes;
        char *from;
        void *to;

        /*
         * Delete a record from a recno leaf page.  Internal records are never
         * deleted from internal pages, regardless of the records that caused
         * them to be added being deleted.  Pages made empty by deletion are
         * not reclaimed.  They are, however, made available for reuse.
         *
         * Pack the remaining entries at the end of the page, shift the indices
         * down, overwriting the deleted record and its index.  If the record
         * uses overflow pages, make them available for reuse.
         */
        to = rl = GETRLEAF(h, idx);
        if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
                return (RET_ERROR);
        nbytes = NRLEAF(rl);

        /*
         * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
         * offsets.  Reset the headers.
         */
        from = (char *)h + h->upper;
        memmove(from + nbytes, from, (char *)to - from);
        h->upper += nbytes;

        offset = h->linp[idx];
        for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip)
                if (ip[0] < offset)
                        ip[0] += nbytes;
        for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
                ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
        h->lower -= sizeof(indx_t);
        --t->bt_nrecs;
        return (RET_SUCCESS);
}