/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2005-2008 Poul-Henning Kamp
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 <stdio.h>
#include <unistd.h>
#include <assert.h>
#include <err.h>
#include <time.h>
#include <string.h>
#include <stdlib.h>
#include <zlib.h>
#include <sys/endian.h>

#include "fifolog.h"
#include "libfifolog.h"
#include "libfifolog_int.h"
#include "miniobj.h"

/*--------------------------------------------------------------------*/

struct fifolog_reader {
        unsigned                magic;
#define FIFOLOG_READER_MAGIC    0x1036d139
        struct fifolog_file     *ff;
        unsigned                olen;
        unsigned char           *obuf;
        time_t                  now;
};

struct fifolog_reader *
fifolog_reader_open(const char *fname)
{
        const char *retval;
        struct fifolog_reader *fr;
        int i;

        fr = calloc(1, sizeof(*fr));
        if (fr == NULL)
                err(1, "Cannot malloc");

        retval = fifolog_int_open(&fr->ff, fname, 0);
        if (retval != NULL)
                err(1, "%s", retval);

        fr->obuf = calloc(16, fr->ff->recsize);
        if (fr->obuf == NULL)
                err(1, "Cannot malloc");
        fr->olen = fr->ff->recsize * 16;

        i = inflateInit(fr->ff->zs);
        assert(i == Z_OK);

        fr->magic = FIFOLOG_READER_MAGIC;
        return (fr);
}

/*
 * Find the next SYNC block
 *
 * Return:
 *      0 - empty fifolog
 *      1 - found sync block
 *      2 - would have wrapped around
 *      3 - End of written log.
 */

static int
fifolog_reader_findsync(const struct fifolog_file *ff, off_t *o)
{
        int e;
        unsigned seq, seqs;

        assert(*o < ff->logsize);
        e = fifolog_int_read(ff, *o);
        if (e)
                err(1, "Read error (%d) while looking for SYNC", e);
        seq = be32dec(ff->recbuf);
        if (*o == 0 && seq == 0)
                return (0);

        if (ff->recbuf[4] & FIFOLOG_FLG_SYNC)
                return (1);             /* That was easy... */
        while(1) {
                assert(*o < ff->logsize);
                (*o)++;
                seq++;
                if (*o == ff->logsize)
                        return (2);     /* wraparound */
                e = fifolog_int_read(ff, *o);
                if (e)
                        err(1, "Read error (%d) while looking for SYNC", e);
                seqs = be32dec(ff->recbuf);
                if (seqs != seq)
                        return (3);             /* End of log */
                if (ff->recbuf[4] & FIFOLOG_FLG_SYNC)
                        return (1);             /* Bingo! */
        }
}

/*
 * Seek out a given timestamp
 */

off_t
fifolog_reader_seek(const struct fifolog_reader *fr, time_t t0)
{
        off_t o, s, st;
        time_t t, tt;
        unsigned seq, seqs;
        const char *retval;
        int e;

        CHECK_OBJ_NOTNULL(fr, FIFOLOG_READER_MAGIC);

        /*
         * First, find the first SYNC block
         */
        o = 0;
        e = fifolog_reader_findsync(fr->ff, &o);
        if (e == 0)
                return (0);                     /* empty fifolog */
        assert(e == 1);

        assert(fr->ff->recbuf[4] & FIFOLOG_FLG_SYNC);
        seq = be32dec(fr->ff->recbuf);
        t = be32dec(fr->ff->recbuf + 5);

        if (t > t0) {
                /* Check if there is a second older part we can use */
                retval = fifolog_int_findend(fr->ff, &s);
                if (retval != NULL)
                        err(1, "%s", retval);
                s++;
                e = fifolog_reader_findsync(fr->ff, &s);
                if (e == 0)
                        return (0);             /* empty fifolog */
                if (e == 1) {
                        o = s;
                        seq = be32dec(fr->ff->recbuf);
                        t = be32dec(fr->ff->recbuf + 5);
                }
        }

        /* Now do a binary search to find the sync block right before t0 */
        s = st = (fr->ff->logsize - o) / 2;
        while (s > 1) {
                /* We know we shouldn't wrap */
                if (o + st > fr->ff->logsize + 1) {
                        s = st = s / 2;
                        continue;
                }
                e = fifolog_int_read(fr->ff, o + st);
                if (e) {
                        s = st = s / 2;
                        continue;
                }
                /* If not in same part, sequence won't match */
                seqs = be32dec(fr->ff->recbuf);
                if (seqs != seq + st) {
                        s = st = s / 2;
                        continue;
                }
                /* If not sync block, try next */
                if (!(fr->ff->recbuf[4] & FIFOLOG_FLG_SYNC)) {
                        st++;
                        continue;
                }
                /* Check timestamp */
                tt = be32dec(fr->ff->recbuf + 5);
                if (tt >= t0) {
                        s = st = s / 2;
                        continue;
                }
                o += st;
                seq = seqs;
        }
        fprintf(stderr, "Read from %jx\n", o * fr->ff->recsize);
        return (o);
}

static unsigned char *
fifolog_reader_chop(struct fifolog_reader *fr, fifolog_reader_render_t *func, void *priv)
{
        u_char *p, *q;
        uint32_t v, w, u;

        p = fr->obuf;
        q = fr->obuf + (fr->olen - fr->ff->zs->avail_out);

        while (1) {
                /* Make sure we have a complete header */
                if (p + 5 >= q)
                        return (p);
                w = 4;
                u = be32dec(p);
                if (u & FIFOLOG_TIMESTAMP) {
                        fr->now = be32dec(p + 4);
                        w += 4;
                }
                if (u & FIFOLOG_LENGTH) {
                        v = p[w];
                        w++;
                        if (p + w + v >= q)
                                return (p);
                } else {
                        for (v = 0; p + v + w < q && p[v + w] != '\0'; v++)
                                continue;
                        if (p + v + w >= q)
                                return (p);
                        v++;
                }
                func(priv, fr->now, u, p + w, v);
                p += w + v;
        }
}

/*
 * Process fifolog until end of written log or provided timestamp
 */

void
fifolog_reader_process(struct fifolog_reader *fr, off_t from, fifolog_reader_render_t *func, void *priv, time_t end)
{
        uint32_t seq, lseq;
        off_t o = from;
        int i, e;
        time_t t;
        u_char *p, *q;
        z_stream *zs;

        CHECK_OBJ_NOTNULL(fr, FIFOLOG_READER_MAGIC);
        zs = fr->ff->zs;
        lseq = 0;
        while (1) {
                e = fifolog_int_read(fr->ff, o);
                if (e)
                        err(1, "Read error (%d)", e);
                if (++o >= fr->ff->logsize)
                        o = 0;
                seq = be32dec(fr->ff->recbuf);
                if (lseq != 0 && seq != lseq + 1)
                        break;
                lseq = seq;
                zs->avail_in = fr->ff->recsize - 5;
                zs->next_in = fr->ff->recbuf + 5;
                if (fr->ff->recbuf[4] & FIFOLOG_FLG_1BYTE)
                        zs->avail_in -= fr->ff->recbuf[fr->ff->recsize - 1];
                if (fr->ff->recbuf[4] & FIFOLOG_FLG_4BYTE)
                        zs->avail_in -=
                            be32dec(fr->ff->recbuf + fr->ff->recsize - 4);
                if (fr->ff->recbuf[4] & FIFOLOG_FLG_SYNC) {
                        i = inflateReset(zs);
                        assert(i == Z_OK);
                        zs->next_out = fr->obuf;
                        zs->avail_out = fr->olen;
                        t = be32dec(fr->ff->recbuf + 5);
                        if (t > end)
                                break;
                        zs->next_in += 4;
                        zs->avail_in -= 4;
                }

                while(zs->avail_in > 0) {
                        i = inflate(zs, 0);
                        if (i == Z_BUF_ERROR) {
#if 1
                                fprintf(stderr,
                                    "Z_BUF_ERROR [%d,%d] [%d,%d,%d]\n",
                                    (int)(zs->next_in - fr->ff->recbuf),
                                    zs->avail_in,
                                    (int)(zs->next_out - fr->obuf),
                                    zs->avail_out, fr->olen);
                                exit (250);
#else

                                i = Z_OK;
#endif
                        }
                        if (i == Z_STREAM_END) {
                                i = inflateReset(zs);
                        }
                        if (i != Z_OK) {
                                fprintf(stderr, "inflate = %d\n", i);
                                exit (250);
                        }
                        assert(i == Z_OK);
                        if (zs->avail_out != fr->olen) {
                                q = fr->obuf + (fr->olen - zs->avail_out);
                                p = fifolog_reader_chop(fr, func, priv);
                                if (p < q)
                                        (void)memmove(fr->obuf, p, q - p);
                                zs->avail_out = fr->olen - (q - p);
                                zs->next_out = fr->obuf + (q - p);
                        }
                }
        }
}