/*      $OpenBSD: dbm.c,v 1.5 2019/07/01 22:43:03 schwarze Exp $ */
/*
 * Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Map-based version of the mandoc database, for read-only access.
 * The interface is defined in "dbm.h".
 */
#include <assert.h>
#include <endian.h>
#include <err.h>
#include <errno.h>
#include <regex.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "mansearch.h"
#include "dbm_map.h"
#include "dbm.h"

struct macro {
        int32_t value;
        int32_t pages;
};

struct page {
        int32_t name;
        int32_t sect;
        int32_t arch;
        int32_t desc;
        int32_t file;
};

enum iter {
        ITER_NONE = 0,
        ITER_NAME,
        ITER_SECT,
        ITER_ARCH,
        ITER_DESC,
        ITER_MACRO
};

static struct macro     *macros[MACRO_MAX];
static int32_t           nvals[MACRO_MAX];
static struct page      *pages;
static int32_t           npages;
static enum iter         iteration;

static struct dbm_res    page_bytitle(enum iter, const struct dbm_match *);
static struct dbm_res    page_byarch(const struct dbm_match *);
static struct dbm_res    page_bymacro(int32_t, const struct dbm_match *);
static char             *macro_bypage(int32_t, int32_t);


/*** top level functions **********************************************/

/*
 * Open a disk-based mandoc database for read-only access.
 * Map the pages and macros[] arrays.
 * Return 0 on success.  Return -1 and set errno on failure.
 */
int
dbm_open(const char *fname)
{
        const int32_t   *mp, *ep;
        int32_t          im;

        if (dbm_map(fname) == -1)
                return -1;

        if ((npages = be32toh(*dbm_getint(4))) < 0) {
                warnx("dbm_open(%s): Invalid number of pages: %d",
                    fname, npages);
                goto fail;
        }
        pages = (struct page *)dbm_getint(5);

        if ((mp = dbm_get(*dbm_getint(2))) == NULL) {
                warnx("dbm_open(%s): Invalid offset of macros array", fname);
                goto fail;
        }
        if (be32toh(*mp) != MACRO_MAX) {
                warnx("dbm_open(%s): Invalid number of macros: %d",
                    fname, be32toh(*mp));
                goto fail;
        }
        for (im = 0; im < MACRO_MAX; im++) {
                if ((ep = dbm_get(*++mp)) == NULL) {
                        warnx("dbm_open(%s): Invalid offset of macro %d",
                            fname, im);
                        goto fail;
                }
                nvals[im] = be32toh(*ep);
                macros[im] = (struct macro *)++ep;
        }
        return 0;

fail:
        dbm_unmap();
        errno = EFTYPE;
        return -1;
}

void
dbm_close(void)
{
        dbm_unmap();
}


/*** functions for handling pages *************************************/

int32_t
dbm_page_count(void)
{
        return npages;
}

/*
 * Give the caller pointers to the data for one manual page.
 */
struct dbm_page *
dbm_page_get(int32_t ip)
{
        static struct dbm_page   res;

        assert(ip >= 0);
        assert(ip < npages);
        res.name = dbm_get(pages[ip].name);
        if (res.name == NULL)
                res.name = "(NULL)\0";
        res.sect = dbm_get(pages[ip].sect);
        if (res.sect == NULL)
                res.sect = "(NULL)\0";
        res.arch = pages[ip].arch ? dbm_get(pages[ip].arch) : NULL;
        res.desc = dbm_get(pages[ip].desc);
        if (res.desc == NULL)
                res.desc = "(NULL)";
        res.file = dbm_get(pages[ip].file);
        if (res.file == NULL)
                res.file = " (NULL)\0";
        res.addr = dbm_addr(pages + ip);
        return &res;
}

/*
 * Functions to start filtered iterations over manual pages.
 */
void
dbm_page_byname(const struct dbm_match *match)
{
        assert(match != NULL);
        page_bytitle(ITER_NAME, match);
}

void
dbm_page_bysect(const struct dbm_match *match)
{
        assert(match != NULL);
        page_bytitle(ITER_SECT, match);
}

void
dbm_page_byarch(const struct dbm_match *match)
{
        assert(match != NULL);
        page_byarch(match);
}

void
dbm_page_bydesc(const struct dbm_match *match)
{
        assert(match != NULL);
        page_bytitle(ITER_DESC, match);
}

void
dbm_page_bymacro(int32_t im, const struct dbm_match *match)
{
        assert(im >= 0);
        assert(im < MACRO_MAX);
        assert(match != NULL);
        page_bymacro(im, match);
}

/*
 * Return the number of the next manual page in the current iteration.
 */
struct dbm_res
dbm_page_next(void)
{
        struct dbm_res                   res = {-1, 0};

        switch(iteration) {
        case ITER_NONE:
                return res;
        case ITER_ARCH:
                return page_byarch(NULL);
        case ITER_MACRO:
                return page_bymacro(0, NULL);
        default:
                return page_bytitle(iteration, NULL);
        }
}

/*
 * Functions implementing the iteration over manual pages.
 */
static struct dbm_res
page_bytitle(enum iter arg_iter, const struct dbm_match *arg_match)
{
        static const struct dbm_match   *match;
        static const char               *cp;
        static int32_t                   ip;
        struct dbm_res                   res = {-1, 0};

        assert(arg_iter == ITER_NAME || arg_iter == ITER_DESC ||
            arg_iter == ITER_SECT);

        /* Initialize for a new iteration. */

        if (arg_match != NULL) {
                iteration = arg_iter;
                match = arg_match;
                switch (iteration) {
                case ITER_NAME:
                        cp = dbm_get(pages[0].name);
                        break;
                case ITER_SECT:
                        cp = dbm_get(pages[0].sect);
                        break;
                case ITER_DESC:
                        cp = dbm_get(pages[0].desc);
                        break;
                default:
                        abort();
                }
                if (cp == NULL) {
                        iteration = ITER_NONE;
                        match = NULL;
                        cp = NULL;
                        ip = npages;
                } else
                        ip = 0;
                return res;
        }

        /* Search for a name. */

        while (ip < npages) {
                if (iteration == ITER_NAME)
                        cp++;
                if (dbm_match(match, cp))
                        break;
                cp = strchr(cp, '\0') + 1;
                if (iteration == ITER_DESC)
                        ip++;
                else if (*cp == '\0') {
                        cp++;
                        ip++;
                }
        }

        /* Reached the end without a match. */

        if (ip == npages) {
                iteration = ITER_NONE;
                match = NULL;
                cp = NULL;
                return res;
        }

        /* Found a match; save the quality for later retrieval. */

        res.page = ip;
        res.bits = iteration == ITER_NAME ? cp[-1] : 0;

        /* Skip the remaining names of this page. */

        if (++ip < npages) {
                do {
                        cp++;
                } while (cp[-1] != '\0' ||
                    (iteration != ITER_DESC && cp[-2] != '\0'));
        }
        return res;
}

static struct dbm_res
page_byarch(const struct dbm_match *arg_match)
{
        static const struct dbm_match   *match;
        struct dbm_res                   res = {-1, 0};
        static int32_t                   ip;
        const char                      *cp;

        /* Initialize for a new iteration. */

        if (arg_match != NULL) {
                iteration = ITER_ARCH;
                match = arg_match;
                ip = 0;
                return res;
        }

        /* Search for an architecture. */

        for ( ; ip < npages; ip++)
                if (pages[ip].arch)
                        for (cp = dbm_get(pages[ip].arch);
                            *cp != '\0';
                            cp = strchr(cp, '\0') + 1)
                                if (dbm_match(match, cp)) {
                                        res.page = ip++;
                                        return res;
                                }

        /* Reached the end without a match. */

        iteration = ITER_NONE;
        match = NULL;
        return res;
}

static struct dbm_res
page_bymacro(int32_t arg_im, const struct dbm_match *arg_match)
{
        static const struct dbm_match   *match;
        static const int32_t            *pp;
        static const char               *cp;
        static int32_t                   im, iv;
        struct dbm_res                   res = {-1, 0};

        assert(im >= 0);
        assert(im < MACRO_MAX);

        /* Initialize for a new iteration. */

        if (arg_match != NULL) {
                iteration = ITER_MACRO;
                match = arg_match;
                im = arg_im;
                cp = nvals[im] ? dbm_get(macros[im]->value) : NULL;
                pp = NULL;
                iv = -1;
                return res;
        }
        if (iteration != ITER_MACRO)
                return res;

        /* Find the next matching macro value. */

        while (pp == NULL || *pp == 0) {
                if (++iv == nvals[im]) {
                        iteration = ITER_NONE;
                        return res;
                }
                if (iv)
                        cp = strchr(cp, '\0') + 1;
                if (dbm_match(match, cp))
                        pp = dbm_get(macros[im][iv].pages);
        }

        /* Found a matching page. */

        res.page = (struct page *)dbm_get(*pp++) - pages;
        return res;
}


/*** functions for handling macros ************************************/

int32_t
dbm_macro_count(int32_t im)
{
        assert(im >= 0);
        assert(im < MACRO_MAX);
        return nvals[im];
}

struct dbm_macro *
dbm_macro_get(int32_t im, int32_t iv)
{
        static struct dbm_macro macro;

        assert(im >= 0);
        assert(im < MACRO_MAX);
        assert(iv >= 0);
        assert(iv < nvals[im]);
        macro.value = dbm_get(macros[im][iv].value);
        macro.pp = dbm_get(macros[im][iv].pages);
        return &macro;
}

/*
 * Filtered iteration over macro entries.
 */
void
dbm_macro_bypage(int32_t im, int32_t ip)
{
        assert(im >= 0);
        assert(im < MACRO_MAX);
        assert(ip != 0);
        macro_bypage(im, ip);
}

char *
dbm_macro_next(void)
{
        return macro_bypage(MACRO_MAX, 0);
}

static char *
macro_bypage(int32_t arg_im, int32_t arg_ip)
{
        static const int32_t    *pp;
        static int32_t           im, ip, iv;

        /* Initialize for a new iteration. */

        if (arg_im < MACRO_MAX && arg_ip != 0) {
                im = arg_im;
                ip = arg_ip;
                pp = dbm_get(macros[im]->pages);
                iv = 0;
                return NULL;
        }
        if (im >= MACRO_MAX)
                return NULL;

        /* Search for the next value. */

        while (iv < nvals[im]) {
                if (*pp == ip)
                        break;
                if (*pp == 0)
                        iv++;
                pp++;
        }

        /* Reached the end without a match. */

        if (iv == nvals[im]) {
                im = MACRO_MAX;
                ip = 0;
                pp = NULL;
                return NULL;
        }

        /* Found a match; skip the remaining pages of this entry. */

        if (++iv < nvals[im])
                while (*pp++ != 0)
                        continue;

        return dbm_get(macros[im][iv - 1].value);
}