/** @file
 * @brief Iterator for the spelling correction words in a honey database.
 */
/* Copyright (C) 2004,2005,2006,2007,2008,2009,2017,2018,2024,2026 Olly Betts
 * Copyright (C) 2007 Lemur Consulting Ltd
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see
 * <https://www.gnu.org/licenses/>.
 */

#include <config.h>

#include "honey_spellingwordslist.h"

#include "xapian/error.h"
#include "xapian/types.h"

#include "clamp_cast.h"
#include "debuglog.h"
#include "honey_database.h"
#include "pack.h"
#include "stringutils.h"

using namespace std;

HoneySpellingWordsList::~HoneySpellingWordsList()
{
    LOGCALL_DTOR(DB, "HoneySpellingWordsList");
    delete cursor;
}

Xapian::termcount
HoneySpellingWordsList::get_approx_size() const
{
    // This is an over-estimate, but we only use this value to build a balanced
    // or-tree, and it'll do a decent enough job for that.
    auto entry_count = database->spelling_table.get_approx_entry_count();
    return clamp_cast<Xapian::termcount>(entry_count);
}

Xapian::doccount
HoneySpellingWordsList::get_termfreq() const
{
    LOGCALL(DB, Xapian::doccount, "HoneySpellingWordsList::get_termfreq", NO_ARGS);
    Assert(cursor);
    Assert(!cursor->after_end());
    Assert(!cursor->current_key.empty());
    AssertRel(static_cast<unsigned char>(cursor->current_key[0]), >=,
              Honey::KEY_PREFIX_WORD);
    cursor->read_tag();

    Xapian::termcount freq;
    const char* p = cursor->current_tag.data();
    if (!unpack_uint_last(&p, p + cursor->current_tag.size(), &freq)) {
        throw Xapian::DatabaseCorruptError("Bad spelling word freq");
    }
    RETURN(freq);
}

TermList*
HoneySpellingWordsList::next()
{
    LOGCALL(DB, TermList*, "HoneySpellingWordsList::next", NO_ARGS);
    Assert(cursor);

    if (cursor->after_end()) {
        // This is the first action on a new HoneySpellingWordsList.
        (void)cursor->find_entry_ge(string(1, char(Honey::KEY_PREFIX_WORD)));
    } else {
        cursor->next();
    }
    if (cursor->after_end()) {
        // We've reached the end of the prefixed terms.
        RETURN(this);
    }
    const string& key = cursor->current_key;
    unsigned char first = key[0];
    AssertRel(first, >=, Honey::KEY_PREFIX_WORD);
    if (first > Honey::KEY_PREFIX_WORD) {
        current_term = key;
    } else {
        current_term.assign(key, 1);
    }
    RETURN(NULL);
}

TermList*
HoneySpellingWordsList::skip_to(string_view term)
{
    LOGCALL(DB, TermList*, "HoneySpellingWordsList::skip_to", term);
    Assert(cursor);

    if (cursor->find_entry_ge(Honey::make_spelling_wordlist_key(term))) {
        // Exact match.
        current_term = term;
    } else {
        // The exact term we asked for isn't there, so check if the next term
        // after it also has a W prefix.
        if (cursor->after_end()) {
            // We've reached the end of the prefixed terms.
            RETURN(this);
        }
        const string& key = cursor->current_key;
        unsigned char first = key[0];
        AssertRel(first, >=, Honey::KEY_PREFIX_WORD);
        if (first > Honey::KEY_PREFIX_WORD) {
            current_term = key;
        } else {
            current_term.assign(key, 1);
        }
    }
    RETURN(NULL);
}
