/* 
 *  libpinyin
 *  Library to deal with pinyin.
 *  
 *  Copyright (C) 2016 Peng Wu <alexepico@gmail.com>
 *  
 *  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 3 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 <http://www.gnu.org/licenses/>.
 */

#include "chewing_large_table2.h"
#include <kchashdb.h>
#include <kccachedb.h>
#include "pinyin_utils.h"
#include "kyotodb_utils.h"

using namespace kyotocabinet;

namespace pinyin{

/* keep dbm key compare function inside the corresponding dbm file
   to get more flexibility. */

bool kyotodb_chewing_continue_search(const char* akbuf, size_t aksiz,
                                     const char* bkbuf, size_t bksiz) {
    ChewingKey * lhs_chewing = (ChewingKey *) akbuf;
    int lhs_chewing_length = aksiz / sizeof(ChewingKey);
    ChewingKey * rhs_chewing = (ChewingKey *) bkbuf;
    int rhs_chewing_length = bksiz / sizeof(ChewingKey);

    /* The key in dbm is longer than the key in application. */
    if (lhs_chewing_length >= rhs_chewing_length)
        return false;

    int min_chewing_length = lhs_chewing_length;

    int result = pinyin_exact_compare2
        (lhs_chewing, rhs_chewing, min_chewing_length);
    if (0 != result)
        return false;

    /* continue the longer chewing search. */
    return true;
}

ChewingLargeTable2::ChewingLargeTable2() {
    /* create in-memory db. */
    m_db = new ProtoTreeDB;
    check_result(m_db->open("-", BasicDB::OREADER|BasicDB::OWRITER|BasicDB::OCREATE));

    m_entries = NULL;
    init_entries();
}

void ChewingLargeTable2::reset() {
    if (m_db) {
        m_db->synchronize();
        m_db->close();
        delete m_db;
        m_db = NULL;
    }

    fini_entries();
}

/* attach method */
bool ChewingLargeTable2::attach(const char * dbfile, guint32 flags) {
    reset();

    init_entries();

    uint32_t mode = attach_options(flags);

    if (!dbfile)
        return false;

    m_db = new TreeDB;

    return m_db->open(dbfile, mode);
}

/* load/store method */
/* use in-memory DBM here, for better performance. */
bool ChewingLargeTable2::load_db(const char * filename) {
    reset();

    init_entries();

    /* create in-memory db. */
    m_db = new ProtoTreeDB;

    if (!m_db->open("-", BasicDB::OREADER|BasicDB::OWRITER|BasicDB::OCREATE))
        return false;

    if (!m_db->load_snapshot(filename, NULL))
        return false;

#if 0
    /* load db into memory. */
    BasicDB * tmp_db = new TreeDB;
    if (!tmp_db->open(filename, BasicDB::OREADER))
        return false;

    CopyVisitor visitor(m_db);
    tmp_db->iterate(&visitor, false);

    tmp_db->close();
    delete tmp_db;
#endif

    return true;
}

bool ChewingLargeTable2::save_db(const char * new_filename) {
    int ret = unlink(new_filename);
    if ( ret != 0 && errno != ENOENT)
        return false;

    if (!m_db->dump_snapshot(new_filename, NULL))
        return false;

#if 0
    BasicDB * tmp_db = new TreeDB;
    if (!tmp_db->open(new_filename, BasicDB::OWRITER|BasicDB::OCREATE))
        return false;

    CopyVisitor visitor(tmp_db);
    m_db->iterate(&visitor, false);

    tmp_db->synchronize();
    tmp_db->close();
    delete tmp_db;
#endif

    return true;
}

template<int phrase_length>
int ChewingLargeTable2::search_internal(/* in */ const ChewingKey index[],
                                        /* in */ const ChewingKey keys[],
                                        /* out */ PhraseIndexRanges ranges) const {
    int result = SEARCH_NONE;

    ChewingTableEntry<phrase_length> * entry =
        (ChewingTableEntry<phrase_length> *)
        g_ptr_array_index(m_entries, phrase_length);
    assert(NULL != entry);

    const char * kbuf = (char *) index;
    const int32_t vsiz = m_db->check(kbuf, phrase_length * sizeof(ChewingKey));
    /* -1 on failure. */
    if (-1 == vsiz)
        return result;

    /* continue searching. */
    result |= SEARCH_CONTINUED;
    if (0 == vsiz)
        return result;

    entry->m_chunk.set_size(vsiz);
    /* m_chunk may re-allocate here. */
    char * vbuf = (char *) entry->m_chunk.begin();
    check_result(vsiz == m_db->get(kbuf, phrase_length * sizeof(ChewingKey),
                                   vbuf, vsiz));

    result = entry->search(keys, ranges) | result;

    return result;
}

int ChewingLargeTable2::search_internal(int phrase_length,
                                        /* in */ const ChewingKey index[],
                                        /* in */ const ChewingKey keys[],
                                        /* out */ PhraseIndexRanges ranges) const {
#define CASE(len) case len:                                 \
    {                                                       \
        return search_internal<len>(index, keys, ranges);   \
    }

    switch(phrase_length) {
        CASE(1);
        CASE(2);
        CASE(3);
        CASE(4);
        CASE(5);
        CASE(6);
        CASE(7);
        CASE(8);
        CASE(9);
        CASE(10);
        CASE(11);
        CASE(12);
        CASE(13);
        CASE(14);
        CASE(15);
        CASE(16);
    default:
        abort();
    }

#undef CASE

    return SEARCH_NONE;
}

template<int phrase_length>
int ChewingLargeTable2::search_suggestion_internal
(/* in */ const MemoryChunk & chunk,
 int prefix_len,
 /* in */ const ChewingKey prefix_keys[],
 /* out */ PhraseTokens tokens) const {
    int result = SEARCH_NONE;

    ChewingTableEntry<phrase_length> * entry =
        (ChewingTableEntry<phrase_length> *)
        g_ptr_array_index(m_entries, phrase_length);
    assert(NULL != entry);

    entry->m_chunk.set_chunk(chunk.begin(), chunk.size(), NULL);

    result = entry->search_suggestion(prefix_len, prefix_keys, tokens) | result;

    entry->m_chunk.set_size(0);

    return result;
}

int ChewingLargeTable2::search_suggestion_internal
(int phrase_length,
 /* in */ const MemoryChunk & chunk,
 int prefix_len,
 /* in */ const ChewingKey prefix_keys[],
 /* out */ PhraseTokens tokens) const {

#define CASE(len) case len:                             \
    {                                                   \
        return search_suggestion_internal<len>          \
            (chunk, prefix_len, prefix_keys, tokens);   \
    }

    switch(phrase_length) {
        CASE(1);
        CASE(2);
        CASE(3);
        CASE(4);
        CASE(5);
        CASE(6);
        CASE(7);
        CASE(8);
        CASE(9);
        CASE(10);
        CASE(11);
        CASE(12);
        CASE(13);
        CASE(14);
        CASE(15);
        CASE(16);
    default:
        abort();
    }

#undef CASE

    return SEARCH_NONE;
}

template<int phrase_length>
int ChewingLargeTable2::add_index_internal(/* in */ const ChewingKey index[],
                                           /* in */ const ChewingKey keys[],
                                           /* in */ phrase_token_t token) {
    ChewingTableEntry<phrase_length> * entry =
        (ChewingTableEntry<phrase_length> *)
        g_ptr_array_index(m_entries, phrase_length);
    assert(NULL != entry);

    bool retval = false;

    /* load chewing table entry. */
    const char * kbuf = (char *) index;
    size_t ksiz = phrase_length * sizeof(ChewingKey);
    char * vbuf = NULL;
    int32_t vsiz = m_db->check(kbuf, ksiz);
    if (-1 == vsiz) {
        /* new entry. */
        ChewingTableEntry<phrase_length> new_entry;
        new_entry.add_index(keys, token);

        vbuf = (char *) new_entry.m_chunk.begin();
        vsiz = new_entry.m_chunk.size();
        retval = m_db->set(kbuf, ksiz, vbuf, vsiz);
        if (!retval)
            return ERROR_FILE_CORRUPTION;

        /* recursively add keys for continued information. */
        for (size_t len = phrase_length - 1; len > 0; --len) {
            ksiz = len * sizeof(ChewingKey);

            vsiz = m_db->check(kbuf, ksiz);
            /* found entry. */
            if (-1 != vsiz)
                return ERROR_OK;

            /* new entry with empty content. */
            retval = m_db->set(kbuf, ksiz, empty_vbuf, 0);
            if (!retval)
                return ERROR_FILE_CORRUPTION;
        }

        return ERROR_OK;
    }

    /* already have keys. */
    entry->m_chunk.set_size(vsiz);
    /* m_chunk may re-allocate here. */
    vbuf = (char *) entry->m_chunk.begin();
    check_result(vsiz == m_db->get(kbuf, ksiz, vbuf, vsiz));

    int result = entry->add_index(keys, token);

    /* store the entry. */
    vbuf = (char *) entry->m_chunk.begin();
    vsiz = entry->m_chunk.size();
    retval = m_db->set(kbuf, ksiz, vbuf, vsiz);
    if (!retval)
        return ERROR_FILE_CORRUPTION;

    return result;
}

int ChewingLargeTable2::add_index_internal(int phrase_length,
                                           /* in */ const ChewingKey index[],
                                           /* in */ const ChewingKey keys[],
                                           /* in */ phrase_token_t token) {
#define CASE(len) case len:                                     \
    {                                                           \
        return add_index_internal<len>(index, keys, token);     \
    }

    switch(phrase_length) {
        CASE(1);
        CASE(2);
        CASE(3);
        CASE(4);
        CASE(5);
        CASE(6);
        CASE(7);
        CASE(8);
        CASE(9);
        CASE(10);
        CASE(11);
        CASE(12);
        CASE(13);
        CASE(14);
        CASE(15);
        CASE(16);
    default:
        abort();
    }

#undef CASE

    return ERROR_FILE_CORRUPTION;
}

template<int phrase_length>
int ChewingLargeTable2::remove_index_internal(/* in */ const ChewingKey index[],
                                              /* in */ const ChewingKey keys[],
                                              /* in */ phrase_token_t token) {
    ChewingTableEntry<phrase_length> * entry =
        (ChewingTableEntry<phrase_length> *)
        g_ptr_array_index(m_entries, phrase_length);
    assert(NULL != entry);

    const char * kbuf = (char *) index;
    const size_t ksiz = phrase_length * sizeof(ChewingKey);
    char * vbuf = NULL;
    int32_t vsiz = m_db->check(kbuf, ksiz);
    if (vsiz < (signed) sizeof(phrase_token_t))
        return ERROR_REMOVE_ITEM_DONOT_EXISTS;

    /* contains at least one index item. */
    entry->m_chunk.set_size(vsiz);
    /* m_chunk may re-allocate here. */
    vbuf = (char *) entry->m_chunk.begin();
    check_result(vsiz == m_db->get(kbuf, ksiz, vbuf, vsiz));

    int result = entry->remove_index(keys, token);
    if (ERROR_OK != result)
        return result;

    /* for safety. */
    vbuf = (char *) entry->m_chunk.begin();
    vsiz = entry->m_chunk.size();

    if (!m_db->set(kbuf, ksiz, vbuf, vsiz))
        return ERROR_FILE_CORRUPTION;

    return ERROR_OK;
}

int ChewingLargeTable2::remove_index_internal(int phrase_length,
                                              /* in */ const ChewingKey index[],
                                              /* in */ const ChewingKey keys[],
                                              /* in */ phrase_token_t token) {
#define CASE(len) case len:                                     \
    {                                                           \
        return remove_index_internal<len>(index, keys, token);  \
    }

    switch(phrase_length) {
        CASE(1);
        CASE(2);
        CASE(3);
        CASE(4);
        CASE(5);
        CASE(6);
        CASE(7);
        CASE(8);
        CASE(9);
        CASE(10);
        CASE(11);
        CASE(12);
        CASE(13);
        CASE(14);
        CASE(15);
        CASE(16);
    default:
        abort();
    }

#undef CASE

    return ERROR_FILE_CORRUPTION;
}

/* use MaskOutVisitor2 to avoid linking problem. */
class MaskOutVisitor2 : public DB::Visitor {
    GPtrArray * m_entries;

    phrase_token_t m_mask;
    phrase_token_t m_value;
public:
    MaskOutVisitor2(GPtrArray * entries,
                    phrase_token_t mask, phrase_token_t value) {
        m_entries = entries;
        m_mask = mask; m_value = value;
    }

    virtual const char* visit_full(const char* kbuf, size_t ksiz,
                                   const char* vbuf, size_t vsiz, size_t* sp) {

        int phrase_length = ksiz / sizeof(ChewingKey);

#define CASE(len) case len:                                     \
        {                                                       \
            ChewingTableEntry<len> * entry =                    \
                (ChewingTableEntry<len> *)                      \
                g_ptr_array_index(m_entries, phrase_length);    \
            assert(NULL != entry);                              \
                                                                \
            entry->m_chunk.set_content(0, vbuf, vsiz);          \
            entry->mask_out(m_mask, m_value);                   \
                                                                \
            vbuf = (char *) entry->m_chunk.begin();             \
            vsiz = entry->m_chunk.size();                       \
                                                                \
            *sp = vsiz;                                         \
            return vbuf;                                        \
        }

        switch(phrase_length) {
            CASE(1);
            CASE(2);
            CASE(3);
            CASE(4);
            CASE(5);
            CASE(6);
            CASE(7);
            CASE(8);
            CASE(9);
            CASE(10);
            CASE(11);
            CASE(12);
            CASE(13);
            CASE(14);
            CASE(15);
            CASE(16);
        default:
            abort();
        }

#undef CASE

        abort();
        return NOP;
    }

    virtual const char* visit_empty(const char* kbuf, size_t ksiz, size_t* sp) {
        return NOP;
    }
};

/* mask out method */
bool ChewingLargeTable2::mask_out(phrase_token_t mask,
                                  phrase_token_t value) {
    MaskOutVisitor2 visitor(m_entries, mask, value);
    m_db->iterate(&visitor, true);

    m_db->synchronize();
    return true;
}

/* search_suggesion method */
int ChewingLargeTable2::search_suggestion
(int prefix_len,
 /* in */ const ChewingKey prefix_keys[],
 /* out */ PhraseTokens tokens) const {
    ChewingKey index[MAX_PHRASE_LENGTH];
    int result = SEARCH_NONE;

    if (NULL == m_db)
        return result;

    if (contains_incomplete_pinyin(prefix_keys, prefix_len))
        compute_incomplete_chewing_index(prefix_keys, index, prefix_len);
    else
        compute_chewing_index(prefix_keys, index, prefix_len);

    const char * akbuf = (char *) index;
    const size_t aksiz = prefix_len * sizeof(ChewingKey);
    const int32_t vsiz = m_db->check(akbuf, aksiz);
    /* -1 on failure. */
    if (-1 == vsiz)
        return result;

    BasicDB::Cursor * cursor = m_db->cursor();
    bool retval = cursor->jump(akbuf, aksiz);
    if (!retval) {
        delete cursor;
        return result;
    }

    /* Get the next entry */
    retval = cursor->step();
    if (!retval) {
        delete cursor;
        return result;
    }

    size_t bksiz = 0;
    const char * bkbuf = cursor->get_key(&bksiz);
    MemoryChunk chunk;
    while(kyotodb_chewing_continue_search(akbuf, aksiz, bkbuf, bksiz)) {
        int phrase_length = bksiz / sizeof(ChewingKey);
        size_t bvsiz = 0;
        char * bvbuf = cursor->get_value(&bvsiz);
        chunk.set_chunk(bvbuf, bvsiz, NULL);
        result = search_suggestion_internal
            (phrase_length, chunk, prefix_len, prefix_keys, tokens) | result;
        chunk.set_size(0);
        delete [] bkbuf;
        delete [] bvbuf;

        retval = cursor->step();
        if (!retval) {
            delete cursor;
            return result;
        }

        bksiz = 0;
        bkbuf = cursor->get_key(&bksiz);
    }

    if (bkbuf) {
        delete [] bkbuf;
    }

    delete cursor;
    return result;
}

};
