/*
 * Copyright (C) 2022, KylinSoft Co., 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 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 <https://www.gnu.org/licenses/>.
 *
 * Authors: iaom <zhangpengfei@kylinos.cn>
 *
 */
#include "index-scheduler.h"
#include "index-updater.h"
#include "compatible-define.h"

using namespace UkuiSearch;
IndexScheduler::IndexScheduler(QObject *parent) :
    QObject(parent),
    m_statusRecorder(IndexStatusRecorder::getInstance()),
    m_config(FileIndexerConfig::getInstance()),
    m_state(Startup),
    m_stop(0)
{
    qRegisterMetaType<IndexerState>("IndexerState");
    qRegisterMetaType<BatchIndexer::WorkMode>("BatchIndexer::WorkMode");
    m_threadPool.setMaxThreadCount(1);
    connect(&m_fileWatcher, &FileWatcher::filesUpdate, this, &IndexScheduler::updateIndex);
    connect(m_config, &FileIndexerConfig::fileIndexEnableStatusChanged, this, &IndexScheduler::fileIndexEnable);
    connect(m_config, &FileIndexerConfig::appendIndexDir, this, &IndexScheduler::addNewPath);
    connect(m_config, &FileIndexerConfig::removeIndexDir, this, &IndexScheduler::removeIndex);
    m_state = Startup;
    if(m_config->isFileIndexEnable()) {
        start();
    } else {
        m_stop.fetchAndStoreRelaxed(1);
    }
}

void IndexScheduler::addNewPath(const QString &folders, const QStringList &blackList)
{
    if(m_stop.LOAD) {
        qDebug() << "Index Scheduler is being stopped, add operation will be executed when started up next time.";
        return;
    }
    m_state = Running;
    Q_EMIT stateChange(m_state);
    BatchIndexer::Targets target = BatchIndexer::Target::None;
    if(m_config->isFileIndexEnable()) {
        target |= BatchIndexer::Target::Basic;
    }
    if(m_config->isContentIndexEnable()) {
        target |= BatchIndexer::Target::Content;
    }
    BatchIndexer::WorkMode mode = BatchIndexer::WorkMode::Add;
    startIndexJob(QStringList() << folders, blackList, mode, target);
    if(BatchIndexer::Target::None != target) {
        m_fileWatcher.addWatch(folders, blackList);
    }
}

void IndexScheduler::removeIndex(const QString &folders)
{
    if(m_stop.LOAD) {
        qDebug() << "Index Scheduler is being stopped, remove operation will be executed when started up next time.";
        return;
    }
    m_fileWatcher.removeWatch(folders, true);
}

void IndexScheduler::stop()
{
    m_stop.fetchAndStoreRelaxed(1);
    m_fileWatcher.removeWatch();
    m_threadPool.clear();
    m_threadPool.waitForDone(-1);
    m_state = Stop;
    qDebug() << "Index scheduler has been stopped.";
    Q_EMIT stateChange(m_state);
    m_statusRecorder->setStatus(INDEX_DATABASE_STATE_KEY, IndexStatusRecorder::State::Off);
    m_statusRecorder->setStatus(CONTENT_INDEX_DATABASE_STATE_KEY, IndexStatusRecorder::State::Off);
}

void IndexScheduler::start()
{
    qDebug() << "Index scheduler start.";
    if(!m_isFirstRunFinished || !m_isRebuildFinished) {
        qDebug() << "Index scheduler running, start operation ignored. FirstRun finished: " << m_isFirstRunFinished << "Rebuild finished: " << m_isRebuildFinished;
        return;
    }
    m_stop.fetchAndStoreRelaxed(0);
    m_state = Running;
    Q_EMIT stateChange(m_state);
    BatchIndexer::Targets rebuiltTarget = checkAndRebuild();

    BatchIndexer::WorkMode mode = BatchIndexer::WorkMode::Update;
    BatchIndexer::Targets target = BatchIndexer::Target::None;

    //如果数据库被执行过重建，那么跳过增量更新步骤。
    if(m_config->isFileIndexEnable() && !(rebuiltTarget & BatchIndexer::Target::Basic)) {
        target |= BatchIndexer::Target::Basic;
        m_statusRecorder->setStatus(INDEX_DATABASE_STATE_KEY, IndexStatusRecorder::State::Updating);
    }
    if(m_config->isContentIndexEnable() && !(rebuiltTarget & BatchIndexer::Target::Content)) {
        target |= BatchIndexer::Target::Content;
        m_statusRecorder->setStatus(CONTENT_INDEX_DATABASE_STATE_KEY, IndexStatusRecorder::State::Updating);
    }
    startIndexJob(m_config->currentIndexableDir(), m_config->currentBlackListOfIndex(), mode, target);

    //启动监听
    m_fileWatcher.installWatches();
}

IndexScheduler::IndexerState IndexScheduler::getIndexState()
{
    return m_state;
}

BatchIndexer::Targets IndexScheduler::checkAndRebuild()
{
    BatchIndexer::WorkMode mode = BatchIndexer::WorkMode::Rebuild;
    BatchIndexer::Targets target = BatchIndexer::Target::None;
    if((m_statusRecorder->getStatus(INDEX_DATABASE_STATE_KEY).toInt() == IndexStatusRecorder::State::Error
        || !m_statusRecorder->versionCheck(INDEX_DATABASE_VERSION_KEY, INDEX_DATABASE_VERSION))
            && m_config->isFileIndexEnable()) {
        qDebug() << "Basic database need rebuild";
        target |= BatchIndexer::Target::Basic;
        m_statusRecorder->setStatus(INDEX_DATABASE_STATE_KEY, IndexStatusRecorder::State::Initializing);
    }

    if((m_statusRecorder->getStatus(CONTENT_INDEX_DATABASE_STATE_KEY).toInt() == IndexStatusRecorder::State::Error
        || !m_statusRecorder->versionCheck(CONTENT_DATABASE_VERSION_KEY, CONTENT_DATABASE_VERSION))
            && m_config->isFileIndexEnable()) {
        qDebug() << "Content database need rebuild";
        target |= BatchIndexer::Target::Content;
        m_statusRecorder->setStatus(CONTENT_INDEX_DATABASE_STATE_KEY, IndexStatusRecorder::State::Initializing);
    }
    startIndexJob(m_config->currentIndexableDir(), m_config->currentBlackListOfIndex(), mode, target);
    return target;
}

void IndexScheduler::startIndexJob(const QStringList& folders,const QStringList& blackList, BatchIndexer::WorkMode mode, BatchIndexer::Targets target)
{
    if(BatchIndexer::Target::None != target) {
        switch (mode) {
        case BatchIndexer::WorkMode::Add:
            m_isAddNewPathFinished = false;
            break;
        case BatchIndexer::WorkMode::Rebuild:
            m_isRebuildFinished = false;
            break;
        case BatchIndexer::WorkMode::Update:
            m_isFirstRunFinished = false;
            break;
        default:
            break;
        }
        BatchIndexer *indexer = new BatchIndexer(folders, blackList, m_stop, mode, target);
        connect(indexer, &BatchIndexer::done, this, &IndexScheduler::firstRunFinished, Qt::QueuedConnection);
        connect(indexer, &BatchIndexer::progress, this, &IndexScheduler::process);

        connect(indexer, &BatchIndexer::basicIndexDone, this, [&](uint size){
            bool success = false;
            if(!(m_statusRecorder->getStatus(INDEX_DATABASE_STATE_KEY).toInt() == IndexStatusRecorder::State::Error)) {
                m_statusRecorder->setStatus(INDEX_DATABASE_STATE_KEY, IndexStatusRecorder::State::Ready);
                success = true;
            }
            Q_EMIT basicIndexDone(size, success);
        });

        connect(indexer, &BatchIndexer::contentIndexDone, this, [&](uint size){
            bool success = false;
            if(!(m_statusRecorder->getStatus(CONTENT_INDEX_DATABASE_STATE_KEY).toInt() == IndexStatusRecorder::State::Error)) {
                m_statusRecorder->setStatus(CONTENT_INDEX_DATABASE_STATE_KEY, IndexStatusRecorder::State::Ready);
                success = true;
            }
            Q_EMIT contentIndexDone(size, success);
        });

        m_threadPool.start(indexer);
    }
}

void IndexScheduler::fileIndexEnable(bool enable)
{
    //Fix me: 快速反复开关会导致反复执行增量更新操作，可优化。
    if(enable) {
        start();
    } else {
        stop();
    }
}

void IndexScheduler::updateIndex(const QVector<PendingFile> &files)
{
    qDebug() << "updateIndex=====";
    m_isUpdateFinished = false;
    m_state = Running;
    IndexUpdater *updateJob = new IndexUpdater(files, m_stop);
    connect(updateJob, &IndexUpdater::done, this, &IndexScheduler::updateFinished, Qt::QueuedConnection);
    m_threadPool.start(updateJob);
}

void IndexScheduler::firstRunFinished(BatchIndexer::WorkMode mode)
{
    switch (mode) {
    case BatchIndexer::WorkMode::Add:
        m_isAddNewPathFinished = true;
        break;
    case BatchIndexer::WorkMode::Rebuild:
        m_isRebuildFinished = true;
        break;
    case BatchIndexer::WorkMode::Update:
        m_isFirstRunFinished = true;
        break;
    default:
        break;
    }
    if(isIdle()) {
        m_state = Idle;
        Q_EMIT stateChange(m_state);
    }
}

void IndexScheduler::updateFinished()
{
    m_isUpdateFinished = true;
    if(isIdle()) {
        m_state = Idle;
        Q_EMIT stateChange(m_state);
    }
}

bool IndexScheduler::isIdle()
{
    return m_isFirstRunFinished && m_isAddNewPathFinished && m_isUpdateFinished && m_isRebuildFinished;
}