/******************************************************************************
 *
 * This file is part of Log4Qt library.
 *
 * Copyright (C) 2007 - 2020 Log4Qt contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 ******************************************************************************/

#ifndef LOG4QT_HELPERS_CONFIGURATORHELPER_H
#define LOG4QT_HELPERS_CONFIGURATORHELPER_H

#include "log4qt/log4qtshared.h"
#include "log4qt/loggingevent.h"

#include <QObject>
#include <QList>
#include <QMutex>
#include <QFileInfo>

class QFileSystemWatcher;

namespace Log4Qt
{

/*!
 * \brief The class ConfiguratorHelper provides a confiuration file watch
 *        and last error for configurator classes.
 *
 * A configuration file can be set using setConfigurationFile(). The file
 * is watched for changes. If a change occurs the configuration is reloaded
 * and the ConfigurationFileChanged() signal is Q_EMITted. Error information
 * for the last call to a configure function or the last configuration file
 * change can be accessed using configureError().
 *
 * \note All the functions declared in this class are thread-safe.
 */
class LOG4QT_EXPORT ConfiguratorHelper : public QObject
{
    Q_OBJECT

public:
    /*!
         * Prototype for a configure callback function. The function is called
         * when then configuration file is changed and takes the
         * configuration file as a parameter.
         *
         * \sa setConfigurationFile(),
         *     PropertyConfigurator::configure(const QString &)
     */
    typedef bool (*ConfigureFunc)(const QString &fileName);

private:
    ConfiguratorHelper(QObject *parent = nullptr);
    virtual ~ConfiguratorHelper();

    Q_DISABLE_COPY(ConfiguratorHelper)

public:

    /*!
     * Returns the error information for the last configuration operation
     * that took place. The configuration operation could be the result of
     * a call to one of the configure methods or through a change
     * to the configuration file.
     *
     * \sa setConfigureError(), PropertyConfigurator::configure(),
     *     setConfigurationFile()
     */
    static QList<LoggingEvent> configureError();

    /*!
     * Returns the current configuration file.
     *
     * \sa setConfigurationFile()
     */
    static QString configurationFile();

    /*!
         * Returns the ConfiguratorHelper instance.
         */
    static ConfiguratorHelper *instance();

    /*!
     * Sets the configuration error information for the last configuration
     * operation.
     *
     * \sa configureError()
     */
    static void setConfigureError(const QList<LoggingEvent> &configureError);

    /*!
     * Sets the configuration file to \a fileName. The file is watched for
     * changes. On a file change the function \a pConfigureFunc will be called
     * and the signal configurationFileChange() will be Q_EMITted.
     *
     * Setting the configuration file to an empty string stops the file watch.
     *
     * \sa configurationFile(), PropertyConfigurator::configureAndWatch(),
     *     configureError()
     */
    static void setConfigurationFile(const QString &fileName = QString(),
                                     ConfigureFunc pConfigureFunc = nullptr);

Q_SIGNALS:
    /*!
     * The signal is Q_EMITted after a change to the file \a fileName
     * was processed. If an error occured during the configuration, the
     * flag \a error will be true and error information is available
     * over configureError().
     */
    void configurationFileChanged(const QString &fileName,
                                  bool error);

private Q_SLOTS:
    void doConfigurationFileChanged(const QString &fileName);
    void doConfigurationFileDirectoryChanged(const QString &path);
    void tryToReAddConfigurationFile();

private:
    void doSetConfigurationFile(const QString &fileName,
                                ConfigureFunc pConfigureFunc);

private:
    mutable QMutex mObjectGuard;
    QFileInfo mConfigurationFile;
    ConfigureFunc mConfigureFunc;
    QFileSystemWatcher *mConfigurationFileWatch;
    QList<LoggingEvent> mConfigureError;
};

inline QList<LoggingEvent> ConfiguratorHelper::configureError()
{
    QMutexLocker locker(&instance()->mObjectGuard);
    return instance()->mConfigureError;
}

inline QString ConfiguratorHelper::configurationFile()
{
    QMutexLocker locker(&instance()->mObjectGuard);
    return instance()->mConfigurationFile.absoluteFilePath();
}

inline void ConfiguratorHelper::setConfigureError(const QList<LoggingEvent> &configureError)
{
    QMutexLocker locker(&instance()->mObjectGuard);
    instance()->mConfigureError = configureError;
}

inline void ConfiguratorHelper::setConfigurationFile(const QString &fileName,
        ConfigureFunc pConfigureFunc)
{
    instance()->doSetConfigurationFile(fileName, pConfigureFunc);
}

} // namespace Log4Qt

#endif // LOG4QT_HELPERS_CONFIGURATORHELPER_H