/**
 * @file Common/iapp.h
 * @brief eVaf application interface
 * @author Enar Vaikene
 *
 * Copyright (c) 2011 Enar Vaikene
 *
 * This file is part of the eVaf C++ cross-platform application development framework.
 *
 * This file can be used under the terms of the GNU General Public License
 * version 3.0 as published by the Free Software Foundation and appearing in
 * the file LICENSE included in the packaging of this file. Please review the
 * the following information to ensure the GNU General Public License version
 * 3.0 requirements will be met: http://www.gnu.org/copyleft/gpl.html.
 *
 * Alternatively, this file may be used in accordance with the Commercial License
 * Agreement provided with the Software.
 */

#ifndef __COMMON_IAPP_H
#define __COMMON_IAPP_H

#include "libcommon.h"

#include <QObject>
#include <QString>

namespace eVaf {
namespace Common {

/**
 * eVaf application interface
 * @code#include <Common/iApp>@endcode
 *
 * The iApp interface provides information about current eVaf application.
 *
 * All the resources returned by this interface have default values, that should work in most of the cases.
 *
 * Default values can be overwritten with environment variables and command line arguments. If both are used,
 * then command line arguments have higher priorities.
 */
class COMMON_EXPORT iApp : public QObject
{
    Q_OBJECT

public:

    /// Application return values
    enum {
        RC_Quit     = 0,        ///< Normal exit
        RC_Error    = 1,        ///< Exit due to an error
        RC_Restart  = 2         ///< The application is restarting
    };

    /// Event that requests the eVaf application to quit
    static char const * const EV_QUIT;

    /// Event that requests the eVaf application to restart
    static char const * const EV_RESTART;

    /// Event informing that the eVaf application is ready
    static char const * const EV_READY;

    /// Event informing that the  eVaf application is restarting
    static char const * const EV_TERMINATING;

    /// Interface constructor
    iApp() : QObject() {}

    /// Empty virtual destructor
    virtual ~iApp() {}

    /**
     * Returns the iApp interface instance
     * @return The iApp interface
     *
     * This function returns the global iApp interface instance. As all the eVaf modules and applications
     * are expected to be linked against the common library, then this is the preferred method of obtaining
     * the iApp interface. The other method is by using the iRegistry interface.
     */
    static iApp * instance();

    /**
     * Returns the name of the eVaf application
     *
     * This function returns the name of the eVaf application, which is a string that identifies the application.
     * The default name of the application is "eVaf".
     *
     * This name of the application can be changed with the EVAF_APP_NAME environment variable or with the
     * -app[lication]=&lt;name&gt; command line argument.
     */
    virtual QString const name() const = 0;

    /**
     * Returns the current language and country used by the application.
     *
     * This function returns the current lowercase two-letter ISO 639 language code and uppercase
     * two-letter ISO 3166 country code if set.
     *
     * The default language is queried from the operating system.
     *
     * The language can be changed with the EVAF_LANGUAGE environment variabel or with the
     * -lang[uage]=&lt;language&gt; command line argument.
     */
    virtual QString const language() const = 0;

    /**
     * Returns the name of the application's XML file.
     *
     * This function returns the name of the application's XML file.
     * It tries to find the most specific file name for the given language. If not found, then
     * defaults to the generic name.
     *
     * For example, if the language is set to "et_EE" and the application's name is "eVaf", then
     * it tries to find XML files with the following names "eVaf_et_EE.xml" and "eVaf_et.xml". If
     * neither is found, defaults to the name "eVaf.xml".
     *
     * The path is not included in the returned file name. Use the eVaf::Common::iEnv::etcDir() function
     * for the location of the file.
     */
    virtual QString const xmlFileName() const = 0;

    /**
     * Requests the eVaf application to restart.
     *
     * This function requests the eVaf application to restart itself. Restarting the application
     * reloads all the plugins and re-initializes them.
     */
    virtual void restart() = 0;

    /**
     * Requests the eVaf application to quit.
     * @param err If true, then indicates that the application exits due to a fatal error
     *
     * This function requests the eVaf application to quit.
     */
    virtual void quit(bool err = false) = 0;

    /**
     * Returns true if the eVaf application is ready.
     */
     virtual bool isReady() const = 0;


signals:

    /**
     * Ready signal.
     *
     * This signal is emitted when the eVaf application is ready, ie the application initialized and all the
     * modules loaded.
     */
    void ready();

    /**
     * Terminating signal.
     *
     * This signal is emitted when the eVaf application is about to terminate.
     */
    void terminating();

};

} // namespace eVaf::Common
} // namespace eVaf

#endif