utilities/src/logger.cpp

/********************************************************************************
 *  FARSA Utilities Library                                                     *
 *  Copyright (C) 2007-2011 Gianluca Massera <emmegian@yahoo.it>                *
 *                                                                              *
 *  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, write to the Free Software                 *
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA  *
 ********************************************************************************/

#include "logger.h"
#include <QFile>
#include <QTextStream>
#include <QTextEdit>
#include <QDateTime>
#include <iostream>
#include <QObject>
#include <QEvent>
#include <QApplication>
#include <QMutex>
#include <QMutexLocker>
#include <QMessageBox>

namespace farsa {

namespace {
    //--- This and the following are utilities class for updating textEdit into the GUI Thread
    class TextToAppend : public QEvent {
    public:
        TextToAppend( QString text, QString level, QString pureMessage ) :
            QEvent((Type)type),
            text(text),
            level(level),
            pureMessage(pureMessage) { };
        QString getText() {
            return text;
        };
        QString getLevel() {
            return level;
        };
        QString getPureMessage() {
            return pureMessage;
        };
    private:
        static int type;
        QString text;
        QString level;
        QString pureMessage;
    };
    int TextToAppend::type = QEvent::registerEventType();

    class TextEditUpdater : public QObject {
    public:
        TextEditUpdater() :
            QObject(),
            textEdit(NULL)
        {
        }

        void setTextEditToUpdate(QTextEdit* e)
        {
            textEdit = e;
        }

        bool hasTextEdit() const
        {
            return (textEdit != NULL);
        }

    protected:
        virtual void customEvent( QEvent* event ) {
            // If textEdit is NULL we will crash here (this should never happend)
            TextToAppend* tevent = dynamic_cast<TextToAppend*>( event );
            if ( tevent ) {
                textEdit->append( tevent->getText() );
                textEdit->moveCursor( QTextCursor::End );
                textEdit->moveCursor( QTextCursor::StartOfLine );
                if ( tevent->getLevel() == "ERROR" ) {
                    QMessageBox::critical( 0, "Error from Component", tevent->getPureMessage() );
                }
                tevent->accept();
            } else {
                QObject::customEvent( event );
            }
        };

        QTextEdit* textEdit;
    };

    // This class contains the core functionalities for logging. It is implemented
    // as a singleton to have the correct initialization of all needed variables
    // when the Logger is used for the first time
    class LoggerImplementation
    {
    public:
        // Returns the only instance of this class
        static LoggerImplementation& getInstance();

        void info(QString msg);

        void warning(QString msg);

        void error(QString msg);

        void setQTextEdit(QTextEdit* textedit);

        void enableStdOut(bool enabled);

        void setLogLevel(Logger::LogLevel level);

        void setLogFilename(QString logfile);

    private:
        // Constructor
        LoggerImplementation();

        // Destructor
        ~LoggerImplementation();

        // This is the main function for logging. This function is thread-safe
        void logIt(QString level, QString msg);

        bool stdOut;
        QFile* file;
        QTextStream* fileStream;
        QTextStream* outStream;
        TextEditUpdater* textEditUpdater;
        Logger::LogLevel logLevel;
        // The semaphores protecting the streams. The logger can be called from multiple threads simultaneously
        QMutex outStreamMutex;
        QMutex fileStreamMutex;

    private:
        // Copy constructor, not implemented
        LoggerImplementation(LoggerImplementation&);

        // Copy operator, not implemented
        LoggerImplementation& operator=(LoggerImplementation&);
    };

    LoggerImplementation& LoggerImplementation::getInstance()
    {
        // The meyer singleton
        static LoggerImplementation loggerImplementation;

        return loggerImplementation;
    }

    void LoggerImplementation::info(QString msg)
    {
        if (logLevel <= Logger::Default) {
            logIt("INFO", msg);
        }
    }

    void LoggerImplementation::warning(QString msg)
    {
        if (logLevel <= Logger::Warning) {
            logIt("WARNING", msg);
        }
    }

    void LoggerImplementation::error(QString msg)
    {
        if (logLevel <= Logger::Quiet) {
            logIt("ERROR", msg);
        }
    }

    void LoggerImplementation::setQTextEdit(QTextEdit* textedit)
    {
        textEditUpdater->setTextEditToUpdate(textedit);
    }

    void LoggerImplementation::enableStdOut(bool enabled)
    {
        stdOut = enabled;
    }

    void LoggerImplementation::setLogLevel(Logger::LogLevel level)
    {
        logLevel = level;
    }

    void LoggerImplementation::setLogFilename(QString logfile)
    {
        QFile* oldfile = file;
        file = new QFile(logfile);
        fileStream->setDevice(file);
        //--- the delete on the File has to be after the setDevice on QTextStream
        delete oldfile;
    }

    LoggerImplementation::LoggerImplementation() :
        stdOut(true),
        file(NULL),
        fileStream(new QTextStream()),
        outStream(new QTextStream(stdout)),
        textEditUpdater(new TextEditUpdater()),
        logLevel(Logger::Default),
        outStreamMutex(),
        fileStreamMutex()
    {
    }

    LoggerImplementation::~LoggerImplementation()
    {
        delete textEditUpdater;
        delete outStream;
        delete fileStream;
        delete file;

        // These lines are here to have a "clean" crash if somebody tries to access
        // the logger after returning from the main function
        textEditUpdater = NULL;
        outStream = NULL;
        fileStream = NULL;
        file = NULL;
    }

    //--- this is the main function for logging. This function is thread-safe
    void LoggerImplementation::logIt(QString level, QString msg)
    {
        QString logtmpl("[%1] %2: %3");
        QString timestamp = QDateTime::currentDateTime().toString( "dd-MM-yyyy hh:mm:ss.zzz" );
        QString logmsg = logtmpl.arg( timestamp ).arg( level, -10 ).arg( msg );
        if ( stdOut ) {
            QMutexLocker locker(&outStreamMutex);

            (*outStream) << logmsg << "\n";
            outStream->flush();
        }
        if ( textEditUpdater->hasTextEdit() ) {
            // No semaphore here as we use the thread-safe postEvent function
            QString color = "#ffffff";
            if ( level == "INFO" ) {
                color = "#afeeee";
            } else if ( level == "WARNING" ) {
                color = "#f0e68c";
            } else if ( level == "ERROR" ) {
                color = "#ff4500";
            }
            // --- here the postEvent is used because it is not possible to modify directly the content of
            //     textEdit because it is not thread-safe. In fact, this function might be called from multiple
            //     threads and outside the GUI thread
            qApp->postEvent( textEditUpdater, new TextToAppend( QString("<pre style=\"margin-top: 0px; margin-bottom: 0px; color: ")+color+";\">"+logmsg+QString("</pre>"), level, msg ) );
            //textEdit->append( QString("<pre style=\"margin-top: 0px; margin-bottom: 0px; color: ")+color+";\">"+logmsg+QString("</pre>") );
            //textEdit->moveCursor( QTextCursor::End );
            //textEdit->moveCursor( QTextCursor::StartOfLine );
        }
        if ( fileStream && fileStream->device() ) {
            QMutexLocker locker(&fileStreamMutex);

            (*fileStream) << logmsg << "\n";
            fileStream->flush();
        }
    }
} //end anonymous namespace for LoggerImplementation class

void Logger::info(QString msg)
{
    LoggerImplementation::getInstance().info(msg);
}

void Logger::warning(QString msg)
{
    LoggerImplementation::getInstance().warning(msg);
}

void Logger::error(QString msg)
{
    LoggerImplementation::getInstance().error(msg);
}

void Logger::setLogFilename(QString logfile)
{
    LoggerImplementation::getInstance().setLogFilename(logfile);
}

void Logger::setQTextEdit(QTextEdit* textedit)
{
    LoggerImplementation::getInstance().setQTextEdit(textedit);
}

void Logger::enableStdOut(bool enabled)
{
    LoggerImplementation::getInstance().enableStdOut(enabled);
}

void Logger::setLogLevel(LogLevel level) {
    LoggerImplementation::getInstance().setLogLevel(level);
}

QString Logger::logLevelToString(Logger::LogLevel level)
{
    QString str = "unknown";

    switch(level)
    {
        case Default:
            str = "Default";
            break;
        case Warning:
            str = "Warning";
            break;
        case Quiet:
            str = "Quiet";
            break;
        case Superquiet:
            str = "Superquiet";
            break;
    }

    return str;
}

Logger::LogLevel Logger::stringToLogLevel(QString level)
{
    LogLevel l = Default;

    if (level.toUpper() == "DEFAULT") {
        l = Default;
    } else if (level.toUpper() == "WARNING") {
        l = Warning;
    } else if (level.toUpper() == "QUIET") {
        l = Quiet;
    } else if (level.toUpper() == "SUPERQUIET") {
        l = Superquiet;
    }

    return l;
}

} // end namespace farsa