/****************************************************************************
**
** Copyright (C) 1992-2005 Trolltech AS. All rights reserved.
**
** This file is part of the Qt Assistant of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License version 2.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of
** this file.  Please review the following information to ensure GNU
** General Public Licensing requirements will be met:
** http://www.trolltech.com/products/qt/opensource.html
**
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://www.trolltech.com/products/qt/licensing.html or contact the
** sales department at sales@trolltech.com.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include "qassistantclient.h"

#include <qtcpsocket.h>
#include <qtextstream.h>
#include <qtimer.h>
#include <qfileinfo.h>
#include <qmap.h>

class QAssistantClientPrivate
{
    friend class QAssistantClient;
    QStringList arguments;
};

static QMap<const QAssistantClient*,QAssistantClientPrivate*> *dpointers = 0;

static QAssistantClientPrivate *data( const QAssistantClient *client, bool create=false )
{
    if( !dpointers )
        dpointers = new QMap<const QAssistantClient*,QAssistantClientPrivate*>;
    QAssistantClientPrivate *d = (*dpointers)[client];
    if( !d && create ) {
        d = new QAssistantClientPrivate;
        dpointers->insert( client, d );
    }
    return d;
}

/*!
    \class QAssistantClient
    \brief The QAssistantClient class provides a means of using Qt
    Assistant as an application's help tool.

    \inmodule QtAssistant
    \ingroup helpsystem

    Using Qt Assistant is simple: create a QAssistantClient instance,
    then call showPage() as often as necessary to show your help
    pages. When you call showPage(), Qt Assistant will be launched if
    it isn't already running.

    The QAssistantClient instance can open (openAssistant()) or close
    (closeAssistant()) Qt Assistant whenever required. If Qt Assistant
    is open, isOpen() returns true.

    One QAssistantClient instance interacts with one Qt Assistant
    instance, so every time you call openAssistant(), showPage() or
    closeAssistant() they are applied to the particular Qt Assistant
    instance associated with the QAssistantClient.

    When you call openAssistant() the assistantOpened() signal is
    emitted. Similarly when closeAssistant() is called,
    assistantClosed() is emitted. In either case, if an error occurs,
    error() is emitted.

    This class is not included in the Qt library itself. To use it you
    must link against \c libqassistantclient.a (Unix) or \c
    qassistantclient.lib (Windows), which is built into \c INSTALL/lib
    if you built the Qt tools (\c INSTALL is the directory where Qt is
    installed). If you use qmake, then you can simply add the following
    line to your pro file:

    \code
        LIBS += -lqassistantclient
    \endcode

    See also \l{Qt Assistant Manual#Modifying The Default Documentation Set}{Modifying The Default Documentation Set}.
    \omit
    \sa \link assistant-manual.html#modifying-the-default-documentation-set \endlink
    \endomit
*/

/*!
    \fn void QAssistantClient::assistantOpened()

    This signal is emitted when Qt Assistant is open and the
    client-server communication is set up.
*/

/*!
    \fn void QAssistantClient::assistantClosed()

    This signal is emitted when the connection to Qt Assistant is
    closed. This happens when the user exits Qt Assistant, if an
    error in the server or client occurs, or if closeAssistant() is
    called.
*/

/*!
    \fn void QAssistantClient::error( const QString &message )

    This signal is emitted if Qt Assistant cannot be started, or if an
    error occurs during the initialization of the connection between
    Qt Assistant and the calling application. The \a message provides an
    explanation of the error.
*/

/*!
    Constructs an assistant client with the given \a parent.
    The \a path specifies the path to the Qt Assistant executable.
    If \a path is an empty string the system path (\c{%PATH%} or \c $PATH)
    is used.
*/
QAssistantClient::QAssistantClient( const QString &path, QObject *parent )
    : QObject( parent ), host ( "localhost" )
{
    if ( path.isEmpty() )
        assistantCommand = "assistant";
    else {
        QFileInfo fi( path );
        if ( fi.isDir() )
            assistantCommand = path + "/assistant";
        else
            assistantCommand = path;
    }

#if defined(Q_OS_MAC)
    assistantCommand += ".app/Contents/MacOS/assistant";
#endif

    socket = new QTcpSocket( this );
    connect( socket, SIGNAL(connected()),
            SLOT(socketConnected()) );
    connect( socket, SIGNAL(disconnected()),
            SLOT(socketConnectionClosed()) );
    connect( socket, SIGNAL(error(QAbstractSocket::SocketError)),
             SLOT(socketError(QAbstractSocket::SocketError)) );
    opened = false;
    proc = new QProcess( this );
    port = 0;
    pageBuffer = "";
    connect( proc, SIGNAL(readyReadStandardError()),
             this, SLOT(readStdError()) );
    connect( proc, SIGNAL(error(QProcess::ProcessError)),
        this, SLOT(procError(QProcess::ProcessError)) );    
}

/*!
    Destroys the assistant client object.
*/
QAssistantClient::~QAssistantClient()
{
    if ( proc->state() == QProcess::Running )
        proc->terminate();

    if( dpointers ) {
        QAssistantClientPrivate *d = (*dpointers)[ this ];
        if ( d ) {
            dpointers->remove(this);
            delete d;
            if( dpointers->isEmpty() ) {
                delete dpointers;
                dpointers = 0;
            }
        }
    }
}

/*!
    This function opens Qt Assistant, and sets up the client-server
    communiction between the application and Qt Assistant. If it is
    already open, this function does nothing. If an error occurs,
    error() is emitted.

    \sa assistantOpened()
*/
void QAssistantClient::openAssistant()
{
    if ( proc->state() == QProcess::Running )
        return;

    QStringList args;
    args.append("-server");
    if( !pageBuffer.isEmpty() ) {
        args.append( "-file" );
        args.append( pageBuffer );
    }

    QAssistantClientPrivate *d = data( this );
    if( d ) {
        QStringList::ConstIterator it = d->arguments.begin();
        while( it!=d->arguments.end() ) {
            args.append( *it );
            ++it;
        }
    }

    connect( proc, SIGNAL(readyReadStandardOutput()),
        this, SLOT(readPort()) );
    
    proc->start(assistantCommand, args);
}

void QAssistantClient::procError(QProcess::ProcessError err)
{
    switch (err)
    {
    case QProcess::FailedToStart:
        emit error( tr( "Failed to start Qt Assistant." ) );
        break;
    case QProcess::Crashed:
        emit error( tr( "Qt Assistant crashed." ) );
        break;
    default:
        emit error( tr( "Error while running Qt Assistant." ) );
    }
}

void QAssistantClient::readPort()
{
    QString p = proc->readAllStandardOutput();
    quint16 port = p.toUShort();
    if ( port == 0 ) {
        emit error( tr( "Cannot connect to Qt Assistant." ) );
        return;
    }
    socket->connectToHost( host, port );
    disconnect( proc, SIGNAL(readyReadStandardOutput()),
                this, SLOT(readPort()) );
}

/*!
    Use this function to close Qt Assistant.

    \sa assistantClosed()
*/
void QAssistantClient::closeAssistant()
{
    if ( !opened )
        return;
    proc->terminate();
}

/*!
    Call this function to make Qt Assistant show a particular \a page.
    The \a page is a filename (e.g. \c myhelpfile.html).
    See \l{Qt Assistant Manual#Modifying the Default Documentation Set}
    for further information.

    If Qt Assistant hasn't been \link openAssistant() opened\endlink
    yet, this function will do nothing. You can use isOpen() to
    determine whether Qt Assistant is up and running, or you can
    connect to the asssistantOpened() signal.

    \sa isOpen(), assistantOpened()
*/
void QAssistantClient::showPage( const QString &page )
{
    if ( !opened ) {
        pageBuffer = page;
        openAssistant();
        pageBuffer.clear();
        return;
    }
    QTextStream os( socket );
    os << page << "\n";
}

/*!
    \property QAssistantClient::open
    \brief whether Qt Assistant is open

*/
bool QAssistantClient::isOpen() const
{
    return opened;
}

void QAssistantClient::socketConnected()
{
    opened = true;
    if ( !pageBuffer.isEmpty() )
        showPage( pageBuffer );
    emit assistantOpened();
}

void QAssistantClient::socketConnectionClosed()
{
    opened = false;
    emit assistantClosed();
}

void QAssistantClient::socketError(QAbstractSocket::SocketError err)
{
    if (err == QTcpSocket::ConnectionRefusedError)
        emit error( tr( "Could not connect to Assistant: Connection refused" ) );
    else if (err == QTcpSocket::HostNotFoundError)
        emit error( tr( "Could not connect to Assistant: Host not found" ) );
    else if (err != QTcpSocket::RemoteHostClosedError)
        emit error( tr( "Communication error" ) );
}

void QAssistantClient::readStdError()
{
    QString errmsg = proc->readAllStandardError();

    if (!errmsg.isEmpty())
        emit error( errmsg.simplified() );
}

/*!
    \fn void QAssistantClient::setArguments(const QStringList &arguments)

    Sets the command line \a arguments used when Qt Assistant is
    started.
*/
void QAssistantClient::setArguments( const QStringList &args )
{
    QAssistantClientPrivate *d = data( this, true );
    d->arguments = args;
}
