/**************************************************************
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 * 
 *************************************************************/


// MARKER(update_precomp.py): autogen include statement, do not remove
#include "precompiled_vcl.hxx"

#include <unx/svunx.h>
#include <tools/prex.h>
#include <X11/Xatom.h>
#include <tools/postx.h>

#include "rtl/ustrbuf.hxx"
#include "osl/module.h"
#include "osl/process.h"
#include "osl/thread.h"

#include "vclpluginapi.h"

#include <unistd.h>

using namespace rtl;

enum {
    DESKTOP_NONE = 0,
    DESKTOP_UNKNOWN,
    DESKTOP_GNOME,
    DESKTOP_KDE,
    DESKTOP_KDE4,
    DESKTOP_CDE
};

static const char * desktop_strings[] = { "none", "unknown", "GNOME", "KDE", "KDE4", "CDE" };

static bool is_gnome_desktop( Display* pDisplay )
{
    bool ret = false;
    
    // warning: these checks are coincidental, GNOME does not
    // explicitly advertise itself
    
    if ( NULL != getenv( "GNOME_DESKTOP_SESSION_ID" ) )
        ret = true;
    
    if( ! ret )
    {
        Atom nAtom1 = XInternAtom( pDisplay, "GNOME_SM_PROXY", True );
        Atom nAtom2 = XInternAtom( pDisplay, "NAUTILUS_DESKTOP_WINDOW_ID", True );
        if( nAtom1 || nAtom2 )
        {
            int nProperties = 0;
            Atom* pProperties = XListProperties( pDisplay, DefaultRootWindow( pDisplay ), &nProperties );
            if( pProperties && nProperties )
            {
                for( int i = 0; i < nProperties; i++ )
                    if( pProperties[ i ] == nAtom1 ||
                        pProperties[ i ] == nAtom2 )
                {
                    ret = true;
                }
                XFree( pProperties );
            }
        }
    }
    
    if( ! ret )
    {
        Atom nUTFAtom		= XInternAtom( pDisplay, "UTF8_STRING", True );
        Atom nNetWMNameAtom	= XInternAtom( pDisplay, "_NET_WM_NAME", True );
        if( nUTFAtom && nNetWMNameAtom )
        {
            // another, more expensive check: search for a gnome-panel
            XLIB_Window aRoot, aParent, *pChildren = NULL;
            unsigned int nChildren = 0;
            XQueryTree( pDisplay, DefaultRootWindow( pDisplay ),
                        &aRoot, &aParent, &pChildren, &nChildren );
            if( pChildren && nChildren )
            {
                for( unsigned int i = 0; i < nChildren && ! ret; i++ )
                {
                    Atom nType = None;
                    int nFormat = 0;
                    unsigned long nItems = 0, nBytes = 0;
                    unsigned char* pProp = NULL;
                    XGetWindowProperty( pDisplay,
                                        pChildren[i],
                                        nNetWMNameAtom,
                                        0, 8,
                                        False,
                                        nUTFAtom,
                                        &nType,
                                        &nFormat,
                                        &nItems,
                                        &nBytes,
                                        &pProp );
                    if( pProp && nType == nUTFAtom )
                    {
                        OString aWMName( (sal_Char*)pProp );
                        if( aWMName.equalsIgnoreAsciiCase( "gnome-panel" ) )
                            ret = true;
                    }
                    if( pProp )
                        XFree( pProp );
                }
                XFree( pChildren );
            }
        }
    }

    return ret;
}

static bool bWasXError = false;

static inline bool WasXError()
{
    bool bRet = bWasXError;
    bWasXError = false;
    return bRet;
}

extern "C"
{
    static int autodect_error_handler( Display*, XErrorEvent* )
    {
        bWasXError = true;
        return 0;
    }
    
    typedef int(* XErrorHandler)(Display*,XErrorEvent*);
}

static int KDEVersion( Display* pDisplay )
{
    int nRet = 0;

    Atom nFullSession = XInternAtom( pDisplay, "KDE_FULL_SESSION", True );
    Atom nKDEVersion  = XInternAtom( pDisplay, "KDE_SESSION_VERSION", True );

    if( nFullSession )
    {
        if( !nKDEVersion )
            return 3;

        Atom				aRealType	= None;
        int					nFormat		= 8;
        unsigned long		nItems		= 0;
        unsigned long		nBytesLeft	= 0;
        unsigned char*	pProperty	= NULL;
        XGetWindowProperty( pDisplay,
                            DefaultRootWindow( pDisplay ),
                            nKDEVersion,
                            0, 1,
                            False,
                            AnyPropertyType,
                            &aRealType,
                            &nFormat,
                            &nItems,
                            &nBytesLeft,
                            &pProperty );
        if( !WasXError() && nItems != 0 && pProperty )
        {
            nRet = *reinterpret_cast< sal_Int32* >( pProperty );                        
        }
        if( pProperty )
        {
            XFree( pProperty );
            pProperty = NULL;
        }
    }
    return nRet;
}

static bool is_kde_desktop( Display* pDisplay )
{
    if ( NULL != getenv( "KDE_FULL_SESSION" ) )
    {
        const char *pVer = getenv( "KDE_SESSION_VERSION" );
        if ( !pVer || pVer[0] == '0' )
		{
            return true; // does not exist => KDE3
		}

        rtl::OUString aVer( RTL_CONSTASCII_USTRINGPARAM( "3" ) );
        if ( aVer.equalsIgnoreAsciiCaseAscii( pVer ) )
		{
            return true;
		}
    }

    if ( KDEVersion( pDisplay ) == 3 )
        return true;

    return false;
}

static bool is_kde4_desktop( Display* pDisplay )
{
    if ( NULL != getenv( "KDE_FULL_SESSION" ) )
    {
        rtl::OUString aVer( RTL_CONSTASCII_USTRINGPARAM( "4" ) );

        const char *pVer = getenv( "KDE_SESSION_VERSION" );
        if ( pVer && aVer.equalsIgnoreAsciiCaseAscii( pVer ) )
            return true;
    }

    if ( KDEVersion( pDisplay ) == 4 )
        return true;

    return false;
}

static bool is_cde_desktop( Display* pDisplay )
{
    void* pLibrary = NULL;

    Atom nDtAtom = XInternAtom( pDisplay, "_DT_WM_READY", True );
    if( nDtAtom && ( pLibrary = osl_loadAsciiModule( "file:///usr/dt/lib/libDtSvc.so", SAL_LOADMODULE_DEFAULT ) ) )
    {
        osl_unloadModule( (oslModule)pLibrary );
        return true;
    }
    
    return false;
}


extern "C"
{
    
DESKTOP_DETECTOR_PUBLIC rtl::OUString get_desktop_environment()
{
    rtl::OUStringBuffer aRet( 8 );
    static const char *pOverride = getenv( "OOO_FORCE_DESKTOP" );
     
    if ( pOverride && *pOverride )
    {
        OString aOver( pOverride );
        
        if ( aOver.equalsIgnoreAsciiCase( "cde" ) )
            aRet.appendAscii( desktop_strings[DESKTOP_CDE] );
        if ( aOver.equalsIgnoreAsciiCase( "kde4" ) )
            aRet.appendAscii( desktop_strings[DESKTOP_KDE4] );
        if ( aOver.equalsIgnoreAsciiCase( "gnome" ) )
            aRet.appendAscii( desktop_strings[DESKTOP_GNOME] );
        if ( aOver.equalsIgnoreAsciiCase( "kde" ) )
            aRet.appendAscii( desktop_strings[DESKTOP_KDE] );
        if ( aOver.equalsIgnoreAsciiCase( "none" ) )
            aRet.appendAscii( desktop_strings[DESKTOP_UNKNOWN] );
    }

    if( aRet.getLength() == 0 )
    {
        // get display to connect to
        const char* pDisplayStr = getenv( "DISPLAY" );
        int nParams = osl_getCommandArgCount();
        OUString aParam;
        OString aBParm;
        for( int i = 0; i < nParams; i++ )
        {
            osl_getCommandArg( i, &aParam.pData );
            if( aParam.equalsAscii( "-headless" ) )
            {
                pDisplayStr = NULL;
                break;
            }
            if( i < nParams-1 && (aParam.equalsAscii( "-display" ) || aParam.equalsAscii( "--display" )) )
            {
                osl_getCommandArg( i+1, &aParam.pData );
                aBParm = OUStringToOString( aParam, osl_getThreadTextEncoding() );
                pDisplayStr = aBParm.getStr();
                break;
            }
        }
    
        // no server at all
        if( ! pDisplayStr || !*pDisplayStr )
            aRet.appendAscii( desktop_strings[DESKTOP_NONE] );
        else
        {
            /* #i92121# workaround deadlocks in the X11 implementation
            */
            static const char* pNoXInitThreads = getenv( "SAL_NO_XINITTHREADS" );
            /* #i90094#
               from now on we know that an X connection will be
               established, so protect X against itself
            */
            if( ! ( pNoXInitThreads && *pNoXInitThreads ) )
                XInitThreads();
            
            Display* pDisplay = XOpenDisplay( pDisplayStr );
            if( pDisplay )
            {
                XErrorHandler pOldHdl = XSetErrorHandler( autodect_error_handler );
            
                if ( is_kde4_desktop( pDisplay ) )
                    aRet.appendAscii( desktop_strings[DESKTOP_KDE4] );
                else if ( is_gnome_desktop( pDisplay ) )
                    aRet.appendAscii( desktop_strings[DESKTOP_GNOME] );
                else if ( is_cde_desktop( pDisplay ) )
                    aRet.appendAscii( desktop_strings[DESKTOP_CDE] );
                else if ( is_kde_desktop( pDisplay ) )
                    aRet.appendAscii( desktop_strings[DESKTOP_KDE] );
                else
                    aRet.appendAscii( desktop_strings[DESKTOP_UNKNOWN] );
                    
                // set the default handler again
                XSetErrorHandler( pOldHdl );
                
                XCloseDisplay( pDisplay );
            }
        }
    }

    return aRet.makeStringAndClear();
}

}