/****************************************************************************************

 * Copyright (c) 2006 Gbor Lehel <illissius@gmail.com>                                  *

 *                                                                                      *

 * 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, see <http://www.gnu.org/licenses/>.                           *

 ****************************************************************************************/

#include "Expression.h"

#include "core/support/Debug.h"

ExpressionParser::ExpressionParser( const QString &expression )

    : m_expression( expression )

    , m_state( ExpectMinus )

    , m_haveGroup( false )

    , m_inQuote( false )

    , m_inOrGroup( false )

{ }

ParsedExpression ExpressionParser::parse()

{

    const uint length = m_expression.length();

    for( uint pos = 0; pos < length; ++pos )

        parseChar( m_expression.at( pos ) );

    finishedToken();

    finishedOrGroup();

    return m_parsed;

}

ParsedExpression ExpressionParser::parse( const QString &expression ) //static

{

    ExpressionParser p( expression );

    return p.parse();

}

bool ExpressionParser::isAdvancedExpression( const QString &expression ) //static

{

    return ( expression.contains( '"'   ) ||

             expression.contains( ':'   ) ||

             expression.contains( '-'   ) ||

             expression.contains( "AND" ) ||

             expression.contains( "OR"  ) );

}

/* PRIVATE */

void ExpressionParser::parseChar( const QChar &c )

{

    if( m_inQuote && c != '"' )

        m_string += c;

    else if( c.isSpace() )

        handleSpace( c );

    else if( c == '-' )

        handleMinus( c );

    else if( c == ':' )

        handleColon( c );

    else if( c == '>' || c == '<' )

        handleMod( c );

    else if( c == '"' )

        handleQuote( c );

    else

        handleChar( c );

}

void ExpressionParser::handleSpace( const QChar& )

{

    if( m_state > ExpectMinus )

        finishedToken();

}

void ExpressionParser::handleMinus( const QChar &c )

{

    if( m_state == ExpectMinus )

    {

        m_element.negate = true;

        m_state = ExpectField;

    }

    else

        handleChar( c );

}

void ExpressionParser::handleColon( const QChar &c )

{

    if( m_state <= ExpectField && !m_string.isEmpty() )

    {

        m_element.field = m_string;

        m_string.clear();

        m_state = ExpectMod;

    }

    else

        handleChar( c );

}

void ExpressionParser::handleMod( const QChar &c )

{

    if( m_state == ExpectMod )

    {

        m_element.match = ( c == '>' ) ? expression_element::More : expression_element::Less;

        m_state = ExpectText;

    }

    else

        handleChar( c );

}

void ExpressionParser::handleQuote( const QChar& )

{

    if( m_inQuote )

    {

        finishedElement();

        m_inQuote = false;

    }

    else

    {

        if( !m_string.isEmpty() )

            finishedToken();

        m_state = ExpectText;

        m_inQuote = true;

    }

}

void ExpressionParser::handleChar( const QChar &c )

{

    m_string += c;

    if( m_state <= ExpectField )

        m_state = ExpectField;

    else if( m_state <= ExpectText )

        m_state = ExpectText;

}

void ExpressionParser::finishedToken()

{

    enum { And, Or, Neither };

    int s;

    if( m_haveGroup || !m_element.field.isEmpty() )

        s = Neither;

    else if( m_string == "AND" )

        s = And;

    else if( m_string == "OR" )

        s = Or;

    else

        s = Neither;

    if( s == Neither )

        finishedElement();

    else

    {

        m_haveGroup = true;

        if( s == Or )

            m_inOrGroup = true;

        else

            finishedOrGroup();

        m_string.clear();

        m_state = ExpectMinus;

    }

}

void ExpressionParser::finishedElement()

{

    if( !m_inOrGroup )

        finishedOrGroup();

    m_inOrGroup = m_haveGroup = false;

    m_element.text = m_string;

    m_string.clear();

    if( !m_element.text.isEmpty() )

        m_or.append( m_element );

    //m_element = expression_element();

    m_element.field.clear();

    m_element.negate = false;

    m_element.match = expression_element::Contains;

    m_state = ExpectMinus;

}

void ExpressionParser::finishedOrGroup()

{

    if( !m_or.isEmpty() )

        m_parsed.append( m_or );

    m_or.clear();

    m_inOrGroup = false;

}