/*

* Copyright (c) 2007 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  Read entities from dtd files

 *

*/

package com.nokia.tools.themeinstaller.localisation;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.Vector;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import com.nokia.tools.themeinstaller.logger.LogWriter;

import com.nokia.tools.themeinstaller.odtconverter.ConverterProperties;

/**

 * Reads entities from dtd files.

 */

public class DTDReader

    {

    /** The Regular expression for entity. */

    private static final String ENTITY_REGEX = "<!ENTITY(\\s*)%s(.*)>";

    /** The Regular expression for entity's value. */

    private static final String VALUE_REGEX = "(\")(.*)(\")";

    /** Line separator */

    private static final String LINE_SEPARATOR =

            System.getProperty( "line.separator" );

    /** Property key for character encoding of DTD files */

    private static final String ENCODING_KEY = "dtd_encoding";

    /**

     * Read DTD Entities. Reads a set of DTD files and searches

     * for localised string defined in a entity named aLocString.

     * If there are more than one instances found, the one that

     * is found first is returned.

     *

     * @param aDtdFiles DTD files containing entities

     * @param aLocString Entity's localisation string

     *

     * @return Localised string

     *

     * @throws IOException Signals that an I/O exception has occurred.

     */

    public static String readFiles( Vector aDtdFiles, String aLocString )

            throws IOException

        {

        String tempResult = null;

        Vector results = new Vector();

        for ( int i = 0; i < aDtdFiles.size(); i++ )

            {

            tempResult = readEntity( ( File ) aDtdFiles.get( i ), aLocString );

            if ( tempResult != null )

                {

                results.add( tempResult );

                }

            }

        if ( results.isEmpty() )

            {

            return null;

            }

        else

            {

            return ( String ) results.firstElement();

            }

        }

    /**

     * Read localized entity from the dtd.

     *

     * @param aDTD DTD file containing the localization

     * @param aLocString Localization string

     * @return Localized entity

     * @throws IOException if FileInputStream can not be opened

     */

    public static String readEntity( File aDTD, String aLocString )

            throws IOException

        {

        StringBuffer strbuf = new StringBuffer();

        // Read the assumed character encoding of DTD files

        String encoding =

                ConverterProperties.getInstance().getProperty( ENCODING_KEY );

        BufferedReader rdr = null;

        if( encoding != null )

            {

            // Use specified encoding

            rdr = new BufferedReader( new InputStreamReader(

                    new FileInputStream( aDTD ), encoding ) );

            }

        else

            {

            // Use default encoding

            LogWriter.getInstance().logWarning( "DTDReader: Character " +

            		"encoding of DTD files is not specified in the " +

            		"properties file, using system default encoding." );

            rdr = new BufferedReader( new InputStreamReader(

                    new FileInputStream( aDTD ) ) );

            }

        // Add all lines from the DTD file to the buffer

        for ( String line = rdr.readLine(); line != null; line = rdr.readLine() )

            {

            strbuf.append( line + LINE_SEPARATOR );

            }

        String[] formatArguments = { aLocString };

        String regex = String.format( ENTITY_REGEX, formatArguments );

        // Search for an entity containing the aLocString

        String result = findString( regex, strbuf.toString() );

        if ( result != null )

            {

            // Search for the entity's value

            result = findString( VALUE_REGEX, result );

            // Remove "-marks from the value

            result = result.replaceAll( "\"", "" );

            }

        return result;

        }

    /**

     * Find a substring. Also verifies that exactly one match is found.

     *

     * @param aRegex Regular expression for matching

     * @param aSearchString String for searching

     * @return Found string

     */

    private static String findString( String aRegex, String aSearchString )

        {

        String result = null;

        Pattern pattern = Pattern.compile( aRegex );

        Matcher matcher = pattern.matcher( aSearchString );

        int count = 0;

        while ( matcher.find() )

            {

            result = matcher.group();

            count++;

            }

        if ( count > 1 )

            {

            throw new IllegalArgumentException( "DTD parsing: "

                    + "found more than one localized value for the "

                    + "entity" );

            }

        return result;

        }

    }