/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Copyright 1999-2004 The Apache Software Foundation.

 *

 * Licensed 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.

 */

/*

 * $Id: Encodings.java,v 1.3 2005/09/28 13:49:04 pvedula Exp $

 */

package com.sun.org.apache.xml.internal.serializer;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.OutputStreamWriter;

import java.io.UnsupportedEncodingException;

import java.io.Writer;

import java.io.BufferedWriter;

import java.net.URL;

import java.util.Enumeration;

import java.util.HashMap;

import java.util.Properties;

import java.util.StringTokenizer;

import com.sun.org.apache.xalan.internal.utils.SecuritySupport;

/**

 * Provides information about encodings. Depends on the Java runtime

 * to provides writers for the different encodings, but can be used

 * to override encoding names and provide the last printable character

 * for each encoding.

 *

 * @version $Revision: 1.11 $ $Date: 2010-11-01 04:34:44 $

 * @author <a href="mailto:arkin@intalio.com">Assaf Arkin</a>

 */

public final class Encodings extends Object

{

    /**

     * The last printable character for unknown encodings.

     */

    private static final int m_defaultLastPrintable = 0x7F;

    /**

     * Standard filename for properties file with encodings data.

     */

    private static final String ENCODINGS_FILE = "com/sun/org/apache/xml/internal/serializer/Encodings.properties";

    /**

     * Standard filename for properties file with encodings data.

     */

    private static final String ENCODINGS_PROP = "com.sun.org.apache.xalan.internal.serialize.encodings";

    /**

     * Returns a writer for the specified encoding based on

     * an output stream.

     *

     * @param output The output stream

     * @param encoding The encoding

     * @return A suitable writer

     * @throws UnsupportedEncodingException There is no convertor

     *  to support this encoding

     */

    static Writer getWriter(OutputStream output, String encoding)

        throws UnsupportedEncodingException

    {

        for (int i = 0; i < _encodings.length; ++i)

        {

            if (_encodings[i].name.equalsIgnoreCase(encoding))

            {

                try

                {

                    return new BufferedWriter(new OutputStreamWriter(

                        output,

                        _encodings[i].javaName));

                }

                catch (java.lang.IllegalArgumentException iae) // java 1.1.8

                {

                    // keep trying

                }

                catch (UnsupportedEncodingException usee)

                {

                    // keep trying

                }

            }

        }

        try

        {

            return new BufferedWriter(new OutputStreamWriter(output, encoding));

        }

        catch (java.lang.IllegalArgumentException iae) // java 1.1.8

        {

            throw new UnsupportedEncodingException(encoding);

        }

    }

    /**

     * Returns the last printable character for an unspecified

     * encoding.

     *

     * @return the default size

     */

    public static int getLastPrintable()

    {

        return m_defaultLastPrintable;

    }

    /**

     * Returns the EncodingInfo object for the specified

     * encoding.

     * <p>

     * This is not a public API.

     *

     * @param encoding The encoding

     * @return The object that is used to determine if

     * characters are in the given encoding.

     * @xsl.usage internal

     */

    static EncodingInfo getEncodingInfo(String encoding)

    {

        EncodingInfo ei;

        String normalizedEncoding = toUpperCaseFast(encoding);

        ei = (EncodingInfo) _encodingTableKeyJava.get(normalizedEncoding);

        if (ei == null)

            ei = (EncodingInfo) _encodingTableKeyMime.get(normalizedEncoding);

        if (ei == null) {

            // We shouldn't have to do this, but just in case.

            ei = new EncodingInfo(null,null);

        }

        return ei;

    }

    /**

     * A fast and cheap way to uppercase a String that is

     * only made of printable ASCII characters.

     * <p>

     * This is not a public API.

     * @param s a String of ASCII characters

     * @return an uppercased version of the input String,

     * possibly the same String.

     * @xsl.usage internal

     */

    static private String toUpperCaseFast(final String s) {

        boolean different = false;

        final int mx = s.length();

                char[] chars = new char[mx];

        for (int i=0; i < mx; i++) {

                char ch = s.charAt(i);

            // is the character a lower case ASCII one?

                if ('a' <= ch && ch <= 'z') {

                // a cheap and fast way to uppercase that is good enough

                        ch = (char) (ch + ('A' - 'a'));

                        different = true; // the uppercased String is different

                }

                chars[i] = ch;

        }

        // A little optimization, don't call String.valueOf() if

        // the uppercased string is the same as the input string.

        final String upper;

        if (different)

                upper = String.valueOf(chars);

        else

                upper = s;

        return upper;

    }

    /** The default encoding, ISO style, ISO style.   */

    static final String DEFAULT_MIME_ENCODING = "UTF-8";

    /**

     * Get the proper mime encoding.  From the XSLT recommendation: "The encoding

     * attribute specifies the preferred encoding to use for outputting the result

     * tree. XSLT processors are required to respect values of UTF-8 and UTF-16.

     * For other values, if the XSLT processor does not support the specified

     * encoding it may signal an error; if it does not signal an error it should

     * use UTF-8 or UTF-16 instead. The XSLT processor must not use an encoding

     * whose name does not match the EncName production of the XML Recommendation

     * [XML]. If no encoding attribute is specified, then the XSLT processor should

     * use either UTF-8 or UTF-16."

     *

     * @param encoding Reference to java-style encoding string, which may be null,

     * in which case a default will be found.

     *

     * @return The ISO-style encoding string, or null if failure.

     */

    static String getMimeEncoding(String encoding)

    {

        if (null == encoding)

        {

            try

            {

                // Get the default system character encoding.  This may be

                // incorrect if they passed in a writer, but right now there

                // seems to be no way to get the encoding from a writer.

                if (null != encoding)

                {

                    /*

                    * See if the mime type is equal to UTF8.  If you don't

                    * do that, then  convertJava2MimeEncoding will convert

                    * 8859_1 to "ISO-8859-1", which is not what we want,

                    * I think, and I don't think I want to alter the tables

                    * to convert everything to UTF-8.

                    */

                    String jencoding =

                        (encoding.equalsIgnoreCase("Cp1252")

                            || encoding.equalsIgnoreCase("ISO8859_1")

                            || encoding.equalsIgnoreCase("8859_1")

                            || encoding.equalsIgnoreCase("UTF8"))

                            ? DEFAULT_MIME_ENCODING

                            : convertJava2MimeEncoding(encoding);

                    encoding =

                        (null != jencoding) ? jencoding : DEFAULT_MIME_ENCODING;

                }

                else

                {

                    encoding = DEFAULT_MIME_ENCODING;

                }

            }

            catch (SecurityException se)

            {

                encoding = DEFAULT_MIME_ENCODING;

            }

        }

        else

        {

            encoding = convertJava2MimeEncoding(encoding);

        }

        return encoding;

    }

    /**

     * Try the best we can to convert a Java encoding to a XML-style encoding.

     *

     * @param encoding non-null reference to encoding string, java style.

     *

     * @return ISO-style encoding string.

     */

    private static String convertJava2MimeEncoding(String encoding)

    {

        EncodingInfo enc =

            (EncodingInfo) _encodingTableKeyJava.get(encoding.toUpperCase());

        if (null != enc)

            return enc.name;

        return encoding;

    }

    /**

     * Try the best we can to convert a Java encoding to a XML-style encoding.

     *

     * @param encoding non-null reference to encoding string, java style.

     *

     * @return ISO-style encoding string.

     */

    public static String convertMime2JavaEncoding(String encoding)

    {

        for (int i = 0; i < _encodings.length; ++i)

        {

            if (_encodings[i].name.equalsIgnoreCase(encoding))

            {

                return _encodings[i].javaName;

            }

        }

        return encoding;

    }

    /**

     * Load a list of all the supported encodings.

     *

     * System property "encodings" formatted using URL syntax may define an

     * external encodings list. Thanks to Sergey Ushakov for the code

     * contribution!

     */

    private static EncodingInfo[] loadEncodingInfo()

    {

        try

        {

            String urlString = null;

            InputStream is = null;

            try

            {

            }

            catch (SecurityException e)

            {

            }

            if (urlString != null && urlString.length() > 0) {

                URL url = new URL(urlString);

                is = url.openStream();

            }

            if (is == null) {

                is = SecuritySupport.getResourceAsStream(ENCODINGS_FILE);

            }

            Properties props = new Properties();

            if (is != null) {

                props.load(is);

                is.close();

            } else {

                // Seems to be no real need to force failure here, let the

                // system do its best... The issue is not really very critical,

                // and the output will be in any case _correct_ though maybe not

                // always human-friendly... :)

                // But maybe report/log the resource problem?

                // Any standard ways to report/log errors (in static context)?

            }

            int totalEntries = props.size();

            int totalMimeNames = 0;

            Enumeration keys = props.keys();

            for (int i = 0; i < totalEntries; ++i)

            {

                String javaName = (String) keys.nextElement();

                String val = props.getProperty(javaName);

                totalMimeNames++;

                int pos = val.indexOf(' ');

                for (int j = 0; j < pos; ++j)

                    if (val.charAt(j) == ',')

                        totalMimeNames++;

            }

            EncodingInfo[] ret = new EncodingInfo[totalMimeNames];

            int j = 0;

            keys = props.keys();

            for (int i = 0; i < totalEntries; ++i)

            {

                String javaName = (String) keys.nextElement();

                String val = props.getProperty(javaName);

                int pos = val.indexOf(' ');

                String mimeName;

                //int lastPrintable;

                if (pos < 0)

                {

                    // Maybe report/log this problem?

                    //  "Last printable character not defined for encoding " +

                    //  mimeName + " (" + val + ")" ...

                    mimeName = val;

                    //lastPrintable = 0x00FF;

                }

                else

                {

                    //lastPrintable =

                    //    Integer.decode(val.substring(pos).trim()).intValue();

                    StringTokenizer st =

                        new StringTokenizer(val.substring(0, pos), ",");

                    for (boolean first = true;

                        st.hasMoreTokens();

                        first = false)

                    {

                        mimeName = st.nextToken();

                        ret[j] =

                            new EncodingInfo(mimeName, javaName);

                        _encodingTableKeyMime.put(

                            mimeName.toUpperCase(),

                            ret[j]);

                        if (first)

                            _encodingTableKeyJava.put(

                                javaName.toUpperCase(),

                                ret[j]);

                        j++;

                    }

                }

            }

            return ret;

        }

        catch (java.net.MalformedURLException mue)

        {

            throw new com.sun.org.apache.xml.internal.serializer.utils.WrappedRuntimeException(mue);

        }

        catch (java.io.IOException ioe)

        {

            throw new com.sun.org.apache.xml.internal.serializer.utils.WrappedRuntimeException(ioe);

        }

    }

    /**

     * Return true if the character is the high member of a surrogate pair.

     * <p>

     * This is not a public API.

     * @param ch the character to test

     * @xsl.usage internal

     */

    static boolean isHighUTF16Surrogate(char ch) {

        return ('\uD800' <= ch && ch <= '\uDBFF');

    }

    /**

     * Return true if the character is the low member of a surrogate pair.

     * <p>

     * This is not a public API.

     * @param ch the character to test

     * @xsl.usage internal

     */

    static boolean isLowUTF16Surrogate(char ch) {

        return ('\uDC00' <= ch && ch <= '\uDFFF');

    }

    /**

     * Return the unicode code point represented by the high/low surrogate pair.

     * <p>

     * This is not a public API.

     * @param highSurrogate the high char of the high/low pair

     * @param lowSurrogate the low char of the high/low pair

     * @xsl.usage internal

     */

    static int toCodePoint(char highSurrogate, char lowSurrogate) {

        int codePoint =

            ((highSurrogate - 0xd800) << 10)

                + (lowSurrogate - 0xdc00)

                + 0x10000;

        return codePoint;

    }

    /**

     * Return the unicode code point represented by the char.

     * A bit of a dummy method, since all it does is return the char,

     * but as an int value.

     * <p>

     * This is not a public API.

     * @param ch the char.

     * @xsl.usage internal

     */

    static int toCodePoint(char ch) {

        int codePoint = ch;

        return codePoint;

    }

    private static final HashMap _encodingTableKeyJava = new HashMap();

    private static final HashMap _encodingTableKeyMime = new HashMap();

    private static final EncodingInfo[] _encodings = loadEncodingInfo();

}