/*

 * 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 java.io.IOException;

import java.net.MalformedURLException;

import java.nio.charset.Charset;

import java.nio.charset.IllegalCharsetNameException;

import java.nio.charset.UnsupportedCharsetException;

import java.util.Collections;

import java.util.Map;

import java.util.Map.Entry;

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.

 *

 * @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

    {

        final EncodingInfo ei = _encodingInfos.findEncoding(toUpperCaseFast(encoding));

        if (ei != null) {

            try {

                return new BufferedWriter(new OutputStreamWriter(

                        output, ei.javaName));

            } catch (UnsupportedEncodingException usee) {

                // keep trying

            }

        }

        return new BufferedWriter(new OutputStreamWriter(output, 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 = _encodingInfos.findEncoding(normalizedEncoding);

        if (ei == null) {

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

            try {

                // This may happen if the caller tries to use

                // an encoding that wasn't registered in the

                // (java name)->(preferred mime name) mapping file.

                // In that case we attempt to load the charset for the

                // given encoding, and if that succeeds - we create a new

                // EncodingInfo instance - assuming the canonical name

                // of the charset can be used as the mime name.

                final Charset c = Charset.forName(encoding);

                final String name = c.name();

                ei = new EncodingInfo(name, name);

                _encodingInfos.putEncoding(normalizedEncoding, ei);

            } catch (IllegalCharsetNameException | UnsupportedCharsetException x) {

                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.

                encoding = SecuritySupport.getSystemProperty("file.encoding", "UTF8");

                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)

    {

        final EncodingInfo enc =

             _encodingInfos.getEncodingFromJavaKey(toUpperCaseFast(encoding));

        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)

    {

        final EncodingInfo info = _encodingInfos.findEncoding(toUpperCaseFast(encoding));

        return info != null ? info.javaName : encoding;

    }

    // Using an inner static class here prevent initialization races

    // where the hash maps could be used before they were populated.

    //

    private final static class EncodingInfos {

        // These maps are final and not modified after initialization.

        private final Map<String, EncodingInfo> _encodingTableKeyJava = new HashMap<>();

        private final Map<String, EncodingInfo> _encodingTableKeyMime = new HashMap<>();

        // This map will be added to after initialization: make sure it's

        // thread-safe. This map should not be used frequently - only in cases

        // where the mapping requested was not declared in the Encodings.properties

        // file.

        private final Map<String, EncodingInfo> _encodingDynamicTable =

                Collections.synchronizedMap(new HashMap<String, EncodingInfo>());

        private EncodingInfos() {

            loadEncodingInfo();

        }

        // Opens the file/resource containing java charset name -> preferred mime

        // name mapping and returns it as an InputStream.

        private InputStream openEncodingsFileStream() throws MalformedURLException, IOException {

            String urlString = null;

            InputStream is = null;

            try {

                urlString = SecuritySupport.getSystemProperty(ENCODINGS_PROP, "");

            } 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);

            }

            return is;

        }

        // Loads the Properties resource containing the mapping:

        //    java charset name -> preferred mime name

        // and returns it.

        private Properties loadProperties() throws MalformedURLException, IOException {

            Properties props = new Properties();

            try (InputStream is = openEncodingsFileStream()) {

                if (is != null) {

                    props.load(is);

                } 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)?

                }

            }

            return props;

        }

        // Parses the mime list associated to a java charset name.

        // The first mime name in the list is supposed to be the preferred

        // mime name.

        private String[] parseMimeTypes(String val) {

            int pos = val.indexOf(' ');

            //int lastPrintable;

            if (pos < 0) {

                // Maybe report/log this problem?

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

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

                return new String[] { val };

                //lastPrintable = 0x00FF;

            }

            //lastPrintable =

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

            StringTokenizer st =

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

            String[] values = new String[st.countTokens()];

            for (int i=0; st.hasMoreTokens(); i++) {

                values[i] = st.nextToken();

            }

            return values;

        }

        // This method here attempts to find the canonical charset name for the

        // the given name - which is supposed to be either a java name or a mime

        // name.

        // For that, it attempts to load the charset using the given name, and

        // then returns the charset's canonical name.

        // If the charset could not be loaded from the given name,

        // the method returns null.

        private String findCharsetNameFor(String name) {

            try {

                return Charset.forName(name).name();

            } catch (Exception x) {

                return null;

            }

        }

        // This method here attempts to find the canonical charset name for the

        // the set javaName+mimeNames - which are supposed to all refer to the

        // same charset.

        // For that it attempts to load the charset using the javaName, and if

        // not found, attempts again using each of the mime names in turn.

        // If the charset could be loaded from the javaName, then the javaName

        // itself is returned as charset name. Otherwise, each of the mime names

        // is tried in turn, until a charset can be loaded from one of the names,

        // and the loaded charset's canonical name is returned.

        // If no charset can be loaded from either the javaName or one of the

        // mime names, then null is returned.

        //

        // Note that the returned name is the 'java' name that will be used in

        // instances of EncodingInfo.

        // This is important because EncodingInfo uses that 'java name' later on

        // in calls to String.getBytes(javaName).

        // As it happens, sometimes only one element of the set mime names/javaName

        // is known by Charset: sometimes only one of the mime names is known,

        // sometime only the javaName is known, sometimes all are known.

        //

        // By using this method here, we fix the problem where one of the mime

        // names is known but the javaName is unknown, by associating the charset

        // loaded from one of the mime names with the unrecognized javaName.

        //

        // When none of the mime names or javaName are known - there's not much we can

        // do... It can mean that this encoding is not supported for this

        // OS. If such a charset is ever use it will result in having all characters

        // escaped.

        //

        private String findCharsetNameFor(String javaName, String[] mimes) {

            String cs = findCharsetNameFor(javaName);

            if (cs != null) return javaName;

            for (String m : mimes) {

                cs = findCharsetNameFor(m);

                if (cs != null) break;

            }

            return cs;

        }

        /**

         * Loads 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 void loadEncodingInfo() {

            try {

                // load (java name)->(preferred mime name) mapping.

                final Properties props = loadProperties();

                // create instances of EncodingInfo from the loaded mapping

                Enumeration keys = props.keys();

                Map<String, EncodingInfo> canonicals = new HashMap<>();

                while (keys.hasMoreElements()) {

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

                    final String[] mimes = parseMimeTypes(props.getProperty(javaName));

                    final String charsetName = findCharsetNameFor(javaName, mimes);

                    if (charsetName != null) {

                        final String kj = toUpperCaseFast(javaName);

                        final String kc = toUpperCaseFast(charsetName);

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

                            final String mimeName = mimes[i];

                            final String km = toUpperCaseFast(mimeName);

                            EncodingInfo info = new EncodingInfo(mimeName, charsetName);

                            _encodingTableKeyMime.put(km, info);

                            if (!canonicals.containsKey(kc)) {

                                // canonicals will map the charset name to

                                //   the info containing the prefered mime name

                                //   (the preferred mime name is the first mime

                                //   name in the list).

                                canonicals.put(kc, info);

                                _encodingTableKeyJava.put(kc, info);

                            }

                            _encodingTableKeyJava.put(kj, info);

                        }

                    } else {

                        // None of the java or mime names on the line were

                        // recognized => this charset is not supported?

                    }

                }

                // Fix up the _encodingTableKeyJava so that the info mapped to

                // the java name contains the preferred mime name.

                // (a given java name can correspond to several mime name,

                //  but we want the _encodingTableKeyJava to point to the

                //  preferred mime name).

                for (Entry<String, EncodingInfo> e : _encodingTableKeyJava.entrySet()) {

                    e.setValue(canonicals.get(toUpperCaseFast(e.getValue().javaName)));

                }

            } 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);

            }

        }

        EncodingInfo findEncoding(String normalizedEncoding) {

            EncodingInfo info = _encodingTableKeyJava.get(normalizedEncoding);

            if (info == null) {