/**
 * Title: ToolboxCodePage
 * Copyright:   Copyright (c) 2001, 2002, 2003
 * Company:
 * @author  Kenneth J. Pouncey
 *          rewritten by LDC, WVL, Luc
 * @version 0.4
 *
 * Description:
 *
 * 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, 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 software; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307 USA
 *
 */
package org.tn5250j.encoding;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

import android.util.Log;


class ToolboxCodePageFactory {
    private static final String TAG = "ToolboxCodePageFactory";
    private final static String[] CODEPAGES = { "Big5", "Cp037", "Cp273", "Cp277", "Cp278",
                                                "Cp280", "Cp284", "Cp285", "Cp297", "Cp420", "Cp424", "Cp437",
                                                "Cp500", "Cp737", "Cp775", "Cp838", "Cp850", "Cp852", "Cp855",
                                                "Cp856", "Cp857", "Cp858", "Cp860", "Cp861", "Cp862", "Cp863",
                                                "Cp864", "Cp865", "Cp866", "Cp868", "Cp869", "Cp870",
                                                "Cp871", "Cp874", "Cp875", "Cp918", "Cp921", "Cp922",
                                                "Cp923", // IBM Latin-9.
                                                "Cp930", "Cp933", "Cp935", "Cp937", "Cp939", "Cp942", "Cp943",
                                                "Cp948", "Cp949", "Cp950", "Cp964", "Cp970", "Cp1006", "Cp1025",
                                                "Cp1026", "Cp1046", "Cp1097", "Cp1098", "Cp1112", "Cp1122",
                                                "Cp1123", "Cp1124", "Cp1140", "Cp1141", "Cp1142", "Cp1143",
                                                "Cp1144", "Cp1145", "Cp1146", "Cp1147", "Cp1148", "Cp1149",
                                                "Cp1252", "Cp1250", "Cp1251", "Cp1253", "Cp1254", "Cp1255",
                                                "Cp1256", "Cp1257", "Cp1258", "Cp1381", "Cp1383", "Cp33722"
                                              };

    private static final String CONVERTER_NAME = "com.ibm.as400.access.CharConverter";
    private static final String TOBYTES_NAME = "stringToByteArray";
    private static final String TOSTRING_NAME = "byteArrayToString";

    private static ToolboxCodePageFactory singleton;



    private ToolboxCodePageFactory() {
        /* private for singleton */
    }

    public static synchronized ToolboxCodePageFactory getInstance() {
        if (singleton == null) {
            singleton = new ToolboxCodePageFactory();
        }

        return singleton;
    }

    /**
     * @return
     */
    public String[] getAvailableCodePages() {
        try {
            final ClassLoader loader = getClassLoader();
            Class.forName(CONVERTER_NAME, false, loader);
            return CODEPAGES;
        }
        catch (Exception e) {
            Log.i(TAG, "Couldn't locate JT400 Toolbox in classpath. Charset converters can't be used.");
            return new String[0];
        }
    }

    /**
     * @param encoding
     * @return
     */
    public ICodePage getCodePage(String encoding) {
        try {
            ClassLoader loader = getClassLoader();
            Class<?> conv_class = Class.forName(CONVERTER_NAME, true, loader);
            Constructor<?> conv_constructor = conv_class.getConstructor(new Class[] { String.class });
            Method toBytes_method = conv_class.getMethod(TOBYTES_NAME, new Class[] { String.class });
            Method toString_method = conv_class.getMethod(TOSTRING_NAME, new Class[] { byte[].class });
            Object convobj = conv_constructor.newInstance(new Object[] { encoding });
            return new ToolboxConverterProxy(convobj, toBytes_method, toString_method);
        }
        catch (Exception e) {
            Log.w(TAG, "Can't load charset converter from JT400 Toolbox for code page " + encoding, e);
            return null;
        }
    }

    private static final ClassLoader getClassLoader() {
        ClassLoader loader = ToolboxCodePageFactory.class.getClassLoader();

        if (loader == null) {
            loader = ClassLoader.getSystemClassLoader();
        }

        return loader;
    }

    private static class ToolboxConverterProxy implements ICodePage {

        private final Object converter;
        private final Method tobytesMethod;
        private final Method tostringMethod;

        private ToolboxConverterProxy(Object converterObject, Method tobytesMethod, Method tostringMethod) {
            super();
            this.converter = converterObject;
            this.tobytesMethod = tobytesMethod;
            this.tostringMethod = tostringMethod;
        }

        public char ebcdic2uni(int index) {
            Object result;

            try {
                result = tostringMethod.invoke(converter, new Object[] { new byte[] { (byte)(index & 0xFF) } });
            }
            catch (Throwable t) {
                result = null;
            }

            if (result == null)
                return 0x00;

            return ((String) result).charAt(0);
        }

        public byte uni2ebcdic(char index) {
            Object result;

            try {
                result = tobytesMethod.invoke(converter, new Object[] { new String(new char[] { index }) });
            }
            catch (Throwable t) {
                result = null;
            }

            if (result == null)
                return 0x00;

            return ((byte[]) result)[0];
        }
    }

}