/*

 * Copyright 2003-2004 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.awt;

import java.awt.Color;

import java.io.UnsupportedEncodingException;

import java.util.HashMap;

import java.util.Map;

/**

 * Per-screen XSETTINGS.

 */

public class XSettings {

    /**

     */

    private long serial = -1;

    /**

     * Update these settings with <code>data</code> obtained from

     * XSETTINGS manager.

     *

     * @param data settings data obtained from

     *     <code>_XSETTINGS_SETTINGS</code> window property of the

     *     settings manager.

     * @return a <code>Map</code> of changed settings.

     */

    public Map update(byte[] data) {

        return (new Update(data)).update();

    }

    /**

     * TBS ...

     */

    class Update {

        /* byte order mark */

        private static final int LITTLE_ENDIAN = 0;

        private static final int BIG_ENDIAN    = 1;

        /* setting type */

        private static final int TYPE_INTEGER = 0;

        private static final int TYPE_STRING  = 1;

        private static final int TYPE_COLOR   = 2;

        private byte[] data;

        private int dlen;

        private int idx;

        private boolean isLittle;

        private long serial = -1;

        private int nsettings = 0;

        private boolean isValid;

        private HashMap updatedSettings;

        /**

         * Construct an Update object for the data read from

         * <code>_XSETTINGS_SETTINGS</code> property of the XSETTINGS

         * selection owner.

         *

         * @param data <code>_XSETTINGS_SETTINGS</code> contents.

         */

        Update(byte[] data) {

            this.data = data;

            dlen = data.length;

            if (dlen < 12) {

                // XXX: debug trace?

                return;

            }

            // first byte gives endianness of the data

            // next 3 bytes are unused (pad to 32 bit)

            idx = 0;

            isLittle = (getCARD8() == LITTLE_ENDIAN);

            idx = 4;

            serial = getCARD32();

            // N_SETTINGS is actually CARD32 (i.e. unsigned), but

            // since java doesn't have an unsigned int type, and

            // N_SETTINGS cannot realistically exceed 2^31 (so we

            // gonna use int anyway), just read it as INT32.

            idx = 8;

            nsettings = getINT32();

            updatedSettings = new HashMap();

            isValid = true;

        }

        private void needBytes(int n)

            throws IndexOutOfBoundsException

        {

            if (idx + n <= dlen) {

                return;

            }

            throw new IndexOutOfBoundsException("at " + idx

                                                + " need " + n

                                                + " length " + dlen);

        }

        private int getCARD8()

            throws IndexOutOfBoundsException

        {

            needBytes(1);

            int val = data[idx] & 0xff;

            ++idx;

            return val;

        }

        private int getCARD16()

            throws IndexOutOfBoundsException

        {

            needBytes(2);

            int val;

            if (isLittle) {

                val = ((data[idx + 0] & 0xff)      )

                    | ((data[idx + 1] & 0xff) <<  8);

            } else {

                val = ((data[idx + 0] & 0xff) <<  8)

                    | ((data[idx + 1] & 0xff)      );

            }

            idx += 2;

            return val;

        }

        private int getINT32()

            throws IndexOutOfBoundsException

        {

            needBytes(4);

            int val;

            if (isLittle) {

                val = ((data[idx + 0] & 0xff)      )

                    | ((data[idx + 1] & 0xff) <<  8)

                    | ((data[idx + 2] & 0xff) << 16)

                    | ((data[idx + 3] & 0xff) << 24);

            } else {

                val = ((data[idx + 0] & 0xff) << 24)

                    | ((data[idx + 1] & 0xff) << 16)

                    | ((data[idx + 2] & 0xff) <<  8)

                    | ((data[idx + 3] & 0xff) <<  0);

            }

            idx += 4;

            return val;

        }

        private long getCARD32()

            throws IndexOutOfBoundsException

        {

            return getINT32() & 0x00000000ffffffffL;

        }

        private String getString(int len)

            throws IndexOutOfBoundsException

        {

            needBytes(len);

            String str = null;

            try {

                str = new String(data, idx, len, "UTF-8");

            } catch (UnsupportedEncodingException e) {

                // XXX: cannot happen, "UTF-8" is always supported

            }

            idx = (idx + len + 3) & ~0x3;

            return str;

        }

        /**

         * Update settings.

         */

        public Map update() {

            if (!isValid) {

                return null;

            }

            synchronized (XSettings.this) {

                long currentSerial = XSettings.this.serial;

                if (this.serial <= currentSerial) {

                    return null;

                }

                for (int i = 0; i < nsettings && idx < dlen; ++i) {

                    updateOne(currentSerial);

                }

                XSettings.this.serial = this.serial;

            }

            return updatedSettings;

        }

        /**

         * Parses a particular x setting.

         *

         * @exception IndexOutOfBoundsException if there isn't enough

         *     data for a setting.

         */

        private void updateOne(long currentSerial)

            throws IndexOutOfBoundsException,

                   IllegalArgumentException

        {

            int type = getCARD8();

            ++idx;              // pad to next CARD16

            // save position of the property name, skip to serial

            int nameLen = getCARD16();

            int nameIdx = idx;

            // check if we should bother

            idx = (idx + nameLen + 3) & ~0x3; // pad to 32 bit

            long lastChanged = getCARD32();

            // Avoid constructing garbage for properties that has not

            // changed, skip the data for this property.

            if (lastChanged <= currentSerial) { // skip

                if (type == TYPE_INTEGER) {

                    idx += 4;

                } else if (type == TYPE_STRING) {

                    int len = getINT32();

                    idx = (idx + len + 3) & ~0x3;

                } else if (type == TYPE_COLOR) {

                    idx += 8;   // 4 CARD16

                } else {

                    throw new IllegalArgumentException("Unknown type: "

                                                       + type);

                }

                return;

            }

            idx = nameIdx;

            String name = getString(nameLen);

            idx += 4;           // skip serial, parsed above

            Object value = null;

            if (type == TYPE_INTEGER) {

                value = Integer.valueOf(getINT32());

            }

            else if (type == TYPE_STRING) {

                value = getString(getINT32());

            }

            else if (type == TYPE_COLOR) {

                int r = getCARD16();

                int g = getCARD16();

                int b = getCARD16();

                int a = getCARD16();

                value = new Color(r / 65535.0f,

                                  g / 65535.0f,

                                  b / 65535.0f,

                                  a / 65535.0f);

            }

            else {

                throw new IllegalArgumentException("Unknown type: " + type);

            }

            if (name == null) {

                // dtrace???

                return;

            }

            updatedSettings.put(name, value);

        }

    } // class XSettings.Update

}