/*

 * 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.xml.internal.bind.v2.runtime.output;

import java.io.IOException;

/**

 * Buffer for UTF-8 encoded string.

 *

 * See http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8 for the UTF-8 encoding.

 *

 * @author Kohsuke Kawaguchi

 */

public final class Encoded {

    public byte[] buf;

    public int len;

    public Encoded() {}

    public Encoded(String text) {

        set(text);

    }

    public void ensureSize(int size) {

        if(buf==null || buf.length<size)

            buf = new byte[size];

    }

    public final void set( String text ) {

        int length = text.length();

        ensureSize(length*3+1); // +1 for append

        int ptr = 0;

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

            final char chr = text.charAt(i);

            if (chr > 0x7F) {

                if (chr > 0x7FF) {

                    if(Character.MIN_HIGH_SURROGATE<=chr && chr<=Character.MAX_LOW_SURROGATE) {

                        // surrogate

                        int uc = (((chr & 0x3ff) << 10) | (text.charAt(++i) & 0x3ff)) + 0x10000;

                        buf[ptr++] = (byte)(0xF0 | ((uc >> 18)));

                        buf[ptr++] = (byte)(0x80 | ((uc >> 12) & 0x3F));

                        buf[ptr++] = (byte)(0x80 | ((uc >> 6) & 0x3F));

                        buf[ptr++] = (byte)(0x80 + (uc & 0x3F));

                        continue;

                    }

                    buf[ptr++] = (byte)(0xE0 + (chr >> 12));

                    buf[ptr++] = (byte)(0x80 + ((chr >> 6) & 0x3F));

                } else {

                    buf[ptr++] = (byte)(0xC0 + (chr >> 6));

                }

                buf[ptr++] = (byte)(0x80 + (chr & 0x3F));

            } else {

                buf[ptr++] = (byte)chr;

            }

        }

        len = ptr;

    }

    /**

     * Fill in the buffer by encoding the specified characters

     * while escaping characters like <

     *

     * @param isAttribute

     *      if true, characters like \t, \r, and \n are also escaped.

     */

    public final void setEscape(String text, boolean isAttribute) {

        int length = text.length();

        ensureSize(length*6+1);     // in the worst case the text is like """""", so we need 6 bytes per char

        int ptr = 0;

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

            final char chr = text.charAt(i);

            int ptr1 = ptr;

            if (chr > 0x7F) {

                if (chr > 0x7FF) {

                    if(Character.MIN_HIGH_SURROGATE<=chr && chr<=Character.MAX_LOW_SURROGATE) {

                        // surrogate

                        int uc = (((chr & 0x3ff) << 10) | (text.charAt(++i) & 0x3ff)) + 0x10000;

                        buf[ptr++] = (byte)(0xF0 | ((uc >> 18)));

                        buf[ptr++] = (byte)(0x80 | ((uc >> 12) & 0x3F));

                        buf[ptr++] = (byte)(0x80 | ((uc >> 6) & 0x3F));

                        buf[ptr++] = (byte)(0x80 + (uc & 0x3F));

                        continue;

                    }

                    buf[ptr1++] = (byte)(0xE0 + (chr >> 12));

                    buf[ptr1++] = (byte)(0x80 + ((chr >> 6) & 0x3F));

                } else {

                    buf[ptr1++] = (byte)(0xC0 + (chr >> 6));

                }

                buf[ptr1++] = (byte)(0x80 + (chr & 0x3F));

            } else {

                byte[] ent;

                if((ent=attributeEntities[chr])!=null) {

                    // the majority of the case is just printed as a char,

                    // so it's very important to reject them as quickly as possible

                    // check again to see if this really needs to be escaped

                    if(isAttribute || entities[chr]!=null)

                        ptr1 = writeEntity(ent,ptr1);

                    else

                        buf[ptr1++] = (byte)chr;

                } else

                    buf[ptr1++] = (byte)chr;

            }

            ptr = ptr1;

        }

        len = ptr;

    }

    private int writeEntity( byte[] entity, int ptr ) {

        System.arraycopy(entity,0,buf,ptr,entity.length);

        return ptr+entity.length;

    }

    /**

     * Writes the encoded bytes to the given output stream.

     */

    public final void write(UTF8XmlOutput out) throws IOException {

        out.write(buf,0,len);

    }

    /**

     * Appends a new character to the end of the buffer.

     * This assumes that you have enough space in the buffer.

     */

    public void append(char b) {

        buf[len++] = (byte)b;

    }

    /**

     * Reallocate the buffer to the exact size of the data

     * to reduce the memory footprint.

     */

    public void compact() {

        byte[] b = new byte[len];

        System.arraycopy(buf,0,b,0,len);

        buf = b;

    }

    /**

     * UTF-8 encoded entities keyed by their character code.

     * e.g., entities['&'] == AMP_ENTITY.

     *

     * In attributes we need to encode more characters.

     */

    private static final byte[][] entities = new byte[0x80][];

    private static final byte[][] attributeEntities = new byte[0x80][];

    static {

        add('&',"&",false);

        add('<',"&lt;",false);

        add('>',">",false);

        add('"',""",true);

        add('\t',"	",true);

        add('\r',"
",false);

        add('\n',"
",true);

    }

    private static void add(char c, String s, boolean attOnly) {

        byte[] image = UTF8XmlOutput.toBytes(s);

        attributeEntities[c] = image;

        if(!attOnly)

            entities[c] = image;

    }

}