/*

 * Copyright (c) 2012, Oracle and/or its affiliates. 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.  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 jdk.internal.util.xml.impl;

import java.io.Reader;

import java.io.InputStream;

import java.io.IOException;

/**

 * UTF-16 encoded stream reader.

 */

public class ReaderUTF16 extends Reader {

    private InputStream is;

    private char bo;

    /**

     * Constructor.

     *

     * Byte order argument can be: 'l' for little-endian or 'b' for big-endian.

     *

     * @param is A byte input stream.

     * @param bo A byte order in the input stream.

     */

    public ReaderUTF16(InputStream is, char bo) {

        switch (bo) {

            case 'l':

                break;

            case 'b':

                break;

            default:

                throw new IllegalArgumentException("");

        }

        this.bo = bo;

        this.is = is;

    }

    /**

     * Reads characters into a portion of an array.

     *

     * @param cbuf Destination buffer.

     * @param off Offset at which to start storing characters.

     * @param len Maximum number of characters to read.

     * @exception IOException If any IO errors occur.

     */

    public int read(char[] cbuf, int off, int len) throws IOException {

        int num = 0;

        int val;

        if (bo == 'b') {

            while (num < len) {

                if ((val = is.read()) < 0) {

                    return (num != 0) ? num : -1;

                }

                cbuf[off++] = (char) ((val << 8) | (is.read() & 0xff));

                num++;

            }

        } else {

            while (num < len) {

                if ((val = is.read()) < 0) {

                    return (num != 0) ? num : -1;

                }

                cbuf[off++] = (char) ((is.read() << 8) | (val & 0xff));

                num++;

            }

        }

        return num;

    }

    /**

     * Reads a single character.

     *

     * @return The character read, as an integer in the range 0 to 65535

     *  (0x0000-0xffff), or -1 if the end of the stream has been reached.

     * @exception IOException If any IO errors occur.

     */

    public int read() throws IOException {

        int val;

        if ((val = is.read()) < 0) {

            return -1;

        }

        if (bo == 'b') {

            val = (char) ((val << 8) | (is.read() & 0xff));

        } else {

            val = (char) ((is.read() << 8) | (val & 0xff));

        }

        return val;

    }

    /**

     * Closes the stream.

     *

     * @exception IOException If any IO errors occur.

     */

    public void close() throws IOException {

        is.close();

    }

}