/*

 * Copyright (c) 2019, 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.jfr.internal.consumer;

import java.io.IOException;

import java.nio.charset.Charset;

public final class StringParser extends Parser {

    public enum Encoding {

        NULL(0),

        EMPTY_STRING(1),

        CONSTANT_POOL(2),

        UT8_BYTE_ARRAY(3),

        CHAR_ARRAY(4),

        LATIN1_BYTE_ARRAY(5);

        private byte byteValue;

        private Encoding(int byteValue) {

            this.byteValue = (byte) byteValue;

        }

        public byte byteValue() {

            return byteValue;

        }

        public boolean is(byte value) {

            return value == byteValue;

        }

    }

    private final static Charset UTF8 = Charset.forName("UTF-8");

    private final static Charset LATIN1 = Charset.forName("ISO-8859-1");

    private final static class CharsetParser extends Parser {

        private final Charset charset;

        private int lastSize;

        private byte[] buffer = new byte[16];

        private String lastString;

        CharsetParser(Charset charset) {

            this.charset = charset;

        }

        @Override

        public Object parse(RecordingInput input) throws IOException {

            int size = input.readInt();

            ensureSize(size);

            if (lastSize == size) {

                boolean equalsLastString = true;

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

                    // TODO: No need to read byte per byte

                    byte b = input.readByte();

                    if (buffer[i] != b) {

                        equalsLastString = false;

                        buffer[i] = b;

                    }

                }

                if (equalsLastString) {

                    return lastString;

                }

            } else {

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

                    buffer[i] = input.readByte();

                }

            }

            lastString = new String(buffer, 0, size, charset);

            lastSize = size;

            return lastString;

        }

        @Override

        public void skip(RecordingInput input) throws IOException {

            int size = input.readInt();

            input.skipBytes(size);

        }

        private void ensureSize(int size) {

            if (buffer.length < size) {

                buffer = new byte[size];

            }

        }

    }

    private final static class CharArrayParser extends Parser {

        private char[] buffer = new char[16];

        private int lastSize = -1;

        private String lastString = null;

        @Override

        public Object parse(RecordingInput input) throws IOException {

            int size = input.readInt();

            ensureSize(size);

            if (lastSize == size) {

                boolean equalsLastString = true;

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

                    char c = input.readChar();

                    if (buffer[i] != c) {

                        equalsLastString = false;

                        buffer[i] = c;

                    }

                }

                if (equalsLastString) {

                    return lastString;

                }

            } else {

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

                    buffer[i] = input.readChar();

                }

            }

            lastString = new String(buffer, 0, size);

            lastSize = size;

            return lastString;

        }

        @Override

        public void skip(RecordingInput input) throws IOException {

            int size = input.readInt();

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

                input.readChar();

            }

        }

        private void ensureSize(int size) {

            if (buffer.length < size) {

                buffer = new char[size];

            }

        }

    }

    private final ConstantLookup stringLookup;

    private final CharArrayParser charArrayParser = new CharArrayParser();

    private final CharsetParser utf8parser = new CharsetParser(UTF8);

    private final CharsetParser latin1parser = new CharsetParser(LATIN1);

    private final boolean event;

    public StringParser(ConstantLookup stringLookup, boolean event) {

        this.stringLookup = stringLookup;

        this.event = event;

    }

    @Override

    public Object parse(RecordingInput input) throws IOException {

        byte encoding = input.readByte();

        if (Encoding.CONSTANT_POOL.is(encoding)) {

            long key = input.readLong();

            if (event) {

                return stringLookup.getCurrentResolved(key);

            } else {

                return stringLookup.getCurrent(key);

            }

        }

        if (Encoding.NULL.is(encoding)) {

            return null;

        }

        if (Encoding.EMPTY_STRING.is(encoding)) {

            return "";

        }

        if (Encoding.CHAR_ARRAY.is(encoding)) {

            return charArrayParser.parse(input);

        }

        if (Encoding.UT8_BYTE_ARRAY.is(encoding)) {

            return utf8parser.parse(input);

        }

        if (Encoding.LATIN1_BYTE_ARRAY.is(encoding)) {

            return latin1parser.parse(input);

        }

        throw new IOException("Unknown string encoding " + encoding);

    }

    @Override

    public void skip(RecordingInput input) throws IOException {

        byte encoding = input.readByte();

        if (Encoding.CONSTANT_POOL.is(encoding)) {

            input.readLong();

            return;

        }

        if (Encoding.EMPTY_STRING.is(encoding)) {

            return;

        }

        if (Encoding.NULL.is(encoding)) {

            return;

        }

        if (Encoding.CHAR_ARRAY.is(encoding)) {

            charArrayParser.skip(input);

            return;

        }

        if (Encoding.UT8_BYTE_ARRAY.is(encoding)) {

            utf8parser.skip(input);

            return;

        }

        if (Encoding.LATIN1_BYTE_ARRAY.is(encoding)) {

            latin1parser.skip(input);

            return;

        }

        throw new IOException("Unknown string encoding " + encoding);

    }

}