/*

 * Copyright (c) 2015, 2018, 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.

 */

import java.nio.ByteBuffer;

import java.util.Arrays;

//

//          0   1   2   3   4   5   6   7

//        +---+---+---+---+---+---+---+---+

//        | H |    String Length (7+)     |

//        +---+---------------------------+

//        |  String Data (Length octets)  |

//        +-------------------------------+

//

// StringWriter does not require a notion of endOfInput (isLast) in 'write'

// methods due to the nature of string representation in HPACK. Namely, the

// length of the string is put before string's contents. Therefore the length is

// always known beforehand.

//

// Expected use:

//

//     configure write* (reset configure write*)*

//

final class StringWriter {

    private static final int NEW            = 0;

    private static final int CONFIGURED     = 1;

    private static final int LENGTH_WRITTEN = 2;

    private static final int DONE           = 4;

    private final IntegerWriter intWriter = new IntegerWriter();

    private final Huffman.Writer huffmanWriter = new Huffman.Writer();

    private final ISO_8859_1.Writer plainWriter = new ISO_8859_1.Writer();

    private int state = NEW;

    private boolean huffman;

    StringWriter configure(CharSequence input, boolean huffman) {

        return configure(input, 0, input.length(), huffman);

    }

    StringWriter configure(CharSequence input,

                           int start,

                           int end,

                           boolean huffman) {

        if (start < 0 || end < 0 || end > input.length() || start > end) {

            throw new IndexOutOfBoundsException(

                    String.format("input.length()=%s, start=%s, end=%s",

                            input.length(), start, end));

        }

        if (!huffman) {

            plainWriter.configure(input, start, end);

            intWriter.configure(end - start, 7, 0b0000_0000);

        } else {

            huffmanWriter.from(input, start, end);

            intWriter.configure(Huffman.INSTANCE.lengthOf(input, start, end),

                    7, 0b1000_0000);

        }

        this.huffman = huffman;

        state = CONFIGURED;

        return this;

    }

    boolean write(ByteBuffer output) {

        if (state == DONE) {

            return true;

        }

        if (state == NEW) {

            throw new IllegalStateException("Configure first");

        }

        if (!output.hasRemaining()) {

            return false;

        }

        if (state == CONFIGURED) {

            if (intWriter.write(output)) {

                state = LENGTH_WRITTEN;

            } else {

                return false;

            }

        }

        if (state == LENGTH_WRITTEN) {

            boolean written = huffman

                    ? huffmanWriter.write(output)

                    : plainWriter.write(output);

            if (written) {

                state = DONE;

                return true;

            } else {

                return false;

            }

        }

        throw new InternalError(Arrays.toString(new Object[]{state, huffman}));

    }

    void reset() {

        intWriter.reset();

        if (huffman) {

            huffmanWriter.reset();

        } else {

            plainWriter.reset();

        }

        state = NEW;

    }

}