/*

 * Copyright (c) 2016, 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.jshell.execution;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

/**

 *

 * @author Jan Lahoda

 */

class PipeInputStream extends InputStream {

    private static final int INITIAL_SIZE = 128;

    private int[] buffer = new int[INITIAL_SIZE];

    private int start;

    private int end;

    private boolean closed;

    @Override

    public synchronized int read() throws IOException {

        if (start == end && !closed) {

            inputNeeded();

        }

        while (start == end) {

            if (closed) {

                return -1;

            }

            try {

                wait();

            } catch (InterruptedException ex) {

                //ignore

            }

        }

        try {

            return buffer[start];

        } finally {

            start = (start + 1) % buffer.length;

        }

    }

    @Override

    public synchronized int read(byte[] b, int off, int len) throws IOException {

        if (b == null) {

            throw new NullPointerException();

        } else if (off < 0 || len < 0 || len > b.length - off) {

            throw new IndexOutOfBoundsException();

        } else if (len == 0) {

            return 0;

        }

        int c = read();

        if (c == -1) {

            return -1;

        }

        b[off] = (byte)c;

        int totalRead = 1;

        while (totalRead < len && start != end) {

            int r = read();

            if (r == (-1))

                break;

            b[off + totalRead++] = (byte) r;

        }

        return totalRead;

    }

    protected void inputNeeded() throws IOException {}

    private synchronized void write(int b) {

        if (closed) {

            throw new IllegalStateException("Already closed.");

        }

        int newEnd = (end + 1) % buffer.length;

        if (newEnd == start) {

            //overflow:

            int[] newBuffer = new int[buffer.length * 2];

            int rightPart = (end > start ? end : buffer.length) - start;

            int leftPart = end > start ? 0 : start - 1;

            System.arraycopy(buffer, start, newBuffer, 0, rightPart);

            System.arraycopy(buffer, 0, newBuffer, rightPart, leftPart);

            buffer = newBuffer;

            start = 0;

            end = rightPart + leftPart;

            newEnd = end + 1;

        }

        buffer[end] = b;

        end = newEnd;

        notifyAll();

    }

    @Override

    public synchronized void close() {

        closed = true;

        notifyAll();

    }

    public OutputStream createOutput() {

        return new OutputStream() {

            @Override public void write(int b) throws IOException {

                PipeInputStream.this.write(b);

            }

            @Override

            public void write(byte[] b, int off, int len) throws IOException {

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

                    write(Byte.toUnsignedInt(b[off + i]));

                }

            }

            @Override

            public void close() throws IOException {

                PipeInputStream.this.close();

            }

        };

    }

}