/*
 * Copyright (c) 2020, 2020, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * The Universal Permissive License (UPL), Version 1.0
 *
 * Subject to the condition set forth below, permission is hereby granted to any
 * person obtaining a copy of this software, associated documentation and/or
 * data (collectively the "Software"), free of charge and under any and all
 * copyright rights in the Software, and any and all patent rights owned or
 * freely licensable by each licensor hereunder covering either (i) the
 * unmodified Software as contributed to or provided by such licensor, or (ii)
 * the Larger Works (as defined below), to deal in both
 *
 * (a) the Software, and
 *
 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
 * is contributed by such licensors),
 *
 * without restriction, including without limitation the rights to copy, create
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
 *
 * This license is subject to the following condition:
 *
 * The above copyright notice and either this complete permission notice or at a
 * minimum a reference to the UPL must be included in all copies or substantial
 * portions of the Software.
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 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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package com.oracle.truffle.js.test.builtins;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.SeekableByteChannel;

public class ReadOnlySeekableByteArrayChannel implements SeekableByteChannel {
    private byte[] data;
    private int position;
    private boolean closed;

    public ReadOnlySeekableByteArrayChannel(byte[] data) {
        this.data = data;
    }

    @Override
    public long position() {
        return position;
    }

    @Override
    public SeekableByteChannel position(long newPosition) throws IOException {
        ensureOpen();
        position = (int) Math.max(0, Math.min(newPosition, size()));
        return this;
    }

    @Override
    public long size() {
        return data.length;
    }

    @Override
    public int read(ByteBuffer buf) throws IOException {
        ensureOpen();
        int remaining = (int) size() - position;
        if (remaining <= 0) {
            return -1;
        }
        int readBytes = buf.remaining();
        if (readBytes > remaining) {
            readBytes = remaining;
        }
        buf.put(data, position, readBytes);
        position += readBytes;
        return readBytes;
    }

    @Override
    public void close() {
        closed = true;
    }

    @Override
    public boolean isOpen() {
        return !closed;
    }

    @Override
    public int write(ByteBuffer b) throws IOException {
        throw new UnsupportedOperationException();
    }

    @Override
    public SeekableByteChannel truncate(long newSize) {
        throw new UnsupportedOperationException();
    }

    private void ensureOpen() throws ClosedChannelException {
        if (!isOpen()) {
            throw new ClosedChannelException();
        }
    }
}