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/*
 * Copyright 2016 Carlos Ballesteros Velasco
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package java.io;

public abstract class InputStream implements Closeable {
    private static final int MAX_SKIP_BUFFER_SIZE = 2048;

    public abstract int read() throws IOException;

    public int read(byte b[]) throws IOException {
        return read(b, 0, b.length);
    }

    public int read(byte data[], int offset, int length) throws IOException {
        if (length == 0) return 0;

        int c = read();
        if (c == -1) return -1;
        data[offset] = (byte) c;

        int n = 1;
        try {
            while (n < length) {
                c = read();
                if (c == -1) break;
                data[offset + n] = (byte) c;
                n++;
            }
        } catch (IOException e) {
        }
        return n;
    }

    public long skip(long n) throws IOException {
        long remaining = n;
        int nr;

        if (n <= 0) return 0;

        int size = (int) Math.min(MAX_SKIP_BUFFER_SIZE, remaining);
        byte[] skipBuffer = new byte[size];
        while (remaining > 0) {
            nr = read(skipBuffer, 0, (int) Math.min(size, remaining));
            if (nr < 0) break;
            remaining -= nr;
        }

        return n - remaining;
    }

    public int available() throws IOException {
        return 0;
    }

    public void close() throws IOException {
    }

    public synchronized void mark(int readlimit) {
    }

    public synchronized void reset() throws IOException {
        throw new IOException("mark/reset not supported");
    }

    public boolean markSupported() {
        return false;
    }

}