/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.impl.io;

import java.io.IOException;
import java.io.InputStream;

import org.apache.http.io.BufferInfo;
import org.apache.http.io.SessionInputBuffer;
import org.apache.http.util.Args;

/**
 * Input stream that reads data without any transformation. The end of the
 * content entity is demarcated by closing the underlying connection
 * (EOF condition). Entities transferred using this input stream can be of
 * unlimited length.
 * <p>
 * Note that this class NEVER closes the underlying stream, even when close
 * gets called.  Instead, it will read until the end of the stream (until
 * {@code -1} is returned).
 *
 * @since 4.0
 */
public class IdentityInputStream extends InputStream {

    private final SessionInputBuffer in;

    private boolean closed = false;

    /**
     * Wraps session input stream and reads input until the the end of stream.
     *
     * @param in The session input buffer
     */
    public IdentityInputStream(final SessionInputBuffer in) {
        super();
        this.in = Args.notNull(in, "Session input buffer");
    }

    @Override
    public int available() throws IOException {
        if (this.in instanceof BufferInfo) {
            return ((BufferInfo) this.in).length();
        }
        return 0;
    }

    @Override
    public void close() throws IOException {
        this.closed = true;
    }

    @Override
    public int read() throws IOException {
        return this.closed ? -1 : this.in.read();
    }

    @Override
    public int read(final byte[] b, final int off, final int len) throws IOException {
        return this.closed ? -1 : this.in.read(b, off, len);
    }

}
