/**
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2017 Yegor Bugayenko
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package org.takes.rq;

import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import lombok.EqualsAndHashCode;
import org.takes.Request;

/**
 * Request decorator that limits its body, according to
 * the Content-Length header in its head.
 *
 * <p>This decorator may help when you're planning to read
 * the body of the request using its read() and available() methods,
 * but you're not sure that available() is always saying the truth. In
 * most cases, the browser will not close the request and will always
 * return positive number in available() method. Thus, you won't be
 * able to reach the end of the stream ever. The browser wants you
 * to respect the "Content-Length" header and read as many bytes
 * as it requests. To solve that, just wrap your request into this
 * decorator.
 *
 * <p>The class is immutable and thread-safe.
 *
 * @author Yegor Bugayenko (yegor256@gmail.com)
 * @version $Id: 7a6c3562cfcee2b5859853e163fc3d781e98a686 $
 * @since 0.15
 * @see org.takes.rq.RqMultipart
 * @see org.takes.rq.RqPrint
 */
@EqualsAndHashCode(callSuper = true)
public final class RqLengthAware extends RqWrap {

    /**
     * Ctor.
     * @param req Original request
     */
    public RqLengthAware(final Request req) {
        super(
            new Request() {
                @Override
                public Iterable<String> head() throws IOException {
                    return req.head();
                }
                @Override
                public InputStream body() throws IOException {
                    return RqLengthAware.cap(req);
                }
            }
        );
    }

    /**
     * Cap the steam.
     * @param req Request
     * @return Stream with a cap
     * @throws IOException If fails
     */
    private static InputStream cap(final Request req) throws IOException {
        final Iterator<String> hdr = new RqHeaders.Base(req)
            .header("Content-Length").iterator();
        InputStream body = req.body();
        long length = (long) body.available();
        if (hdr.hasNext()) {
            length = Long.parseLong(hdr.next());
        }
        body = new CapInputStream(body, length);
        return body;
    }

}