/**
 * 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.rs;

import java.io.IOException;
import java.io.InputStream;
import java.util.Collections;
import java.util.regex.Pattern;
import lombok.EqualsAndHashCode;
import lombok.ToString;
import org.takes.Response;
import org.takes.misc.Concat;

/**
 * Response decorator, with an additional header.
 *
 * <p>Remember, if a header is already present in the response, this
 * decorator will add another one, with the same name. It doesn't check
 * for duplicates. If you want to avoid duplicate headers, use this
 * decorator in combination with {@link org.takes.rs.RsWithoutHeader},
 * for example:
 *
 * <pre> new RsWithHeader(
 *   new RsWithoutHeader(res, "Host"),
 *   "Host", "www.example.com"
 * )</pre>
 *
 * <p>In this example, {@link org.takes.rs.RsWithoutHeader} will remove the
 * {@code Host} header first and {@link org.takes.rs.RsWithHeader} will
 * add a new one.
 *
 * <p>The class is immutable and thread-safe.
 *
 * @author Yegor Bugayenko (yegor256@gmail.com)
 * @version $Id: ebcf84e277e25a36d76ee0501a18c7a74a629f10 $
 * @since 0.1
 */
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public final class RsWithHeader extends RsWrap {

    /**
     * Pattern for all other lines in the head.
     */
    private static final Pattern HEADER = Pattern.compile(
        "[a-zA-Z0-9\\-]+:\\p{Print}+"
    );

    /**
     * Ctor.
     * @param hdr Header
     * @since 0.8
     */
    public RsWithHeader(final CharSequence hdr) {
        this(new RsEmpty(), hdr);
    }

    /**
     * Ctor.
     * @param name Header name
     * @param value Header value
     * @since 0.8
     */
    public RsWithHeader(final CharSequence name, final CharSequence value) {
        this(new RsEmpty(), name, value);
    }

    /**
     * Ctor.
     * @param res Original response
     * @param name Header name
     * @param value Header value
     */
    public RsWithHeader(final Response res, final CharSequence name,
        final CharSequence value) {
        this(res, String.format("%s: %s", name, value));
    }

    /**
     * Ctor.
     * @param res Original response
     * @param header Header to add
     */
    public RsWithHeader(final Response res, final CharSequence header) {
        super(
            new Response() {
                @Override
                public Iterable<String> head() throws IOException {
                    return RsWithHeader.extend(res.head(), header.toString());
                }
                @Override
                public InputStream body() throws IOException {
                    return res.body();
                }
            }
        );
    }

    /**
     * Add to head additional header.
     * @param head Original head
     * @param header Value witch will be added to head
     * @return Head with additional header
     */
    private static Iterable<String> extend(final Iterable<String> head,
        final String header) {
        if (!RsWithHeader.HEADER.matcher(header).matches()) {
            throw new IllegalArgumentException(
                String.format(
                    // @checkstyle LineLength (1 line)
                    "header line of HTTP response \"%s\" doesn't match \"%s\" regular expression, but it should, according to RFC 7230",
                    header, RsWithHeader.HEADER
                )
            );
        }
        return new Concat<String>(head, Collections.singleton(header));
    }

}