/*
 * ====================================================================
 * 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.hc.core5.http2.protocol;

import java.io.IOException;

import org.apache.hc.core5.annotation.Contract;
import org.apache.hc.core5.annotation.ThreadingBehavior;
import org.apache.hc.core5.http.EntityDetails;
import org.apache.hc.core5.http.Header;
import org.apache.hc.core5.http.HttpException;
import org.apache.hc.core5.http.HttpHeaders;
import org.apache.hc.core5.http.HttpRequest;
import org.apache.hc.core5.http.ProtocolException;
import org.apache.hc.core5.http.ProtocolVersion;
import org.apache.hc.core5.http.protocol.HttpContext;
import org.apache.hc.core5.http.protocol.RequestValidateHost;
import org.apache.hc.core5.net.URIAuthority;
import org.apache.hc.core5.util.Args;
import org.apache.hc.core5.util.TextUtils;

/**
 * HTTP/2 compatible extension of {@link RequestValidateHost}.
 * <p>
 * This interceptor is essential for the HTTP protocol conformance and
 * the correct operation of the server-side message processing pipeline.
 * </p>
 *
 * @since 5.0
 */
@Contract(threading = ThreadingBehavior.IMMUTABLE)
public class H2RequestValidateHost extends RequestValidateHost {

    /**
     * Singleton instance.
     *
     * @since 5.2
     */
    public static final H2RequestValidateHost INSTANCE = new H2RequestValidateHost();

    @Override
    public void process(
            final HttpRequest request,
            final EntityDetails entity,
            final HttpContext context) throws HttpException, IOException {
        Args.notNull(context, "HTTP context");
        Args.notNull(request, "HTTP request");

        final ProtocolVersion ver = context.getProtocolVersion();
        if (ver.getMajor() < 2) {
            super.process(request, entity, context);
            return;
        }

        final URIAuthority authority = request.getAuthority();
        final Header hostHeader = request.getFirstHeader(HttpHeaders.HOST);
        if (authority == null || hostHeader == null) {
            return;
        }

        final String hostValue = hostHeader.getValue();
        final String authorityValue = authority.toString();
        if (TextUtils.isBlank(hostValue) || !hostValue.equalsIgnoreCase(authorityValue)) {
            throw new ProtocolException("Host header does not match :authority");
        }
    }

}
