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/*
 * Copyright 2024 LLC VK
 *
 * 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 one.nio.http;

import java.io.IOException;

/**
 * A Response, which can poll for server emitted events.
 * Unlike regular {@link Response} this object must be close'd to
 * prevent resource leak.
 * 
 * The usage flow is as follows:
 * 

 * Call {@link HttpClient#openEvents(Request, int)}
 * Inspect the result code, if it is not OK process the error
 * Inspect the content-type, it must be text/event-stream; if it is not - process the response body - there will be no events
 * while ( ( event = poll() ) != null ) process( event )
 * call {@link #close()}
 * call {@link HttpClient#reopenEvents(Request, String, int)} with last processed {@link Event#id()} and go to p.2
 * 
 *
 * @see HTML Standard: 9.2 Server-sent events
 * @see HttpClient#openEvents(Request, int)
 */
public class EventSourceResponse extends Response implements EventSource
{
    private EventSource eventSource;

    public EventSourceResponse( String resultCode )
    {
        super( resultCode );
    }

    @Override
    public Event poll() throws IOException, HttpException
    {
        return eventSource == null ? null : eventSource.poll();
    }
    
    void setEventSource( EventSource es ) {
        this.eventSource = es;
    }
    
    @Override
    public void close() throws IOException
    {
        if ( eventSource != null ) {
            eventSource.close();
            eventSource = null;
        }
    }
}