/*
 * Reader.java February 2001
 *
 * Copyright (C) 2001, Niall Gallagher <niallg@users.sf.net>
 *
 * 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 org.simpleframework.http.core;

import java.nio.channels.SocketChannel;

import org.simpleframework.transport.Channel;
import org.simpleframework.transport.reactor.Operation;

/**
 * The <code>Reader</code> object is used to read the bytes to form a request
 * entity. In order to execute a read operation the socket must be read ready.
 * This is determined using the socket object, which is registered with a
 * selector. If at any point the reading results in an error the operation is
 * canceled and the collector is closed, which shuts down the connection.
 * 
 * @author Niall Gallagher
 * 
 * @see org.simpleframework.transport.reactor.Reactor
 */
class Reader implements Operation {

    /**
     * This is the selector used to process the collection events.
     */
    private final Selector source;

    /**
     * This is the collector used to consume the entity bytes.
     */
    private final Collector task;

    /**
     * This is the channel object associated with the collector.
     */
    private final Channel channel;

    /**
     * Constructor for the <code>Reader</code> object. This requires a selector
     * and a collector object in order to consume the data from the connected
     * socket which forms a HTTP request entity.
     * 
     * @param source
     *            the selector object used to process events
     * @param task
     *            this is the task used to collect the entity
     */
    public Reader(Selector source, Collector task) {
        this.channel = task.getChannel();
        this.source = source;
        this.task = task;
    }

    /**
     * This is the <code>SocketChannel</code> used to determine if the
     * connection has some bytes that can be read. If it contains any data then
     * that data is read from and is used to compose the request entity, which
     * consists of a HTTP header and body.
     * 
     * @return this returns the socket for the connected pipeline
     */
    @Override
    public SocketChannel getChannel() {
        return this.task.getSocket();
    }

    /**
     * This <code>run</code> method is used to collect the bytes from the
     * connected channel. If a sufficient amount of data is read from the socket
     * to form a HTTP entity then the collector uses the <code>Selector</code>
     * object to dispatch the request. This is sequence of events that occur for
     * each transaction.
     */
    @Override
    public void run() {
        try {
            this.task.collect(this.source);
        } catch (Throwable e) {
            this.cancel();
        }
    }

    /**
     * This is used to cancel the operation if it has timed out. If the retry is
     * waiting too long to read content from the socket then the retry is
     * canceled and the underlying transport is closed. This helps to clean up
     * occupied resources.
     */
    @Override
    public void cancel() {
        try {
            this.channel.close();
        } catch (Throwable e) {
            return;
        }
    }
}