DMDirc-Plugins/src/com/dmdirc/addons/relaybot/RelayCallbackManager.java

/*
 * Copyright (c) 2006-2009 Chris Smith, Shane Mc Cormack, Gregory Holmes
 *
 * 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 NONINFRINGEMENT. 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 com.dmdirc.addons.relaybot;

import com.dmdirc.Channel;
import com.dmdirc.ChannelEventHandler;
import com.dmdirc.parser.common.CallbackManager;
import com.dmdirc.parser.common.CallbackNotFoundException;
import com.dmdirc.parser.common.CallbackObject;
import com.dmdirc.parser.interfaces.Parser;
import com.dmdirc.parser.interfaces.callbacks.CallbackInterface;
import com.dmdirc.parser.interfaces.callbacks.ChannelMessageListener;
import com.dmdirc.parser.interfaces.callbacks.SocketCloseListener;
import com.dmdirc.parser.irc.IRCCallbackManager;
import com.dmdirc.parser.irc.IRCParser;

import java.lang.reflect.Field;
import java.util.Date;
import java.util.Map;

/**
 * This is a callback manager that when created will replace the callback
 * manager of the given parser with itself.
 *
 * When a new callback is added it will be allowed unless the RelayBotPlugin
 * says otherwise.
 *
 * When the parser disconnects, the original CBM is restored.
 *
 * @author shane
 */
public class RelayCallbackManager extends IRCCallbackManager implements SocketCloseListener {

    /** Pluign that created this callback manager. */
    private final RelayBotPlugin myPlugin;

    /** Original CallbackManager */
    private final IRCCallbackManager originalCBM;

    /**
     * Create a new RelayCallbackManager and replace
     *
     * @param myPlugin
     * @param parser
     */
    public RelayCallbackManager(final RelayBotPlugin myPlugin, final IRCParser parser) {
        super(parser);

        this.myPlugin = myPlugin;
        this.originalCBM = (IRCCallbackManager) parser.getCallbackManager();
        setCallbackManager(parser, this);
        addCallback(SocketCloseListener.class, this);
    }

    /** {@inheritDoc} */
    @Override
    public <T extends CallbackInterface> void addCallback(final Class<T> callback, final T o, final String target) throws CallbackNotFoundException {
        // Don't allow the core to give itself a ChannelMessageListener if we
        // already have a listener for this channel.
        if (o instanceof ChannelEventHandler && callback == ChannelMessageListener.class) {
            try {
                // Get the old callback manager
                final Field field = o.getClass().getDeclaredField("owner");
                field.setAccessible(true);
                final Channel channel = (Channel) field.get(o);

                if (myPlugin.isListening(channel)) {
                    return;
                }
            } catch (NoSuchFieldException ex) {
                ex.printStackTrace();
            } catch (SecurityException ex) {
                ex.printStackTrace();
            } catch (IllegalArgumentException ex) {
                ex.printStackTrace();
            } catch (IllegalAccessException ex) {
                ex.printStackTrace();
            }
        }

        // Unless the plugin says we are listening instead of this channel, then
        // we can add the callback.
        forceAddCallback(callback, o, target);
    }

    /**
     * Add a callback with a specific target.
     * This method will throw a CallbackNotFoundException if the callback does not exist.
     *
     * @param <T> The type of callback
     * @param callback Type of callback object.
     * @param o instance of ICallbackInterface to add.
     * @param target Parameter to specify that a callback should only fire for specific things
     * @throws CallbackNotFoundException If callback is not found.
     * @throws NullPointerException If 'o' is null
     */
    public <T extends CallbackInterface> void forceAddCallback(final Class<T> callback, final T o, final String target) throws CallbackNotFoundException {
        super.addCallback(callback, o, target);
    }


    /**
     * Set the Callback Manager of a given parser.
     *
     * @param parser
     * @param cbm
     */
    private void setCallbackManager(final IRCParser parser, final CallbackManager<IRCParser> cbm) {
        try {
            // Get the old callback manager
            final Field field = parser.getClass().getDeclaredField("myCallbackManager");
            field.setAccessible(true);
            @SuppressWarnings("unchecked")
            final CallbackManager<IRCParser> oldCBM = (CallbackManager<IRCParser>) field.get(parser);

            // Clone the known CallbackObjects list (horrible code ahoy!)
            // First get the old map of callbacks
            final Field cbField = CallbackManager.class.getDeclaredField("callbackHash");
            cbField.setAccessible(true);
            @SuppressWarnings("unchecked")
            final Map<Class<? extends CallbackInterface>, CallbackObject> oldCallbackHash = (Map<Class<? extends CallbackInterface>, CallbackObject>) cbField.get(oldCBM);

            // Clear my map of callbacks
            @SuppressWarnings("unchecked")
            final Map<Class<? extends CallbackInterface>, CallbackObject> myCallbackHash = (Map<Class<? extends CallbackInterface>, CallbackObject>) cbField.get(cbm);
            myCallbackHash.clear();

            // Now add them all to the new cbm.
            for (CallbackObject callback : oldCallbackHash.values()) {
                // Change their manager to the new one.
                final Field ownerField = CallbackObject.class.getDeclaredField("myManager");
                ownerField.setAccessible(true);
                ownerField.set(callback, cbm);

                // And add them to the CBM
                cbm.addCallbackType(callback);
            }

            // Replace the old one with the new one.
            field.set(parser, cbm);
        } catch (IllegalArgumentException ex) {
            ex.printStackTrace();
        } catch (IllegalAccessException ex) {
            ex.printStackTrace();
        } catch (NoSuchFieldException ex) {
            ex.printStackTrace();
        } catch (SecurityException ex) {
            ex.printStackTrace();
        }
    }

    /**
     * When the socket closes, reset the callback manager.
     *
     * @param parser
     */
    @Override
    public void onSocketClosed(final Parser parser, final Date date) {
        if (parser.getCallbackManager() instanceof RelayCallbackManager) {
            setCallbackManager((IRCParser)parser, originalCBM);
        }
    }
}