/*
 * WorldEdit, a Minecraft world manipulation toolkit
 * Copyright (C) sk89q <http://www.sk89q.com>
 * Copyright (C) WorldEdit team and contributors
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

package com.sk89q.worldedit.extension.platform;

import com.sk89q.worldedit.LocalConfiguration;
import com.sk89q.worldedit.ServerInterface;
import com.sk89q.worldedit.WorldEdit;

import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

import static com.google.common.base.Preconditions.checkNotNull;

/**
 * Manages registered {@link Platform}s for WorldEdit. Platforms are
 * implementations of WorldEdit.
 * </p>
 * This class is thread-safe.
 */
public class PlatformManager {

    private static final Logger logger = Logger.getLogger(PlatformManager.class.getCanonicalName());

    private final LocalConfiguration defaultConfig = new DefaultConfiguration();
    private final List<Platform> platforms = new ArrayList<Platform>();
    private final CommandManager commandManager;
    private @Nullable Platform primary = null;

    /**
     * Create a new platform manager.
     *
     * @param worldEdit the WorldEdit instance
     */
    public PlatformManager(WorldEdit worldEdit) {
        checkNotNull(worldEdit);
        this.commandManager = new CommandManager(worldEdit);
    }

    /**
     * Register a platform with WorldEdit.
     *
     * @param platform the platform
     * @throws PlatformRejectionException thrown if the registration is rejected
     */
    public synchronized void register(Platform platform) throws PlatformRejectionException {
        checkNotNull(platform);
        logger.log(Level.INFO, "Got request to register " + platform.getClass() + " with WorldEdit [" + super.toString() + "]");
        platforms.add(platform);
        if (this.primary == null) {
            commandManager.register(platform);
            this.primary = platform;
        }
    }

    /**
     * Unregister a platform from WorldEdit.
     *
     * @param platform the platform
     */
    public synchronized boolean unregister(Platform platform) {
        checkNotNull(platform);
        boolean removed = platforms.remove(platform);
        if (removed) {
            logger.log(Level.FINE, "Unregistering " + platform.getClass().getCanonicalName() + " from WorldEdit");

            if (platform == primary) {
                primary = null;
                commandManager.unregister();
            }
        }
        return removed;
    }

    /**
     * Get the command manager.
     *
     * @return the command manager
     */
    public CommandManager getCommandManager() {
        return commandManager;
    }

    /**
     * Get the current configuration.
     * </p>
     * If no platform has been registered yet, then a default configuration
     * will be returned.
     *
     * @return the configuration
     */
    public LocalConfiguration getConfiguration() {
        Platform platform = primary;
        if (platform != null) {
            return platform.getConfiguration();
        } else {
            return defaultConfig;
        }
    }
    /**
     * Return a {@link Platform}.
     *
     * @return a {@link Platform}
     * @throws IllegalStateException if no platform has been registered
     */
    public Platform getPlatform() throws IllegalStateException {
        Platform platform = primary;
        if (platform != null) {
            return platform;
        } else {
            throw new IllegalStateException("No platform has been registered");
        }
    }

    /**
     * Return a legacy {@link ServerInterface}.
     *
     * @return a {@link ServerInterface}
     * @throws IllegalStateException if no platform has been registered
     */
    public ServerInterface getServerInterface() throws IllegalStateException {
        Platform platform = primary;
        if (platform != null) {
            if (platform instanceof ServerInterface) {
                return (ServerInterface) platform;
            } else {
                return new ServerInterfaceAdapter(platform);
            }
        } else {
            throw new IllegalStateException("No platform has been registered");
        }
    }

    /**
     * A default configuration for when none is set.
     */
    private static class DefaultConfiguration extends LocalConfiguration {
        @Override
        public void load() {
        }
    }

}