package com.github.theholywaffle.teamspeak3;

/*
 * #%L
 * TeamSpeak 3 Java API
 * %%
 * Copyright (C) 2014 Bert De Geyter
 * %%
 * 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.
 * #L%
 */

import com.github.theholywaffle.teamspeak3.api.exception.TS3ConnectionFailedException;
import com.github.theholywaffle.teamspeak3.api.exception.TS3QueryShutDownException;
import com.github.theholywaffle.teamspeak3.api.reconnect.ConnectionHandler;
import com.github.theholywaffle.teamspeak3.api.reconnect.DisconnectingConnectionHandler;
import com.github.theholywaffle.teamspeak3.api.reconnect.ReconnectStrategy;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicBoolean;

public class TS3Query {

        private static final Logger log = LoggerFactory.getLogger(TS3Query.class);

        /**
         * Artificial delay between sending commands, measured in milliseconds.
         * <p>
         * If the query's hostname / IP has not been added to the server's {@code query_ip_whitelist.txt},
         * you need to use {@link FloodRate#DEFAULT} to prevent the query from being flood-banned.
         * </p><p>
         * Calling {@link FloodRate#custom} allows you to use a custom command delay if neither
         * {@link FloodRate#UNLIMITED} nor {@link FloodRate#DEFAULT} fit your needs.
         * </p>
         */
        public static class FloodRate {

                /**
                 * Default delay of 350 milliseconds between commands for queries that are not whitelisted.
                 */
                public static final FloodRate DEFAULT = new FloodRate(350);

                /**
                 * No delay between commands. If a query uses this without being whitelisted, it will likely be flood-banned.
                 */
                public static final FloodRate UNLIMITED = new FloodRate(0);

                /**
                 * Creates a FloodRate object that represents a custom command delay.
                 *
                 * @param milliseconds
                 *              the delay between sending commands in milliseconds
                 *
                 * @return a new {@code FloodRate} object representing a custom delay
                 */
                public static FloodRate custom(int milliseconds) {
                        if (milliseconds < 0) throw new IllegalArgumentException("Timeout must be positive");
                        return new FloodRate(milliseconds);
                }

                private final int ms;

                private FloodRate(int ms) {
                        this.ms = ms;
                }

                public int getMs() {
                        return ms;
                }
        }

        /**
         * The protocol used to communicate with the TeamSpeak3 server.
         */
        public enum Protocol {
                RAW, SSH
        }

        private final ConnectionHandler connectionHandler;
        private final EventManager eventManager;
        private final ExecutorService userThreadPool;
        private final FileTransferHelper fileTransferHelper;
        private final CommandQueue globalQueue;
        private final TS3Config config;

        private final AtomicBoolean connected = new AtomicBoolean(false);

        private Connection connection;

        /**
         * Creates a TS3Query that connects to a TS3 server at
         * {@code localhost:10011} using default settings.
         */
        public TS3Query() {
                this(new TS3Config());
        }

        /**
         * Creates a customized TS3Query that connects to a server
         * specified by {@code config}.
         *
         * @param config
         *              configuration for this TS3Query
         */
        public TS3Query(TS3Config config) {
                this.config = config.freeze();
                this.eventManager = new EventManager(this);
                this.userThreadPool = Executors.newCachedThreadPool();
                this.fileTransferHelper = new FileTransferHelper(config.getHost());
                this.connectionHandler = config.getReconnectStrategy().create(config.getConnectionHandler());
                this.globalQueue = CommandQueue.newGlobalQueue(this, connectionHandler instanceof DisconnectingConnectionHandler);
        }

        // PUBLIC

        /**
         * Tries to establish a connection to the TeamSpeak3 server.
         *
         * @throws IllegalStateException
         *              if this method was called from {@link ConnectionHandler#onConnect}
         * @throws TS3ConnectionFailedException
         *              if the query can't connect to the server or the {@link ConnectionHandler} throws an exception
         */
        public void connect() {
                if (Thread.holdsLock(this)) {
                        // Check that connect is not called from onConnect
                        throw new IllegalStateException("Cannot call connect from onConnect handler");
                }

                doConnect();
        }

        private synchronized void doConnect() {
                if (userThreadPool.isShutdown()) {
                        throw new IllegalStateException("The query has already been shut down");
                }

                disconnect(); // If we're already connected

                try {
                        CommandQueue queue = CommandQueue.newConnectQueue(this);
                        Connection con = new Connection(this, config, queue);

                        try {
                                TS3Api api = queue.getApi();
                                if (config.getProtocol() == Protocol.RAW && config.hasLoginCredentials()) {
                                        api.login(config.getUsername(), config.getPassword());
                                }
                                connectionHandler.onConnect(api);
                        } catch (TS3QueryShutDownException e) {
                                // Disconnected during onConnect, re-throw as a TS3ConnectionFailedException
                                queue.failRemainingCommands();
                                throw new TS3ConnectionFailedException(e);
                        } catch (Exception e) {
                                con.disconnect();
                                queue.failRemainingCommands();
                                throw new TS3ConnectionFailedException("ConnectionHandler threw exception in connect handler", e);
                        }

                        // Reject new commands and wait until the onConnect queue is empty
                        queue.shutDown();

                        connection = con;
                        con.setCommandQueue(globalQueue);
                        connected.set(true);
                } catch (TS3ConnectionFailedException conFailed) {
                        // If this is the first connection attempt, we won't run the handleDisconnect method,
                        // so we need to call shutDown from this method instead.
                        if (connection == null) shutDown();
                        throw conFailed;
                }
        }

        /**
         * Disconnects the query and closes all open resources.
         * <p>
         * If the command queue still contains commands when this method is called,
         * the query will first process these commands, causing this method to block.
         * However, the query will reject any new commands as soon as this method is called.
         * </p>
         *
         * @throws IllegalStateException
         *              if this method was called from {@link ConnectionHandler#onConnect}
         */
        public void exit() {
                if (Thread.holdsLock(this)) {
                        // Check that exit is not called from onConnect
                        throw new IllegalStateException("Cannot call exit from onConnect handler");
                }

                try {
                        globalQueue.quit();
                } finally {
                        shutDown();
                }
        }

        private synchronized void shutDown() {
                if (userThreadPool.isShutdown()) return;

                disconnect();
                globalQueue.failRemainingCommands();
                userThreadPool.shutdown();
        }

        private synchronized void disconnect() {
                if (connection == null) return;

                connection.disconnect();
                connected.set(false);
        }

        /**
         * Returns {@code true} if the query is likely connected,
         * {@code false} if the query is disconnected or currently trying to reconnect.
         * <p>
         * Note that the only way to really determine whether the query is connected or not
         * is to send a command and check whether it succeeds.
         * Thus this method could return {@code true} almost a minute after the connection
         * has been lost, when the last keep-alive command was sent.
         * </p><p>
         * Please do not use this method to write your own connection handler.
         * Instead, use the built-in classes in the {@code api.reconnect} package.
         * </p>
         *
         * @return whether the query is connected or not
         *
         * @see TS3Config#setReconnectStrategy(ReconnectStrategy)
         * @see TS3Config#setConnectionHandler(ConnectionHandler)
         */
        public boolean isConnected() {
                return connected.get();
        }

        /**
         * Gets the API object that can be used to send commands to the TS3 server.
         *
         * @return a {@code TS3Api} object
         */
        public TS3Api getApi() {
                return globalQueue.getApi();
        }

        /**
         * Gets the asynchronous API object that can be used to send commands to the TS3 server
         * in a non-blocking manner.
         * <p>
         * Please only use the asynchronous API if it is really necessary and if you understand
         * the implications of having multiple threads interact with your program.
         * </p>
         *
         * @return a {@code TS3ApiAsync} object
         */
        public TS3ApiAsync getAsyncApi() {
                return globalQueue.getAsyncApi();
        }

        // INTERNAL

        void submitUserTask(final String name, final Runnable task) {
                userThreadPool.submit(() -> {
                        try {
                                task.run();
                        } catch (Throwable throwable) {
                                log.error(name + " threw an exception", throwable);
                        }
                });
        }

        EventManager getEventManager() {
                return eventManager;
        }

        FileTransferHelper getFileTransferHelper() {
                return fileTransferHelper;
        }

        void fireDisconnect() {
                connected.set(false);

                submitUserTask("ConnectionHandler disconnect task", this::handleDisconnect);
        }

        private void handleDisconnect() {
                try {
                        connectionHandler.onDisconnect(this);
                } finally {
                        synchronized (this) {
                                if (!connected.get()) {
                                        shutDown();
                                }
                        }
                }
        }
}