package me.StevenLawson.BukkitTelnet.session;

import me.StevenLawson.BukkitTelnet.api.TelnetPreLoginEvent;
import me.StevenLawson.BukkitTelnet.api.TelnetCommandEvent;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;
import me.StevenLawson.BukkitTelnet.BukkitTelnet;
import me.StevenLawson.BukkitTelnet.TelnetConfig;
import me.StevenLawson.BukkitTelnet.TelnetLogger;
import me.StevenLawson.BukkitTelnet.Util;
import org.apache.logging.log4j.LogManager;
import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Server;
import org.bukkit.scheduler.BukkitRunnable;
import org.apache.logging.log4j.core.Logger;

public final class ClientSession extends Thread
{
    public static final Pattern NONASCII_FILTER = Pattern.compile("[^\\x20-\\x7E]");
    public static final Pattern AUTH_INPUT_FILTER = Pattern.compile("[^a-zA-Z0-9]");
    public static final Pattern COMMAND_INPUT_FILTER = Pattern.compile("^[^a-zA-Z0-9/\\?!\\.]+");
    //
    private final Socket clientSocket;
    private final String clientAddress;
    //
    private final SessionCommandSender commandSender;
    private final SessionLogAppender logAppender;
    private FilterMode filterMode = FilterMode.FULL;
    //
    private BufferedWriter writer;
    private BufferedReader reader;
    private String username;
    private boolean hasTerminated;

    public ClientSession(Socket clientSocket)
    {
        this.clientSocket = clientSocket;
        this.clientAddress = clientSocket.getInetAddress().getHostAddress();
        this.username = "";
        this.commandSender = new SessionCommandSender(this);
        this.logAppender = new SessionLogAppender(this);
        this.hasTerminated = false;

        TelnetLogger.info("Client connected: " + clientAddress);
    }

    @Override
    public void run()
    {
        try
        {
            synchronized (clientSocket)
            {
                reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                writer = new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));
            }
        }
        catch (IOException ex)
        {
            TelnetLogger.severe(ex);
            syncTerminateSession();
            return;
        }

        printRaw(":");
        println("Session Started.");

        if (!authenticate())
        {
            println("Authentication failed.");
            syncTerminateSession();
        }

        mainLoop();
        syncTerminateSession();
    }

    public boolean syncIsConnected()
    {
        synchronized (clientSocket)
        {
            return !clientSocket.isClosed();
        }
    }

    private Logger getLogger()
    {
        return (Logger) LogManager.getRootLogger();
    }

    public synchronized void syncTerminateSession()
    {
        if (hasTerminated)
        {
            return;
        }

        hasTerminated = true;

        TelnetLogger.info("Closing connection: " + clientAddress + (username.isEmpty() ? "" : "(" + username + ")"));
        getLogger().removeAppender(logAppender);

        synchronized (clientSocket)
        {
            if (clientSocket == null)
            {
                return;
            }

            println("Closing connection...");
            try
            {
                clientSocket.close();
            }
            catch (IOException ex)
            {
            }

        }
    }

    public String getUserName()
    {
        return username;
    }

    public SessionCommandSender getCommandSender()
    {
        return commandSender;
    }

    public SessionLogAppender getAppender()
    {
        return logAppender;
    }

    public FilterMode getFilterMode()
    {
        return filterMode;
    }

    public void setFilterMode(FilterMode filterMode)
    {
        this.filterMode = filterMode;
    }

    public void printRaw(String message)
    {
        if (writer == null || !syncIsConnected())
        {
            return;
        }

        try
        {
            writer.write(ChatColor.stripColor(message));
            writer.flush();
        }
        catch (IOException ex)
        {
        }
    }

    public void printRawln(String message)
    {
        printRaw(message + "\r\n:");
    }

    public void print(String message)
    {
        printRaw("[" + (username.isEmpty() ? "" : username + "@") + "BukkitTelnet]$ " + message);
    }

    public void println(String message)
    {
        print(message + "\r\n:");
    }

    public void flush()
    {
        if (writer == null || !syncIsConnected())
        {
            return;
        }

        try
        {
            writer.flush();
        }
        catch (IOException ex)
        {
        }
    }

    public void syncExecuteCommand(final String command)
    {
        new BukkitRunnable()
        {
            @Override
            public void run()
            {
                final Server server = Bukkit.getServer();

                final TelnetCommandEvent event = new TelnetCommandEvent(commandSender, command);
                server.getPluginManager().callEvent(event);

                if (event.isCancelled())
                {
                    return;
                }

                if (event.getCommand().isEmpty())
                {
                    return;
                }

                server.dispatchCommand(event.getSender(), event.getCommand());
            }
        }.runTask(BukkitTelnet.plugin);
    }

    private boolean authenticate()
    {
        if (hasTerminated)
        {
            return false;
        }

        boolean authenticated = false;

        // Pre-authenticate IP addresses
        if (clientAddress != null)
        {
            final Map<String, List<String>> admins = TelnetConfig.getInstance().getConfigEntries().getAdmins();

            // For every admin
            for (String name : admins.keySet())
            {

                // For every IP of each admin
                for (String ip : admins.get(name))
                {
                    if (Util.fuzzyIpMatch(ip, clientAddress, 3))
                    {
                        authenticated = true;
                        this.username = name;
                        break;
                    }
                }
            }
        }

        // Send TelnetPreLoginEvent
        final TelnetPreLoginEvent event = new TelnetPreLoginEvent(clientAddress, username, authenticated);
        Bukkit.getServer().getPluginManager().callEvent(event);

        if (event.isCancelled())
        {
            return false;
        }

        if (event.canBypassPassword())
        {
            this.username = event.getName();
            return true;
        }

        // Username / password authentication
        boolean validUsername = false;

        int tries = 0;
        while (tries++ < 3)
        {
            print("Username: ");

            String input;
            try
            {
                input = reader.readLine();
            }
            catch (IOException ex)
            {
                continue;
            }

            printRaw(":");

            if (input == null || input.isEmpty()) // End of stream
            {
                continue;
            }

            input = AUTH_INPUT_FILTER.matcher(input).replaceAll("").trim();

            if (input.isEmpty())
            {
                println("Invalid username.");
                continue;
            }

            this.username = input;
            validUsername = true;
            break;
        }

        if (!validUsername)
        {
            return false;
        }

        tries = 0;
        while (tries++ < 3)
        {
            print("Password: ");

            String input;

            try
            {
                input = reader.readLine();
            }
            catch (IOException ex)
            {
                continue;
            }

            printRaw(":");

            if (input == null || input.isEmpty()) // End of stream
            {
                continue;
            }

            input = AUTH_INPUT_FILTER.matcher(input).replaceAll("").trim();

            if (TelnetConfig.getInstance().getConfigEntries().getPassword().equals(input))
            {
                return true;
            }

            println("Invalid password.");
            try
            {
                Thread.sleep(2000);
            }
            catch (InterruptedException ex)
            {
            }
        }

        return false;
    }

    private void mainLoop()
    {
        if (hasTerminated)
        {
            return;
        }

        println("Logged in as " + username + ".");
        TelnetLogger.info(clientAddress + " logged in as \"" + username + "\".");

        // Start feeding data to the client.
        getLogger().addAppender(logAppender);

        while (syncIsConnected())
        {
            // Read a command
            String command;
            try
            {
                command = reader.readLine();
            }
            catch (IOException ex)
            {
                continue;
            }

            printRaw(":");

            if (command == null || command.isEmpty()) // End of stream
            {
                continue;
            }

            command = COMMAND_INPUT_FILTER.matcher(NONASCII_FILTER.matcher(command).replaceAll("")).replaceFirst("").trim();
            if (command.isEmpty())
            {
                continue;
            }

            if (command.toLowerCase().startsWith("telnet"))
            {
                executeTelnetCommand(command);
                continue;
            }

            syncExecuteCommand(command);
        }
    }

    private void executeTelnetCommand(String command)
    {
        if (command.equalsIgnoreCase("telnet.help"))
        {
            println("--- Telnet commands ---");
            println("telnet.help  - See all of the telnet commands.");
            println("telnet.stop  - Shut the server down.");
            println("telnet.log   - Change your logging settings.");
            println("telnet.exit  - Quit the telnet session.");
            return;
        }

        if (command.equalsIgnoreCase("telnet.stop"))
        {
            println("Shutting down the server...");
            TelnetLogger.warning(username + ": Shutting down the server...");
            System.exit(0);
            return;
        }

        if (command.equalsIgnoreCase("telnet.log"))
        {
            if (filterMode == FilterMode.FULL)
            {
                filterMode = FilterMode.CHAT_ONLY;
                println("Showing only chat logs.");
                return;
            }

            if (filterMode == FilterMode.CHAT_ONLY)
            {
                filterMode = FilterMode.NONCHAT_ONLY;
                println("Showing only non-chat logs.");
                return;
            }

            if (filterMode == FilterMode.NONCHAT_ONLY)
            {
                filterMode = FilterMode.FULL;
                println("Showing all logs.");
            }

            return;
        }

        if (command.equalsIgnoreCase("telnet.exit"))
        {
            syncTerminateSession();
        }
    }
}