//////////////////////////////////////////////////////////////////////////////////////
//    akashi - a server for Attorney Online 2                                       //
//    Copyright (C) 2020  scatterflower                                             //
//                                                                                  //
//    This program is free software: you can redistribute it and/or modify          //
//    it under the terms of the GNU Affero 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 Affero General Public License for more details.                           //
//                                                                                  //
//    You should have received a copy of the GNU Affero General Public License      //
//    along with this program.  If not, see <https://www.gnu.org/licenses/>.        //
//////////////////////////////////////////////////////////////////////////////////////
#ifndef SERVER_H
#define SERVER_H

#include <QCoreApplication>
#include <QDebug>
#include <QFile>
#include <QMap>
#include <QSettings>
#include <QStack>
#include <QString>
#include <QTcpServer>
#include <QTcpSocket>
#include <QTimer>

#include "include/aopacket.h"

class Advertiser;
class AOClient;
class AreaData;
class ConfigManager;
class DBManager;
class Discord;
class MusicManager;
class ULogger;
class WSProxy;

/**
 * @brief The class that represents the actual server as it is.
 */
class Server : public QObject
{
    Q_OBJECT

  public:
    /**
     * @brief Creates a Server instance.
     *
     * @param p_port The TCP port to listen for connections on.
     * @param p_ws_port The WebSocket port to listen for connections on.
     * @param parent Qt-based parent, passed along to inherited constructor from QObject.
     */
    Server(int p_port, int p_ws_port, QObject *parent = nullptr);

    /**
     * @brief Destructor for the Server class.
     *
     * @details Marks every Client, the WSProxy, the underlying #server, and the database manager to be deleted later.
     */
    ~Server();

    /**
     * @brief Starts the server.
     *
     * @details Amongst other things, this function starts the listening on the given TCP port, sets up the server
     * according to the configuration file, and starts listening on the WebSocket port if it is not `-1`.
     *
     * Advertising is not done here -- see Advertiser::contactMasterServer() for that.
     */
    void start();

    /**
     * @brief Enum to specifc different targets to send altered packets to a specific usergroup.
     */
    enum class TARGET_TYPE
    {
        AUTHENTICATED,
        MODCHAT,
        ADVERT
    };
    Q_ENUM(TARGET_TYPE)

    /**
     * @brief Returns a list of all clients currently in the server.
     *
     * @return A list of all clients currently in the server.
     */
    QVector<AOClient *> getClients();

    /**
     * @brief Gets a pointer to a client by IPID.
     *
     * @param ipid The IPID to look for.
     *
     * @return A pointer to the client if found, a nullpointer if not.
     *
     * @see Server::getClientsByIpid() to get all clients ran by the same user.
     */
    AOClient *getClient(QString ipid);

    /**
     * @brief Gets a list of pointers to all clients with the given IPID.
     *
     * @param ipid The IPID to look for.
     *
     * @return A list of clients whose IPID match. List may be empty.
     */
    QList<AOClient *> getClientsByIpid(QString ipid);

    /**
     * @brief Gets a pointer to a client by user ID.
     *
     * @param id The user ID to look for.
     *
     * @return A pointer to the client if found, a nullpointer if not.
     */
    AOClient *getClientByID(int id);

    /**
     * @brief Returns the overall player count in the server.
     *
     * @return The overall player count in the server.
     */
    int getPlayerCount();

    /**
     * @brief Returns a list of the available characters on the server to use.
     *
     * @return A list of the available characters on the server to use.
     */
    QStringList getCharacters();

    /**
     * @brief Returns the count of available characters on the server to use.
     *
     * @return The count of available characters on the server to use.
     */
    int getCharacterCount();

    /**
     * @brief Get the available character by index.
     *
     * @param f_chr_id The index of the character.
     *
     * @return The character if it exist, otherwise an empty stirng.
     */
    QString getCharacterById(int f_chr_id);

    /**
     * @brief Updates which characters are taken in the given area, and sends out an update packet to
     * all clients present the area.
     *
     * @param area The area in which to update the list of characters.
     */
    void updateCharsTaken(AreaData *area);

    /**
     * @brief Sends a packet to all clients in a given area.
     *
     * @param packet The packet to send to the clients.
     *
     * @param area_index The index of the area to look for clients in.
     *
     * @note Does nothing if an area by the given index does not exist.
     */
    void broadcast(AOPacket packet, int area_index);

    /**
     * @brief Sends a packet to all clients in the server.
     *
     * @param packet The packet to send to the clients.
     */
    void broadcast(AOPacket packet);

    /**
     * @brief Sends a packet to a specific usergroup..
     *
     * @param The packet to send to the clients.
     *
     * @param ENUM to determine the targets of the altered packet.
     */
    void broadcast(AOPacket packet, TARGET_TYPE target);

    /**
     * @brief Sends a packet to clients, sends an altered packet to a specific usergroup.
     *
     * @param The packet to send to the clients.
     *
     * @param The altered packet to send to the other clients.
     *
     * @param ENUM to determine the targets of the altered packet.
     */
    void broadcast(AOPacket packet, AOPacket other_packet, enum TARGET_TYPE target);

    /**
     * @brief Sends a packet to a single client.
     *
     * @param The packet send to the client.
     *
     * @param The temporary userID of the client.
     */
    void unicast(AOPacket f_packet, int f_client_id);

    /**
     * @brief Returns the character's character ID (= their index in the character list).
     *
     * @param char_name The 'internal' name for the character whose character ID to look up. This is equivalent to
     * the name of the directory of the character.
     *
     * @return The character ID if a character with that name exists in the character selection list, `-1` if not.
     */
    int getCharID(QString char_name);

    /**
     * @brief Checks if an IP is in a subnet of the IPBanlist.
     **/
    bool isIPBanned(QHostAddress f_remote_IP);

    /**
     * @brief Returns the list of areas in the server.
     *
     * @return A list of areas.
     */
    QVector<AreaData *> getAreas();

    /**
     * @brief Returns the number of areas in the server.
     */
    int getAreaCount();

    /**
     * @brief Returns a pointer to the area associated with the index.
     *
     * @param f_area_id The index of the area.
     *
     * @return A pointer to the area or null.
     */
    AreaData *getAreaById(int f_area_id);

    /**
     * @brief Getter for an area specific buffer from the logger.
     */
    QQueue<QString> getAreaBuffer(const QString &f_areaName);

    /**
     * @brief The names of the areas on the server.
     *
     * @return A list of names.
     */
    QStringList getAreaNames();

    /**
     * @brief Returns the name of the area associated with the index.
     *
     * @param f_area_id The index of the area.
     *
     * @return The name of the area or empty.
     */
    QString getAreaName(int f_area_id);

    /**
     * @brief Returns the available songs on the server.
     *
     * @return A list of songs.
     */
    QStringList getMusicList();

    /**
     * @brief Returns the available backgrounds on the server.
     *
     * @return A list of backgrounds.
     */
    QStringList getBackgrounds();

    /**
     * @brief Returns a pointer to a database manager.
     *
     * @return A pointer to database manager.
     */
    DBManager *getDatabaseManager();

    /**
     * @brief The server-wide global timer.
     */
    QTimer *timer;

    QStringList getCursedCharsTaken(AOClient *client, QStringList chars_taken);

    /**
     * @brief Returns whatever a game message may be broadcasted or not.
     *
     * @return True if expired; false otherwise.
     */
    bool isMessageAllowed();

    /**
     * @brief Starts a global timer that determines whatever a game message may be broadcasted or not.
     *
     * @param f_duration The duration of the message floodguard timer.
     */
    void startMessageFloodguard(int f_duration);

    /**
     * @brief Attempts to parse a IPv6 mapped IPv4 to an IPv4.
     */
    QHostAddress parseToIPv4(QHostAddress f_remote_ip);

  public slots:
    /**
     * @brief Convenience class to call a reload of available configuraiton elements.
     */
    void reloadSettings();

    /**
     * @brief Handles a new connection.
     *
     * @details The function creates an AOClient to represent the user, assigns a user ID to them, and
     * checks if the client is banned.
     */
    void clientConnected();

    /**
     * @brief Method to construct and reconstruct Discord Webhook Integration.
     *
     * @details Constructs or rebuilds Discord Object during server startup and configuration reload.
     */
    void handleDiscordIntegration();

    /**
     * @brief Marks a userID as free and ads it back to the available client id queue.
     */
    void markIDFree(const int &f_user_id);

  signals:

    /**
     * @brief Sends the server name and description, emitted by /reload.
     *
     * @param p_name The server name.
     * @param p_desc The server description.
     */
    void reloadRequest(QString p_name, QString p_desc);

    /**
     * @brief This signal is emitted whenever the current player count has changed.
     *
     * @param f_current_player The player count at the time the signal was emitted.
     */
    void playerCountUpdated(int f_current_players);

    /**
     * @brief Triggers a partial update of the modern advertiser as some information, such as ports
     * can't be updated while the server is running.
     */
    void updateHTTPConfiguration();

    /**
     * @brief Sends a modcall webhook request, emitted by AOClient::pktModcall.
     *
     * @param f_name The character or OOC name of the client who sent the modcall.
     * @param f_area The name of the area the modcall was sent from.
     * @param f_reason The reason the client specified for the modcall.
     * @param f_buffer The area's log buffer.
     */
    void modcallWebhookRequest(const QString &f_name, const QString &f_area, const QString &f_reason, const QQueue<QString> &f_buffer);

    /**
     * @brief Sends a ban webhook request, emitted by AOClient::cmdBan
     * @param f_ipid The IPID of the banned client.
     * @param f_moderator The moderator who issued the ban.
     * @param f_duration The duration of the ban in a human readable format.
     * @param f_reason The reason for the ban.
     * @param f_banID The ID of the issued ban.
     */
    void banWebhookRequest(const QString &f_ipid, const QString &f_moderator, const QString &f_duration, const QString &f_reason, const int &f_banID);

    /**
     * @brief Signal connected to universal logger. Logs a client connection attempt.
     * @param f_ip_address The IP Address of the incoming connection.
     * @param f_ipid The IPID of the incoming connection.
     * @param f_hdid The HDID of the incoming connection.
     */
    void logConnectionAttempt(const QString &f_ip_address, const QString &f_ipid, const QString &f_hwid);

  private:
    /**
     * @brief The proxy used for WebSocket connections.
     *
     * @see WSProxy and WSClient for an explanation as to why this is a thing.
     */
    WSProxy *proxy;

    /**
     * @brief Listens for incoming TCP connections.
     */
    QTcpServer *server;

    /**
     * @brief Handles Discord webhooks.
     */
    Discord *discord;

    /**
     * @brief Handles HTTP server advertising.
     */
    Advertiser *ms3_Advertiser;

    /**
     * @brief Advertises the server in a regular intervall.
     */
    QTimer *AdvertiserTimer;

    /**
     * @brief Handles the universal log framework.
     */
    ULogger *logger;

    /**
     * @brief Handles all musiclists.
     */
    MusicManager *music_manager;

    /**
     * @brief The port through which the server will accept TCP connections.
     */
    int port;

    /**
     * @brief The port through which the server will accept WebSocket connections.
     */
    int ws_port;

    /**
     * @brief The collection of all currently connected clients.
     */
    QVector<AOClient *> m_clients;

    /**
     * @brief Collection of all clients with their userID as key.
     */
    QHash<int, AOClient *> m_clients_ids;

    /**
     * @brief Stack of all available IDs for clients. When this is empty the server
     * rejects any new connection attempt.
     */
    QStack<int> m_available_ids;

    /**
     * @brief The overall player count in the server.
     */
    int m_player_count;

    /**
     * @brief The characters available on the server to use.
     */
    QStringList m_characters;

    /**
     * @brief The areas on the server.
     */
    QVector<AreaData *> m_areas;

    /**
     * @brief The names of the areas on the server.
     *
     * @details Equivalent to iterating over #areas and getting the area names individually, but grouped together
     * here for faster access.
     */
    QStringList m_area_names;

    /**
     * @brief The available songs on the server.
     *
     * @details Does **not** include the area names, the actual music list packet should be constructed from
     * #area_names and this combined.
     */
    QStringList m_music_list;

    /**
     * @brief The backgrounds on the server that may be used in areas.
     */
    QStringList m_backgrounds;

    /**
     * @brief Collection of all IPs that are banned.
     */
    QStringList m_ipban_list;

    /**
     * @brief Timer until the next IC message can be sent.
     */
    QTimer *m_message_floodguard_timer;

    /**
     * @brief If false, IC messages will be rejected.
     */
    bool m_can_send_ic_messages = true;

    /**
     * @brief The database manager on the server, used to store users' bans and authorisation details.
     */
    DBManager *db_manager;

    /**
     * @brief Connects new AOClient to logger and disconnect handling.
     **/
    void hookupAOClient(AOClient *client);

  private slots:
    /**
     * @brief Increase the current player count by one.
     */
    void increasePlayerCount();

    /**
     * @brief Decrease the current player count based on the client id provided.
     *
     * @param f_client_id The client id of the client to check.
     */
    void decreasePlayerCount();

    /**
     * @brief Allow game messages to be broadcasted.
     */
    void allowMessage();
};

#endif // SERVER_H