#pragma region CPL License
/*
Nuclex Native Framework
Copyright (C) 2002-2013 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library 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
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#pragma endregion // CPL License

#ifndef NUCLEX_INPUT_DEVICES_VIRTUALGAMEPAD_H
#define NUCLEX_INPUT_DEVICES_VIRTUALGAMEPAD_H

#include "Nuclex/Input/Devices/GamePad.h"

namespace Nuclex { namespace Input { namespace Devices {

  /// <summary>Forwards game pad input from an exchangeable backing device</summary>
  /// <remarks>
  ///   <para>
  ///     If this library directly dealt out instances of the input device implementations,
  ///     disconnecting a device and connecting another one, for example, would mean that
  ///     any pointers the user has to the disconnected device become either invalid.
  ///   </para>
  ///   <para>
  ///     So the design choice was to either let the library's user in on when devices are
  ///     replaced, forcing him to unsubscribe from events, resubscribe, replace pointers
  ///     he has stored to the old device and so on, or to use a forwarder device that
  ///     allows the underlying real input device to be replaced at will without anyone
  ///     outside of the library noticing.
  ///   </para>
  ///   <para>
  ///     Without a forwarding device assigned, this class can also be used as a dummy
  ///     device to fill slots for devices not available or not supported by the current
  ///     system (think keyboard on iPhone, etc.)
  ///   </para>
  /// </remarks>
  class VirtualGamePad : public GamePad, public sigslot::has_slots<> {

    /// <summary>Initializes a new virtual game pad</summary>
    public: VirtualGamePad() :
      forwardingGamePad(nullptr) {
      this->neutralState.Reset();
    }

    /// <summary>Destroys the virtual game pad</summary>
    public: virtual ~VirtualGamePad() {
      if(this->forwardingGamePad != nullptr) {
        unsubscribe(this->forwardingGamePad);
      }
    }

    /// <summary>Retrieves the game pad this instance currently forwards input for</summary>
    /// <returns>The game pad this instance forwards input for</returns>
    public: GamePad *GetForwardingGamePad() const {
      return this->forwardingGamePad;
    }

    /// <summary>Assigns the game pad for which this instance forwards input</summary>
    /// <param name="forwardingGamePad">Game pad for which input will be forwarded</param>
    public: void SetForwardingGamePad(GamePad *forwardingGamePad) {
      if(this->forwardingGamePad != nullptr) {
        unsubscribe(this->forwardingGamePad);
      }
      
      this->forwardingGamePad = forwardingGamePad;

      if(this->forwardingGamePad != nullptr) {
        subscribe(this->forwardingGamePad);
      }
    }

    /// <summary>Whether the input device is currently attached</summary>
    /// <returns>True if the input device is attached, otherwise false</returns>
    public: virtual bool IsAttached() const {
      if(this->forwardingGamePad == nullptr) {
        return false;
      } else {
        return this->forwardingGamePad->IsAttached();
      }
    }

    /// <summary>Retrieves the human-readable name of the input device</summary>
    /// <returns>The human-readable name of the input device</returns>
    public: virtual const std::string &GetName() const {
      static std::string notConnected("No game pad connected");

      if(this->forwardingGamePad == nullptr) {
        return notConnected;
      } else {
        return this->forwardingGamePad->GetName();
      }
    }

    /// <summary>Retrieves the current state of the input device</summary>
    /// <returns>The input device's current state</returns>
    public: virtual const GamePadState &GetState() const {
      if(this->forwardingGamePad == nullptr) {
        return this->neutralState;
      } else {
        return this->forwardingGamePad->GetState();
      }
    }

    /// <summary>Updates the state of the input device</summary>
    protected: virtual void Update() {
      if(this->forwardingGamePad != nullptr) {
        this->forwardingGamePad->Update();
      }
    }

    /// <summary>Takes a snapshot of the input device's current state</summary>
    protected: virtual void TakeSnapshot() {
      if(this->forwardingGamePad != nullptr) {
        this->forwardingGamePad->TakeSnapshot();
      }
    }

    /// <summary>Removes all snapshots the device has taken</summary>
    protected: virtual void ClearSnapshots() {
      if(this->forwardingGamePad != nullptr) {
        this->forwardingGamePad->ClearSnapshots();
      }
    }

    /// <summary>Subscribes to the events of the forwarding game pad</summary>
    /// <param name="gamePad">Game pad to whose events to subscribe</param>
    private: void subscribe(GamePad *gamePad) {
      gamePad->ButtonPressed.connect(this, &VirtualGamePad::onButtonPressed);
      gamePad->ButtonReleased.connect(this, &VirtualGamePad::onButtonReleased);
    }

    /// <summary>Unsubscribes from the events of the forwarding game pad</summary>
    /// <param name="gamePad">Game pad from whose events to unsubscribe</param>
    private: void unsubscribe(GamePad *gamePad) {
      gamePad->ButtonReleased.disconnect(this);
      gamePad->ButtonPressed.disconnect(this);
    }

    /// <summary>Forwards a button press notification to the library user</summary>
    /// <param name="buttonIndex">Index of the pressed button</param>
    private: void onButtonPressed(std::size_t buttonIndex) {
      ButtonPressed(buttonIndex);
    }

    /// <summary>Forwards a button release notification to the library user</summary>
    /// <param name="buttonIndex">Index of the released button</param>
    private: void onButtonReleased(std::size_t buttonIndex) {
      ButtonReleased(buttonIndex);
    }

    /// <summary>Disabled copy constructor for the virtual game pad</summary>
    private: VirtualGamePad(const VirtualGamePad &);
    /// <summary>Disabled assignment operator for the virtual game pad</summary>
    private: void operator =(const VirtualGamePad &);

    /// <summary>Game pad that is forwarded by this instance</summary>
    private: GamePad *forwardingGamePad;
    /// <summary>Neutral state that is returned when no game pad is connected</summary>
    private: GamePadState neutralState;

  };

}}} // namespace Nuclex::Input::Devices

#endif // NUCLEX_INPUT_DEVICES_VIRTUALGAMEPAD_H