#pragma once
#pragma region CPL License
/*
Nuclex Unreal Module
Copyright (C) 2014-2021 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

#include <CoreMinimal.h>
#include <GameFramework/Pawn.h>
#include <Camera/CameraComponent.h>

#include "DialogPawn.generated.h"

// --------------------------------------------------------------------------------------------- //

/// Pawn that can be used as a stationary observer and to interact with 3D UI
/// @remarks
///   When to use: use this pawn for your main menu and simple 3D UI interaction
///   where the player either uses the mouse or selects options by looking at them.
///
///   This is not useful as a base class for complex characters or if you want to
///   create a fancy VR game with support for 3D hand controllers.
UCLASS()
class NUCLEX_API ADialogPawn : public APawn {

  GENERATED_BODY()

  /// Sets default values for this pawn's properties
  public: ADialogPawn();

  //
  // ADialogPawn implementation
  //

  /// Uses the current HMD location and rotation as the identity pose (if VR is active)
  /// @remarks
  ///   SteamVR and other HMD APIs have multiple concepts of centeredness. Room-scale
  ///   VR typically is ground-centered and the HMD camera ends up 2 meters above the
  ///   pawn transform. Seated VR and early HMD use the calibrated center, so the camera
  ///   matches the pawn position (+ BaseEyeHeight).
  ///
  ///   This method lets you do away with all that and uses whatever location and orienation
  ///   the HMD has as the identity transform. This is bullet-proof in that lets you
  ///   reliably remove the uncertain transform for menu scenes or when the player is
  ///   controlling something that's not supposed to be himself.
  public: UFUNCTION(BlueprintCallable, CallInEditor)
  void RecenterHmd();

  /// Clears the HMD counter-transform, placing the HMD camera wherever the VR API wants
  /// @remarks
  ///   This does the opposite of the RecenterHmd() function and places the HMD camera
  ///   wherever the VR API thinks it should be. That may be 2 meters above the pawn
  ///   for room-scale VR or at the pawn base (+ BaseEyeHeight) for seated VR.
  public: UFUNCTION(BlueprintCallable, CallInEditor)
  void ClearHmdCenter();

  //
  // Internal implementation
  //

  /// Called when the game starts or when spawned
  protected: virtual void BeginPlay() override;

#if defined(WANT_TO_HANDLE_INPUT_OURSELVES)

  /// Destroys the player input component when the pawn is no longer possessed
  protected: virtual void DestroyPlayerInputComponent() override;

  /// Sets up pawn-specific input bindings when the pawn is possessed by a player controller
  /// @param  playerInputComponent  Component through which input bindings are registered
  protected: virtual void SetupPlayerInputComponent(
    UInputComponent *playerInputComponent
  ) override;

  /// Sends a mouse down event to the UI on a touch or mouse button press
  private: void pointerPressed();
  /// Sends a mouse up event to the UI on a touch or mouse button release
  private: void pointerReleased();

#endif // defined(WANT_TO_HANDLE_INPUT_OURSELVES)

  /// Transforms from the HMD 'zero' position to the player's chosen rest position
  /// @remarks
  ///   In this game, the player can make the current HMD position the neutral position
  ///   at any time by pressing the space bar. This transform translates from the chosen
  ///   rest position to the HMD's 'zero' position.
	public: UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category="Camera")
  USceneComponent *HmdOffsetCompensation;

  /// Camera from which the scene is viewed
	public: UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category="Camera")
  UCameraComponent *ObserverCamera;

  /// Performs line traces to allow the player to interact with 3D UI
  /// @remarks
  ///   This thing needs to be placed on the active camera in order to use the HMD's
  ///   orientation (it works on the player controller only for mouse input).
  ///   However, input needs to be sent from the player controller to here still
  ///   unless we want to query and process input in the pawn.
  public: UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category="UI")
  class UWidgetInteractionComponent *WidgetInteraction;

  /// Cached key for the left mouse button in Unreal's input system
  private: mutable FKey leftMouseButtonKey;

};

// --------------------------------------------------------------------------------------------- //