#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
#pragma once

#include <CoreMinimal.h>
#include <LatentActions.h>

#include <GameFramework/Actor.h>
#include <Kismet/KismetMathLibrary.h>

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

/// Manages a camera movement running as a latent (background) action
class FFlyCameraAction : public FPendingLatentAction {

  /// Initializes a new camera movement action
  /// @param  latentInfo       Information container for the running latent action
  /// @param  pawn             Pawn (holding the camera) that will fly to a new position
  /// @param  target           Target transformation the camera will assume
  /// @param  durationSeconds  Duration in seconds over which the fade will happen
  /// @param  easingFunction   Easing method that will be used for the camera path
  public: FFlyCameraAction(
    const FLatentActionInfo &latentInfo,
    APawn *pawn,
    const FTransform &target,
    float durationSeconds,
    EEasingFunc::Type easingFunction
  );

  /// Called once per tick to update the state of the latent action
  /// @param  response  Helper providing informations and notification capabilities
  public: void UpdateOperation(FLatentResponse &response) override;

#if defined(WITH_EDITOR) && (WITH_EDITOR == 1)
  /// Returns a human readable description of the latent operation's current state
  public: FString GetDescription() const override {
    return FString::Printf(
      TEXT("Reposition camera (%i %%)"),
      static_cast<int32>(this->elapsedSeconds * 100.0f / this->durationSeconds)
    );
  }
#endif

  /// Updates the position and orientation of the pawn
  /// @param  newTransform  New position and orientation the pawn will assume
  private: void updatePawnTransform(const FTransform &newTransform);

  /// Object on which to invoke the callback function to continue execution
  private: FWeakObjectPtr callbackTarget;
  /// Callback function to continue execution of the blueprint graph
  private: FName executionFunction;
  /// State in which the blueprint graph is current waiting (each node has a number)
  private: int32 outputLink;

  /// Camera on which the fade-in will take place
  private: APawn *pawn;
  /// Transformation at which the camera's path started
  private: FTransform origin;
  /// Transformation the camera will assume at the end of the path
  private: FTransform target;
  /// Total time the operation will run for
  private: float durationSeconds;
  /// Number of seconds the fade has already run for
  private: float elapsedSeconds;
  /// Easing function that will be applied across the camera's movement
  private: EEasingFunc::Type easingFunction;

};

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