/************************************************************************************//*!
\file           Component.hxx
\author         Tng Kah Wei, kahwei.tng, 390009620
\par            email: kahwei.tng\@digipen.edu
\date           Oct 27, 2021
\brief          Contains the definition of the managed Component classes with the
                declaration of functions for working with it.
                
                Note: This file is written in C++17/CLI.
 
Copyright (C) 2021 DigiPen Institute of Technology.
Reproduction or disclosure of this file or its contents without the prior written consent 
of DigiPen Institute of Technology is prohibited.
*//*************************************************************************************/
#pragma once

// External Dependencies
#include "ECS_Base/Components/SHComponent.h"
// Project Includes
#include "Engine/Entity.hxx"
#include "Scripts/Script.hxx"

namespace SHADE
{
    /// <summary>
    /// Class that serves as the base for a wrapper class to Components in native code.
    /// </summary>
    public ref class BaseComponent : public System::IEquatable<BaseComponent^>
    {
      public:
        /*-----------------------------------------------------------------------------*/
        /* Properties                                                                  */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Retrieves the GameObject that this Component belongs to.
        /// </summary>
        property GameObject Owner
        {
            GameObject get() { return owner; }
        }

        /*-----------------------------------------------------------------------------*/
        /* Component Access Functions                                                  */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Adds a Component to this GameObject.
        /// </summary>
        /// <typeparam name="T">Type of the Component to add. </typeparam>
        /// <returns>Reference to the Component that was added.</returns>
        generic<typename T> where T : BaseComponent
        T AddComponent();
        /// <summary>
        /// Gets a Component from this GameObject.
        /// </summary>
        /// <typeparam name="T">Type of the Component to get.</typeparam>
        /// <returns>
        /// Reference to the Component or null if this GameObject does not have the
        /// specified Component.
        /// </returns>
        generic<typename T> where T : BaseComponent
        T GetComponent();
        /// <summary>
        /// Removes a Component from this GameObject. If no Component exists to begin
        /// with, nothing happens.
        /// </summary>
        /// <typeparam name="T">Type of the Component to get.</typeparam>
        generic<typename T> where T : BaseComponent
        void RemoveComponent();

        /*-----------------------------------------------------------------------------*/
        /* Script Access Functions                                                     */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Adds a Script of the specified type to this GameObject.
        /// </summary>
        /// <typeparam name="T">Type of Script to add.</typeparam>
        /// <returns>Reference to the created Script.</returns>
        generic<typename T> where T : ref class, Script
        T AddScript();
        /// <summary>
        /// Retrieves a Script of the specified type from this GameObject.
        /// If multiple Scripts of the same specified type are added on the same
        /// GameObject, this will retrieve the first one added.
        /// </summary>
        /// <typeparam name="T">Type of Script to add.</typeparam>
        /// <returns>Reference to the Script to retrieve.</returns>
        generic<typename T> where T : ref class, Script
        T GetScript();
        /// <summary>
        /// Retrieves a immutable list of Scripts of the specified type from this
        /// GameObject.
        /// </summary>
        /// <typeparam name="T">Type of Scripts to Get.</typeparam>
        /// <returns>Immutable list of Scripts of the specified type.</returns>
        generic<typename T> where T : ref class, Script
        System::Collections::Generic::IEnumerable<T>^ GetScripts();
        /// <summary>
        /// Removes all Scripts of the specified type from this GameObject.
        /// </summary>
        /// <typeparam name="T">Type of PLushieScripts to remove.</typeparam>
        generic<typename T> where T : ref class, Script
        void RemoveScript();

      protected:
        /*-----------------------------------------------------------------------------*/
        /* Constructors                                                                */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Constructor for BaseComponent to tie it to a specific Entity.
        /// Constructors of derived Components should call this Constructor.
        /// </summary>
        /// <param name="entity">Entity that this Component will be tied to.</param>
        BaseComponent(Entity entity);

        /*-----------------------------------------------------------------------------*/
        /* Data Members                                                                */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Entity that this Component belongs to.
        /// </summary>
        GameObject owner;

      public:        
        /*-----------------------------------------------------------------------------*/
        /* IEquatable                                                                  */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Compares equality with an object of the same type.
        /// </summary>
        /// <param name="other">The object to compare with.</param>
        /// <returns>True if both objects are the same.</returns>
        virtual bool Equals(BaseComponent^ other);

        /*-----------------------------------------------------------------------------*/
        /* Object                                                                      */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Compares equality with another unboxed object.
        /// </summary>
        /// <param name="o">The unboxed object to compare with.</param>
        /// <returns>True if both objects are the same.</returns>
        bool Equals(Object^ o) override;
        /// <summary>
        /// Gets a unique hash for this object.
        /// </summary>
        /// <returns>Unique hash for this object.</returns>
        int  GetHashCode() override;
    };

    /// <summary>
    /// C++ template for the BaseComponent class used to generate common template-able
    /// functions and types.
    /// </summary>
    /// <typeparam name="NativeType">
    /// Type of the native component that this Component wraps.
    /// </typeparam>
    template<typename NativeType>
    public ref class Component : public BaseComponent
    {
      internal:
        /*-----------------------------------------------------------------------------*/
        /* Type Definitions                                                            */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Type of the native component that this Component wraps.
        /// </summary>
        using NativeComponent = NativeType;

        /*-----------------------------------------------------------------------------*/
        /* Helper Functions                                                            */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Retrieves a pointer to the native unmanaged component that is tied to the
        /// Entity described by the owner value.
        /// </summary>
        /// <returns>
        /// Pointer to the native component. Will be nullptr if it does not exist.
        /// </returns>
        /// <exception cref="System.InvalidOperationException">
        /// Thrown if the internal ID stored by this native component is invalid.
        /// </exception>
        /// <exception cref="System.NullReferenceException">
        /// Thrown if an attempt to retrieve the native component fails.
        /// </exception>
        NativeComponent* GetNativeComponent();

      protected:
        /*-----------------------------------------------------------------------------*/
        /* Constructors                                                                */
        /*-----------------------------------------------------------------------------*/
        /// <summary>
        /// Constructor for Component to tie it to a specific Entity.
        /// Constructors of derived Components should call this Constructor.
        /// </summary>
        /// <param name="entity">Entity that this Component will be tied to.</param>
        Component(Entity entity);
    };
}

#include "Component.h++"