BansheeEngine/SBansheeEngine/Include/BsScriptResourceManager.h

#pragma once

#include "BsScriptEnginePrerequisites.h"
#include "BsModule.h"
#include <mono/jit/jit.h>

namespace BansheeEngine
{
	/**
	 * @brief	Handles creation and lookup of script interop objects for resources.
	 *			Since resources can be created in native code yet used by managed code
	 *			this manager provides lookups to find managed equivalents of
	 *			native resources.
	 */
	class BS_SCR_BE_EXPORT ScriptResourceManager : public Module<ScriptResourceManager>
	{
	public:
		ScriptResourceManager();
		~ScriptResourceManager();

		/**
		 * @brief	Creates a new managed instance and interop object for the specified resource.
		 *
		 * @param	resourceHandle	Native resource to wrap in a managed instance.
		 * @param	out				Output interop object corresponding to the new managed instance.
		 *
		 * @note	Throws an exception if a managed instance for the provided resource already exists.
		 */
		template<class RetType, class InType>
		void createScriptResource(const ResourceHandle<InType>& resourceHandle, RetType** out);

		/**
		 * @brief	Creates a new interop object for the specified resource using an existing managed instance.
		 *
		 * @param	existingInstance	Existing managed instance. Caller must ensure the managed instance
		 *								matches the native resource type.
		 * @param	resourceHandle		Native resource to link to the managed instance.
		 * @param	out					Output interop object corresponding to the new managed instance.
		 *
		 * @note	Throws an exception if a managed instance for the provided resource already exists.
		 */
		template<class RetType, class InType>
		void createScriptResource(MonoObject* existingInstance, const ResourceHandle<InType>& resourceHandle, RetType** out);

		/**
		 * @brief	Attempts to find an existing interop object for the specified resource, and optionally
		 *			creates a new one if one cannot be found.
		 * 
		 * @param	resourceHandle	Resource to search for.
		 * @param	out				Found or created interop object containing the resource.
		 * @param	create			If a resource cannot be found new one will be created when this
		 *							is true. If false and the resource doesn't exist it will be null.
		 */
		template<class RetType, class InType>
		void getScriptResource(const ResourceHandle<InType>& resourceHandle, RetType** out, bool create = false);

		/**
		 * @brief	Creates a new managed instance and interop object for the specified string table.
		 *
		 * @param	resourceHandle	Native string table resource to wrap in a managed instance.
		 * @param	out				Output string table interop object corresponding to the new managed instance.
		 *
		 * @note	Throws an exception if a managed instance for the provided resource already exists.
		 */
		template<>
		void createScriptResource(const ResourceHandle<StringTable>& resourceHandle, ScriptStringTable** out);

		/**
		 * @brief	Creates a new managed instance and interop object for the specified resource.
		 *
		 * @param	resourceHandle	Native resource to wrap in a managed instance.
		 * @param	out				Output interop object corresponding to the new managed instance.
		 *
		 * @note	Throws an exception if a managed instance for the provided resource already exists.
		 */
		template<>
		void createScriptResource(const HResource& resourceHandle, ScriptResourceBase** out);

		/**
		 * @brief	Attempts to find a resource interop object for a resource with the specified UUID.
		 *			Returns null if the object cannot be found.
		 */
		ScriptResourceBase* getScriptResource(const String& UUID);

		/**
		 * @brief	Deletes the provided resource interop objects. All resource interop objects
		 *			should be deleted using this method.
		 */
		void destroyScriptResource(ScriptResourceBase* resource);

	private:
		/**
		 * @brief	Triggered when the native resource has been unloaded and therefore destroyed.
		 */
		void onResourceDestroyed(const HResource& resource);

		/**
		 * @brief	Throws an exception if the provided UUID already exists in the interop object
		 *			lookup table.
		 */
		void throwExceptionIfInvalidOrDuplicate(const String& uuid) const;

		UnorderedMap<String, ScriptResourceBase*> mScriptResources;
		HEvent mResourceDestroyedConn;
	};
}