// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once

#include "CoreMinimal.h"

#include "MetasoundBuilderInterface.h"
#include "MetasoundGraph.h"
#include "MetasoundFrontendDataTypeRegistry.h"
#include "MetasoundFrontendDocument.h"
#include "MetasoundFrontendRegistries.h"

// Forward Declarations
class FMetasoundAssetBase;

namespace Metasound
{	
	namespace Frontend
	{
		class IRegistryTransaction;
		using FRegistryTransactionID = int32;

		/** Returns all metadata (name, description, author, what to say if it's missing) for a given node.
		 *
		 * @param InInfo - Class info for a already registered external node.
		 *
		 * @return Metadata for node.
		 */
		METASOUNDFRONTEND_API FMetasoundFrontendClassMetadata GenerateClassMetadata(const FNodeRegistryKey& InKey);

		/** Generates a new FMetasoundFrontendClass from Node Metadata 
		 *
		 * @param InNodeMetadata - Metadata describing an external node.
		 *
		 * @return Class description for external node.
		 */
		METASOUNDFRONTEND_API FMetasoundFrontendClass GenerateClassDescription(const FNodeClassMetadata& InNodeMetadata, EMetasoundFrontendClassType ClassType=EMetasoundFrontendClassType::External);

		/** Generates a new FMetasoundFrontendClass from node lookup info.
		 *
		 * @param InInfo - Class info for a already registered external node.
		 *
		 * @return Class description for external node.
		 */
		METASOUNDFRONTEND_API FMetasoundFrontendClass GenerateClassDescription(const Metasound::Frontend::FNodeRegistryKey& InKey);

		/** Generates a new FMetasoundFrontendClass from Node init data
		 *
		 * @tparam NodeType - Type of node to instantiate.
		 * @param InNodeInitData - Data used to call constructor of node.
		 *
		 * @return Class description for external node.
		 */
		template<typename NodeType>
		FMetasoundFrontendClass GenerateClassDescription(const FNodeInitData& InNodeInitData)
		{
			TUniquePtr<INode> Node = MakeUnique<NodeType>(InNodeInitData);

			if (ensure(Node.IsValid()))
			{
				return GenerateClassDescription(Node->GetMetadata());
			}

			return FMetasoundFrontendClass();
		}

		/** Generates a new FMetasoundFrontendClass from a NodeType
		 *
		 * @tparam NodeType - Type of node.
		 *
		 * @return Class description for external node.
		 */
		template<typename NodeType>
		FMetasoundFrontendClass GenerateClassDescription()
		{
			FNodeInitData InitData;
			InitData.InstanceName = TEXT("GenerateClassDescriptionForNode");

			return GenerateClassDescription<NodeType>(InitData);
		}

		// Takes a JSON string and deserializes it into a Metasound document struct.
		// @returns false if the file couldn't be found or parsed into a document.
		METASOUNDFRONTEND_API bool ImportJSONToMetasound(const FString& InJSON, FMetasoundFrontendDocument& OutMetasoundDocument);

		// Opens a json document at the given absolute path and deserializes it into a Metasound document struct.
		// @returns false if the file couldn't be found or parsed into a document.
		METASOUNDFRONTEND_API bool ImportJSONAssetToMetasound(const FString& InPath, FMetasoundFrontendDocument& OutMetasoundDocument);

		// Struct that indicates whether an input and an output can be connected,
		// and whether an intermediate node is necessary to connect the two.
		struct METASOUNDFRONTEND_API FConnectability
		{
			enum class EConnectable
			{
				Yes,
				No,
				YesWithConverterNode
			};

			enum class EReason : uint8
			{
				None,
				IncompatibleDataTypes,
				CausesLoop
			};

			EConnectable Connectable = EConnectable::No;

			EReason Reason = EReason::None;


			// If Connectable is EConnectable::YesWithConverterNode,
			// this will be a populated list of nodes we can use 
			// to convert between the input and output.
			TArray<FConverterNodeInfo> PossibleConverterNodeClasses;
		};
	} // namespace Frontend
} // namespace Metasound