UnrealEngineUWP/Engine/Plugins/Web/WebAPI/Source/WebAPIEditor/Public/WebAPIJsonUtilities.inl

// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "WebAPIJsonUtilities.h"

namespace UE::Json
{
	// Numeric
	template <typename ValueType>
	constexpr typename TEnableIf<TypeTraits::TIsNumeric<ValueType>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, ValueType& OutValue)
	{
		return InJsonValue->TryGetNumber(OutValue);
	}

	template <typename ValueType>
	constexpr typename TEnableIf<TypeTraits::TIsNumeric<ValueType>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, ValueType& OutValue)
	{
		return InJsonObject->TryGetNumberField(InFieldName, OutValue);
	}

	// Enum
	template <typename EnumType>
	typename TEnableIf<TIsEnumClass<EnumType>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, EnumType& OutValue, const TMap<FString, EnumType>& InNameToValue)
	{
		// Try int first
		uint8 IntValue;
		bool bResult = InJsonValue->TryGetNumber(IntValue);
		if(bResult)
		{
			OutValue = StaticCast<EnumType>(IntValue);	
		}
		else
		{
			if(InNameToValue.IsEmpty())
			{
				UE_LOG(LogWebAPIEditor, Error, TEXT("Tried to convert enum from string, but no lookup was provided."));
				return bResult;  
			}

			FString StrValue;
			bResult = InJsonValue->TryGetString(StrValue);
			if(bResult)
			{
				if(const EnumType* NameToValue = InNameToValue.Find(StrValue))
				{
					OutValue = *NameToValue;
				}
			}
		}			
		return bResult;
	}

	template <typename EnumType>
	constexpr typename TEnableIf<TIsEnumClass<EnumType>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, EnumType& OutValue, const TMap<FString, EnumType>& InNameToValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet(JsonField, OutValue.Get(), InNameToValue);
		}
		return false;
	}

	// String
	template <typename ValueType>
	constexpr typename TEnableIf<TypeTraits::TIsStringLike<ValueType>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, ValueType& OutValue)
	{
		return InJsonValue->TryGetString(OutValue);
	}

	template <typename ValueType>
	constexpr typename TEnableIf<TypeTraits::TIsStringLike<ValueType>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, ValueType& OutValue)
	{
		return InJsonObject->TryGetStringField(InFieldName, OutValue);
	}

	// Bool
	template <typename ValueType>
	constexpr typename TEnableIf<TIsSame<ValueType, bool>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, ValueType& OutValue)
	{
		return InJsonValue->TryGetBool(OutValue);
	}

	template <typename ValueType>
	constexpr typename TEnableIf<TIsSame<ValueType, bool>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, ValueType& OutValue)
	{
		return InJsonObject->TryGetBoolField(InFieldName, OutValue);
	}

	// Array
	template <typename ContainerType>
	typename TEnableIf<TIsTArray<ContainerType>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, ContainerType& OutValues)
	{
		using ValueType = typename ContainerType::ElementType;
		const TArray<TSharedPtr<FJsonValue>>* Values = nullptr;
		if(InJsonValue->TryGetArray(Values))
		{
			bool bSuccess = true;
			if(Values->Num() > 0)
			{
				OutValues.Reserve(Values->Num());
				for(const TSharedPtr<FJsonValue>& JsonValue : *Values)
				{
					ValueType& Value = OutValues.Emplace_GetRef();
					bSuccess &= TryGet(JsonValue, Value);
				}
			}
			return bSuccess;
		}
		return false;
	}

	template <typename ContainerType>
	constexpr typename TEnableIf<TIsTArray<ContainerType>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, ContainerType& OutValues)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			using ValueType = typename ContainerType::ElementType;
			return TryGet<ContainerType>(JsonField, OutValues);
		}
		return false;
	}

	// Map
	template <typename KeyType, typename ValueType>
	typename TEnableIf<TypeTraits::TIsStringLike<KeyType>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, TMap<KeyType, ValueType>& OutValues)
	{
		const TSharedPtr<FJsonObject>* JsonObject = nullptr;
		if(InJsonValue->TryGetObject(JsonObject))
		{
			OutValues.Reserve(JsonObject->Get()->Values.Num());
			for(TPair<FString, TSharedPtr<FJsonValue, ESPMode::ThreadSafe>>& FieldValuePair : JsonObject->Get()->Values)
			{
				ValueType& ItemValue = OutValues.Emplace(MoveTemp(FieldValuePair.Key));
				TryGet(FieldValuePair.Value, ItemValue);
			}
			return true;
		}
		return false;
	}

	template <typename KeyType, typename ValueType>
	constexpr typename TEnableIf<TypeTraits::TIsStringLike<KeyType>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TMap<KeyType, ValueType>& OutValues)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet(JsonField, OutValues);
		}
		return false;
	}

	// Optional
	template <typename ValueType>
	constexpr typename TEnableIf<!TIsEnumClass<ValueType>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, TOptional<ValueType>& OutValue)
	{
		ValueType Value;
		if(TryGet<TDecay<ValueType>>(InJsonValue, Value))
		{
			OutValue = Value;
			return true;
		}
		return true;
	}

	template <typename ValueType>
	typename TEnableIf<!TIsEnumClass<ValueType>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TOptional<ValueType>& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			if(!OutValue.IsSet())
			{
				OutValue = ValueType{};
			}
				
			return TryGet(JsonField, OutValue.GetValue());
		}
		return true;
	}

	// Optional Enum
	template <typename EnumType>
	constexpr typename TEnableIf<TIsEnumClass<EnumType>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, TOptional<EnumType>& OutValue, const TMap<FString, EnumType>& InNameToValue)
	{
		EnumType Value;
		if(TryGet<TDecay<EnumType>>(InJsonValue, Value, InNameToValue))
		{
			OutValue = Value;
			return true;
		}
		return true;
	}

	template <typename EnumType>
	constexpr typename TEnableIf<TIsEnumClass<EnumType>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TOptional<EnumType>& OutValue, const TMap<FString, EnumType>& InNameToValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			if(!OutValue.IsSet())
			{
				OutValue = EnumType{};
			}
				
			return TryGet(JsonField, OutValue.GetValue(), InNameToValue);
		}
		return true;
	}

	// Object (with FromJson)
	template <typename ValueType>
	typename TEnableIf<
		TAnd<
			TNot<TypeTraits::TIsDerivedFromMap<ValueType>>,
			TypeTraits::THasFromJson<ValueType>>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, ValueType& OutValue)
	{
		const TSharedPtr<FJsonObject>* Value;
		if(InJsonValue->TryGetObject(Value))
		{
			return OutValue.FromJson(Value->ToSharedRef());
		}
		return false;
	}

	template <typename ValueType>
	typename TEnableIf<
		TAnd<
			TNot<TypeTraits::TIsDerivedFromMap<ValueType>>,
			TypeTraits::THasFromJson<ValueType>>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, ValueType& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet(JsonField, OutValue);
		}
		return false;
	}

	// Object (without FromJson)
	template <typename ValueType>
	typename TEnableIf<
		TAnd<
			TNot<TIsTArray<ValueType>>,
			TNot<TypeTraits::TIsStringLike<ValueType>>,
			TNot<TIsPODType<ValueType>>,
			TNot<TypeTraits::THasFromJson<ValueType>>>::Value, bool>::Type
	TryGet(const TSharedPtr<FJsonValue>& InJsonValue, ValueType& OutValue)
	{
		static_assert(TypeTraits::THasFromJson<ValueType>::Value, "ValueType must implement FromJson");
		return false;
	}

	// TIsTMap<ContainerType>,
	template <typename ValueType>
	typename TEnableIf<
		TAnd<
			TNot<TIsTArray<ValueType>>,
			TNot<TypeTraits::TIsStringLike<ValueType>>,
			TNot<TIsPODType<ValueType>>,
			TNot<TypeTraits::THasFromJson<ValueType>>>::Value, bool>::Type
	TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, ValueType& OutValue)
	{
		static_assert(TypeTraits::THasFromJson<ValueType>::Value, "ValueType must implement FromJson");
		return false;
	}

	// UniqueObj
	template <typename ValueType>
	bool TryGet(const TSharedPtr<FJsonValue>& InJsonValue, TUniqueObj<ValueType>& OutValue)
	{
		return Json::TryGet(InJsonValue, OutValue.Get());
	}

	template <typename ValueType>
	bool TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TUniqueObj<ValueType>& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet(JsonField, OutValue.Get());
		}
		return false;
	}

	// TJsonReference
	template <typename ValueType>
	bool TryGet(const TSharedPtr<FJsonValue>& InJsonValue, TJsonReference<ValueType>& OutValue)
	{
		const TSharedPtr<FJsonObject>* JsonObject = nullptr;
		if(InJsonValue->TryGetObject(JsonObject))
		{
			FString ReferencePath;
			if(JsonObject->Get()->TryGetStringField(TEXT("$ref"), ReferencePath))
			{
				OutValue.ResolveDeferred(ReferencePath);
				return true;
			}
		}
		return Json::TryGet(InJsonValue, *OutValue.Get());
	}

	template <typename ValueType>
	bool TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TJsonReference<ValueType>& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet(JsonField, OutValue);
		}
		return false;
	}

	// SharedPtr
	template <typename ValueType>
	bool TryGet(const TSharedPtr<FJsonValue>& InJsonValue,	TSharedPtr<ValueType>& OutValue)
	{
		// Initialize if invalid
		if(!OutValue.IsValid())
		{
			OutValue = MakeShared<ValueType>();
		}
			
		return Json::TryGet(InJsonValue, *OutValue.Get());
	}

	template <typename ValueType>
	bool TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TSharedPtr<ValueType>& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet<ValueType>(JsonField, OutValue);
		}
		return false;
	}

	// SharedRef
	template <typename ValueType>
	bool TryGet(const TSharedPtr<FJsonValue>& InJsonValue, TSharedRef<ValueType>& OutValue)
	{
		return Json::TryGet(InJsonValue, OutValue.Get());
	}

	template <typename ValueType>
	bool TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TSharedRef<ValueType>& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet(JsonField, OutValue);
		}
		return false;
	}

	// Optional UniqueObj
	template <typename ValueType>
	bool TryGet(const TSharedPtr<FJsonValue>& InJsonValue, TOptional<TUniqueObj<ValueType>>& OutValue)
	{
		if(OutValue.IsSet())
		{
			TUniqueObj<ValueType>& Value = OutValue.GetValue();
			if(TryGet(InJsonValue, OutValue.GetValue()))
			{
				OutValue = Value;
				return true;
			}
		}
		else
		{
			TUniqueObj<ValueType> Value;
			if(TryGet(InJsonValue, Value))
			{
				OutValue = Value;
				return true;
			}
		}	

		return true;
	}

	template <typename ValueType>
	bool TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TOptional<TUniqueObj<ValueType>>& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet(JsonField, OutValue);
		}
		return true;
	}

	// Optional SharedRef
	template <typename ValueType>
	bool TryGet(const TSharedPtr<FJsonValue>& InJsonValue,	TOptional<TSharedRef<ValueType>>& OutValue)
	{
		TSharedRef<ValueType> Value = MakeShared<ValueType>();
		if(TryGet(InJsonValue, Value))
		{
			OutValue = Value;
			return true;
		}
		return true;
	}

	template <typename ValueType>
	bool TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TOptional<TSharedRef<ValueType>>& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet(JsonField, OutValue);
		}
		return true;
	}

	// JsonObject
	template <typename ValueType, typename>
	bool TryGet(const TSharedPtr<FJsonValue>& InJsonValue, ValueType& OutValue)
	{
		const TSharedPtr<FJsonObject>* Value = nullptr;
		if(InJsonValue->TryGetObject(Value))
		{
			OutValue = *Value;
			return true;
		}
		return false;
	}

	template <typename ValueType, typename>
	bool TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TSharedPtr<FJsonObject>& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet<>(JsonField, OutValue);
		}
		return false;
	}

	// Variant
	template <typename ... ValueTypes>
	bool TryGet(const TSharedPtr<FJsonValue>& InJsonValue, TVariant<ValueTypes...>& OutValue)
	{
		FVariantValueVisitor Visitor(InJsonValue);

		// @todo: asked Stefan Boberg about this, only ever tests a single type
		return Visit(Visitor, OutValue);
	}

	template <typename ... ValueTypes>
	bool TryGetField(const TSharedPtr<FJsonObject>& InJsonObject, const FString& InFieldName, TVariant<ValueTypes...>& OutValue)
	{
		if(const TSharedPtr<FJsonValue> JsonField = InJsonObject->TryGetField(InFieldName))
		{
			return TryGet(JsonField, OutValue);
		}
		return false;
	}
}