#pragma once

#include "cplt_fwd.hpp"

#include <bit>
#include <cstddef>
#include <cstdint>
#include <fstream>
#include <span>

class SerializationStreamProxy
{
public:
	static constexpr bool IsSerializer()
	{
		return true;
	}

public:
	DataStream* Stream;

	template <class T>
	void Bytes(size_t byteCount, T* buffer) const;

	template <class T>
	void Value(T t) const;

	template <class T>
	void Object(T& obj) const;

	template <class TObject, class TAdapter>
	void ObjectAdapted(TObject& obj, TAdapter&& adapter) const;
};

class DeserializationStreamProxy
{
public:
	static constexpr bool IsSerializer()
	{
		return false;
	}

public:
	DataStream* Stream;

	template <class T>
	void Bytes(size_t byteCount, T* buffer) const;

	template <class T>
	void Value(T& t) const;

	template <class T>
	void Object(T& obj) const;

	template <class TObject, class TAdapter>
	void ObjectAdapted(TObject& obj, TAdapter&& adapter) const;
};

class DataStream
{
private:
	// TODO customizable storage lik QIODevice
	// TODO move read/write into separate classes, removing need of IOAdapters?
	std::fstream mBackend;
	std::endian mEndian;

public:
	DataStream(std::fstream stream);
	~DataStream();

	std::endian GetEndianness() const;
	void SetEndianness(std::endian endianness);

	void WriteBytes(size_t byteCount, const std::byte* buffer);
	void WriteBytes(size_t byteCount, const char* buffer);
	void WriteBytes(size_t byteCount, const signed char* buffer);
	void WriteBytes(size_t byteCount, const unsigned char* buffer);

	template <class TIterator>
	void WriteBytes(TIterator&& begin, TIterator&& end)
	{
		for (; begin != end; ++begin) {
			uint8_t byte = *begin;
			Write(byte);
		}
	}

	void ReadBytes(size_t byteCount, std::byte* buffer);
	void ReadBytes(size_t byteCount, char* buffer);
	void ReadBytes(size_t byteCount, signed char* buffer);
	void ReadBytes(size_t byteCount, unsigned char* buffer);

	template <class TInserter>
	void ReadBytes(size_t byteCount, TInserter&& inserter)
	{
		for (size_t i = 0; i < byteCount; ++i) {
			uint8_t byte;
			Read(byte);

			inserter = byte;
		}
	}

	void Write(int8_t n);
	void Write(int16_t n);
	void Write(int32_t n);
	void Write(int64_t n);

	void Read(int8_t& n);
	void Read(int16_t& n);
	void Read(int32_t& n);
	void Read(int64_t& n);

	void Write(uint8_t n);
	void Write(uint16_t n);
	void Write(uint32_t n);
	void Write(uint64_t n);

	void Read(uint8_t& n);
	void Read(uint16_t& n);
	void Read(uint32_t& n);
	void Read(uint64_t& n);

	void Write(float n);
	void Write(double n);

	void Read(float& n);
	void Read(double& n);

	template <class TObject>
	void WriteObject(TObject& obj)
	{
		if constexpr (requires(TObject t) { t.WriteToDataStream(std::declval<DataStream>()); }) {
			obj.WriteToDataStream(*this);
		} else if constexpr (requires(TObject t) { t.OperateIOProxy(std::declval<SerializationStreamProxy>()); }) {
			SerializationStreamProxy adapter{ this };
			obj.OperateIOProxy(adapter);
		} else {
			static_assert(false && sizeof(TObject), "This type does not have integration with DataStream.");
		}
	}

	template <class TObject, class TAdapter>
	void WriteObjectAdapted(TObject& obj, TAdapter&& adapter)
	{
		adapter.WriteToDataStream(*this, obj);
	}

	template <class TObject>
	void ReadObject(TObject& obj)
	{
		if constexpr (requires(TObject t) { t.ReadFromDataStream(std::declval<DataStream>()); }) {
			obj.ReadFromDataStream(*this);
		} else if constexpr (requires(TObject t) { t.OperateIOProxy(std::declval<DeserializationStreamProxy>()); }) {
			DeserializationStreamProxy adapter{ this };
			obj.OperateIOProxy(adapter);
		} else {
			static_assert(false && sizeof(TObject), "This type does not have integration with DataStream.");
		}
	}

	template <class TObject, class TAdapter>
	void ReadObjectAdapted(TObject& obj, TAdapter&& adapter)
	{
		adapter.ReadFromDataStream(*this, obj);
	}
};

template <class T>
void SerializationStreamProxy::Bytes(size_t byteCount, T* buffer) const
{
	Stream->WriteBytes(byteCount, buffer);
}

template <class T>
void SerializationStreamProxy::Value(T t) const
{
	Stream->Write(t);
}

template <class T>
void SerializationStreamProxy::Object(T& obj) const
{
	Stream->WriteObject(obj);
}

template <class TObject, class TAdapter>
void SerializationStreamProxy::ObjectAdapted(TObject& obj, TAdapter&& adapter) const
{
	Stream->WriteObjectAdapted(obj, adapter);
}

template <class T>
void DeserializationStreamProxy::Bytes(size_t byteCount, T* buffer) const
{
	Stream->WriteBytes(byteCount, buffer);
}

template <class T>
void DeserializationStreamProxy::Value(T& t) const
{
	Stream->Read(t);
}

template <class T>
void DeserializationStreamProxy::Object(T& obj) const
{
	Stream->ReadObject(obj);
}

template <class TObject, class TAdapter>
void DeserializationStreamProxy::ObjectAdapted(TObject& obj, TAdapter&& adapter) const
{
	Stream->ReadObjectAdapted(obj, adapter);
}