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

#include "asiohttpserver.h"

#include <zencore/base64.h>
#include <zencore/compactbinarybuilder.h>
#include <zencore/compactbinaryvalidation.h>
#include <zencore/enumflags.h>
#include <zencore/intmath.h>
#include <zencore/iobuffer.h>
#include <zencore/logging.h>
#include <zencore/memory.h>
#include <zencore/sha1.h>
#include <zencore/stream.h>
#include <zencore/string.h>
#include <zencore/trace.h>

#include <zenhttp/httpserver.h>

#include <chrono>
#include <optional>
#include <shared_mutex>
#include <span>
#include <system_error>
#include <thread>

ZEN_THIRD_PARTY_INCLUDES_START
#include <fmt/format.h>
#include <http_parser.h>
#include <asio.hpp>
ZEN_THIRD_PARTY_INCLUDES_END

#if ZEN_PLATFORM_WINDOWS
#	include <mstcpip.h>
#endif

namespace zen::asio_http {

using namespace std::literals;

ZEN_DEFINE_LOG_CATEGORY_STATIC(LogHttp, "http"sv);

using Clock		= std::chrono::steady_clock;
using TimePoint = Clock::time_point;

///////////////////////////////////////////////////////////////////////////////
namespace http_header {
	static constexpr std::string_view SecWebSocketKey	   = "Sec-WebSocket-Key"sv;
	static constexpr std::string_view SecWebSocketOrigin   = "Sec-WebSocket-Origin"sv;
	static constexpr std::string_view SecWebSocketProtocol = "Sec-WebSocket-Protocol"sv;
	static constexpr std::string_view SecWebSocketVersion  = "Sec-WebSocket-Version"sv;
	static constexpr std::string_view SecWebSocketAccept   = "Sec-WebSocket-Accept"sv;
	static constexpr std::string_view Upgrade			   = "Upgrade"sv;
}  // namespace http_header

///////////////////////////////////////////////////////////////////////////////
class HttpConnectionId
{
	static std::atomic_uint32_t NextId;

public:
	HttpConnectionId() = default;

	uint32_t Value() const { return m_Value; }

	auto operator<=>(const HttpConnectionId&) const = default;

	static HttpConnectionId New() { return HttpConnectionId(NextId.fetch_add(1)); }

private:
	HttpConnectionId(uint32_t Value) : m_Value(Value) {}

	uint32_t m_Value{};
};

std::atomic_uint32_t HttpConnectionId::NextId{1};

///////////////////////////////////////////////////////////////////////////////
enum class ParseMessageStatus : uint32_t
{
	kError,
	kContinue,
	kDone,
};

struct ParseMessageResult
{
	ParseMessageStatus		   Status{};
	size_t					   ByteCount{};
	std::optional<std::string> Reason;
};

class MessageParser
{
public:
	virtual ~MessageParser() = default;

	ParseMessageResult ParseMessage(MemoryView Msg);
	void			   Reset();

protected:
	MessageParser() = default;

	virtual ParseMessageResult OnParseMessage(MemoryView Msg) = 0;
	virtual void			   OnReset()					  = 0;

	BinaryWriter m_Stream;
};

ParseMessageResult
MessageParser::ParseMessage(MemoryView Msg)
{
	return OnParseMessage(Msg);
}

void
MessageParser::Reset()
{
	OnReset();

	m_Stream.Reset();
}

///////////////////////////////////////////////////////////////////////////////
class HttpHeaderData
{
public:
	struct Entry
	{
		uint32_t Offset{0};
		uint32_t Size{0};
	};

	struct HeaderEntry
	{
		Entry Name{};
		Entry Value{};
	};

	static constexpr size_t kMaxHeaderSize		  = 2048;
	static constexpr size_t kMaxHeaderCount		  = 16;
	static constexpr size_t kHeaderIndexSize	  = kMaxHeaderCount * sizeof(HeaderEntry);
	static constexpr size_t kMaxHeaderContentSize = kMaxHeaderSize - kHeaderIndexSize;

	HttpHeaderData() { Reset(); }

	std::string_view StatusLine() const
	{
		const Entry* StatusEntry = reinterpret_cast<const Entry*>(m_Buffer);
		const char*	 Buffer		 = reinterpret_cast<const char*>(m_Buffer) + StatusEntry->Offset;

		return std::string_view(Buffer, size_t(StatusEntry->Size));
	}

	std::string_view Url() const
	{
		const Entry* UrlEntry = reinterpret_cast<const Entry*>(m_Buffer + sizeof(Entry));
		const char*	 Buffer	  = reinterpret_cast<const char*>(m_Buffer) + UrlEntry->Offset;

		return std::string_view(Buffer, size_t(UrlEntry->Size));
	}

	void Reset()
	{
		memset(m_Buffer, 0, kMaxHeaderSize);

		m_CursorView  = MutableMemoryView(&m_Buffer[kHeaderIndexSize], kMaxHeaderContentSize);
		m_HeaderCount = 0;
	}

	void AppendData(MemoryView Data)
	{
		m_CursorView.CopyFrom(Data);
		m_CursorView += Data.GetSize();
	}

	void AppendStatus(Entry StatusEntry)
	{
		MutableMemoryView BufferView(&m_Buffer, sizeof(Entry));
		BufferView.CopyFrom(MemoryView(&StatusEntry, sizeof(Entry)));
	}

	void AppendUrl(Entry StatusEntry)
	{
		MutableMemoryView BufferView(&m_Buffer + sizeof(Entry), sizeof(Entry));
		BufferView.CopyFrom(MemoryView(&StatusEntry, sizeof(Entry)));
	}

	void AppendHeader(HeaderEntry Header)
	{
		MutableMemoryView HeaderView(&m_Buffer + ((m_HeaderCount + 1) * sizeof(HeaderEntry)), sizeof(HeaderEntry));
		HeaderView.CopyFrom(MemoryView(&Header, sizeof(HeaderEntry)));

		m_HeaderCount++;
	}

private:
	uint8_t			  m_Buffer[kMaxHeaderSize];
	MutableMemoryView m_CursorView;
	size_t			  m_HeaderCount{0};
};

///////////////////////////////////////////////////////////////////////////////
class HttpRequestMessage final : public HttpServerRequest
{
public:
	HttpRequestMessage() = default;

	virtual void WriteResponse(HttpResponseCode ResponseCode, HttpContentType ContentType, std::span<IoBuffer> Blobs) override;
	virtual void WriteResponse(HttpResponseCode ResponseCode) override;
	virtual void WriteResponse(HttpResponseCode ResponseCode, HttpContentType ContentType, std::u8string_view ResponseString) override;
	virtual void WriteResponse(HttpResponseCode ResponseCode, HttpContentType ContentType, CompositeBuffer& Payload) override;

private:
	virtual Oid		 ParseSessionId() const;
	virtual uint32_t ParseRequestId() const;
};

void
HttpRequestMessage::WriteResponse(HttpResponseCode ResponseCode, HttpContentType ContentType, std::span<IoBuffer> Blobs)
{
	ZEN_UNUSED(ResponseCode, ContentType, Blobs);
}

void
HttpRequestMessage::WriteResponse(HttpResponseCode ResponseCode)
{
	ZEN_UNUSED(ResponseCode);
}

void
HttpRequestMessage::WriteResponse(HttpResponseCode ResponseCode, HttpContentType ContentType, std::u8string_view ResponseString)
{
	ZEN_UNUSED(ResponseCode, ContentType, ResponseString);
}

void
HttpRequestMessage::WriteResponse(HttpResponseCode ResponseCode, HttpContentType ContentType, CompositeBuffer& Payload)
{
	ZEN_UNUSED(ResponseCode, ContentType, Payload);
}

Oid
HttpRequestMessage::ParseSessionId() const
{
	return Oid::NewOid();
}

uint32_t
HttpRequestMessage::ParseRequestId() const
{
	return 0u;
}

///////////////////////////////////////////////////////////////////////////////
enum class HttpMessageParserType
{
	kRequest,
	kResponse,
	kBoth
};

class HttpMessageParser final : public MessageParser
{
public:
	using HttpHeaders = std::unordered_map<std::string_view, std::string_view>;

	HttpMessageParser(HttpMessageParserType Type) : MessageParser(), m_Type(Type) { Initialize(); }

	virtual ~HttpMessageParser() = default;

	int32_t		 StatusCode() const { return m_Parser.status_code; }
	bool		 IsUpgrade() const { return m_Parser.upgrade != 0; }
	HttpHeaders& Headers() { return m_Headers; }
	MemoryView	 Body() const { return MemoryView(m_Stream.Data() + m_BodyEntry.Offset, m_BodyEntry.Size); }

	std::string_view StatusText() const
	{
		return std::string_view(reinterpret_cast<const char*>(m_Stream.Data() + m_StatusEntry.Offset), m_StatusEntry.Size);
	}

	bool ValidateWebSocketHandshake(std::string& OutAcceptHash, std::string& OutReason);

private:
	void					   Initialize();
	virtual ParseMessageResult OnParseMessage(MemoryView Msg) override;
	virtual void			   OnReset() override;
	int						   OnMessageBegin();
	int						   OnUrl(MemoryView Url);
	int						   OnStatus(MemoryView Status);
	int						   OnHeaderField(MemoryView HeaderField);
	int						   OnHeaderValue(MemoryView HeaderValue);
	int						   OnHeadersComplete();
	int						   OnBody(MemoryView Body);
	int						   OnMessageComplete();

	struct StreamEntry
	{
		uint64_t Offset{};
		uint64_t Size{};
	};

	struct HeaderStreamEntry
	{
		StreamEntry Field{};
		StreamEntry Value{};
	};

	HttpMessageParserType		   m_Type;
	http_parser					   m_Parser;
	StreamEntry					   m_UrlEntry;
	StreamEntry					   m_StatusEntry;
	StreamEntry					   m_BodyEntry;
	HeaderStreamEntry			   m_CurrentHeader;
	std::vector<HeaderStreamEntry> m_HeaderEntries;
	HttpHeaders					   m_Headers;
	bool						   m_IsMsgComplete{false};

	static http_parser_settings ParserSettings;
};

http_parser_settings HttpMessageParser::ParserSettings = {
	.on_message_begin = [](http_parser* P) { return reinterpret_cast<HttpMessageParser*>(P->data)->OnMessageBegin(); },

	.on_url = [](http_parser* P,
				 const char*  Data,
				 size_t		  Size) { return reinterpret_cast<HttpMessageParser*>(P->data)->OnUrl(MemoryView(Data, Size)); },

	.on_status = [](http_parser* P,
					const char*	 Data,
					size_t		 Size) { return reinterpret_cast<HttpMessageParser*>(P->data)->OnStatus(MemoryView(Data, Size)); },

	.on_header_field = [](http_parser* P,
						  const char*  Data,
						  size_t Size) { return reinterpret_cast<HttpMessageParser*>(P->data)->OnHeaderField(MemoryView(Data, Size)); },

	.on_header_value = [](http_parser* P,
						  const char*  Data,
						  size_t Size) { return reinterpret_cast<HttpMessageParser*>(P->data)->OnHeaderValue(MemoryView(Data, Size)); },

	.on_headers_complete = [](http_parser* P) { return reinterpret_cast<HttpMessageParser*>(P->data)->OnHeadersComplete(); },

	.on_body = [](http_parser* P,
				  const char*  Data,
				  size_t	   Size) { return reinterpret_cast<HttpMessageParser*>(P->data)->OnBody(MemoryView(Data, Size)); },

	.on_message_complete = [](http_parser* P) { return reinterpret_cast<HttpMessageParser*>(P->data)->OnMessageComplete(); }};

void
HttpMessageParser::Initialize()
{
	http_parser_init(&m_Parser,
					 m_Type == HttpMessageParserType::kRequest	  ? HTTP_REQUEST
					 : m_Type == HttpMessageParserType::kResponse ? HTTP_RESPONSE
																  : HTTP_BOTH);
	m_Parser.data = this;

	m_UrlEntry		= {};
	m_StatusEntry	= {};
	m_CurrentHeader = {};
	m_BodyEntry		= {};

	m_IsMsgComplete = false;

	m_HeaderEntries.clear();
}

ParseMessageResult
HttpMessageParser::OnParseMessage(MemoryView Msg)
{
	const size_t ByteCount = http_parser_execute(&m_Parser, &ParserSettings, reinterpret_cast<const char*>(Msg.GetData()), Msg.GetSize());

	auto Status = m_IsMsgComplete ? ParseMessageStatus::kDone : ParseMessageStatus::kContinue;

	if (m_Parser.http_errno != 0)
	{
		Status = ParseMessageStatus::kError;
	}

	return {.Status = Status, .ByteCount = uint64_t(ByteCount)};
}

void
HttpMessageParser::OnReset()
{
	Initialize();
}

int
HttpMessageParser::OnMessageBegin()
{
	ZEN_ASSERT(m_IsMsgComplete == false);
	ZEN_ASSERT(m_HeaderEntries.empty());
	ZEN_ASSERT(m_Headers.empty());

	return 0;
}

int
HttpMessageParser::OnStatus(MemoryView Status)
{
	m_StatusEntry = {m_Stream.CurrentOffset(), Status.GetSize()};

	m_Stream.Write(Status);

	return 0;
}

int
HttpMessageParser::OnUrl(MemoryView Url)
{
	m_UrlEntry = {m_Stream.CurrentOffset(), Url.GetSize()};

	m_Stream.Write(Url);

	return 0;
}

int
HttpMessageParser::OnHeaderField(MemoryView HeaderField)
{
	if (m_CurrentHeader.Value.Size > 0)
	{
		m_HeaderEntries.push_back(m_CurrentHeader);
		m_CurrentHeader = {};
	}

	if (m_CurrentHeader.Field.Size == 0)
	{
		m_CurrentHeader.Field.Offset = m_Stream.CurrentOffset();
	}

	m_CurrentHeader.Field.Size += HeaderField.GetSize();

	m_Stream.Write(HeaderField);

	return 0;
}

int
HttpMessageParser::OnHeaderValue(MemoryView HeaderValue)
{
	if (m_CurrentHeader.Value.Size == 0)
	{
		m_CurrentHeader.Value.Offset = m_Stream.CurrentOffset();
	}

	m_CurrentHeader.Value.Size += HeaderValue.GetSize();

	m_Stream.Write(HeaderValue);

	return 0;
}

int
HttpMessageParser::OnHeadersComplete()
{
	if (m_CurrentHeader.Value.Size > 0)
	{
		m_HeaderEntries.push_back(m_CurrentHeader);
		m_CurrentHeader = {};
	}

	m_Headers.clear();
	m_Headers.reserve(m_HeaderEntries.size());

	const char* StreamData = reinterpret_cast<const char*>(m_Stream.Data());

	for (const auto& Entry : m_HeaderEntries)
	{
		auto Field = std::string_view(StreamData + Entry.Field.Offset, Entry.Field.Size);
		auto Value = std::string_view(StreamData + Entry.Value.Offset, Entry.Value.Size);

		m_Headers.try_emplace(std::move(Field), std::move(Value));
	}

	return 0;
}

int
HttpMessageParser::OnBody(MemoryView Body)
{
	m_BodyEntry = {m_Stream.CurrentOffset(), Body.GetSize()};

	m_Stream.Write(Body);

	return 0;
}

int
HttpMessageParser::OnMessageComplete()
{
	m_IsMsgComplete = true;

	return 0;
}

bool
HttpMessageParser::ValidateWebSocketHandshake(std::string& OutAcceptHash, std::string& OutReason)
{
	static constexpr std::string_view WebSocketGuid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"sv;

	OutAcceptHash = std::string();

	if (m_Headers.contains(http_header::SecWebSocketKey) == false)
	{
		OutReason = "Missing header Sec-WebSocket-Key";
		return false;
	}

	if (m_Headers.contains(http_header::Upgrade) == false)
	{
		OutReason = "Missing header Upgrade";
		return false;
	}

	ExtendableStringBuilder<128> Sb;
	Sb << m_Headers[http_header::SecWebSocketKey] << WebSocketGuid;

	SHA1Stream HashStream;
	HashStream.Append(Sb.Data(), Sb.Size());

	SHA1 Hash = HashStream.GetHash();

	OutAcceptHash.resize(Base64::GetEncodedDataSize(sizeof(SHA1::Hash)));
	Base64::Encode(Hash.Hash, sizeof(SHA1::Hash), OutAcceptHash.data());

	return true;
}
///////////////////////////////////////////////////////////////////////////////
enum class ConnectionFlags : uint32_t
{
	kNone	   = 0,
	kHttp	   = 1 << 0,
	kWebSocket = 1 << 1,
	kConnected = 1 << 2
};

ENUM_CLASS_FLAGS(ConnectionFlags);

struct HttpConnection : public std::enable_shared_from_this<HttpConnection>
{
	HttpConnection(HttpConnectionId ConnId, asio::ip::tcp::socket&& S)
	: Id(ConnId)
	, Socket(std::move(S))
	, StartTime(Clock::now())
	, FlagsValue(uint32_t(ConnectionFlags::kHttp | ConnectionFlags::kConnected))
	, Parser(new HttpMessageParser(HttpMessageParserType::kRequest))
	{
	}

	std::shared_ptr<HttpConnection> AsShared() { return shared_from_this(); }
	std::string						RemoteAddr() const { return Socket.remote_endpoint().address().to_string(); }
	ConnectionFlags					Flags() const { return static_cast<ConnectionFlags>(FlagsValue.load(std::memory_order_relaxed)); }

	HttpConnectionId			   Id;
	std::atomic<uint32_t>		   FlagsValue;
	asio::ip::tcp::socket		   Socket;
	TimePoint					   StartTime;
	std::unique_ptr<MessageParser> Parser;
	asio::streambuf				   ReadBuffer;
	std::mutex					   WriteMutex;
};

///////////////////////////////////////////////////////////////////////////////
class AsioThreadPool
{
public:
	AsioThreadPool(asio::io_context& IoCtx) : m_IoCtx(IoCtx) {}
	void Start(uint32_t ThreadCount);
	void Stop();

private:
	asio::io_context&		 m_IoCtx;
	std::vector<std::thread> m_Threads;
	std::atomic_bool		 m_Running{false};
};

void
AsioThreadPool::Start(uint32_t ThreadCount)
{
	ZEN_ASSERT(m_Threads.empty());

	ZEN_LOG_DEBUG(LogHttp, "starting '{}' HTTP I/O thread(s)", ThreadCount);

	m_Running = true;

	for (uint32_t Idx = 0; Idx < ThreadCount; Idx++)
	{
		m_Threads.emplace_back([this, ThreadId = Idx + 1] {
			for (;;)
			{
				if (m_Running == false)
				{
					break;
				}

				try
				{
					m_IoCtx.run();
				}
				catch (std::exception& Err)
				{
					ZEN_LOG_ERROR(LogHttp, "process HTTP I/O FAILED, reason '{}'", Err.what());
				}
			}
		});
	}
}

void
AsioThreadPool::Stop()
{
	if (m_Running)
	{
		m_Running = false;

		for (std::thread& Thread : m_Threads)
		{
			if (Thread.joinable())
			{
				Thread.join();
			}
		}

		m_Threads.clear();
	}
}

///////////////////////////////////////////////////////////////////////////////
class AsioHttpServer final : public HttpServer
{
public:
	AsioHttpServer(const zen::AsioHttpServerOptions& Options);

	virtual void RegisterService(HttpService& Service) override;
	virtual int	 Initialize(int Port) override;
	virtual void Run(bool IsInteractiveSession) override;
	virtual void RequestExit() override;

private:
	void AcceptConnection();
	void CloseConnection(std::shared_ptr<HttpConnection>& Connection, const asio::error_code& Ec);
	void ReadMessage(std::shared_ptr<HttpConnection>& Connection);

	struct IdHasher
	{
		size_t operator()(HttpConnectionId Id) const { return size_t(Id.Value()); }
	};

	using ConnectionMap = std::unordered_map<HttpConnectionId, std::shared_ptr<HttpConnection>, IdHasher>;

	zen::AsioHttpServerOptions				 m_Options;
	asio::io_service						 m_IoCtx;
	std::unique_ptr<AsioThreadPool>			 m_ThreadPool;
	std::unique_ptr<asio::ip::tcp::acceptor> m_Acceptor;
	std::optional<asio::ip::tcp::socket>	 m_ListeningSocket;
	std::mutex								 m_ShutdownMutex;
	std::condition_variable					 m_ShutdownSignal;
	std::vector<HttpService*>				 m_Services;
	ConnectionMap							 m_Connections;
	std::shared_mutex						 m_ConnMutex;
	std::atomic_bool						 m_Running{false};
};

AsioHttpServer::AsioHttpServer(const AsioHttpServerOptions& Options) : m_Options(Options)
{
}

void
AsioHttpServer::RegisterService(HttpService& Service)
{
	m_Services.push_back(&Service);
}

int
AsioHttpServer::Initialize(int Port)
{
	m_Acceptor = std::make_unique<asio::ip::tcp::acceptor>(m_IoCtx, asio::ip::tcp::v6());

	m_Acceptor->set_option(asio::ip::v6_only(false));
	m_Acceptor->set_option(asio::socket_base::reuse_address(true));
	m_Acceptor->set_option(asio::ip::tcp::no_delay(true));
	m_Acceptor->set_option(asio::socket_base::receive_buffer_size(m_Options.ReceiveBufferSize));
	m_Acceptor->set_option(asio::socket_base::send_buffer_size(m_Options.SendBufferSize));

#if ZEN_PLATFORM_WINDOWS
	// On Windows, loopback connections can take advantage of a faster code path optionally with this flag.
	// This must be used by both the client and server side, and is only effective in the absence of
	// Windows Filtering Platform (WFP) callouts which can be installed by security software.
	// https://docs.microsoft.com/en-us/windows/win32/winsock/sio-loopback-fast-path
	SOCKET NativeSocket				   = m_Acceptor->native_handle();
	int	   LoopbackOptionValue		   = 1;
	DWORD  OptionNumberOfBytesReturned = 0;
	WSAIoctl(NativeSocket,
			 SIO_LOOPBACK_FAST_PATH,
			 &LoopbackOptionValue,
			 sizeof(LoopbackOptionValue),
			 NULL,
			 0,
			 &OptionNumberOfBytesReturned,
			 0,
			 0);
#endif

	asio::error_code Ec;
	m_Acceptor->bind(asio::ip::tcp::endpoint(asio::ip::address_v6::any(), asio::ip::port_type(Port)), Ec);

	if (Ec)
	{
		ZEN_LOG_ERROR(LogHttp, "bind endpoint FAILED, reason '{}'", Ec.message());

		return -1;
	}

	m_Acceptor->listen();
	m_Running = true;

	ZEN_LOG_INFO(LogHttp, "web socket server running on port '{}'", Port);

	AcceptConnection();

	m_ThreadPool = std::make_unique<AsioThreadPool>(m_IoCtx);
	m_ThreadPool->Start(m_Options.ThreadCount);

	return 0;
}

void
AsioHttpServer::Run(bool IsInteractiveSession)
{
	if (IsInteractiveSession)
	{
		zen::logging::ConsoleLog().info("Zen Server running (asio HTTP). Ctrl-C to quit");
	}

	for (;;)
	{
		if (IsApplicationExitRequested())
		{
			break;
		}

		std::unique_lock Lock(m_ShutdownMutex);
		m_ShutdownSignal.wait_for(Lock, std::chrono::seconds(2));
	}
}

void
AsioHttpServer::RequestExit()
{
	m_ShutdownSignal.notify_one();
}

void
AsioHttpServer::AcceptConnection()
{
	m_ListeningSocket.emplace(m_IoCtx);

	m_Acceptor->async_accept(m_ListeningSocket.value(), [this](const asio::error_code& Ec) mutable {
		if (m_Running)
		{
			if (Ec)
			{
				ZEN_LOG_WARN(LogHttp, "accept connection FAILED, reason '{}'", Ec.message());
			}
			else
			{
				auto Connection = std::make_shared<HttpConnection>(HttpConnectionId::New(), std::move(m_ListeningSocket.value()));

				ZEN_LOG_TRACE(LogHttp, "accept connection '#{} {}' OK", Connection->Id.Value(), Connection->RemoteAddr());

				{
					std::unique_lock _(m_ConnMutex);
					m_Connections[Connection->Id] = Connection;
				}

				ReadMessage(Connection);
			}

			AcceptConnection();
		}
	});
}

void
AsioHttpServer::CloseConnection(std::shared_ptr<HttpConnection>& Connection, const asio::error_code& Ec)
{
	if (Ec)
	{
		ZEN_LOG_INFO(LogHttp, "connection '{}' closed, reason '{} ({})'", Connection->Id.Value(), Ec.message(), Ec.value());
	}
	else
	{
		ZEN_LOG_INFO(LogHttp, "connection '{}' closed", Connection->Id.Value());
	}

	const HttpConnectionId Id = Connection->Id;

	{
		std::unique_lock _(m_ConnMutex);
		m_Connections.erase(Id);
	}
}

void
AsioHttpServer::ReadMessage(std::shared_ptr<HttpConnection>& Connection)
{
	Connection->ReadBuffer.prepare(m_Options.ReceiveBufferSize);

	asio::async_read(Connection->Socket,
					 Connection->ReadBuffer,
					 asio::transfer_at_least(1),
					 [this, Connection](const asio::error_code& Ec, std::size_t) mutable {
						 if (Ec)
						 {
							 return CloseConnection(Connection, Ec);
						 }

						 const ConnectionFlags Flags  = Connection->Flags();
						 HttpMessageParser&	   Parser = *reinterpret_cast<HttpMessageParser*>(Connection->Parser.get());

						 uint64_t RemainingBytes = Connection->ReadBuffer.size();

						 while (RemainingBytes > 0)
						 {
							 MemoryView				  MessageData = MemoryView(Connection->ReadBuffer.data().data(), RemainingBytes);
							 const ParseMessageResult Result	  = Parser.ParseMessage(MessageData);

							 Connection->ReadBuffer.consume(Result.ByteCount);
							 RemainingBytes = Connection->ReadBuffer.size();

							 if (Result.Status == ParseMessageStatus::kError)
							 {
								 ZEN_LOG_WARN(LogHttp, "parse websocket message FAILED, reason '{}'", Result.Reason.value());

								 return CloseConnection(Connection, std::error_code());
							 }

							 if (Result.Status == ParseMessageStatus::kContinue)
							 {
								 ZEN_ASSERT(RemainingBytes == 0);
								 continue;
							 }
						 }

						 ReadMessage(Connection);

						 // ParseMessageResult Result = Parser.ParseMessage(MemoryView(Buffer.data(), Buffer.size()));

						 // Connection->ReadBuffer.consume(Result.ByteCount);

						 // if (Result.Status == ParseMessageStatus::kContinue)
						 //{
						 //    return ReadMessage(Connection);
						 //}

						 // if (Result.Status == ParseMessageStatus::kError)
						 //{
						 //    const std::string Reason = Result.Reason.has_value() ? std::move(Result.Reason.value()) : "HTTP parse error";
						 //    ZEN_LOG_WARN(LogHttp, "parse message FAILED, connection #{}, reason '{}'", Connection->Id.Value(), Reason);

						 //    return CloseConnection(Connection, std::error_code());
						 //}
					 });
}

}  // namespace zen::asio_http

namespace zen {

Ref<HttpServer>
CreateAsioHttpServer(const AsioHttpServerOptions& Options)
{
	return new zen::asio_http::AsioHttpServer(Options);
}

}  // namespace zen