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

#include "httpclientcurl.h"

#include <zencore/compactbinary.h>
#include <zencore/compactbinarybuilder.h>
#include <zencore/compactbinarypackage.h>
#include <zencore/compactbinaryutil.h>
#include <zencore/compress.h>
#include <zencore/except.h>
#include <zencore/filesystem.h>
#include <zencore/iobuffer.h>
#include <zencore/iohash.h>
#include <zencore/session.h>
#include <zencore/stream.h>
#include <zencore/string.h>
#include <zenhttp/packageformat.h>
#include <algorithm>

namespace zen {

HttpClientBase*
CreateCurlHttpClient(std::string_view BaseUri, const HttpClientSettings& ConnectionSettings, std::function<bool()>&& CheckIfAbortFunction)
{
	return new CurlHttpClient(BaseUri, ConnectionSettings, std::move(CheckIfAbortFunction));
}

static std::atomic<uint32_t> CurlHttpClientRequestIdCounter{0};

//////////////////////////////////////////////////////////////////////////

static HttpClientErrorCode
MapCurlError(CURLcode Code)
{
	switch (Code)
	{
		case CURLE_OK:
			return HttpClientErrorCode::kOK;
		case CURLE_COULDNT_CONNECT:
			return HttpClientErrorCode::kConnectionFailure;
		case CURLE_COULDNT_RESOLVE_HOST:
			return HttpClientErrorCode::kHostResolutionFailure;
		case CURLE_COULDNT_RESOLVE_PROXY:
			return HttpClientErrorCode::kProxyResolutionFailure;
		case CURLE_RECV_ERROR:
			return HttpClientErrorCode::kNetworkReceiveError;
		case CURLE_SEND_ERROR:
			return HttpClientErrorCode::kNetworkSendFailure;
		case CURLE_OPERATION_TIMEDOUT:
			return HttpClientErrorCode::kOperationTimedOut;
		case CURLE_SSL_CONNECT_ERROR:
			return HttpClientErrorCode::kSSLConnectError;
		case CURLE_SSL_CERTPROBLEM:
			return HttpClientErrorCode::kSSLCertificateError;
		case CURLE_PEER_FAILED_VERIFICATION:
			return HttpClientErrorCode::kSSLCACertError;
		case CURLE_SSL_CIPHER:
		case CURLE_SSL_ENGINE_NOTFOUND:
		case CURLE_SSL_ENGINE_SETFAILED:
			return HttpClientErrorCode::kGenericSSLError;
		case CURLE_ABORTED_BY_CALLBACK:
			return HttpClientErrorCode::kRequestCancelled;
		default:
			return HttpClientErrorCode::kOtherError;
	}
}

//////////////////////////////////////////////////////////////////////////
//
// Curl callback helpers

struct WriteCallbackData
{
	std::string*		   Body					= nullptr;
	std::function<bool()>* CheckIfAbortFunction = nullptr;
};

static size_t
CurlWriteCallback(char* Ptr, size_t Size, size_t Nmemb, void* UserData)
{
	auto*  Data		  = static_cast<WriteCallbackData*>(UserData);
	size_t TotalBytes = Size * Nmemb;

	if (Data->CheckIfAbortFunction && *Data->CheckIfAbortFunction && (*Data->CheckIfAbortFunction)())
	{
		return 0;  // Signal abort to curl
	}

	Data->Body->append(Ptr, TotalBytes);
	return TotalBytes;
}

struct HeaderCallbackData
{
	std::vector<std::pair<std::string, std::string>>* Headers = nullptr;
};

// Trims trailing CRLF, splits on the first colon, and trims whitespace from key and value.
// Returns nullopt for blank lines or lines without a colon (e.g. HTTP status lines).
static std::optional<std::pair<std::string_view, std::string_view>>
ParseHeaderLine(std::string_view Line)
{
	while (!Line.empty() && (Line.back() == '\r' || Line.back() == '\n'))
	{
		Line.remove_suffix(1);
	}

	if (Line.empty())
	{
		return std::nullopt;
	}

	size_t ColonPos = Line.find(':');
	if (ColonPos == std::string_view::npos)
	{
		return std::nullopt;
	}

	std::string_view Key   = Line.substr(0, ColonPos);
	std::string_view Value = Line.substr(ColonPos + 1);

	while (!Key.empty() && Key.back() == ' ')
	{
		Key.remove_suffix(1);
	}
	while (!Value.empty() && Value.front() == ' ')
	{
		Value.remove_prefix(1);
	}

	return std::pair{Key, Value};
}

static size_t
CurlHeaderCallback(char* Buffer, size_t Size, size_t Nmemb, void* UserData)
{
	auto*  Data		  = static_cast<HeaderCallbackData*>(UserData);
	size_t TotalBytes = Size * Nmemb;

	if (auto Header = ParseHeaderLine(std::string_view(Buffer, TotalBytes)))
	{
		auto& [Key, Value] = *Header;
		Data->Headers->emplace_back(std::string(Key), std::string(Value));
	}

	return TotalBytes;
}

struct ReadCallbackData
{
	const uint8_t*		   DataPtr				= nullptr;
	size_t				   DataSize				= 0;
	size_t				   Offset				= 0;
	std::function<bool()>* CheckIfAbortFunction = nullptr;
};

static size_t
CurlReadCallback(char* Buffer, size_t Size, size_t Nmemb, void* UserData)
{
	auto*  Data	   = static_cast<ReadCallbackData*>(UserData);
	size_t MaxRead = Size * Nmemb;

	if (Data->CheckIfAbortFunction && *Data->CheckIfAbortFunction && (*Data->CheckIfAbortFunction)())
	{
		return CURL_READFUNC_ABORT;
	}

	size_t Remaining = Data->DataSize - Data->Offset;
	size_t ToRead	 = std::min(MaxRead, Remaining);

	if (ToRead > 0)
	{
		memcpy(Buffer, Data->DataPtr + Data->Offset, ToRead);
		Data->Offset += ToRead;
	}

	return ToRead;
}

struct StreamReadCallbackData
{
	detail::CompositeBufferReadStream* Reader				= nullptr;
	std::function<bool()>*			   CheckIfAbortFunction = nullptr;
};

static size_t
CurlStreamReadCallback(char* Buffer, size_t Size, size_t Nmemb, void* UserData)
{
	auto*  Data	   = static_cast<StreamReadCallbackData*>(UserData);
	size_t MaxRead = Size * Nmemb;

	if (Data->CheckIfAbortFunction && *Data->CheckIfAbortFunction && (*Data->CheckIfAbortFunction)())
	{
		return CURL_READFUNC_ABORT;
	}

	return Data->Reader->Read(Buffer, MaxRead);
}

struct FileReadCallbackData
{
	detail::BufferedReadFileStream* Buffer				 = nullptr;
	uint64_t						TotalSize			 = 0;
	uint64_t						Offset				 = 0;
	std::function<bool()>*			CheckIfAbortFunction = nullptr;
};

static size_t
CurlFileReadCallback(char* Buffer, size_t Size, size_t Nmemb, void* UserData)
{
	auto*  Data	   = static_cast<FileReadCallbackData*>(UserData);
	size_t MaxRead = Size * Nmemb;

	if (Data->CheckIfAbortFunction && *Data->CheckIfAbortFunction && (*Data->CheckIfAbortFunction)())
	{
		return CURL_READFUNC_ABORT;
	}

	size_t Remaining = Data->TotalSize - Data->Offset;
	size_t ToRead	 = std::min(MaxRead, Remaining);

	if (ToRead > 0)
	{
		Data->Buffer->Read(Buffer, ToRead);
		Data->Offset += ToRead;
	}

	return ToRead;
}

static int
CurlDebugCallback(CURL* Handle, curl_infotype Type, char* Data, size_t Size, void* UserPtr)
{
	ZEN_UNUSED(Handle);
	LoggerRef LogRef = *static_cast<LoggerRef*>(UserPtr);
	auto	  Log	 = [&]() -> LoggerRef { return LogRef; };

	std::string_view DataView(Data, Size);

	// Trim trailing newlines
	while (!DataView.empty() && (DataView.back() == '\r' || DataView.back() == '\n'))
	{
		DataView.remove_suffix(1);
	}

	switch (Type)
	{
		case CURLINFO_TEXT:
			if (DataView.find("need more data"sv) == std::string_view::npos)
			{
				ZEN_INFO("TEXT: {}", DataView);
			}
			break;
		case CURLINFO_HEADER_IN:
			ZEN_INFO("HIN : {}", DataView);
			break;
		case CURLINFO_HEADER_OUT:
			if (auto TokenPos = DataView.find("Authorization: Bearer "sv); TokenPos != std::string_view::npos)
			{
				std::string Copy(DataView);
				auto		BearerStart = TokenPos + 22;
				auto		BearerEnd	= Copy.find_first_of("\r\n", BearerStart);
				if (BearerEnd == std::string::npos)
				{
					BearerEnd = Copy.length();
				}
				Copy.replace(Copy.begin() + BearerStart, Copy.begin() + BearerEnd, fmt::format("[{} char token]", BearerEnd - BearerStart));
				ZEN_INFO("HOUT: {}", Copy);
			}
			else
			{
				ZEN_INFO("HOUT: {}", DataView);
			}
			break;
		default:
			break;
	}

	return 0;
}

//////////////////////////////////////////////////////////////////////////

static std::pair<std::string, std::string>
HeaderContentType(ZenContentType ContentType)
{
	return std::make_pair("Content-Type", std::string(MapContentTypeToString(ContentType)));
}

static curl_slist*
BuildHeaderList(const HttpClient::KeyValueMap&							AdditionalHeader,
				std::string_view										SessionId,
				const std::optional<HttpClientAccessToken>&				AccessToken,
				const std::vector<std::pair<std::string, std::string>>& ExtraHeaders = {})
{
	curl_slist* Headers = nullptr;

	for (const auto& [Key, Value] : *AdditionalHeader)
	{
		ExtendableStringBuilder<64> HeaderLine;
		HeaderLine << Key << ": " << Value;
		Headers = curl_slist_append(Headers, HeaderLine.c_str());
	}

	if (!SessionId.empty())
	{
		ExtendableStringBuilder<64> SessionHeader;
		SessionHeader << "UE-Session: " << SessionId;
		Headers = curl_slist_append(Headers, SessionHeader.c_str());
	}

	if (AccessToken)
	{
		ExtendableStringBuilder<128> AuthHeader;
		AuthHeader << "Authorization: " << AccessToken->Value;
		Headers = curl_slist_append(Headers, AuthHeader.c_str());
	}

	for (const auto& [Key, Value] : ExtraHeaders)
	{
		ExtendableStringBuilder<128> HeaderLine;
		HeaderLine << Key << ": " << Value;
		Headers = curl_slist_append(Headers, HeaderLine.c_str());
	}

	return Headers;
}

static HttpClient::KeyValueMap
BuildHeaderMap(const std::vector<std::pair<std::string, std::string>>& Headers)
{
	HttpClient::KeyValueMap HeaderMap;
	for (const auto& [Key, Value] : Headers)
	{
		HeaderMap->insert_or_assign(Key, Value);
	}
	return HeaderMap;
}

// Scans response headers for Content-Type and applies it to the buffer.
static void
ApplyContentTypeFromHeaders(IoBuffer& Buffer, const std::vector<std::pair<std::string, std::string>>& Headers)
{
	for (const auto& [Key, Value] : Headers)
	{
		if (StrCaseCompare(Key, "Content-Type") == 0)
		{
			Buffer.SetContentType(ParseContentType(Value));
			break;
		}
	}
}

static void
AppendUrlEncoded(StringBuilderBase& Out, std::string_view Input)
{
	static constexpr char	  HexDigits[] = "0123456789ABCDEF";
	static constexpr AsciiSet Unreserved("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.~");

	for (char C : Input)
	{
		if (Unreserved.Contains(C))
		{
			Out.Append(C);
		}
		else
		{
			uint8_t Byte	   = static_cast<uint8_t>(C);
			char	Encoded[3] = {'%', HexDigits[Byte >> 4], HexDigits[Byte & 0x0F]};
			Out.Append(std::string_view(Encoded, 3));
		}
	}
}

static void
BuildUrlWithParameters(StringBuilderBase&			  Url,
					   std::string_view				  BaseUrl,
					   std::string_view				  ResourcePath,
					   const HttpClient::KeyValueMap& Parameters)
{
	Url.Append(BaseUrl);
	Url.Append(ResourcePath);

	if (!Parameters->empty())
	{
		char Separator = '?';
		for (const auto& [Key, Value] : *Parameters)
		{
			Url.Append(Separator);
			AppendUrlEncoded(Url, Key);
			Url.Append('=');
			AppendUrlEncoded(Url, Value);
			Separator = '&';
		}
	}
}

//////////////////////////////////////////////////////////////////////////

CurlHttpClient::CurlHttpClient(std::string_view			 BaseUri,
							   const HttpClientSettings& ConnectionSettings,
							   std::function<bool()>&&	 CheckIfAbortFunction)
: HttpClientBase(BaseUri, ConnectionSettings, std::move(CheckIfAbortFunction))
{
}

CurlHttpClient::~CurlHttpClient()
{
	ZEN_TRACE_CPU("CurlHttpClient::~CurlHttpClient");
	m_SessionLock.WithExclusiveLock([&] {
		for (auto* Handle : m_Sessions)
		{
			curl_easy_cleanup(Handle);
		}
		m_Sessions.clear();
	});
}

CurlHttpClient::Session::~Session()
{
	if (HeaderList)
	{
		curl_slist_free_all(HeaderList);
	}
	Outer->ReleaseSession(Handle);
}

void
CurlHttpClient::Session::SetHeaders(curl_slist* Headers)
{
	if (HeaderList)
	{
		curl_slist_free_all(HeaderList);
	}
	HeaderList = Headers;
	curl_easy_setopt(Handle, CURLOPT_HTTPHEADER, HeaderList);
}

CurlHttpClient::CurlResult
CurlHttpClient::Session::PerformWithResponseCallbacks()
{
	std::string										 Body;
	WriteCallbackData								 WriteData{.Body = &Body,
															   .CheckIfAbortFunction = Outer->m_CheckIfAbortFunction ? &Outer->m_CheckIfAbortFunction : nullptr};
	HeaderCallbackData								 HdrData{};
	std::vector<std::pair<std::string, std::string>> ResponseHeaders;
	HdrData.Headers = &ResponseHeaders;

	curl_easy_setopt(Handle, CURLOPT_WRITEFUNCTION, CurlWriteCallback);
	curl_easy_setopt(Handle, CURLOPT_WRITEDATA, &WriteData);
	curl_easy_setopt(Handle, CURLOPT_HEADERFUNCTION, CurlHeaderCallback);
	curl_easy_setopt(Handle, CURLOPT_HEADERDATA, &HdrData);

	CurlResult Result = Perform();
	Result.Body		  = std::move(Body);
	Result.Headers	  = std::move(ResponseHeaders);

	return Result;
}

CurlHttpClient::CurlResult
CurlHttpClient::Session::Perform()
{
	CurlResult Result;

	char ErrorBuffer[CURL_ERROR_SIZE] = {};
	curl_easy_setopt(Handle, CURLOPT_ERRORBUFFER, ErrorBuffer);

	Result.ErrorCode = curl_easy_perform(Handle);

	if (Result.ErrorCode != CURLE_OK)
	{
		Result.ErrorMessage = ErrorBuffer[0] ? std::string(ErrorBuffer) : curl_easy_strerror(Result.ErrorCode);
	}

	curl_easy_getinfo(Handle, CURLINFO_RESPONSE_CODE, &Result.StatusCode);

	double Elapsed = 0;
	curl_easy_getinfo(Handle, CURLINFO_TOTAL_TIME, &Elapsed);
	Result.ElapsedSeconds = Elapsed;

	curl_off_t UpBytes = 0;
	curl_easy_getinfo(Handle, CURLINFO_SIZE_UPLOAD_T, &UpBytes);
	Result.UploadedBytes = static_cast<int64_t>(UpBytes);

	curl_off_t DownBytes = 0;
	curl_easy_getinfo(Handle, CURLINFO_SIZE_DOWNLOAD_T, &DownBytes);
	Result.DownloadedBytes = static_cast<int64_t>(DownBytes);

	return Result;
}

bool
CurlHttpClient::ShouldLogErrorCode(HttpResponseCode ResponseCode) const
{
	if (m_CheckIfAbortFunction && m_CheckIfAbortFunction())
	{
		return false;
	}
	const auto& Expected = m_ConnectionSettings.ExpectedErrorCodes;
	return std::find(Expected.begin(), Expected.end(), ResponseCode) == Expected.end();
}

HttpClient::Response
CurlHttpClient::ResponseWithPayload(std::string_view									   SessionId,
									CurlResult&&										   Result,
									const HttpResponseCode								   WorkResponseCode,
									IoBuffer&&											   Payload,
									std::vector<HttpClient::Response::MultipartBoundary>&& BoundaryPositions)
{
	IoBuffer ResponseBuffer = Payload ? std::move(Payload) : IoBuffer(IoBuffer::Clone, Result.Body.data(), Result.Body.size());

	ApplyContentTypeFromHeaders(ResponseBuffer, Result.Headers);

	if (!IsHttpSuccessCode(WorkResponseCode) && WorkResponseCode != HttpResponseCode::NotFound)
	{
		if (ShouldLogErrorCode(WorkResponseCode))
		{
			ZEN_WARN("HttpClient request failed (session: {}): status={}, url={}",
					 SessionId,
					 static_cast<int>(WorkResponseCode),
					 m_BaseUri);
		}
	}

	std::sort(BoundaryPositions.begin(),
			  BoundaryPositions.end(),
			  [](const HttpClient::Response::MultipartBoundary& Lhs, const HttpClient::Response::MultipartBoundary& Rhs) {
				  return Lhs.RangeOffset < Rhs.RangeOffset;
			  });

	return HttpClient::Response{.StatusCode		 = WorkResponseCode,
								.ResponsePayload = std::move(ResponseBuffer),
								.Header			 = BuildHeaderMap(Result.Headers),
								.UploadedBytes	 = Result.UploadedBytes,
								.DownloadedBytes = Result.DownloadedBytes,
								.ElapsedSeconds	 = Result.ElapsedSeconds,
								.Ranges			 = std::move(BoundaryPositions)};
}

HttpClient::Response
CurlHttpClient::CommonResponse(std::string_view										  SessionId,
							   CurlResult&&											  Result,
							   IoBuffer&&											  Payload,
							   std::vector<HttpClient::Response::MultipartBoundary>&& BoundaryPositions)
{
	const HttpResponseCode WorkResponseCode = HttpResponseCode(Result.StatusCode);
	if (Result.ErrorCode != CURLE_OK)
	{
		const bool Quiet = m_CheckIfAbortFunction && m_CheckIfAbortFunction();
		if (!Quiet)
		{
			if (Result.ErrorCode != CURLE_OPERATION_TIMEDOUT && Result.ErrorCode != CURLE_COULDNT_CONNECT &&
				Result.ErrorCode != CURLE_ABORTED_BY_CALLBACK)
			{
				ZEN_WARN("HttpClient client failure (session: {}): ({}) '{}'",
						 SessionId,
						 static_cast<int>(Result.ErrorCode),
						 Result.ErrorMessage);
			}
		}

		return HttpClient::Response{
			.StatusCode		 = WorkResponseCode,
			.ResponsePayload = IoBufferBuilder::MakeCloneFromMemory(Result.Body.data(), Result.Body.size()),
			.Header			 = BuildHeaderMap(Result.Headers),
			.UploadedBytes	 = Result.UploadedBytes,
			.DownloadedBytes = Result.DownloadedBytes,
			.ElapsedSeconds	 = Result.ElapsedSeconds,
			.Error			 = HttpClient::ErrorContext{.ErrorCode = MapCurlError(Result.ErrorCode), .ErrorMessage = Result.ErrorMessage}};
	}

	if (WorkResponseCode == HttpResponseCode::NoContent || (Result.Body.empty() && !Payload))
	{
		return HttpClient::Response{.StatusCode		 = WorkResponseCode,
									.Header			 = BuildHeaderMap(Result.Headers),
									.UploadedBytes	 = Result.UploadedBytes,
									.DownloadedBytes = Result.DownloadedBytes,
									.ElapsedSeconds	 = Result.ElapsedSeconds};
	}
	else
	{
		return ResponseWithPayload(SessionId, std::move(Result), WorkResponseCode, std::move(Payload), std::move(BoundaryPositions));
	}
}

bool
CurlHttpClient::ValidatePayload(CurlResult& Result, std::unique_ptr<detail::TempPayloadFile>& PayloadFile)
{
	ZEN_TRACE_CPU("ValidatePayload");

	IoBuffer ResponseBuffer = (Result.Body.empty() && PayloadFile) ? PayloadFile->BorrowIoBuffer()
																   : IoBuffer(IoBuffer::Wrap, Result.Body.data(), Result.Body.size());

	// Collect relevant headers in a single pass
	std::string_view ContentLengthValue;
	std::string_view IoHashValue;
	std::string_view ContentTypeValue;

	for (const auto& [Key, Value] : Result.Headers)
	{
		if (ContentLengthValue.empty() && StrCaseCompare(Key, "Content-Length") == 0)
		{
			ContentLengthValue = Value;
		}
		else if (IoHashValue.empty() && StrCaseCompare(Key, "X-Jupiter-IoHash") == 0)
		{
			IoHashValue = Value;
		}
		else if (ContentTypeValue.empty() && StrCaseCompare(Key, "Content-Type") == 0)
		{
			ContentTypeValue = Value;
		}
	}

	// Validate Content-Length
	if (!ContentLengthValue.empty())
	{
		std::optional<uint64_t> ExpectedContentSize = ParseInt<uint64_t>(ContentLengthValue);
		if (!ExpectedContentSize.has_value())
		{
			Result.ErrorCode	= CURLE_RECV_ERROR;
			Result.ErrorMessage = fmt::format("Can not parse Content-Length header. Value: '{}'", ContentLengthValue);
			return false;
		}
		if (ExpectedContentSize.value() != ResponseBuffer.GetSize())
		{
			Result.ErrorCode = CURLE_RECV_ERROR;
			Result.ErrorMessage =
				fmt::format("Payload size {} does not match Content-Length {}", ResponseBuffer.GetSize(), ContentLengthValue);
			return false;
		}
	}

	if (Result.StatusCode == static_cast<long>(HttpResponseCode::PartialContent))
	{
		return true;
	}

	// Validate X-Jupiter-IoHash
	if (!IoHashValue.empty())
	{
		IoHash ExpectedPayloadHash;
		if (IoHash::TryParse(IoHashValue, ExpectedPayloadHash))
		{
			IoHash PayloadHash = IoHash::HashBuffer(ResponseBuffer);
			if (PayloadHash != ExpectedPayloadHash)
			{
				Result.ErrorCode	= CURLE_RECV_ERROR;
				Result.ErrorMessage = fmt::format("Payload hash {} does not match X-Jupiter-IoHash {}",
												  PayloadHash.ToHexString(),
												  ExpectedPayloadHash.ToHexString());
				return false;
			}
		}
	}

	// Validate content-type specific payload
	if (ContentTypeValue == "application/x-ue-comp")
	{
		IoHash	 RawHash;
		uint64_t RawSize;
		if (CompressedBuffer::ValidateCompressedHeader(ResponseBuffer,
													   RawHash,
													   RawSize,
													   /*OutOptionalTotalCompressedSize*/ nullptr))
		{
			return true;
		}
		else
		{
			Result.ErrorCode	= CURLE_RECV_ERROR;
			Result.ErrorMessage = "Compressed binary failed validation";
			return false;
		}
	}
	if (ContentTypeValue == "application/x-ue-cb")
	{
		if (CbValidateError Error = ValidateCompactBinary(ResponseBuffer.GetView(), CbValidateMode::Default);
			Error == CbValidateError::None)
		{
			return true;
		}
		else
		{
			Result.ErrorCode	= CURLE_RECV_ERROR;
			Result.ErrorMessage = fmt::format("Compact binary failed validation: {}", ToString(Error));
			return false;
		}
	}

	return true;
}

bool
CurlHttpClient::ShouldRetry(const CurlResult& Result)
{
	switch (Result.ErrorCode)
	{
		case CURLE_OK:
			break;
		case CURLE_RECV_ERROR:
		case CURLE_SEND_ERROR:
		case CURLE_OPERATION_TIMEDOUT:
			return true;
		default:
			return false;
	}
	switch (static_cast<HttpResponseCode>(Result.StatusCode))
	{
		case HttpResponseCode::RequestTimeout:
		case HttpResponseCode::TooManyRequests:
		case HttpResponseCode::InternalServerError:
		case HttpResponseCode::BadGateway:
		case HttpResponseCode::ServiceUnavailable:
		case HttpResponseCode::GatewayTimeout:
			return true;
		default:
			return false;
	}
}

CurlHttpClient::CurlResult
CurlHttpClient::DoWithRetry(std::string_view SessionId, std::function<CurlResult()>&& Func, std::function<bool(CurlResult&)>&& Validate)
{
	uint8_t	   Attempt = 0;
	CurlResult Result  = Func();
	while (Attempt < m_ConnectionSettings.RetryCount)
	{
		if (m_CheckIfAbortFunction && m_CheckIfAbortFunction())
		{
			return Result;
		}
		if (!ShouldRetry(Result))
		{
			if (Result.ErrorCode != CURLE_OK || !IsHttpSuccessCode(Result.StatusCode))
			{
				break;
			}
			if (Validate(Result))
			{
				break;
			}
		}
		Sleep(100 * (Attempt + 1));
		Attempt++;
		if (ShouldLogErrorCode(HttpResponseCode(Result.StatusCode)))
		{
			if (Result.ErrorCode != CURLE_OK)
			{
				ZEN_INFO("Retry (session: {}): HTTP error ({}) '{}' Attempt {}/{}",
						 SessionId,
						 static_cast<int>(MapCurlError(Result.ErrorCode)),
						 Result.ErrorMessage,
						 Attempt,
						 m_ConnectionSettings.RetryCount + 1);
			}
			else
			{
				ZEN_INFO("Retry (session: {}): HTTP status ({}) '{}' Attempt {}/{}",
						 SessionId,
						 Result.StatusCode,
						 zen::ToString(HttpResponseCode(Result.StatusCode)),
						 Attempt,
						 m_ConnectionSettings.RetryCount + 1);
			}
		}
		Result = Func();
	}
	return Result;
}

CurlHttpClient::CurlResult
CurlHttpClient::DoWithRetry(std::string_view						  SessionId,
							std::function<CurlResult()>&&			  Func,
							std::unique_ptr<detail::TempPayloadFile>& PayloadFile)
{
	return DoWithRetry(SessionId, std::move(Func), [&](CurlResult& Result) { return ValidatePayload(Result, PayloadFile); });
}

//////////////////////////////////////////////////////////////////////////

CurlHttpClient::Session
CurlHttpClient::AllocSession(std::string_view ResourcePath, const KeyValueMap& Parameters)
{
	ZEN_TRACE_CPU("CurlHttpClient::AllocSession");
	CURL* Handle = nullptr;
	m_SessionLock.WithExclusiveLock([&] {
		if (!m_Sessions.empty())
		{
			Handle = m_Sessions.back();
			m_Sessions.pop_back();
		}
	});

	if (Handle == nullptr)
	{
		Handle = curl_easy_init();
		if (Handle == nullptr)
		{
			ThrowOutOfMemory("curl_easy_init");
		}
	}
	else
	{
		curl_easy_reset(Handle);
	}

	// Unix domain socket
	if (!m_ConnectionSettings.UnixSocketPath.empty())
	{
		std::string SocketPathUtf8 = PathToUtf8(m_ConnectionSettings.UnixSocketPath);
		curl_easy_setopt(Handle, CURLOPT_UNIX_SOCKET_PATH, SocketPathUtf8.c_str());
	}

	// Build URL with parameters
	ExtendableStringBuilder<256> Url;
	BuildUrlWithParameters(Url, m_BaseUri, ResourcePath, Parameters);
	curl_easy_setopt(Handle, CURLOPT_URL, Url.c_str());

	// Timeouts
	if (m_ConnectionSettings.ConnectTimeout.count() > 0)
	{
		curl_easy_setopt(Handle, CURLOPT_CONNECTTIMEOUT_MS, static_cast<long>(m_ConnectionSettings.ConnectTimeout.count()));
	}
	if (m_ConnectionSettings.Timeout.count() > 0)
	{
		curl_easy_setopt(Handle, CURLOPT_TIMEOUT_MS, static_cast<long>(m_ConnectionSettings.Timeout.count()));
	}

	// HTTP/2
	if (m_ConnectionSettings.AssumeHttp2)
	{
		curl_easy_setopt(Handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE);
	}

	// Verbose/debug
	if (m_ConnectionSettings.Verbose)
	{
		curl_easy_setopt(Handle, CURLOPT_VERBOSE, 1L);
		curl_easy_setopt(Handle, CURLOPT_DEBUGFUNCTION, CurlDebugCallback);
		curl_easy_setopt(Handle, CURLOPT_DEBUGDATA, &m_Log);
	}

	// SSL options
	if (m_ConnectionSettings.InsecureSsl)
	{
		curl_easy_setopt(Handle, CURLOPT_SSL_VERIFYPEER, 0L);
		curl_easy_setopt(Handle, CURLOPT_SSL_VERIFYHOST, 0L);
	}
	if (!m_ConnectionSettings.CaBundlePath.empty())
	{
		curl_easy_setopt(Handle, CURLOPT_CAINFO, m_ConnectionSettings.CaBundlePath.c_str());
	}

	// Disable signal handling for thread safety
	curl_easy_setopt(Handle, CURLOPT_NOSIGNAL, 1L);

	if (m_ConnectionSettings.ForbidReuseConnection)
	{
		curl_easy_setopt(Handle, CURLOPT_FORBID_REUSE, 1L);
	}

	// Note: Headers are NOT set here. Each method builds its own header list
	// (potentially adding method-specific headers like Content-Type) and passes
	// ownership to the Session via SetHeaders().

	return Session(this, Handle);
}

void
CurlHttpClient::ReleaseSession(CURL* Handle)
{
	ZEN_TRACE_CPU("CurlHttpClient::ReleaseSession");
	m_SessionLock.WithExclusiveLock([&] { m_Sessions.push_back(Handle); });
}

//////////////////////////////////////////////////////////////////////////

// TransactPackage is a two-phase protocol (offer + send) with server-side state
// between phases, so retrying individual phases would be incorrect.
CurlHttpClient::Response
CurlHttpClient::TransactPackage(std::string_view Url, CbPackage Package, const KeyValueMap& AdditionalHeader)
{
	ZEN_TRACE_CPU("CurlHttpClient::TransactPackage");

	// First, list of offered chunks for filtering on the server end

	std::vector<IoHash>			  AttachmentsToSend;
	std::span<const CbAttachment> Attachments = Package.GetAttachments();

	const uint32_t RequestId	   = ++CurlHttpClientRequestIdCounter;
	auto		   RequestIdString = fmt::to_string(RequestId);

	if (!Attachments.empty())
	{
		CbObjectWriter Writer;
		Writer.BeginArray("offer");

		for (const CbAttachment& Attachment : Attachments)
		{
			Writer.AddHash(Attachment.GetHash());
		}

		Writer.EndArray();

		BinaryWriter MemWriter;
		Writer.Save(MemWriter);

		std::vector<std::pair<std::string, std::string>> OfferExtraHeaders;
		OfferExtraHeaders.emplace_back(HeaderContentType(HttpContentType::kCbPackageOffer));
		OfferExtraHeaders.emplace_back("UE-Request", RequestIdString);

		Session Sess = AllocSession(Url, {});
		CURL*	H	 = Sess.Get();

		Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken(), OfferExtraHeaders));
		curl_easy_setopt(H, CURLOPT_POST, 1L);
		curl_easy_setopt(H, CURLOPT_POSTFIELDS, reinterpret_cast<const char*>(MemWriter.Data()));
		curl_easy_setopt(H, CURLOPT_POSTFIELDSIZE_LARGE, static_cast<curl_off_t>(MemWriter.Size()));

		CurlResult Result = Sess.PerformWithResponseCallbacks();

		if (Result.ErrorCode == CURLE_OK && IsHttpSuccessCode(Result.StatusCode))
		{
			IoBuffer		ResponseBuffer(IoBuffer::Wrap, Result.Body.data(), Result.Body.size());
			CbValidateError ValidationError = CbValidateError::None;
			if (CbObject ResponseObject = ValidateAndReadCompactBinaryObject(std::move(ResponseBuffer), ValidationError);
				ValidationError == CbValidateError::None)
			{
				for (CbFieldView& Entry : ResponseObject["need"])
				{
					ZEN_ASSERT(Entry.IsHash());
					AttachmentsToSend.push_back(Entry.AsHash());
				}
			}
		}
	}

	// Prepare package for send

	CbPackage SendPackage;
	SendPackage.SetObject(Package.GetObject(), Package.GetObjectHash());

	for (const IoHash& AttachmentCid : AttachmentsToSend)
	{
		const CbAttachment* Attachment = Package.FindAttachment(AttachmentCid);

		if (Attachment)
		{
			SendPackage.AddAttachment(*Attachment);
		}
	}

	// Transmit package payload

	CompositeBuffer Message		= FormatPackageMessageBuffer(SendPackage);
	SharedBuffer	FlatMessage = Message.Flatten();

	std::vector<std::pair<std::string, std::string>> PkgExtraHeaders;
	PkgExtraHeaders.emplace_back(HeaderContentType(HttpContentType::kCbPackage));
	PkgExtraHeaders.emplace_back("UE-Request", RequestIdString);

	Session Sess = AllocSession(Url, {});
	CURL*	H	 = Sess.Get();

	Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken(), PkgExtraHeaders));
	curl_easy_setopt(H, CURLOPT_POST, 1L);
	curl_easy_setopt(H, CURLOPT_POSTFIELDS, reinterpret_cast<const char*>(FlatMessage.GetData()));
	curl_easy_setopt(H, CURLOPT_POSTFIELDSIZE_LARGE, static_cast<curl_off_t>(FlatMessage.GetSize()));

	CurlResult Result = Sess.PerformWithResponseCallbacks();

	return CommonResponse(m_SessionId, std::move(Result), {}, {});
}

//////////////////////////////////////////////////////////////////////////
//
// Standard HTTP verbs
//

CurlHttpClient::Response
CurlHttpClient::Put(std::string_view Url, const IoBuffer& Payload, const KeyValueMap& AdditionalHeader)
{
	ZEN_TRACE_CPU("CurlHttpClient::Put");

	return CommonResponse(
		m_SessionId,
		DoWithRetry(
			m_SessionId,
			[&]() -> CurlResult {
				Session Sess = AllocSession(Url, {});
				CURL*	H	 = Sess.Get();

				Sess.SetHeaders(
					BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken(), {HeaderContentType(Payload.GetContentType())}));

				curl_easy_setopt(H, CURLOPT_UPLOAD, 1L);
				curl_easy_setopt(H, CURLOPT_INFILESIZE_LARGE, static_cast<curl_off_t>(Payload.GetSize()));

				ReadCallbackData ReadData{.DataPtr				= static_cast<const uint8_t*>(Payload.GetData()),
										  .DataSize				= Payload.GetSize(),
										  .CheckIfAbortFunction = m_CheckIfAbortFunction ? &m_CheckIfAbortFunction : nullptr};
				curl_easy_setopt(H, CURLOPT_READFUNCTION, CurlReadCallback);
				curl_easy_setopt(H, CURLOPT_READDATA, &ReadData);

				return Sess.PerformWithResponseCallbacks();
			}),
		{});
}

CurlHttpClient::Response
CurlHttpClient::Put(std::string_view Url, const KeyValueMap& Parameters)
{
	ZEN_TRACE_CPU("CurlHttpClient::Put");

	return CommonResponse(
		m_SessionId,
		DoWithRetry(m_SessionId,
					[&]() -> CurlResult {
						KeyValueMap HeaderWithContentLength{std::pair<std::string_view, std::string_view>{"Content-Length", "0"}};
						Session		Sess = AllocSession(Url, Parameters);
						CURL*		H	 = Sess.Get();

						Sess.SetHeaders(BuildHeaderList(HeaderWithContentLength, m_SessionId, GetAccessToken()));

						curl_easy_setopt(H, CURLOPT_UPLOAD, 1L);
						curl_easy_setopt(H, CURLOPT_INFILESIZE_LARGE, 0LL);

						return Sess.PerformWithResponseCallbacks();
					}),
		{});
}

CurlHttpClient::Response
CurlHttpClient::Get(std::string_view Url, const KeyValueMap& AdditionalHeader, const KeyValueMap& Parameters)
{
	ZEN_TRACE_CPU("CurlHttpClient::Get");
	return CommonResponse(m_SessionId,
						  DoWithRetry(
							  m_SessionId,
							  [&]() -> CurlResult {
								  Session Sess = AllocSession(Url, Parameters);
								  Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken()));
								  curl_easy_setopt(Sess.Get(), CURLOPT_HTTPGET, 1L);
								  return Sess.PerformWithResponseCallbacks();
							  },
							  [this](CurlResult& Result) {
								  std::unique_ptr<detail::TempPayloadFile> NoTempFile;
								  return ValidatePayload(Result, NoTempFile);
							  }),
						  {});
}

CurlHttpClient::Response
CurlHttpClient::Head(std::string_view Url, const KeyValueMap& AdditionalHeader)
{
	ZEN_TRACE_CPU("CurlHttpClient::Head");

	return CommonResponse(m_SessionId,
						  DoWithRetry(m_SessionId,
									  [&]() -> CurlResult {
										  Session Sess = AllocSession(Url, {});
										  Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken()));
										  curl_easy_setopt(Sess.Get(), CURLOPT_NOBODY, 1L);
										  return Sess.PerformWithResponseCallbacks();
									  }),
						  {});
}

CurlHttpClient::Response
CurlHttpClient::Delete(std::string_view Url, const KeyValueMap& AdditionalHeader)
{
	ZEN_TRACE_CPU("CurlHttpClient::Delete");

	return CommonResponse(m_SessionId,
						  DoWithRetry(m_SessionId,
									  [&]() -> CurlResult {
										  Session Sess = AllocSession(Url, {});
										  Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken()));
										  curl_easy_setopt(Sess.Get(), CURLOPT_CUSTOMREQUEST, "DELETE");
										  return Sess.PerformWithResponseCallbacks();
									  }),
						  {});
}

CurlHttpClient::Response
CurlHttpClient::Post(std::string_view Url, const KeyValueMap& AdditionalHeader, const KeyValueMap& Parameters)
{
	ZEN_TRACE_CPU("CurlHttpClient::PostNoPayload");

	return CommonResponse(m_SessionId,
						  DoWithRetry(m_SessionId,
									  [&]() -> CurlResult {
										  Session Sess = AllocSession(Url, Parameters);
										  Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken()));
										  curl_easy_setopt(Sess.Get(), CURLOPT_POST, 1L);
										  curl_easy_setopt(Sess.Get(), CURLOPT_POSTFIELDSIZE, 0L);
										  return Sess.PerformWithResponseCallbacks();
									  }),
						  {});
}

CurlHttpClient::Response
CurlHttpClient::Post(std::string_view Url, const IoBuffer& Payload, const KeyValueMap& AdditionalHeader)
{
	return Post(Url, Payload, Payload.GetContentType(), AdditionalHeader);
}

CurlHttpClient::Response
CurlHttpClient::Post(std::string_view Url, const IoBuffer& Payload, ZenContentType ContentType, const KeyValueMap& AdditionalHeader)
{
	ZEN_TRACE_CPU("CurlHttpClient::PostWithPayload");

	return CommonResponse(
		m_SessionId,
		DoWithRetry(
			m_SessionId,
			[&]() -> CurlResult {
				Session Sess = AllocSession(Url, {});
				CURL*	H	 = Sess.Get();

				Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken(), {HeaderContentType(ContentType)}));

				IoBufferFileReference FileRef = {nullptr, 0, 0};
				if (Payload.GetFileReference(FileRef))
				{
					detail::BufferedReadFileStream Buffer(FileRef.FileHandle, FileRef.FileChunkOffset, FileRef.FileChunkSize, 512u * 1024u);

					FileReadCallbackData ReadData{.Buffer				= &Buffer,
												  .TotalSize			= Payload.GetSize(),
												  .CheckIfAbortFunction = m_CheckIfAbortFunction ? &m_CheckIfAbortFunction : nullptr};

					curl_easy_setopt(H, CURLOPT_POST, 1L);
					curl_easy_setopt(H, CURLOPT_POSTFIELDSIZE_LARGE, static_cast<curl_off_t>(Payload.GetSize()));
					curl_easy_setopt(H, CURLOPT_READFUNCTION, CurlFileReadCallback);
					curl_easy_setopt(H, CURLOPT_READDATA, &ReadData);

					return Sess.PerformWithResponseCallbacks();
				}

				curl_easy_setopt(H, CURLOPT_POST, 1L);
				curl_easy_setopt(H, CURLOPT_POSTFIELDS, reinterpret_cast<const char*>(Payload.GetData()));
				curl_easy_setopt(H, CURLOPT_POSTFIELDSIZE_LARGE, static_cast<curl_off_t>(Payload.GetSize()));

				return Sess.PerformWithResponseCallbacks();
			}),
		{});
}

CurlHttpClient::Response
CurlHttpClient::Post(std::string_view			  Url,
					 CbObject					  Payload,
					 const KeyValueMap&			  AdditionalHeader,
					 const std::filesystem::path& TempFolderPath)
{
	ZEN_TRACE_CPU("CurlHttpClient::PostObjectPayload");

	std::string								 PayloadString;
	std::unique_ptr<detail::TempPayloadFile> PayloadFile;

	CurlResult Result = DoWithRetry(
		m_SessionId,
		[&]() -> CurlResult {
			PayloadString.clear();
			PayloadFile.reset();

			Session Sess = AllocSession(Url, {});
			CURL*	H	 = Sess.Get();

			Sess.SetHeaders(
				BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken(), {HeaderContentType(ZenContentType::kCbObject)}));

			curl_easy_setopt(H, CURLOPT_POST, 1L);
			curl_easy_setopt(H, CURLOPT_POSTFIELDS, reinterpret_cast<const char*>(Payload.GetBuffer().GetData()));
			curl_easy_setopt(H, CURLOPT_POSTFIELDSIZE_LARGE, static_cast<curl_off_t>(Payload.GetBuffer().GetSize()));

			struct PostHeaderCallbackData
			{
				std::vector<std::pair<std::string, std::string>>* Headers		  = nullptr;
				std::unique_ptr<detail::TempPayloadFile>*		  PayloadFile	  = nullptr;
				std::string*									  PayloadString	  = nullptr;
				const std::filesystem::path*					  TempFolderPath  = nullptr;
				uint64_t										  MaxInMemorySize = 0;
				LoggerRef										  Log;
			};

			PostHeaderCallbackData							 PostHdrData;
			std::vector<std::pair<std::string, std::string>> ResponseHeaders;
			PostHdrData.Headers			= &ResponseHeaders;
			PostHdrData.PayloadFile		= &PayloadFile;
			PostHdrData.PayloadString	= &PayloadString;
			PostHdrData.TempFolderPath	= &TempFolderPath;
			PostHdrData.MaxInMemorySize = m_ConnectionSettings.MaximumInMemoryDownloadSize;
			PostHdrData.Log				= m_Log;

			auto HeaderCb = [](char* Buffer, size_t Size, size_t Nmemb, void* UserData) -> size_t {
				auto*  Data		  = static_cast<PostHeaderCallbackData*>(UserData);
				size_t TotalBytes = Size * Nmemb;

				if (auto Header = ParseHeaderLine(std::string_view(Buffer, TotalBytes)))
				{
					auto& [Key, Value] = *Header;

					if (StrCaseCompare(Key, "Content-Length") == 0)
					{
						std::optional<size_t> ContentLength = ParseInt<size_t>(Value);
						if (ContentLength.has_value())
						{
							if (!Data->TempFolderPath->empty() && ContentLength.value() > Data->MaxInMemorySize)
							{
								*Data->PayloadFile = std::make_unique<detail::TempPayloadFile>();
								std::error_code Ec = (*Data->PayloadFile)->Open(*Data->TempFolderPath, ContentLength.value());
								if (Ec)
								{
									auto Log = [&]() -> LoggerRef { return Data->Log; };
									ZEN_WARN("Failed to create temp file in '{}' for HttpClient::Post. Reason: {}",
											 Data->TempFolderPath->string(),
											 Ec.message());
									Data->PayloadFile->reset();
								}
							}
							else
							{
								Data->PayloadString->reserve(ContentLength.value());
							}
						}
					}

					Data->Headers->emplace_back(std::string(Key), std::string(Value));
				}

				return TotalBytes;
			};

			curl_easy_setopt(H, CURLOPT_HEADERFUNCTION, static_cast<size_t (*)(char*, size_t, size_t, void*)>(HeaderCb));
			curl_easy_setopt(H, CURLOPT_HEADERDATA, &PostHdrData);

			struct PostWriteCallbackData
			{
				std::string*							  PayloadString		   = nullptr;
				std::unique_ptr<detail::TempPayloadFile>* PayloadFile		   = nullptr;
				std::function<bool()>*					  CheckIfAbortFunction = nullptr;
				const std::filesystem::path*			  TempFolderPath	   = nullptr;
				LoggerRef								  Log;
			};

			PostWriteCallbackData PostWriteData;
			PostWriteData.PayloadString		   = &PayloadString;
			PostWriteData.PayloadFile		   = &PayloadFile;
			PostWriteData.CheckIfAbortFunction = m_CheckIfAbortFunction ? &m_CheckIfAbortFunction : nullptr;
			PostWriteData.TempFolderPath	   = &TempFolderPath;
			PostWriteData.Log				   = m_Log;

			auto WriteCb = [](char* Ptr, size_t Size, size_t Nmemb, void* UserData) -> size_t {
				auto*  Data		  = static_cast<PostWriteCallbackData*>(UserData);
				size_t TotalBytes = Size * Nmemb;

				if (Data->CheckIfAbortFunction && *Data->CheckIfAbortFunction && (*Data->CheckIfAbortFunction)())
				{
					return 0;
				}

				if (*Data->PayloadFile)
				{
					std::error_code Ec = (*Data->PayloadFile)->Write(std::string_view(Ptr, TotalBytes));
					if (Ec)
					{
						auto Log = [&]() -> LoggerRef { return Data->Log; };
						ZEN_WARN("Failed to write to temp file in '{}' for HttpClient::Post. Reason: {}",
								 Data->TempFolderPath->string(),
								 Ec.message());
						return 0;
					}
				}
				else
				{
					Data->PayloadString->append(Ptr, TotalBytes);
				}
				return TotalBytes;
			};

			curl_easy_setopt(H, CURLOPT_WRITEFUNCTION, static_cast<size_t (*)(char*, size_t, size_t, void*)>(WriteCb));
			curl_easy_setopt(H, CURLOPT_WRITEDATA, &PostWriteData);

			CurlResult Res = Sess.Perform();
			Res.Headers	   = std::move(ResponseHeaders);

			if (!PayloadString.empty())
			{
				Res.Body = std::move(PayloadString);
			}

			return Res;
		},
		PayloadFile);

	return CommonResponse(m_SessionId, std::move(Result), PayloadFile ? PayloadFile->DetachToIoBuffer() : IoBuffer{}, {});
}

CurlHttpClient::Response
CurlHttpClient::Post(std::string_view Url, CbPackage Pkg, const KeyValueMap& AdditionalHeader)
{
	return Post(Url, zen::FormatPackageMessageBuffer(Pkg), ZenContentType::kCbPackage, AdditionalHeader);
}

CurlHttpClient::Response
CurlHttpClient::Post(std::string_view Url, const CompositeBuffer& Payload, ZenContentType ContentType, const KeyValueMap& AdditionalHeader)
{
	ZEN_TRACE_CPU("CurlHttpClient::Post");

	return CommonResponse(
		m_SessionId,
		DoWithRetry(m_SessionId,
					[&]() -> CurlResult {
						Session Sess = AllocSession(Url, {});
						CURL*	H	 = Sess.Get();

						Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken(), {HeaderContentType(ContentType)}));

						detail::CompositeBufferReadStream Reader(Payload, 512u * 1024u);

						StreamReadCallbackData ReadData{.Reader				  = &Reader,
														.CheckIfAbortFunction = m_CheckIfAbortFunction ? &m_CheckIfAbortFunction : nullptr};

						curl_easy_setopt(H, CURLOPT_POST, 1L);
						curl_easy_setopt(H, CURLOPT_POSTFIELDSIZE_LARGE, static_cast<curl_off_t>(Payload.GetSize()));
						curl_easy_setopt(H, CURLOPT_READFUNCTION, CurlStreamReadCallback);
						curl_easy_setopt(H, CURLOPT_READDATA, &ReadData);

						return Sess.PerformWithResponseCallbacks();
					}),
		{});
}

CurlHttpClient::Response
CurlHttpClient::Upload(std::string_view Url, const IoBuffer& Payload, const KeyValueMap& AdditionalHeader)
{
	ZEN_TRACE_CPU("CurlHttpClient::Upload");

	return CommonResponse(
		m_SessionId,
		DoWithRetry(
			m_SessionId,
			[&]() -> CurlResult {
				Session Sess = AllocSession(Url, {});
				CURL*	H	 = Sess.Get();

				Sess.SetHeaders(
					BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken(), {HeaderContentType(Payload.GetContentType())}));

				curl_easy_setopt(H, CURLOPT_UPLOAD, 1L);
				curl_easy_setopt(H, CURLOPT_INFILESIZE_LARGE, static_cast<curl_off_t>(Payload.GetSize()));

				IoBufferFileReference FileRef = {nullptr, 0, 0};
				if (Payload.GetFileReference(FileRef))
				{
					detail::BufferedReadFileStream Buffer(FileRef.FileHandle, FileRef.FileChunkOffset, FileRef.FileChunkSize, 512u * 1024u);

					FileReadCallbackData ReadData{.Buffer				= &Buffer,
												  .TotalSize			= Payload.GetSize(),
												  .CheckIfAbortFunction = m_CheckIfAbortFunction ? &m_CheckIfAbortFunction : nullptr};

					curl_easy_setopt(H, CURLOPT_READFUNCTION, CurlFileReadCallback);
					curl_easy_setopt(H, CURLOPT_READDATA, &ReadData);

					return Sess.PerformWithResponseCallbacks();
				}

				ReadCallbackData ReadData{.DataPtr				= static_cast<const uint8_t*>(Payload.GetData()),
										  .DataSize				= Payload.GetSize(),
										  .CheckIfAbortFunction = m_CheckIfAbortFunction ? &m_CheckIfAbortFunction : nullptr};
				curl_easy_setopt(H, CURLOPT_READFUNCTION, CurlReadCallback);
				curl_easy_setopt(H, CURLOPT_READDATA, &ReadData);

				return Sess.PerformWithResponseCallbacks();
			}),
		{});
}

CurlHttpClient::Response
CurlHttpClient::Upload(std::string_view		  Url,
					   const CompositeBuffer& Payload,
					   ZenContentType		  ContentType,
					   const KeyValueMap&	  AdditionalHeader)
{
	ZEN_TRACE_CPU("CurlHttpClient::Upload");

	return CommonResponse(
		m_SessionId,
		DoWithRetry(m_SessionId,
					[&]() -> CurlResult {
						Session Sess = AllocSession(Url, {});
						CURL*	H	 = Sess.Get();

						Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken(), {HeaderContentType(ContentType)}));

						curl_easy_setopt(H, CURLOPT_UPLOAD, 1L);
						curl_easy_setopt(H, CURLOPT_INFILESIZE_LARGE, static_cast<curl_off_t>(Payload.GetSize()));

						detail::CompositeBufferReadStream Reader(Payload, 512u * 1024u);

						StreamReadCallbackData ReadData{.Reader				  = &Reader,
														.CheckIfAbortFunction = m_CheckIfAbortFunction ? &m_CheckIfAbortFunction : nullptr};

						curl_easy_setopt(H, CURLOPT_READFUNCTION, CurlStreamReadCallback);
						curl_easy_setopt(H, CURLOPT_READDATA, &ReadData);

						return Sess.PerformWithResponseCallbacks();
					}),
		{});
}

CurlHttpClient::Response
CurlHttpClient::Download(std::string_view Url, const std::filesystem::path& TempFolderPath, const KeyValueMap& AdditionalHeader)
{
	ZEN_TRACE_CPU("CurlHttpClient::Download");

	std::string								 PayloadString;
	std::unique_ptr<detail::TempPayloadFile> PayloadFile;

	HttpContentType					ContentType = HttpContentType::kUnknownContentType;
	detail::MultipartBoundaryParser BoundaryParser;
	bool							IsMultiRangeResponse = false;

	CurlResult Result = DoWithRetry(
		m_SessionId,
		[&]() -> CurlResult {
			Session Sess = AllocSession(Url, {});
			CURL*	H	 = Sess.Get();

			Sess.SetHeaders(BuildHeaderList(AdditionalHeader, m_SessionId, GetAccessToken()));
			curl_easy_setopt(H, CURLOPT_HTTPGET, 1L);

			// Reset state from any previous attempt
			PayloadString.clear();
			PayloadFile.reset();
			BoundaryParser.Boundaries.clear();
			ContentType			 = HttpContentType::kUnknownContentType;
			IsMultiRangeResponse = false;

			// Track requested content length from Range header (sum all ranges)
			uint64_t RequestedContentLength = (uint64_t)-1;
			if (auto RangeIt = AdditionalHeader.Entries.find("Range"); RangeIt != AdditionalHeader.Entries.end())
			{
				if (RangeIt->second.starts_with("bytes"))
				{
					std::string_view RangeValue(RangeIt->second);
					size_t			 RangeStartPos = RangeValue.find('=', 5);
					if (RangeStartPos != std::string_view::npos)
					{
						RangeStartPos++;
						while (RangeStartPos < RangeValue.length() && RangeValue[RangeStartPos] == ' ')
						{
							RangeStartPos++;
						}
						RequestedContentLength = 0;

						while (RangeStartPos < RangeValue.length())
						{
							size_t RangeEnd = RangeValue.find_first_of(", \r\n", RangeStartPos);
							if (RangeEnd == std::string_view::npos)
							{
								RangeEnd = RangeValue.length();
							}

							std::string_view RangeString   = RangeValue.substr(RangeStartPos, RangeEnd - RangeStartPos);
							size_t			 RangeSplitPos = RangeString.find('-');
							if (RangeSplitPos != std::string_view::npos)
							{
								std::optional<size_t> RequestedRangeStart = ParseInt<size_t>(RangeString.substr(0, RangeSplitPos));
								std::optional<size_t> RequestedRangeEnd	  = ParseInt<size_t>(RangeString.substr(RangeSplitPos + 1));
								if (RequestedRangeStart.has_value() && RequestedRangeEnd.has_value())
								{
									RequestedContentLength += RequestedRangeEnd.value() - RequestedRangeStart.value() + 1;
								}
							}
							RangeStartPos = RangeEnd;
							while (RangeStartPos != RangeValue.length() &&
								   (RangeValue[RangeStartPos] == ',' || RangeValue[RangeStartPos] == ' '))
							{
								RangeStartPos++;
							}
						}
					}
				}
			}

			// Header callback that detects Content-Length and switches to file-backed storage when needed
			struct DownloadHeaderCallbackData
			{
				std::vector<std::pair<std::string, std::string>>* Headers		  = nullptr;
				std::unique_ptr<detail::TempPayloadFile>*		  PayloadFile	  = nullptr;
				std::string*									  PayloadString	  = nullptr;
				const std::filesystem::path*					  TempFolderPath  = nullptr;
				uint64_t										  MaxInMemorySize = 0;
				LoggerRef										  Log;
				detail::MultipartBoundaryParser*				  BoundaryParser = nullptr;
				bool*											  IsMultiRange	 = nullptr;
				HttpContentType*								  ContentTypeOut = nullptr;
			};

			DownloadHeaderCallbackData						 DlHdrData;
			std::vector<std::pair<std::string, std::string>> ResponseHeaders;
			DlHdrData.Headers		  = &ResponseHeaders;
			DlHdrData.PayloadFile	  = &PayloadFile;
			DlHdrData.PayloadString	  = &PayloadString;
			DlHdrData.TempFolderPath  = &TempFolderPath;
			DlHdrData.MaxInMemorySize = m_ConnectionSettings.MaximumInMemoryDownloadSize;
			DlHdrData.Log			  = m_Log;
			DlHdrData.BoundaryParser  = &BoundaryParser;
			DlHdrData.IsMultiRange	  = &IsMultiRangeResponse;
			DlHdrData.ContentTypeOut  = &ContentType;

			auto HeaderCb = [](char* Buffer, size_t Size, size_t Nmemb, void* UserData) -> size_t {
				auto*  Data		  = static_cast<DownloadHeaderCallbackData*>(UserData);
				size_t TotalBytes = Size * Nmemb;

				if (auto Header = ParseHeaderLine(std::string_view(Buffer, TotalBytes)))
				{
					auto& [KeyView, Value] = *Header;
					const std::string Key(KeyView);

					if (StrCaseCompare(Key, "Content-Length") == 0)
					{
						std::optional<size_t> ContentLength = ParseInt<size_t>(Value);
						if (ContentLength.has_value())
						{
							if (ContentLength.value() > Data->MaxInMemorySize)
							{
								*Data->PayloadFile = std::make_unique<detail::TempPayloadFile>();
								std::error_code Ec = (*Data->PayloadFile)->Open(*Data->TempFolderPath, ContentLength.value());
								if (Ec)
								{
									auto Log = [&]() -> LoggerRef { return Data->Log; };
									ZEN_WARN("Failed to create temp file in '{}' for HttpClient::Download. Reason: {}",
											 Data->TempFolderPath->string(),
											 Ec.message());
									Data->PayloadFile->reset();
								}
							}
							else
							{
								Data->PayloadString->reserve(ContentLength.value());
							}
						}
					}
					else if (StrCaseCompare(Key, "Content-Type") == 0)
					{
						*Data->IsMultiRange = Data->BoundaryParser->Init(Value);
						if (!*Data->IsMultiRange)
						{
							*Data->ContentTypeOut = ParseContentType(Value);
						}
					}
					else if (StrCaseCompare(Key, "Content-Range") == 0)
					{
						if (!*Data->IsMultiRange)
						{
							std::pair<uint64_t, uint64_t> Range = detail::ParseContentRange(Value);
							if (Range.second != 0)
							{
								Data->BoundaryParser->Boundaries.push_back(
									HttpClient::Response::MultipartBoundary{.OffsetInPayload = 0,
																			.RangeOffset	 = Range.first,
																			.RangeLength	 = Range.second,
																			.ContentType	 = *Data->ContentTypeOut});
							}
						}
					}

					Data->Headers->emplace_back(Key, std::string(Value));
				}

				return TotalBytes;
			};

			curl_easy_setopt(H, CURLOPT_HEADERFUNCTION, static_cast<size_t (*)(char*, size_t, size_t, void*)>(HeaderCb));
			curl_easy_setopt(H, CURLOPT_HEADERDATA, &DlHdrData);

			// Write callback that directs data to file or string
			struct DownloadWriteCallbackData
			{
				std::string*							  PayloadString		   = nullptr;
				std::unique_ptr<detail::TempPayloadFile>* PayloadFile		   = nullptr;
				std::function<bool()>*					  CheckIfAbortFunction = nullptr;
				const std::filesystem::path*			  TempFolderPath	   = nullptr;
				LoggerRef								  Log;
				detail::MultipartBoundaryParser*		  BoundaryParser = nullptr;
				bool*									  IsMultiRange	 = nullptr;
			};

			DownloadWriteCallbackData DlWriteData;
			DlWriteData.PayloadString		 = &PayloadString;
			DlWriteData.PayloadFile			 = &PayloadFile;
			DlWriteData.CheckIfAbortFunction = m_CheckIfAbortFunction ? &m_CheckIfAbortFunction : nullptr;
			DlWriteData.TempFolderPath		 = &TempFolderPath;
			DlWriteData.Log					 = m_Log;
			DlWriteData.BoundaryParser		 = &BoundaryParser;
			DlWriteData.IsMultiRange		 = &IsMultiRangeResponse;

			auto WriteCb = [](char* Ptr, size_t Size, size_t Nmemb, void* UserData) -> size_t {
				auto*  Data		  = static_cast<DownloadWriteCallbackData*>(UserData);
				size_t TotalBytes = Size * Nmemb;

				if (Data->CheckIfAbortFunction && *Data->CheckIfAbortFunction && (*Data->CheckIfAbortFunction)())
				{
					return 0;
				}

				if (*Data->IsMultiRange)
				{
					Data->BoundaryParser->ParseInput(std::string_view(Ptr, TotalBytes));
				}

				if (*Data->PayloadFile)
				{
					std::error_code Ec = (*Data->PayloadFile)->Write(std::string_view(Ptr, TotalBytes));
					if (Ec)
					{
						auto Log = [&]() -> LoggerRef { return Data->Log; };
						ZEN_WARN("Failed to write to temp file in '{}' for HttpClient::Download. Reason: {}",
								 Data->TempFolderPath->string(),
								 Ec.message());
						return 0;
					}
				}
				else
				{
					Data->PayloadString->append(Ptr, TotalBytes);
				}
				return TotalBytes;
			};

			curl_easy_setopt(H, CURLOPT_WRITEFUNCTION, static_cast<size_t (*)(char*, size_t, size_t, void*)>(WriteCb));
			curl_easy_setopt(H, CURLOPT_WRITEDATA, &DlWriteData);

			CurlResult Res = Sess.Perform();
			Res.Headers	   = std::move(ResponseHeaders);

			// Handle resume logic
			if (m_ConnectionSettings.AllowResume)
			{
				auto SupportsRanges = [](const CurlResult& R) -> bool {
					for (const auto& [K, V] : R.Headers)
					{
						if (StrCaseCompare(K, "Content-Range") == 0)
						{
							return true;
						}
						if (StrCaseCompare(K, "Accept-Ranges") == 0)
						{
							return V == "bytes"sv;
						}
					}
					return false;
				};

				auto ShouldResumeCheck = [&SupportsRanges, &IsMultiRangeResponse](const CurlResult& R) -> bool {
					if (IsMultiRangeResponse)
					{
						return false;
					}
					if (ShouldRetry(R))
					{
						return SupportsRanges(R);
					}
					return false;
				};

				if (ShouldResumeCheck(Res))
				{
					// Find Content-Length
					std::string ContentLengthValue;
					for (const auto& [K, V] : Res.Headers)
					{
						if (StrCaseCompare(K, "Content-Length") == 0)
						{
							ContentLengthValue = V;
							break;
						}
					}

					if (!ContentLengthValue.empty())
					{
						uint64_t ContentLength = RequestedContentLength;
						if (ContentLength == uint64_t(-1))
						{
							if (auto ParsedContentLength = ParseInt<int64_t>(ContentLengthValue); ParsedContentLength.has_value())
							{
								ContentLength = ParsedContentLength.value();
							}
						}

						KeyValueMap HeadersWithRange(AdditionalHeader);
						uint8_t		ResumeAttempt = 0;
						do
						{
							uint64_t DownloadedSize = PayloadFile ? PayloadFile->GetSize() : PayloadString.length();

							std::string Range = fmt::format("bytes={}-{}", DownloadedSize, DownloadedSize + ContentLength - 1);
							if (auto RangeIt = HeadersWithRange.Entries.find("Range"); RangeIt != HeadersWithRange.Entries.end())
							{
								if (RangeIt->second == Range)
								{
									break;	// No progress, abort
								}
							}
							HeadersWithRange.Entries.insert_or_assign("Range", Range);

							Session ResumeSess = AllocSession(Url, {});
							CURL*	ResumeH	   = ResumeSess.Get();

							ResumeSess.SetHeaders(BuildHeaderList(HeadersWithRange, m_SessionId, GetAccessToken()));
							curl_easy_setopt(ResumeH, CURLOPT_HTTPGET, 1L);

							std::vector<std::pair<std::string, std::string>> ResumeHeaders;

							struct ResumeHeaderCbData
							{
								std::vector<std::pair<std::string, std::string>>* Headers		= nullptr;
								std::unique_ptr<detail::TempPayloadFile>*		  PayloadFile	= nullptr;
								std::string*									  PayloadString = nullptr;
							};

							ResumeHeaderCbData ResumeHdrData;
							ResumeHdrData.Headers		= &ResumeHeaders;
							ResumeHdrData.PayloadFile	= &PayloadFile;
							ResumeHdrData.PayloadString = &PayloadString;

							auto ResumeHeaderCb = [](char* Buffer, size_t Size, size_t Nmemb, void* UserData) -> size_t {
								auto*  Data		  = static_cast<ResumeHeaderCbData*>(UserData);
								size_t TotalBytes = Size * Nmemb;

								auto Header = ParseHeaderLine(std::string_view(Buffer, TotalBytes));
								if (!Header)
								{
									return TotalBytes;
								}
								auto& [Key, Value] = *Header;

								if (StrCaseCompare(Key, "Content-Range") == 0)
								{
									if (Value.starts_with("bytes "sv))
									{
										size_t RangeStartEnd = Value.find('-', 6);
										if (RangeStartEnd != std::string_view::npos)
										{
											const std::optional<uint64_t> Start = ParseInt<uint64_t>(Value.substr(6, RangeStartEnd - 6));
											if (Start)
											{
												uint64_t DownloadedSize =
													*Data->PayloadFile ? (*Data->PayloadFile)->GetSize() : Data->PayloadString->length();
												if (Start.value() == DownloadedSize)
												{
													Data->Headers->emplace_back(std::string(Key), std::string(Value));
													return TotalBytes;
												}
												else if (Start.value() > DownloadedSize)
												{
													return 0;
												}
												if (*Data->PayloadFile)
												{
													(*Data->PayloadFile)->ResetWritePos(Start.value());
												}
												else
												{
													*Data->PayloadString = Data->PayloadString->substr(0, Start.value());
												}
												Data->Headers->emplace_back(std::string(Key), std::string(Value));
												return TotalBytes;
											}
										}
									}
									return 0;
								}

								Data->Headers->emplace_back(std::string(Key), std::string(Value));
								return TotalBytes;
							};

							curl_easy_setopt(ResumeH,
											 CURLOPT_HEADERFUNCTION,
											 static_cast<size_t (*)(char*, size_t, size_t, void*)>(ResumeHeaderCb));
							curl_easy_setopt(ResumeH, CURLOPT_HEADERDATA, &ResumeHdrData);
							curl_easy_setopt(ResumeH,
											 CURLOPT_WRITEFUNCTION,
											 static_cast<size_t (*)(char*, size_t, size_t, void*)>(WriteCb));
							curl_easy_setopt(ResumeH, CURLOPT_WRITEDATA, &DlWriteData);

							Res			= ResumeSess.Perform();
							Res.Headers = std::move(ResumeHeaders);

							ResumeAttempt++;
						} while (ResumeAttempt < m_ConnectionSettings.RetryCount && ShouldResumeCheck(Res));
					}
				}
			}

			if (!PayloadString.empty())
			{
				Res.Body = std::move(PayloadString);
			}

			return Res;
		},
		PayloadFile);

	return CommonResponse(m_SessionId,
						  std::move(Result),
						  PayloadFile ? PayloadFile->DetachToIoBuffer() : IoBuffer{},
						  std::move(BoundaryParser.Boundaries));
}

}  // namespace zen