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

#include <zenhttp/httpclientauth.h>

#include <zencore/fmtutils.h>
#include <zencore/logging.h>
#include <zencore/process.h>
#include <zencore/scopeguard.h>
#include <zencore/timer.h>
#include <zencore/uid.h>
#include <zenhttp/auth/authmgr.h>

#include <ctime>

ZEN_THIRD_PARTY_INCLUDES_START
#include <cpr/cpr.h>
#include <fmt/format.h>
#include <json11.hpp>
ZEN_THIRD_PARTY_INCLUDES_END

#if ZEN_PLATFORM_WINDOWS
#	define timegm _mkgmtime
#endif	// ZEN_PLATFORM_WINDOWS

namespace zen { namespace httpclientauth {

	using namespace std::literals;

	std::function<HttpClientAccessToken()> CreateFromStaticToken(HttpClientAccessToken Token)
	{
		return [Token]() { return Token; };
	}

	std::function<HttpClientAccessToken()> CreateFromStaticToken(std::string_view Token)
	{
		return CreateFromStaticToken(
			HttpClientAccessToken{.Value = fmt::format("Bearer {}"sv, Token), .ExpireTime = HttpClientAccessToken::TimePoint::max()});
	}

	std::function<HttpClientAccessToken()> CreateFromOAuthClientCredentials(const OAuthClientCredentialsParams& Params)
	{
		OAuthClientCredentialsParams OAuthParams(Params);
		return [OAuthParams]() {
			using namespace std::chrono;

			std::string Body = fmt::format("client_id={}&scope=cache_access&grant_type=client_credentials&client_secret={}"sv,
										   OAuthParams.ClientId,
										   OAuthParams.ClientSecret);

			cpr::Response Response = cpr::Post(cpr::Url{OAuthParams.Url},
											   cpr::Header{{"Content-Type", "application/x-www-form-urlencoded"}},
											   cpr::Body{std::move(Body)});

			if (Response.error || Response.status_code != 200)
			{
				ZEN_WARN("Failed fetching OAuth access token {}. Reason: '{}'", OAuthParams.Url, Response.reason);
				return HttpClientAccessToken{};
			}

			std::string	 JsonError;
			json11::Json Json = json11::Json::parse(Response.text, JsonError);

			if (JsonError.empty() == false)
			{
				ZEN_WARN("Unable to parse OAuth json response from {}. Reason: '{}'", OAuthParams.Url, JsonError);
				return HttpClientAccessToken{};
			}

			std::string						 Token			  = Json["access_token"].string_value();
			int64_t							 ExpiresInSeconds = static_cast<int64_t>(Json["expires_in"].int_value());
			HttpClientAccessToken::TimePoint ExpireTime		  = HttpClientAccessToken::Clock::now() + seconds(ExpiresInSeconds);

			return HttpClientAccessToken{.Value = fmt::format("Bearer {}"sv, Token), .ExpireTime = ExpireTime};
		};
	}

	std::function<HttpClientAccessToken()> CreateFromOpenIdProvider(AuthMgr& AuthManager, std::string_view OpenIdProvider)
	{
		return [&AuthManager = AuthManager, OpenIdProvider = std::string(OpenIdProvider)]() {
			AuthMgr::OpenIdAccessToken Token = AuthManager.GetOpenIdAccessToken(OpenIdProvider);
			return HttpClientAccessToken{.Value = Token.AccessToken, .ExpireTime = Token.ExpireTime};
		};
	}

	std::function<HttpClientAccessToken()> CreateFromDefaultOpenIdProvider(AuthMgr& AuthManager)
	{
		return CreateFromOpenIdProvider(AuthManager, "Default"sv);
	}

	static HttpClientAccessToken GetOidcTokenFromExe(const std::filesystem::path& OidcExecutablePath,
													 std::string_view			  CloudHost,
													 bool						  Unattended)
	{
		Stopwatch Timer;

		CreateProcOptions ProcOptions;

		const std::filesystem::path AuthTokenPath(std::filesystem::temp_directory_path() / fmt::format(".zen-auth-{}", Oid::NewOid()));
		auto						_ = MakeGuard([AuthTokenPath]() { RemoveFile(AuthTokenPath); });

		const std::string ProcArgs = fmt::format("{} --AuthConfigUrl {} --OutFile {} --Unattended={}",
												 OidcExecutablePath,
												 CloudHost,
												 AuthTokenPath,
												 Unattended ? "true"sv : "false"sv);
		ZEN_DEBUG("Running: {}", ProcArgs);
		ProcessHandle Proc;
		Proc.Initialize(CreateProc(OidcExecutablePath, ProcArgs, ProcOptions));
		if (!Proc.IsValid())
		{
			throw std::runtime_error(fmt::format("failed to launch '{}'", OidcExecutablePath));
		}

		int ExitCode = Proc.WaitExitCode();

		auto EndTime = std::chrono::system_clock::now();

		if (ExitCode == 0)
		{
			IoBuffer	Body = IoBufferBuilder::MakeFromFile(AuthTokenPath);
			std::string JsonText(reinterpret_cast<const char*>(Body.GetData()), Body.GetSize());

			std::string	 JsonError;
			json11::Json Json = json11::Json::parse(JsonText, JsonError);

			if (JsonError.empty() == false)
			{
				ZEN_WARN("Unable to parse Oidcs json response from {}. Reason: '{}'", AuthTokenPath, JsonError);
				return HttpClientAccessToken{};
			}
			std::string Token			   = Json["Token"].string_value();
			std::string ExpiresAtUTCString = Json["ExpiresAtUtc"].string_value();
			ZEN_ASSERT(!ExpiresAtUTCString.empty());

			int Year		= 0;
			int Month		= 0;
			int Day			= 0;
			int Hour		= 0;
			int Minute		= 0;
			int Second		= 0;
			int Millisecond = 0;
			sscanf(ExpiresAtUTCString.c_str(), "%d-%d-%dT%d:%d:%d.%dZ", &Year, &Month, &Day, &Hour, &Minute, &Second, &Millisecond);

			std::tm Time = {
				Second,
				Minute,
				Hour,
				Day,
				Month - 1,
				Year - 1900,
			};

			time_t							 UTCTime	= timegm(&Time);
			HttpClientAccessToken::TimePoint ExpireTime = std::chrono::system_clock::from_time_t(UTCTime);
			ExpireTime += std::chrono::microseconds(Millisecond);

			return HttpClientAccessToken{.Value = fmt::format("Bearer {}"sv, Token), .ExpireTime = ExpireTime};
		}
		else
		{
			ZEN_WARN("Failed running {} to get auth token, error code {}", OidcExecutablePath, ExitCode);
		}
		return HttpClientAccessToken{};
	}

	std::optional<std::function<HttpClientAccessToken()>> CreateFromOidcTokenExecutable(const std::filesystem::path& OidcExecutablePath,
																						std::string_view			 CloudHost)
	{
		HttpClientAccessToken InitialToken = GetOidcTokenFromExe(OidcExecutablePath, CloudHost, false);
		if (InitialToken.IsValid())
		{
			return [OidcExecutablePath = std::filesystem::path(OidcExecutablePath),
					CloudHost		   = std::string(CloudHost),
					InitialToken]() mutable {
				if (InitialToken.IsValid())
				{
					HttpClientAccessToken Result = InitialToken;
					InitialToken				 = {};
					return Result;
				}
				return GetOidcTokenFromExe(OidcExecutablePath, CloudHost, true);
			};
		}
		return {};
	}

}}	// namespace zen::httpclientauth