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

#include "zenhttp/diagsvcs.h"

#include <zencore/compactbinary.h>
#include <zencore/compactbinarybuilder.h>
#include <zencore/config.h>
#include <zencore/filesystem.h>
#include <zencore/logging.h>
#include <zencore/string.h>
#include <fstream>
#include <sstream>

#include <json11.hpp>

namespace zen {

using namespace std::literals;

static bool
ReadLogFile(const std::string& Path, StringBuilderBase& Out)
{
	try
	{
		constexpr auto ReadSize	  = std::size_t{4096};
		auto		   FileStream = std::ifstream{Path};

		std::string Buf(ReadSize, '\0');
		while (FileStream.read(&Buf[0], ReadSize))
		{
			Out.Append(std::string_view(&Buf[0], FileStream.gcount()));
		}
		Out.Append(std::string_view(&Buf[0], FileStream.gcount()));

		return true;
	}
	catch (std::exception&)
	{
		Out.Reset();
		return false;
	}
}

HttpHealthService::HttpHealthService()
{
	m_Router.RegisterRoute(
		"",
		[](HttpRouterRequest& RoutedReq) {
			HttpServerRequest& HttpReq = RoutedReq.ServerRequest();
			HttpReq.WriteResponse(HttpResponseCode::OK, HttpContentType::kText, u8"OK!"sv);
		},
		HttpVerb::kGet);

	m_Router.RegisterRoute(
		"info",
		[this](HttpRouterRequest& RoutedReq) {
			HttpServerRequest& HttpReq = RoutedReq.ServerRequest();

			CbObjectWriter Writer;

			{
				RwLock::SharedLockScope _(m_InfoLock);
				Writer << "DataRoot"sv << m_HealthInfo.DataRoot.string();
				Writer << "AbsLogPath"sv << m_HealthInfo.AbsLogPath.string();
				Writer << "BuildVersion"sv << m_HealthInfo.BuildVersion;
				Writer << "HttpServerClass"sv << m_HealthInfo.HttpServerClass;
			}

			HttpReq.WriteResponse(HttpResponseCode::OK, Writer.Save());
		},
		HttpVerb::kGet);

	m_Router.RegisterRoute(
		"log",
		[this](HttpRouterRequest& RoutedReq) {
			HttpServerRequest& HttpReq = RoutedReq.ServerRequest();

			zen::Log().flush();

			std::filesystem::path Path = [&] {
				RwLock::SharedLockScope _(m_InfoLock);
				return m_HealthInfo.AbsLogPath.empty() ? m_HealthInfo.DataRoot / "logs/zenserver.log" : m_HealthInfo.AbsLogPath;
			}();

			ExtendableStringBuilder<4096> Sb;
			if (ReadLogFile(Path.string(), Sb) && Sb.Size() > 0)
			{
				HttpReq.WriteResponse(HttpResponseCode::OK, HttpContentType::kText, Sb.ToView());
			}
			else
			{
				HttpReq.WriteResponse(HttpResponseCode::NotFound);
			}
		},
		HttpVerb::kGet);

	m_Router.RegisterRoute(
		"version",
		[this](HttpRouterRequest& RoutedReq) {
			HttpServerRequest& HttpReq = RoutedReq.ServerRequest();
			if (HttpReq.GetQueryParams().GetValue("detailed") == "true")
			{
				HttpReq.WriteResponse(HttpResponseCode::OK, HttpContentType::kText, ZEN_CFG_VERSION_BUILD_STRING_FULL);
			}
			else
			{
				HttpReq.WriteResponse(HttpResponseCode::OK, HttpContentType::kText, ZEN_CFG_VERSION);
			}
		},
		HttpVerb::kGet);
}

void
HttpHealthService::SetHealthInfo(HealthServiceInfo&& Info)
{
	RwLock::ExclusiveLockScope _(m_InfoLock);
	m_HealthInfo = std::move(Info);
}

const char*
HttpHealthService::BaseUri() const
{
	return "/health/";
}

void
HttpHealthService::HandleRequest(HttpServerRequest& Request)
{
	if (!m_Router.HandleRequest(Request))
	{
		Request.WriteResponse(HttpResponseCode::OK, HttpContentType::kText, u8"OK!"sv);
	}
}

}  // namespace zen