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

#include "storageserverinstance.h"

#include "hydration.h"

#include <zencore/assertfmt.h>
#include <zencore/filesystem.h>
#include <zencore/fmtutils.h>
#include <zencore/logging.h>

namespace zen {

StorageServerInstance::StorageServerInstance(ZenServerEnvironment& RunEnvironment,
											 std::string_view	   ModuleId,
											 std::filesystem::path FileHydrationPath,
											 std::filesystem::path HydrationTempPath)
: m_ModuleId(ModuleId)
, m_ServerInstance(RunEnvironment, ZenServerInstance::ServerMode::kStorageServer)
, m_HydrationPath(FileHydrationPath)
{
	m_BaseDir = RunEnvironment.CreateChildDir(ModuleId);
	m_TempDir = HydrationTempPath / ModuleId;
}

StorageServerInstance::~StorageServerInstance()
{
}

void
StorageServerInstance::SpawnServerProcess()
{
	ZEN_ASSERT_FORMAT(!m_ServerInstance.IsRunning(), "Storage server instance for module '{}' is already running", m_ModuleId);

	m_ServerInstance.SetServerExecutablePath(GetRunningExecutablePath());
	m_ServerInstance.SetDataDir(m_BaseDir);
#if ZEN_PLATFORM_WINDOWS
	m_ServerInstance.SetJobObject(m_JobObject);
#endif
	const uint16_t BasePort = m_ServerInstance.SpawnServerAndWaitUntilReady();

	ZEN_DEBUG("Storage server instance for module '{}' started, listening on port {}", m_ModuleId, BasePort);

	m_ServerInstance.EnableShutdownOnDestroy();
}

void
StorageServerInstance::Provision()
{
	RwLock::ExclusiveLockScope _(m_Lock);

	if (m_IsProvisioned)
	{
		ZEN_WARN("Storage server instance for module '{}' is already provisioned", m_ModuleId);

		return;
	}

	if (m_IsHibernated)
	{
		WakeLocked();
	}
	else
	{
		ZEN_INFO("Provisioning storage server instance for module '{}', at '{}'", m_ModuleId, m_BaseDir);

		Hydrate();

		SpawnServerProcess();
	}

	m_IsProvisioned = true;
}

void
StorageServerInstance::Deprovision()
{
	RwLock::ExclusiveLockScope _(m_Lock);

	if (!m_IsProvisioned)
	{
		ZEN_WARN("Attempted to deprovision storage server instance for module '{}' which is not provisioned", m_ModuleId);

		return;
	}

	ZEN_INFO("Deprovisioning storage server instance for module '{}'", m_ModuleId);

	m_ServerInstance.Shutdown();

	Dehydrate();

	m_IsProvisioned = false;
}

void
StorageServerInstance::Hibernate()
{
	// Signal server to shut down, but keep data around for later wake

	RwLock::ExclusiveLockScope _(m_Lock);

	if (!m_IsProvisioned)
	{
		ZEN_WARN("Attempted to hibernate storage server instance for module '{}' which is not provisioned", m_ModuleId);

		return;
	}

	if (m_IsHibernated)
	{
		ZEN_WARN("Storage server instance for module '{}' is already hibernated", m_ModuleId);

		return;
	}

	if (!m_ServerInstance.IsRunning())
	{
		ZEN_WARN("Attempted to hibernate storage server instance for module '{}' which is not running", m_ModuleId);

		// This is an unexpected state. Should consider the instance invalid?

		return;
	}

	try
	{
		m_ServerInstance.Shutdown();

		m_IsHibernated	= true;
		m_IsProvisioned = false;

		return;
	}
	catch (const std::exception& Ex)
	{
		ZEN_ERROR("Failed to hibernate storage server instance for module '{}': {}", m_ModuleId, Ex.what());
	}
}

void
StorageServerInstance::Wake()
{
	RwLock::ExclusiveLockScope _(m_Lock);
	WakeLocked();
}

void
StorageServerInstance::WakeLocked()
{
	// Start server in-place using existing data

	if (!m_IsHibernated)
	{
		ZEN_WARN("Attempted to wake storage server instance for module '{}' which is not hibernated", m_ModuleId);

		return;
	}

	ZEN_ASSERT_FORMAT(!m_ServerInstance.IsRunning(), "Storage server instance for module '{}' is already running", m_ModuleId);

	try
	{
		SpawnServerProcess();
		m_IsHibernated = false;
	}
	catch (const std::exception& Ex)
	{
		ZEN_ERROR("Failed to wake storage server instance for module '{}': {}", m_ModuleId, Ex.what());

		// TODO: this instance should be marked as invalid
	}
}

void
StorageServerInstance::Hydrate()
{
	HydrationConfig Config{.ServerStateDir		= m_BaseDir,
						   .TempDir				= m_TempDir,
						   .ModuleId			= m_ModuleId,
						   .TargetSpecification = WideToUtf8(m_HydrationPath.native())};

	std::unique_ptr<HydrationStrategyBase> Hydrator = CreateFileHydrator();

	Hydrator->Configure(Config);
	Hydrator->Hydrate();
}

void
StorageServerInstance::Dehydrate()
{
	HydrationConfig Config{.ServerStateDir		= m_BaseDir,
						   .TempDir				= m_TempDir,
						   .ModuleId			= m_ModuleId,
						   .TargetSpecification = WideToUtf8(m_HydrationPath.native())};

	std::unique_ptr<HydrationStrategyBase> Hydrator = CreateFileHydrator();

	Hydrator->Configure(Config);
	Hydrator->Dehydrate();
}

}  // namespace zen