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

#pragma once

#include "HAL/Platform.h"
#include "Containers/StringView.h"
#include "Containers/UnrealString.h"
#include "Dom/JsonObject.h"
#include "Misc/Optional.h"
#include "Misc/TVariant.h"
#include "Policies/PrettyJsonPrintPolicy.h"
#include "Serialization/JsonWriter.h"
#include "Templates/PimplPtr.h"
#include "Templates/UniquePtr.h"
#include "ZenGlobals.h"
#include "Async/Future.h"

#if UE_WITH_ZEN
#	include "ZenStatistics.h"
#endif

#define UE_API ZEN_API

namespace UE::Zen
{

struct FServiceConnectSettings
{
	FString HostName;
	uint16 Port = 1337;
};

struct FServiceAutoLaunchSettings
{
	FString DataPath;
	FString ExtraArgs;
	uint16 DesiredPort = 1337;
	bool bShowConsole = false;
	bool bLimitProcessLifetime = false;
};

struct FServiceSettings
{
	TVariant<FServiceAutoLaunchSettings, FServiceConnectSettings> SettingsVariant;

	inline bool IsAutoLaunch() const { return SettingsVariant.IsType<FServiceAutoLaunchSettings>(); }
	inline bool IsConnectExisting() const { return SettingsVariant.IsType<FServiceConnectSettings>(); }

	UE_API void ReadFromConfig();
	UE_API void ReadFromJson(FJsonObject& JsonObject);
	UE_API void ReadFromURL(FStringView InstanceURL);

	UE_API void WriteToJson(TJsonWriter<TCHAR, TPrettyJsonPrintPolicy<TCHAR>>& Writer) const;

private:
	bool TryApplyAutoLaunchOverride();
};

}

#if UE_WITH_ZEN

namespace UE::Zen
{

class FZenServiceInstance;

/**
 * Type used to declare usage of a Zen server instance whether the shared default instance or a unique non-default instance.
 * Used to help manage launch, and optionally in the future, shutdown a shared default instance.  Use the default constructor
 * to reference the default instance (which may be launched on demand), or use the non-default constructors with a specific
 * URL or HostName/Port pair which is required to pre-exist (will not be auto-launched).
 */
class FScopeZenService
{
public:
	UE_API FScopeZenService();
	UE_API FScopeZenService(FStringView InstanceURL);
	UE_API FScopeZenService(FServiceSettings&& InSettings);
	UE_API ~FScopeZenService();


	UE_API const FZenServiceInstance& GetInstance() const { return *ServiceInstance; }
	UE_API FZenServiceInstance& GetInstance() { return *ServiceInstance; }

private:
	FZenServiceInstance* ServiceInstance;
	TUniquePtr<UE::Zen::FZenServiceInstance> UniqueNonDefaultInstance;
};

/**
 * Gets the default Zen service instance.  The default instance is configured through ZenServiceInstance INI section.
 * The default instance can (depending on configuration):
 *  - Auto-launched on demand (optionally elevated on Windows)
 *  - Be copied out of the workspace tree before execution
 *  - Shared between multiple tools running concurrently (implemented by launching multiple instances and expecting them to communicate and shutdown as needed)
 *  - Instigate self-shutdown when all processes that requested it have terminated
 *  - Use a subdirectory of the existing local DDC cache path as Zen's data path
 *  - Use an upstream Zen service
 *  - Be overridden by commandline arguments to reference an existing running instance instead of auto-launching a new instance.
 * Note that no assumptions should be made about the hostname/port of the default instance.  Calling code should instead expect
 * that the instance is authoritative over the hostname/port that it will end up using and should query that information from the
 * instance as needed.
 */
UE_API FZenServiceInstance& GetDefaultServiceInstance();
UE_API bool IsDefaultServicePresent();

/**
 * A representation of a Zen service instance.  Generally not accessed directly, but via FScopeZenService.
 */
class FZenServiceInstance
{
public:

	UE_API FZenServiceInstance();
	UE_API FZenServiceInstance(FStringView InstanceURL);
	UE_API FZenServiceInstance(FServiceSettings&& InSettings);
	UE_API ~FZenServiceInstance();

	inline const TCHAR* GetURL() const { return *URL; }
	inline const TCHAR* GetHostName() const { return *HostName; }
	inline uint16 GetPort() const { return Port; }
	inline const FServiceSettings& GetServiceSettings() const { return Settings; }
	UE_API bool GetStats(FZenStats& Stats);
	UE_API bool IsServiceRunning();
	UE_API bool IsServiceReady();
	UE_API bool IsServiceRunningLocally() const { return bIsRunningLocally; }

	static UE_API uint16 GetAutoLaunchedPort();

private:

	void Initialize();
	void PromptUserToStopRunningServerInstance(const FString& ServerFilePath);
	FString ConditionalUpdateLocalInstall();
	static bool AutoLaunch(const FServiceAutoLaunchSettings& InSettings, FString&& ExecutablePath, FString& OutHostName, uint16& OutPort);

	mutable TPimplPtr<class FZenHttpRequest> StatsHttpRequest;
	mutable TFuture<FZenStats> StatsRequest;
	mutable FZenStats LastStats;
	mutable uint64 LastStatsTime = 0;

	FServiceSettings Settings;
	FString URL;
	FString HostName;
	uint16 Port;
	static uint16 AutoLaunchedPort;
	bool bHasLaunchedLocal = false;
	bool bIsRunningLocally = true;
};

} // namespace UE::Zen

#endif // UE_WITH_ZEN

#undef UE_API