Code

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

#pragma once

#include "CoreMinimal.h"
#include "Modules/ModuleInterface.h"

class IOnlineSubsystem;

typedef TSharedPtr<class IOnlineSubsystem, ESPMode::ThreadSafe> IOnlineSubsystemPtr;


/**
 * Online subsystem module class
 * Wraps the loading of an online subsystem by name and allows new services to register themselves for use
 */
class FOnlineSubsystemModule : public IModuleInterface
{
private:

	/** Name of the default online service requested
	 * Specified in DefaultEngine.ini
	 *	[OnlineSubsystem]
	 *	DefaultPlatformService
	 */
	FName DefaultPlatformService;

	/**
	 * Name of the online service associated with the native platform
	 * Specified in Base<Platform>Engine.ini
	 *	[OnlineSubsystem]
	 *	NativePlatformService
	 */
	FName NativePlatformService;

	/**
	* Name of the online service associated with User Defined strings
	* Specified in Base<Platform>Engine.ini
	*	[OnlineSubsystem]
	*	ConfigDefinedPlatformServices
	*/
	TMap<FString, FName> ConfigDefinedSubsystems;

	/** Existing instances of any online subsystems created <PlatformName:InstanceName> */
	TMap<FName, class IOnlineFactory*> OnlineFactories;

	/** Mapping of all currently loaded platform service subsystems to their name */
	TMap<FName, IOnlineSubsystemPtr> OnlineSubsystems;

	/** Have we warned already for a given online subsystem creation failure */
	TMap<FName, bool> OnlineSubsystemFailureNotes;

	/** Config driven override of module name for online subsystem */
	TMap<FString, FName> ModuleRedirects;

	/**
	 * Transform an online subsystem identifier into its Subsystem and Instance constituents
	 *
	 * accepts the following forms:
	 * <subsystem name>:<instance name> -> subsystem name / instance name
	 * :<instance name>					-> default subsystem / instance name
	 * <subsystem name>:				-> subsystem name / default instance
	 * <subsystem name>					-> subsystem name / default instance
	 * <nothing>						-> default subsystem / default instance
	 *
	 * @param FullName full name of the subsystem and instance that is being referenced
	 * @param SubsystemName parsed out value or default subsystem name
	 * @param InstanceName parsed out value or default instance name
	 *
	 * @return Properly formatted key name for accessing the online subsystem in the TMap
	 */
	FName ParseOnlineSubsystemName(const FName& FullName, FName& SubsystemName, FName& InstanceName) const;

	/**
	 * Read any config defined subsystems from the configuration file
	 */
	void ProcessConfigDefinedSubsystems();

	/**
	 * Read any config defined subsystem module overrides from the configuration file
	 */
	void ProcessConfigDefinedModuleRedirects();

	/**
	 * Attempt to load the default subsystem specified in the configuration file
	 */
	bool TryLoadSubsystemAndSetDefault(FName ModuleName);

	/**
	 * Attempt to load the default subsystem specified in the configuration file
	 */
	void LoadDefaultSubsystem();

	/**
	 *	Called before ShutdownOnlineSubsystem, before other modules have been unloaded
	 */
	virtual void PreUnloadOnlineSubsystem();

	/**
	 *	Shuts down all registered online subsystem platforms and unloads their modules
	 */
	virtual void ShutdownOnlineSubsystem();

public:

	FOnlineSubsystemModule() :
		DefaultPlatformService(NAME_None)
	{}
	virtual ~FOnlineSubsystemModule() {}

	/**
	 * Main entry point for accessing an online subsystem by name
	 * Will load the appropriate module if the subsystem isn't currently loaded
	 * It's possible that the subsystem doesn't exist and therefore can return NULL
	 *
	 * @param InSubsystemName - name of subsystem as referenced by consumers
	 *
	 * @return Requested online subsystem, or NULL if that subsystem was unable to load or doesn't exist
	 */
	virtual IOnlineSubsystem* GetOnlineSubsystem(const FName InSubsystemName = NAME_None);

	/**
	 * Get the online subsystem native to the current hardware
	 *
	 * @param bAutoLoad - load the module if not already loaded
	 *
	 * @return pointer to the appropriate online subsystem
	 */
	virtual IOnlineSubsystem* GetNativeSubsystem(bool bAutoLoad);

	/**
	 * Get the online subsystem associated with the given config string
	 *
	 * @param ConfigString - Key to query for
	 * @param bAutoLoad - load the module if not already loaded
	 *
	 * @return pointer to the appropriate online subsystem
	 */
	virtual IOnlineSubsystem* GetSubsystemByConfig(const FString& ConfigString, bool bAutoLoad);

	/**
	 * Destroys an online subsystem created internally via access with GetOnlineSubsystem
	 * Typically destruction of the subsystem is handled at application exit, but
	 * there may be rare instances where the subsystem is destroyed by request
	 *
	 * @param InSubsystemName - name of subsystem as referenced by consumers
	 */
	virtual void DestroyOnlineSubsystem(const FName InSubsystemName);

	/**
	 * Does an instance of subsystem with the given name exist
	 *
	 * @return true if the instance exists, false otherwise
	 */
	ONLINESUBSYSTEM_API "bool DoesInstanceExist(const FName InSubsystemName) const;

	/**
	 * Determine if a subsystem is loaded by the OSS module
	 *
	 * @param SubsystemName - name of subsystem as referenced by consumers
	 * @return true if module for the subsystem is loaded
	 */
	virtual bool IsOnlineSubsystemLoaded(const FName InSubsystemName) const;

	/**
	 * Register a new online subsystem interface with the base level factory provider
	 * @param FactoryName - name of subsystem as referenced by consumers
	 * @param Factory - instantiation of the online subsystem interface, this will take ownership
	 */
	virtual void RegisterPlatformService(const FName FactoryName, class IOnlineFactory* Factory);

	/**
	 * Unregister an existing online subsystem interface from the base level factory provider
	 * @param FactoryName - name of subsystem as referenced by consumers
	 */
	virtual void UnregisterPlatformService(const FName FactoryName);

	/**
	 * Enumerate all loaded online subsystems
	 *
	 * @param EnumCb functor to call for each online subsystem
	 */
	typedef TFunction<void(IOnlineSubsystem*)> FEnumerateOnlineSubsystemCb;
	void ONLINESUBSYSTEM_API EnumerateOnlineSubsystems(FEnumerateOnlineSubsystemCb& EnumCb);

	/**
	 * Shutdown the current default subsystem (may be the fallback) and attempt to reload the one
	 * specified in the configuration file
	 *
	 * **NOTE** This is intended for editor use only, attempting to use this at the wrong time can result
	 * in unexpected crashes/behavior
	 */
	void ONLINESUBSYSTEM_API ReloadDefaultSubsystem();

	// IModuleInterface

	/**
	 * Called right after the module DLL has been loaded and the module object has been created
	 * Overloaded to allow the default subsystem a chance to load
	 */
	virtual void StartupModule() override;

	/**
	 * Called before the module has been unloaded
	 * Overloaded to allow online subsystems to cancel any outstanding http requests
	 */
	virtual void PreUnloadCallback() override;

	/**
	 * Called before the module is unloaded, right before the module object is destroyed.
	 * Overloaded to shut down all loaded online subsystems
	 */
	virtual void ShutdownModule() override;

	/**
	 * Override this to set whether your module is allowed to be unloaded on the fly
	 *
	 * @return	Whether the module supports shutdown separate from the rest of the engine.
	 */
	virtual bool SupportsDynamicReloading() override
	{
		return false;
	}

	/**
	 * Override this to set whether your module would like cleanup on application shutdown
	 *
	 * @return	Whether the module supports shutdown on application exit
	 */
	virtual bool SupportsAutomaticShutdown() override
	{
		return true;
	}

private:
	// Cached instance names for efficient lookup in ParseOnlineSubsystemName
	struct FInstanceNameEntry
	{
		FName SubsystemName;
		FName InstanceName;
		FName FullPath;
	};
	mutable TMap<FName, FInstanceNameEntry> InstanceNames;
};

/** Public references to the online subsystem module pointer should use this */
typedef TSharedPtr<FOnlineSubsystemModule, ESPMode::ThreadSafe> FOnlineSubsystemModulePtr;