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

#pragma once

#include "Containers/Array.h"
#include "Containers/Map.h"
#include "HAL/Platform.h"
#include "HAL/CriticalSection.h"
#include "Containers/UnrealString.h"

#define UE_API INDEXEDCACHESTORAGE_API

namespace Experimental
{

// Manager to handle ref-counting of ICS entries
class FIndexedCacheStorageManager
{
public:

	UE_API static FIndexedCacheStorageManager& Get();

	// Returns whether ICS is supported
	UE_API bool SupportsIndexedCacheStorage();

	// Returns the cache index registered to that storage name. Registration happens in the config section:
	// [IndexedCacheStorage]
	// (Name="StorageName",Index=StorageIndex,Mount="StorageMount")
	UE_API int32 GetStorageIndex(const FString& CacheStorageName);

	// returns all registered storage names. The assoaciated cache storages might not have been created
	UE_API void EnumerateCacheStorages(TArray<FString>& OutCacheStorageNames);

	// Create a new storage at the specified index. Will destroy the previous one if it had a different capacity
	UE_API bool CreateCacheStorage(uint64 RequestNumberOfBytes, int32 CacheIndex);
	
	// Destroy the specified cache storage
	UE_API void DestroyCacheStorage(int32 CacheIndex);
	
	// Returns 0 if no cache currently exists
	UE_API uint64 GetCacheStorageCapacity(int32 CacheIndex);

	// Returns the path of the mounted cache
	UE_API FString MountCacheStorage(int32 CacheIndex);

	// Requests unmounting for CacheIndex. Actually unmounts if # of UnmountCacheEntry == # of MountCacheStorage for the same index
	UE_API void UnmountCacheStorage(int32 CacheIndex);

	// Returns mount name in cache index is mounted, empty if not mounted
	UE_API FString GetMountName(int32 CacheIndex);

	// Helper to retrieve the mount path. Equivalent to GetCacheStorageMountPath(GetMountName)
	UE_API FString GetMountPath(int32 CacheIndex);

private:

	void Initialize();

	FRWLock IndexedCacheEntriesMetaDataLock;

	struct FCacheStorageMetaData
	{
		FString MountName;
		int32 MountRefCount = 0;
		bool bCacheExists = false;
	};
	TArray<FCacheStorageMetaData> IndexedCacheEntriesMetaData;
	TMap<FString, int32> StorageNameToStorageIndex;
	bool bHasRegisteredEntries = false;
};

struct FIndexedCacheStorageScopeMount
{
	FIndexedCacheStorageScopeMount(int32 InMountPoint)
	: MountPoint(InMountPoint)
	{
		MountPath = Experimental::FIndexedCacheStorageManager::Get().MountCacheStorage(MountPoint);
	}

	~FIndexedCacheStorageScopeMount()
	{
		Experimental::FIndexedCacheStorageManager::Get().UnmountCacheStorage(MountPoint);
	}

	FString MountPath;
	const int32 MountPoint = 0;
};


}

#undef UE_API