// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.

#pragma once

struct ECollectionVersion
{
	enum Type
	{
		_ZeroVersion = 0,

		/** The initial version for collection files */
		Initial,

		/** 
		 * Added GUIDs to collections to allow them to be used as a parent of another collection without relying on their name/share-type combo
		 * Collections that are older than this version must be re-saved before they can be used as a parent for another collection
		 */
		AddedCollectionGuid,

		/** -----<new versions can be added before this line>------------------------------------------------- */
		_AutomaticVersionPlusOne,
		CurrentVersion = _AutomaticVersionPlusOne - 1
	};
};

enum class ECollectionCloneMode : uint8
{
	/** Clone this collection exactly as it is now, preserving its existing GUID data */
	Exact,
	/** Clone this collection, but make sure it gets unique GUIDs */
	Unique,
};

/** A class to represent a collection of assets */
class FCollection
{
public:
	FCollection(const FString& InFilename, bool InUseSCC);

	/** Clone this collection to a new location */
	TSharedRef<FCollection> Clone(const FString& InFilename, bool InUseSCC, ECollectionCloneMode InCloneMode) const;

	/** Loads content from the SourceFilename into this collection. If false, OutError is a human readable warning depicting the error. */
	bool Load(FText& OutError);
	/** Saves this collection to SourceFilename. If false, OutError is a human readable warning depicting the error. */
	bool Save(FText& OutError);
	/** Deletes the source file for this collection. If false, OutError is a human readable warning depicting the error. */
	bool DeleteSourceFile(FText& OutError);

	/** Adds a single asset to the collection. Static collections only. */
	bool AddAssetToCollection(FName ObjectPath);
	/** Removes a single asset from the collection. Static collections only. */
	bool RemoveAssetFromCollection(FName ObjectPath);
	/** Gets a list of assets in the collection. Static collections only. */
	void GetAssetsInCollection(TArray<FName>& Assets) const;
	/** Gets a list of classes in the collection. Static collections only. */
	void GetClassesInCollection(TArray<FName>& Classes) const;
	/** Gets a list of objects in the collection. Static collections only. */
	void GetObjectsInCollection(TArray<FName>& Objects) const;
	/** Returns true when the specified object is in the collection. Static collections only. */
	bool IsObjectInCollection(FName ObjectPath) const;

	/** Returns true if the collection contains rules instead of a flat list */
	bool IsDynamic() const;

	/** Whether the collection has any contents */
	bool IsEmpty() const;

	/** Logs the contents of the collection */
	void PrintCollection() const;

	/** Returns the name of the collection */
	FORCEINLINE const FName& GetCollectionName() const { return CollectionName; }

	/** Returns the GUID of the collection */
	FORCEINLINE const FGuid& GetCollectionGuid() const { return CollectionGuid; }

	/** Returns the GUID of the collection we are parented under */
	FORCEINLINE const FGuid& GetParentCollectionGuid() const { return ParentCollectionGuid; }

	/** Set the GUID of the collection we are parented under */
	FORCEINLINE void SetParentCollectionGuid(const FGuid& NewGuid) { ParentCollectionGuid = NewGuid; }

	/** Returns the file version of the collection */
	FORCEINLINE ECollectionVersion::Type GetCollectionVersion() const { return FileVersion; }

private:
	/** Generates the header pairs for the collection file. */
	void SaveHeaderPairs(TMap<FString,FString>& OutHeaderPairs) const;

	/** 
	  * Processes header pairs from the top of a collection file.
	  *
	  * @param InHeaderPairs The header pairs found at the start of a collection file
	  * @return true if the header was valid and loaded properly
	  */
	bool LoadHeaderPairs(const TMap<FString,FString>& InHeaderPairs);

	/** Merges the assets from the specified collection with this collection */
	void MergeWithCollection(const FCollection& Other);
	/** Gets the object differences between collections A and B */
	void GetObjectDifferencesFromDisk(TArray<FName>& ObjectsAdded, TArray<FName>& ObjectsRemoved);
	/** Checks the shared collection out from source control so it may be saved. If false, OutError is a human readable warning depicting the error. */
	bool CheckoutCollection(FText& OutError);
	/** Checks the shared collection in to source control after it is saved. If false, OutError is a human readable warning depicting the error. */
	bool CheckinCollection(FText& OutError);
	/** Reverts the collection in the event that the save was not successful. If false, OutError is a human readable warning depicting the error.*/
	bool RevertCollection(FText& OutError);
	/** Marks the source file for delete in source control. If false, OutError is a human readable warning depicting the error. */
	bool DeleteFromSourceControl(FText& OutError);

private:
	/** Snapshot data for a collection. Used to take snapshots and provide a diff message */
	struct FCollectionSnapshot
	{
		void TakeSnapshot(const FCollection& InCollection)
		{
			ParentCollectionGuid = InCollection.ParentCollectionGuid;
			ObjectSet = InCollection.ObjectSet;
		}

		/** The GUID of the collection we are parented under */
		FGuid ParentCollectionGuid;

		/** The set of objects in the collection. Takes the form PackageName.AssetName */
		TSet<FName> ObjectSet;
	};

	/** The name of the collection */
	FName CollectionName;

	/** The GUID of the collection */
	FGuid CollectionGuid;

	/** The GUID of the collection we are parented under */
	FGuid ParentCollectionGuid;

	/** Source control is used if true */
	bool bUseSCC;

	/** The filename used to load this collection. Empty if it is new or never loaded from disk. */
	FString SourceFilename;

	/** The set of objects in the collection. Takes the form PackageName.AssetName */
	TSet<FName> ObjectSet;

	/** The file version for this collection */
	ECollectionVersion::Type FileVersion;

	/** The state of the collection the last time it was loaded from or saved to disk. */
	FCollectionSnapshot DiskSnapshot;
};