//  Copyright 2004-present Facebook. All Rights Reserved.

#import <UIKit/UIKit.h>
#import <AsyncDisplayKit/ASDealloc2MainObject.h>

/**
 Enable the data fetching in async mode.

 If enabled, we will fetch data through `dataController:nodeAtIndexPath:` and `dataController:rowsInSection:` in background thread.
 Otherwise, the methods will be invoked synchronically in calling thread.

 Enabling data fetching in async mode could avoid blocking main thread while allocating cell on main thread, which is frequently reported
 issue for handing large scale data. On another hand, the application code will take the responsibility to avoid data inconsistence. 
 Specifically, we will lock the data source through `dataControllerLockDataSourceForDataUpdating`, and unlock it by `dataControllerUnlockDataSourceForDataUpdating`
 after the data fetching. The application should not update the data source while the data source is locked.
 */
#define ENABLE_ASYNC_DATA_FETCHING 1

@class ASCellNode;
@class ASDataController;

typedef NSUInteger ASDataControllerAnimationOptions;

/**
 Data source for data controller
 It will be invoked in the same thread as the api call of ASDataController.
 */
@protocol ASDataControllerSource <NSObject>

/**
 Fetch the ASCellNode for specific index path.
 */
- (ASCellNode *)dataController:(ASDataController *)dataController nodeAtIndexPath:(NSIndexPath *)indexPath;

/**
 The constrained size for layout.
 */
- (CGSize)dataController:(ASDataController *)dataController constrainedSizeForNodeAtIndexPath:(NSIndexPath *)indexPath;

/**
 Fetch the number of rows in specific section.
 */
- (NSUInteger)dataController:(ASDataController *)dataController rowsInSection:(NSUInteger)section;

/**
 Fetch the number of sections.
 */
- (NSUInteger)dataControllerNumberOfSections:(ASDataController *)dataController;

/**
 Lock the data source for data fetching.
 */
- (void)dataControllerLockDataSourceForDataUpdating;

/**
 Unlock the data source after data fetching.
 */
- (void)dataControllerUnlockDataSourceForDataUpdating;

@end

/**
 Delegate for notify the data updating of data controller.
 These methods will be invoked from main thread right now, but it may be moved to background thread in the future.
 */
@protocol ASDataControllerDelegate <NSObject>

@optional

/**
 Called for batch update.
 */
- (void)dataControllerBeginUpdates:(ASDataController *)dataController;
- (void)dataControllerEndUpdates:(ASDataController *)dataController completion:(void (^)(BOOL))completion;

/**
 Called for insertion of elements.
 */
- (void)dataController:(ASDataController *)dataController willInsertNodes:(NSArray *)nodes atIndexPaths:(NSArray *)indexPaths withAnimationOption:(ASDataControllerAnimationOptions)animationOption;
- (void)dataController:(ASDataController *)dataController didInsertNodes:(NSArray *)nodes atIndexPaths:(NSArray *)indexPaths withAnimationOption:(ASDataControllerAnimationOptions)animationOption;

/**
 Called for deletion of elements.
 */
- (void)dataController:(ASDataController *)dataController willDeleteNodesAtIndexPaths:(NSArray *)indexPaths withAnimationOption:(ASDataControllerAnimationOptions)animationOption;
- (void)dataController:(ASDataController *)dataController didDeleteNodesAtIndexPaths:(NSArray *)indexPaths withAnimationOption:(ASDataControllerAnimationOptions)animationOption;

/**
 Called for insertion of sections.
 */
- (void)dataController:(ASDataController *)dataController willInsertSections:(NSArray *)sections atIndexSet:(NSIndexSet *)indexSet withAnimationOption:(ASDataControllerAnimationOptions)animationOption;
- (void)dataController:(ASDataController *)dataController didInsertSections:(NSArray *)sections atIndexSet:(NSIndexSet *)indexSet withAnimationOption:(ASDataControllerAnimationOptions)animationOption;

/**
 Called for deletion of sections.
 */
- (void)dataController:(ASDataController *)dataController willDeleteSectionsAtIndexSet:(NSIndexSet *)indexSet withAnimationOption:(ASDataControllerAnimationOptions)animationOption;
- (void)dataController:(ASDataController *)dataController didDeleteSectionsAtIndexSet:(NSIndexSet *)indexSet withAnimationOption:(ASDataControllerAnimationOptions)animationOption;

@end


/**
 * Controller to layout data in background, and managed data updating.
 *
 * All operations are asynchronous and thread safe. You can call it from background thread (it is recommendated) and the data
 * will be updated asynchronously. The dataSource must be updated to reflect the changes before these methods has been called.
 * For each data updatin, the corresponding methods in delegate will be called.
 */
@interface ASDataController : ASDealloc2MainObject

/**
 Data source for fetching data info.
 */
@property (nonatomic, weak) id<ASDataControllerSource> dataSource;

/**
 Delegate to notify when data is updated.
 */
@property (nonatomic, weak) id<ASDataControllerDelegate> delegate;

/** @name Initial loading */

- (void)initialDataLoadingWithAnimationOption:(ASDataControllerAnimationOptions)animationOption;

/** @name Data Updating */

- (void)beginUpdates;

- (void)endUpdates;

- (void)endUpdatesWithCompletion:(void (^)(BOOL))completion;

- (void)insertSections:(NSIndexSet *)sections withAnimationOption:(ASDataControllerAnimationOptions)animationOption;

- (void)deleteSections:(NSIndexSet *)sections withAnimationOption:(ASDataControllerAnimationOptions)animationOption;;

- (void)reloadSections:(NSIndexSet *)sections withAnimationOption:(ASDataControllerAnimationOptions)animationOption;

- (void)moveSection:(NSInteger)section toSection:(NSInteger)newSection withAnimationOption:(ASDataControllerAnimationOptions)animationOption;;

- (void)insertRowsAtIndexPaths:(NSArray *)indexPaths withAnimationOption:(ASDataControllerAnimationOptions)animationOption;

- (void)deleteRowsAtIndexPaths:(NSArray *)indexPaths withAnimationOption:(ASDataControllerAnimationOptions)animationOption;

- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withAnimationOption:(ASDataControllerAnimationOptions)animationOption;

- (void)moveRowAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath withAnimationOption:(ASDataControllerAnimationOptions)animationOption;;

- (void)reloadDataWithAnimationOption:(ASDataControllerAnimationOptions)animationOption;;

/** @name Data Querying */

- (NSUInteger)numberOfSections;

- (NSUInteger)numberOfRowsInSection:(NSUInteger)section;

- (ASCellNode *)nodeAtIndexPath:(NSIndexPath *)indexPath;

- (NSArray *)nodesAtIndexPaths:(NSArray *)indexPaths;

@end