#import "NNDiffReloader.h"

#import "NNSectionsDiffChange.h"

@implementation NNDiffReloader

#pragma mark - Public

- (void)reloadWithSectionsDiff:(NNSectionsDiff *)diff

options:(NNDiffReloadOptions *)options

completion:(void (^)())completion

{

NSParameterAssert(diff != nil);

NSParameterAssert(options != nil);

if ([diff isEqual:[[NNSectionsDiff alloc] init]]) {

if (completion) {

completion();

}

return;

}

[self performUpdates:^{

[self deleteSections:diff.deletedSections];

[self insertSections:diff.insertedSections];

[self deleteItemsAtIndexPaths:[diff.deleted allObjects]];

[self insertItemsAtIndexPaths:[diff.inserted allObjects]];

for (NNSectionsDiffChange *change in diff.changed) {

if (change.type & NNDiffChangeUpdate) {

if (options.useUpdateBlockForReload) {

[self updateItemsAtIndexPaths:@[ change.before ]];

} else {

[self reloadItemsAtIndexPaths:@[ change.before ]];

}

}

if (change.type & NNDiffChangeMove) {

if (options.useMoveIfPossible) {

[self moveItemAtIndexPath:change.before toIndexPath:change.after];

} else {

[self deleteItemsAtIndexPaths:@[ change.before ]];

[self insertItemsAtIndexPaths:@[ change.after ]];

}

}

}

} withOptions:options completion:completion];

}

#pragma mark - Abstract

#define methodNotImplemented() \

@throw [NSException exceptionWithName:NSInternalInconsistencyException \

reason:[NSString stringWithFormat:@"You must override %@ in a subclass.", NSStringFromSelector(_cmd)] \

userInfo:nil]

- (void)performUpdates:(void (^)())updates withOptions:(NNDiffReloadOptions *)options completion:(void (^)())completion { methodNotImplemented(); }

- (void)insertSections:(NSIndexSet *)sections { methodNotImplemented(); }

- (void)deleteSections:(NSIndexSet *)sections { methodNotImplemented(); }

- (void)insertItemsAtIndexPaths:(NSArray *)indexPaths { methodNotImplemented(); }

- (void)deleteItemsAtIndexPaths:(NSArray *)indexPaths { methodNotImplemented(); }

- (void)reloadItemsAtIndexPaths:(NSArray *)indexPaths { methodNotImplemented(); }

- (void)updateItemsAtIndexPaths:(NSArray *)indexPaths { methodNotImplemented(); }

- (void)moveItemAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath { methodNotImplemented(); }