PSTCollectionViewUpdateItem.m

//
//  PSTCollectionViewUpdateItem.m
//  PSPDFKit
//
//  Copyright (c) 2012-2013 Peter Steinberger. All rights reserved.
//  Contributed by Sergey Gavrilyuk.
//

#import "PSTCollectionViewUpdateItem.h"
#import "NSIndexPath+PSTCollectionViewAdditions.h"

@interface PSTCollectionViewUpdateItem () {
    NSIndexPath *_initialIndexPath;
    NSIndexPath *_finalIndexPath;
    PSTCollectionUpdateAction _updateAction;
    id _gap;
}
@end

@implementation PSTCollectionViewUpdateItem

@synthesize updateAction = _updateAction;
@synthesize indexPathBeforeUpdate = _initialIndexPath;
@synthesize indexPathAfterUpdate = _finalIndexPath;

- (id)initWithInitialIndexPath:(NSIndexPath *)initialIndexPath finalIndexPath:(NSIndexPath *)finalIndexPath updateAction:(PSTCollectionUpdateAction)updateAction {
    if ((self = [super init])) {
        _initialIndexPath = initialIndexPath;
        _finalIndexPath = finalIndexPath;
        _updateAction = updateAction;
    }
    return self;
}

- (id)initWithAction:(PSTCollectionUpdateAction)updateAction forIndexPath:(NSIndexPath *)indexPath {
    if (updateAction == PSTCollectionUpdateActionInsert)
        return [self initWithInitialIndexPath:nil finalIndexPath:indexPath updateAction:updateAction];
    else if (updateAction == PSTCollectionUpdateActionDelete)
        return [self initWithInitialIndexPath:indexPath finalIndexPath:nil updateAction:updateAction];
    else if (updateAction == PSTCollectionUpdateActionReload)
        return [self initWithInitialIndexPath:indexPath finalIndexPath:indexPath updateAction:updateAction];

    return nil;
}

- (id)initWithOldIndexPath:(NSIndexPath *)oldIndexPath newIndexPath:(NSIndexPath *)newIndexPath {
    return [self initWithInitialIndexPath:oldIndexPath finalIndexPath:newIndexPath updateAction:PSTCollectionUpdateActionMove];
}

- (NSString *)description {
    NSString *action = nil;
    switch (_updateAction) {
        case PSTCollectionUpdateActionInsert: action = @"insert"; break;
        case PSTCollectionUpdateActionDelete: action = @"delete"; break;
        case PSTCollectionUpdateActionMove:   action = @"move";   break;
        case PSTCollectionUpdateActionReload: action = @"reload"; break;
        default: break;
    }

    return [NSString stringWithFormat:@"Index path before update (%@) index path after update (%@) action (%@).",  _initialIndexPath, _finalIndexPath, action];
}

- (void)setNewIndexPath:(NSIndexPath *)indexPath {
    _finalIndexPath = indexPath;
}

- (void)setGap:(id)gap {
    _gap = gap;
}

- (BOOL)isSectionOperation {
    return (_initialIndexPath.item == NSNotFound || _finalIndexPath.item == NSNotFound);
}

- (NSIndexPath *)newIndexPath {
    return _finalIndexPath;
}

- (id)gap {
    return _gap;
}

- (PSTCollectionUpdateAction)action {
    return _updateAction;
}

- (id)indexPath {
    //TODO: check this
    return _initialIndexPath;
}

- (NSComparisonResult)compareIndexPaths:(PSTCollectionViewUpdateItem *)otherItem {
    NSComparisonResult result = NSOrderedSame;
    NSIndexPath *selfIndexPath = nil;
    NSIndexPath *otherIndexPath = nil;

    switch (_updateAction) {
        case PSTCollectionUpdateActionInsert:
            selfIndexPath = _finalIndexPath;
            otherIndexPath = [otherItem newIndexPath];
            break;
        case PSTCollectionUpdateActionDelete:
            selfIndexPath = _initialIndexPath;
            otherIndexPath = [otherItem indexPath];
        default: break;
    }

    if (self.isSectionOperation) result = [@(selfIndexPath.section) compare:@(otherIndexPath.section)];
    else result = [selfIndexPath compare:otherIndexPath];
    return result;
}

- (NSComparisonResult)inverseCompareIndexPaths:(PSTCollectionViewUpdateItem *)otherItem {
    return (NSComparisonResult)([self compareIndexPaths:otherItem] * -1);
}

@end