//
//  RAPhotoLayout.m
//  Apex And Drivers
//
//  Created by Jack on 2018/10/30.
//  Copyright © 2018年 USAI. All rights reserved.
//

#import "RAPhotoLayout.h"

@interface RAPhotoLayout ()

@property (nonatomic,strong) NSArray *attrs;

@end

@implementation RAPhotoLayout

// 漏写了此方法，导致cell没显示。😓
- (CGSize)collectionViewContentSize {
    return [self contentSize];
}

- (CGSize)contentSize {
    
    CGFloat height = 0;
    if (self.delegate) {
        height = [self.delegate layoutContentHeight];
    }
    CGSize size = CGSizeMake(self.collectionView.frame.size.width, height);
    return size;
}

- (void)prepareLayout {
    
    if (self.delegate) {
        self.attrs = [self.delegate prepareLayout];
    }
}

- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect {
    
    __block NSMutableArray *attrsArr = [NSMutableArray array];
    [self.attrs enumerateObjectsUsingBlock:^(UICollectionViewLayoutAttributes *  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        if (CGRectIntersectsRect(rect, obj.frame)) {
            [attrsArr addObject:obj];
        }
    }];
    
    return attrsArr;
}

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewLayoutAttributes *itemtAttrs = [self.attrs objectAtIndex:indexPath.row];
    return itemtAttrs;
}

- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds {
    CGRect oldBounds = self.collectionView.bounds;
    if (!CGSizeEqualToSize(newBounds.size, oldBounds.size)) {
        return YES;
    }
    return NO;
}

@end