#import "CorePullScaleImageView.h"
#define iOS8 ([UIDevice currentDevice].systemVersion.floatValue>=8.0f)

static NSString *const CorePullScaleContentOffset = @"contentOffset";

@interface CorePullScaleImageView (){
    
    UIEdgeInsets                                            _originalContentInset;
    
    CGFloat                                                 _navBarH;
}


@property (nonatomic, weak) UIScrollView *scrollView;
@property(nonatomic, strong)UIImageView *backView;


@end

@implementation CorePullScaleImageView



- (instancetype)init
{
    self = [super init];
    if (self) {
        self.userInteractionEnabled = YES;
        [self pullScaleImageViewPrepare];
    }
    return self;
}

- (UIImageView*)backView {
    if (!_backView) {//【需求】话题卡片视觉调整(BUG:4341)
        _backView = [[UIImageView alloc]initWithFrame:self.bounds];
//        _backView.backgroundColor = [UIColor colorWithHexString:@"0x1b3053"];
        _backView.image = Image(@"topic/topYaAn.png");
//        _backView.alpha = 0.4;
        _backView.autoresizingMask = AutoresizingFull;
    }
    return _backView;
}


-(void)pullScaleImageViewPrepare{
    
    self.imageView.contentMode=UIViewContentModeScaleAspectFill;
    
    self.clipsToBounds=YES;
    
    [self addSubview:self.backView];
}


-(void)willMoveToSuperview:(UIView *)newSuperview{
    [super willMoveToSuperview:newSuperview];
    
    [self.superview removeObserver:self forKeyPath:CorePullScaleContentOffset context:nil];
    
    if (newSuperview) {
        [newSuperview addObserver:self forKeyPath:CorePullScaleContentOffset options:NSKeyValueObservingOptionNew context:nil];

        _scrollView = (UIScrollView *)newSuperview;
        
        _scrollView.alwaysBounceVertical = YES;
        
        if(_hasNavBar) _navBarH=64.0f;
    }
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if (self.alpha <= 0.01 || self.hidden) return;
    
    if ([CorePullScaleContentOffset isEqualToString:keyPath]) {
        [self adjustStateWithContentOffset];
    }
}


- (void)adjustStateWithContentOffset
{
    
    CGFloat y=_scrollView.contentOffset.y + _originalHeight + _navBarH;
        
    if(y>=0) {
        return;
    }
    
    CGRect frame=self.frame;
    frame.origin.y=-_originalHeight + y ;
    frame.size.height=_originalHeight - y;
    self.frame=frame;
    self.backView.frame = self.bounds;
}



-(void)didMoveToSuperview{
    
    [super didMoveToSuperview];
    
    CGFloat h=_originalHeight;
    
    CGFloat y=-h;
    
    CGFloat w=1230/2;

    CGRect frame=CGRectMake(CGRectGetWidth(_scrollView.bounds)/2-1230/4, y, w, h);

    self.frame=frame;
    self.backView.frame = self.bounds;
}




@end