//
//  JXBannerView.m
//  AICity
//
//  Banner 轮播组件实现
//

#import "JXBannerView.h"
#import <SDWebImage/SDWebImage.h>
#import <Masonry/Masonry.h>

static const NSTimeInterval kAutoScrollInterval = 5.0;  // 5秒自动滚动
static NSString * const kBannerCellIdentifier = @"BannerCell";

@interface JXBannerCell : UICollectionViewCell
@property (nonatomic, strong) UIImageView *imageView;
@property (nonatomic, strong) UILabel *titleLabel;
@end

@implementation JXBannerCell

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        self.imageView = [[UIImageView alloc] init];
        self.imageView.contentMode = UIViewContentModeScaleAspectFill;
        self.imageView.clipsToBounds = YES;
        [self.contentView addSubview:self.imageView];
        
        self.titleLabel = [[UILabel alloc] init];
        self.titleLabel.textColor = [UIColor whiteColor];
        self.titleLabel.font = [UIFont boldSystemFontOfSize:16];
        self.titleLabel.numberOfLines = 2;
        self.titleLabel.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5];
        [self.contentView addSubview:self.titleLabel];
        
        [self.imageView mas_makeConstraints:^(MASConstraintMaker *make) {
            make.edges.equalTo(self.contentView);
        }];
        
        [self.titleLabel mas_makeConstraints:^(MASConstraintMaker *make) {
            make.left.right.bottom.equalTo(self.contentView);
            make.height.mas_equalTo(60);
        }];
    }
    return self;
}

@end

#pragma mark - Banner View

@interface JXBannerView () <UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout>

@property (nonatomic, strong) UICollectionView *collectionView;
@property (nonatomic, strong) UIPageControl *pageControl;
@property (nonatomic, strong) NSTimer *autoScrollTimer;
@property (nonatomic, assign) NSInteger currentIndex;

@end

@implementation JXBannerView

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self setupUI];
    }
    return self;
}

- (void)dealloc {
    [self stopAutoScroll];
}

- (void)setupUI {
    // CollectionView Layout
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
    layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
    layout.minimumLineSpacing = 0;
    layout.minimumInteritemSpacing = 0;
    
    // CollectionView
    self.collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
    self.collectionView.delegate = self;
    self.collectionView.dataSource = self;
    self.collectionView.pagingEnabled = YES;
    self.collectionView.showsHorizontalScrollIndicator = NO;
    self.collectionView.backgroundColor = [UIColor colorWithWhite:0.95 alpha:1.0];
    [self.collectionView registerClass:[JXBannerCell class] forCellWithReuseIdentifier:kBannerCellIdentifier];
    [self addSubview:self.collectionView];
    
    // PageControl
    self.pageControl = [[UIPageControl alloc] init];
    self.pageControl.currentPageIndicatorTintColor = [UIColor whiteColor];
    self.pageControl.pageIndicatorTintColor = [[UIColor whiteColor] colorWithAlphaComponent:0.5];
    self.pageControl.userInteractionEnabled = NO;
    [self addSubview:self.pageControl];
    
    // Layout
    [self.collectionView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.edges.equalTo(self);
    }];
    
    [self.pageControl mas_makeConstraints:^(MASConstraintMaker *make) {
        make.centerX.equalTo(self);
        make.bottom.equalTo(self).offset(-10);
        make.height.mas_equalTo(20);
    }];
}

- (void)updateBanners:(NSArray<JXBannerItem *> *)banners {
    self.banners = banners;
    self.currentIndex = 0;
    
    // 更新 PageControl
    self.pageControl.numberOfPages = banners.count;
    self.pageControl.currentPage = 0;
    self.pageControl.hidden = (banners.count <= 1);
    
    // 刷新数据
    [self.collectionView reloadData];
    
    // 如果有多个 Banner，启动自动轮播
    if (banners.count > 1) {
        [self startAutoScroll];
    }
}

#pragma mark - Auto Scroll

- (void)startAutoScroll {
    [self stopAutoScroll];
    
    if (self.banners.count > 1) {
        self.autoScrollTimer = [NSTimer scheduledTimerWithTimeInterval:kAutoScrollInterval
                                                                target:self
                                                              selector:@selector(autoScroll)
                                                              userInfo:nil
                                                               repeats:YES];
    }
}

- (void)stopAutoScroll {
    if (self.autoScrollTimer) {
        [self.autoScrollTimer invalidate];
        self.autoScrollTimer = nil;
    }
}

- (void)autoScroll {
    if (self.banners.count == 0) {
        return;
    }
    
    NSInteger nextIndex = (self.currentIndex + 1) % self.banners.count;
    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:nextIndex inSection:0];
    [self.collectionView scrollToItemAtIndexPath:indexPath
                                atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally
                                        animated:YES];
}

#pragma mark - UICollectionViewDataSource

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return self.banners.count;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    JXBannerCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:kBannerCellIdentifier forIndexPath:indexPath];
    
    JXBannerItem *item = self.banners[indexPath.item];
    
    // 使用横向封面
    NSString *imageUrl = item.hCoverUrl ?: item.vCoverUrl;
    if (imageUrl) {
        [cell.imageView sd_setImageWithURL:[NSURL URLWithString:imageUrl]
                          placeholderImage:nil];
    }
    
    cell.titleLabel.text = item.name;
    
    return cell;
}

#pragma mark - UICollectionViewDelegate

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
    JXBannerItem *item = self.banners[indexPath.item];
    if (self.onBannerClick) {
        self.onBannerClick(item);
    }
}

#pragma mark - UICollectionViewDelegateFlowLayout

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    return collectionView.bounds.size;
}

#pragma mark - UIScrollViewDelegate

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    CGFloat pageWidth = scrollView.frame.size.width;
    NSInteger page = (NSInteger)((scrollView.contentOffset.x + pageWidth / 2) / pageWidth);
    
    if (page >= 0 && page < self.banners.count) {
        self.currentIndex = page;
        self.pageControl.currentPage = page;
    }
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    // 用户开始拖动时停止自动滚动
    [self stopAutoScroll];
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    // 用户停止拖动后重新开始自动滚动
    if (!decelerate) {
        [self startAutoScroll];
    }
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    // 减速停止后重新开始自动滚动
    [self startAutoScroll];
}

@end