//
//  KBKeyboardSubscriptionFeatureMarqueeView.m
//  CustomKeyboard
//

#import "KBKeyboardSubscriptionFeatureMarqueeView.h"
#import "KBKeyboardSubscriptionFeatureItemView.h"
#import "Masonry.h"

@interface KBKeyboardSubscriptionFeatureMarqueeView ()
@property (nonatomic, strong) UIScrollView *scrollView;
@property (nonatomic, strong) UIView *contentView;
@property (nonatomic, strong) CADisplayLink *displayLink;
@property (nonatomic, assign) CGFloat loopWidth;
@property (nonatomic, copy) NSArray<NSDictionary *> *items;
@end

@implementation KBKeyboardSubscriptionFeatureMarqueeView

static const CGFloat kKBFeatureMarqueeItemSpacing = 12.0;
static const CGFloat kKBFeatureMarqueeSpeedPerFrame = 0.35f;

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.backgroundColor = [UIColor clearColor];
        [self addSubview:self.scrollView];
        [self.scrollView addSubview:self.contentView];

        [self.scrollView mas_makeConstraints:^(MASConstraintMaker *make) {
            make.edges.equalTo(self);
        }];
        [self.contentView mas_makeConstraints:^(MASConstraintMaker *make) {
            make.top.bottom.equalTo(self.scrollView);
            make.left.equalTo(self.scrollView);
            make.height.equalTo(self.scrollView);
            make.right.equalTo(self.scrollView);
        }];
    }
    return self;
}

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

- (void)didMoveToWindow {
    [super didMoveToWindow];
    if (self.window) {
        [self startTickerIfNeeded];
    } else {
        [self stopTicker];
    }
}

- (void)setHidden:(BOOL)hidden {
    BOOL oldHidden = self.isHidden;
    [super setHidden:hidden];
    if (oldHidden == hidden) { return; }
    if (hidden) {
        [self stopTicker];
    } else if (self.window) {
        [self startTickerIfNeeded];
    }
}

- (void)layoutSubviews {
    [super layoutSubviews];
    // 宽度变化时重新评估是否需要滚动
    [self rebuildIfNeeded];
}

#pragma mark - Public

- (void)configureWithTitles:(NSArray<NSString *> *)titles images:(NSArray<UIImage *> *)images {
    NSInteger count = MIN(titles.count, images.count);
    if (count <= 0) {
        self.items = @[];
        [self rebuildIfNeeded];
        return;
    }
    NSMutableArray *arr = [NSMutableArray arrayWithCapacity:(NSUInteger)count];
    for (NSInteger i = 0; i < count; i++) {
        NSString *t = titles[(NSUInteger)i] ?: @"";
        UIImage *img = images[(NSUInteger)i] ?: [UIImage new];
        [arr addObject:@{@"title": t, @"image": img}];
    }
    self.items = [arr copy];
    [self rebuildIfNeeded];
}

#pragma mark - Build

- (void)rebuildIfNeeded {
    [self.contentView.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];
    if (self.items.count == 0) {
        self.loopWidth = 0;
        self.scrollView.contentSize = CGSizeZero;
        self.scrollView.contentOffset = CGPointZero;
        [self stopTicker];
        return;
    }

    BOOL shouldLoop = (self.items.count > 1);
    NSInteger baseCount = self.items.count;

    NSMutableArray<NSNumber *> *baseWidths = [NSMutableArray arrayWithCapacity:(NSUInteger)baseCount];
    CGFloat baseTotalWidth = 0;
    for (NSInteger i = 0; i < baseCount; i++) {
        NSDictionary *info = self.items[(NSUInteger)i];
        NSString *title = [info[@"title"] isKindOfClass:NSString.class] ? info[@"title"] : @"";
        CGFloat w = [KBKeyboardSubscriptionFeatureItemView preferredWidthForTitle:title];
        [baseWidths addObject:@(w)];
        baseTotalWidth += w;
        if (i > 0) { baseTotalWidth += kKBFeatureMarqueeItemSpacing; }
    }

    NSArray *loopData = shouldLoop ? [self.items arrayByAddingObjectsFromArray:self.items] : self.items;
    CGFloat totalWidth = shouldLoop ? (baseTotalWidth * 2 + kKBFeatureMarqueeItemSpacing) : baseTotalWidth;

    UIView *previous = nil;
    for (NSInteger idx = 0; idx < loopData.count; idx++) {
        NSDictionary *info = loopData[(NSUInteger)idx];
        UIImage *img = [info[@"image"] isKindOfClass:UIImage.class] ? info[@"image"] : nil;
        NSString *title = [info[@"title"] isKindOfClass:NSString.class] ? info[@"title"] : @"";
        CGFloat width = baseWidths[(NSUInteger)(idx % baseCount)].doubleValue;

        KBKeyboardSubscriptionFeatureItemView *itemView = [[KBKeyboardSubscriptionFeatureItemView alloc] init];
        [itemView configureWithImage:(img ?: [UIImage new]) title:title];
        [self.contentView addSubview:itemView];

        [itemView mas_makeConstraints:^(MASConstraintMaker *make) {
            make.top.bottom.equalTo(self.contentView);
            make.width.mas_equalTo(width);
            if (previous) {
                make.left.equalTo(previous.mas_right).offset(kKBFeatureMarqueeItemSpacing);
            } else {
                make.left.equalTo(self.contentView.mas_left);
            }
        }];
        previous = itemView;
    }

    [self.contentView mas_remakeConstraints:^(MASConstraintMaker *make) {
        make.top.bottom.equalTo(self.scrollView);
        make.left.equalTo(self.scrollView);
        make.height.equalTo(self.scrollView);
        if (previous) {
            make.right.equalTo(previous.mas_right);
        } else {
            make.right.equalTo(self.scrollView);
        }
    }];

    CGFloat minWidth = CGRectGetWidth(self.bounds);
    if (minWidth <= 0) { minWidth = 1; }
    CGFloat height = CGRectGetHeight(self.bounds);
    if (height <= 0) { height = 48; }

    CGFloat contentWidth = totalWidth;
    if (contentWidth <= minWidth) {
        contentWidth = minWidth;
        self.loopWidth = 0;
        [self stopTicker];
        self.scrollView.contentOffset = CGPointZero;
    } else {
        self.loopWidth = shouldLoop ? (baseTotalWidth + kKBFeatureMarqueeItemSpacing) : 0;
        [self startTickerIfNeeded];
    }
    self.scrollView.contentSize = CGSizeMake(contentWidth, height);
}

#pragma mark - Ticker

- (void)startTickerIfNeeded {
    if (self.displayLink || self.loopWidth <= 0) { return; }
    self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(handleTick)];
    self.displayLink.preferredFramesPerSecond = 60;
    [self.displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
}

- (void)stopTicker {
    [self.displayLink invalidate];
    self.displayLink = nil;
}

- (void)handleTick {
    if (self.loopWidth <= 0) { return; }
    CGFloat nextX = self.scrollView.contentOffset.x + kKBFeatureMarqueeSpeedPerFrame;
    if (nextX >= self.loopWidth) {
        nextX -= self.loopWidth;
    }
    self.scrollView.contentOffset = CGPointMake(nextX, 0);
}

#pragma mark - Lazy

- (UIScrollView *)scrollView {
    if (!_scrollView) {
        _scrollView = [[UIScrollView alloc] init];
        _scrollView.showsHorizontalScrollIndicator = NO;
        _scrollView.scrollEnabled = NO;
        _scrollView.clipsToBounds = YES;
    }
    return _scrollView;
}

- (UIView *)contentView {
    if (!_contentView) {
        _contentView = [[UIView alloc] init];
    }
    return _contentView;
}

@end