#import "ViewController.h"
#import <WebKit/WebKit.h>

@interface ViewController () <WKNavigationDelegate>

@property (nonatomic, strong) WKWebView *webView;

@property UIContentSizeCategory currentContentSizeCategory;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    

    WKUserContentController *wkUController = [[WKUserContentController alloc] init];

    WKWebViewConfiguration *webConfiguration = [[WKWebViewConfiguration alloc]init];
    webConfiguration.userContentController = wkUController;
    
    self.webView = [[WKWebView alloc]initWithFrame:self.view.frame configuration:webConfiguration];
    [self.view addSubview:self.webView];
    self.webView.navigationDelegate = self;
    
    NSString *htmlFile = [[NSBundle mainBundle] pathForResource:@"home" ofType:@"html"];
    NSString* htmlString = [NSString stringWithContentsOfFile:htmlFile encoding:NSUTF8StringEncoding error:nil];
    [self.webView loadHTMLString:htmlString baseURL: [[NSBundle mainBundle] bundleURL]];
    
    // Large Text Size changes observer
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(contentSizeCategoryDidChangeNotification:)
                                                 name:UIContentSizeCategoryDidChangeNotification
                                               object:nil];
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    if (@available(iOS 11.0, *)) {
       if (UIContentSizeCategoryIsAccessibilityCategory(self.traitCollection.preferredContentSizeCategory)) {
           self.currentContentSizeCategory = self.traitCollection.preferredContentSizeCategory;
       }
        
    }
    [self performSelector:@selector(updateAccessibilityFontSize) withObject:nil afterDelay:0.2f];
}

#pragma mark - Accessibility Font Size

- (void)contentSizeCategoryDidChangeNotification:(NSNotification *)notification {
    if ([notification.userInfo objectForKey:UIContentSizeCategoryNewValueKey]) {
        self.currentContentSizeCategory = [notification.userInfo objectForKey:UIContentSizeCategoryNewValueKey];
        if (@available(iOS 11.0, *)) {
            if (!UIContentSizeCategoryIsAccessibilityCategory(self.currentContentSizeCategory)) {
                self.currentContentSizeCategory = nil;
            }
        }
        [self updateAccessibilityFontSize];
    }
}

-(void)updateAccessibilityFontSize {
    CGFloat pointSize = [UIFontDescriptor preferredFontDescriptorWithTextStyle: UIFontTextStyleBody].pointSize;
    if (self.currentContentSizeCategory) {
        pointSize = 100 + pointSize;
    } else {
        pointSize = 100;
    }
    
    ViewController * __weak weakSelf = self;
    NSString *jsString = [[NSString alloc] initWithFormat:@"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '%ld%@'",(long)pointSize, @"%"];
    [self.webView evaluateJavaScript:jsString completionHandler:^(id _Nullable result, NSError * _Nullable error) {
        if ( !error ) {
            [weakSelf.webView reload];
        }
    }];
}


- (void)webView:(WKWebView *)webView didFinishNavigation:(null_unspecified WKNavigation *)navigation {
    [self performSelector:@selector(updateAccessibilityFontSize) withObject:nil afterDelay:0.5f];
}

@end