#import <UIKit/UIKit.h>
#import <objc/runtime.h>

@interface RCTOneSignal
+ (RCTOneSignal *)sharedInstance;
- (void)initOneSignal:(NSDictionary *)launchOptions;
@end

@implementation UIApplication (OneSignalReactNative)

/*
    This UIApplication category ensures that OneSignal init() gets called at
   least one time

    If this did not occur, cold-start notifications would not trigger the
   React-Native 'opened' event and other miscellaneous problems would occur.

    First, we swizzle UIApplication's setDelegate method, to get notified when
   the app delegate is assigned. Then we swizzle UIApplication's
   didFinishLaunchingWithOptions() method. When this method gets called, it
   initializes the OneSignal SDK with a nil app ID.
*/

// helper method to swizzle instance methods
static void injectSelector(Class newClass, SEL newSel, Class addToClass,
                           SEL makeLikeSel) {
  Method newMeth = class_getInstanceMethod(newClass, newSel);
  IMP imp = method_getImplementation(newMeth);
  const char *methodTypeEncoding = method_getTypeEncoding(newMeth);

  BOOL successful =
      class_addMethod(addToClass, makeLikeSel, imp, methodTypeEncoding);
  if (!successful) {
    class_addMethod(addToClass, newSel, imp, methodTypeEncoding);
    newMeth = class_getInstanceMethod(addToClass, newSel);

    Method orgMeth = class_getInstanceMethod(addToClass, makeLikeSel);

    method_exchangeImplementations(orgMeth, newMeth);
  }
}

+ (void)load {
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    method_exchangeImplementations(
        class_getInstanceMethod(self, @selector(setDelegate:)),
        class_getInstanceMethod(self,
                                @selector(setOneSignalReactNativeDelegate:)));
  });
}

- (void)setOneSignalReactNativeDelegate:(id<UIApplicationDelegate>)delegate {
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    Class delegateClass = [delegate class];
    injectSelector(
        self.class,
        @selector(oneSignalApplication:didFinishLaunchingWithOptions:),
        delegateClass, @selector(application:didFinishLaunchingWithOptions:));
    [self setOneSignalReactNativeDelegate:delegate];
  });
}

- (BOOL)oneSignalApplication:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  [[RCTOneSignal sharedInstance] initOneSignal:launchOptions];
  if ([self respondsToSelector:
                @selector(oneSignalApplication:didFinishLaunchingWithOptions:)])
    return [self oneSignalApplication:application
        didFinishLaunchingWithOptions:launchOptions];
  return YES;
}

@end