#import "CameraUpdateQueue.h"

@implementation CameraUpdateQueue {
  NSMutableArray<CameraStop *> *queue;
}

- (instancetype)init {
  if (self = [super init]) {
    queue = [[NSMutableArray alloc] init];
  }

  return self;
}

- (void)enqueue:(CameraStop *)cameraUpdateItem {
  [queue addObject:cameraUpdateItem];
}

- (CameraStop *)dequeue {
  if ([self isEmpty]) {
    return nil;
  }
  CameraStop *stop = queue.firstObject;
  [queue removeObjectAtIndex:0];
  return stop;
}

- (void)flush {
  [queue removeAllObjects];
}

- (BOOL)isEmpty {
  return queue.count == 0;
}

- (void)execute:(MLRNMapView *)mapView {
  if (mapView == nil) {
    return;
  }

  if ([self isEmpty]) {
    return;
  }

  CameraStop *stop = [self dequeue];
  if (stop == nil) {
    return;
  }

  CameraUpdateItem *item = [[CameraUpdateItem alloc] init];
  item.cameraStop = stop;

  __weak CameraUpdateQueue *weakSelf = self;
  __weak MLRNMapView *weakMap = mapView;

  [item execute:mapView
      withCompletionHandler:^{
        [weakSelf execute:weakMap];
      }];
}

@end