#import "DeviceProximityBag.h"

@interface DeviceProximityBag () {
    NSInteger _nextKey;
    NSMutableArray *_items;
    NSMutableArray *_itemKeys;
}

@end

@implementation DeviceProximityBag

- (instancetype)init {
    self = [super init];
    if (self != nil) {
        _items = [[NSMutableArray alloc] init];
        _itemKeys = [[NSMutableArray alloc] init];
    }
    return self;
}

- (NSInteger)addItem:(id)item {
    if (item == nil) {
        return -1;
    }
    
    NSInteger key = _nextKey;
    [_items addObject:item];
    [_itemKeys addObject:@(key)];
    _nextKey++;
    
    return key;
}

- (void)enumerateItems:(void (^)(id))block {
    if (block) {
        for (id item in _items) {
            block(item);
        }
    }
}

- (void)removeItem:(NSInteger)key {
    NSUInteger index = 0;
    for (NSNumber *itemKey in _itemKeys) {
        if ([itemKey integerValue] == key) {
            [_items removeObjectAtIndex:index];
            [_itemKeys removeObjectAtIndex:index];
            break;
        }
        index++;
    }
}

- (bool)isEmpty {
    return _items.count == 0;
}

- (NSArray *)copyItems {
    return [[NSArray alloc] initWithArray:_items];
}

@end