@interface NSArray (Duplicates)

- (instancetype)arrayByRemovingDuplicates;

@end

@implementation NSArray (Duplicates)

- (instancetype)arrayByRemovingDuplicates {
    NSMutableSet *returnedObjects = [NSMutableSet set];

    for (id obj in self) {
        if (![returnedObjects containsObject:obj]) {
            [returnedObjects addObject:obj];
        }
    }

    return returnedObjects.allObjects;
}

@end

@implementation SCCalendarTaskPresenter

-(NSArray *)executingTask:(NSDate*)selectedDate {
    if (selectedDate == nil) {
        selectedDate = [NSDate date];
    }

    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];

    NSDateComponents *selectedDateComponent = [calendar components:NSCalendarUnitDay | NSCalendarUnitYear | NSCalendarUnitMonth
                                                              fromDate:selectedDate];
    NSTimeInterval selectedDateInterval = [calendar dateFromComponents:selectedDateComponent].timeIntervalSince1970;

    BOOL (^checkEqualsDateComponents)(NSDateComponents *firstComponents, NSDateComponents *secondComponents) = ^BOOL(NSDateComponents *firstComponents, NSDateComponents *secondComponents) {
        if (firstComponents.day == secondComponents.day &&
            firstComponents.month == secondComponents.month &&
            firstComponents.year == secondComponents.year) {
            return YES;
        } else {
            return NO;
        }
    };

    NSArray<SCTask *> *allTasks = [SCTask MR_findAll];

    NSMutableArray<SCTask *> *filteredTasks = [NSMutableArray array];

    for (SCTask *task in allTasks) {
        NSDateComponents *startDateComponent = [calendar components:NSCalendarUnitDay | NSCalendarUnitYear | NSCalendarUnitMonth
                                                            fromDate:[NSDate dateWithTimeIntervalSince1970:task.startDate.integerValue]];
        NSDateComponents *finishedDateComponent = [calendar components:NSCalendarUnitDay | NSCalendarUnitYear | NSCalendarUnitMonth
                                                               fromDate:[NSDate dateWithTimeIntervalSince1970:task.finishDate.integerValue]];

        //Started task check
        if (checkEqualsDateComponents(startDateComponent, selectedDateComponent)) {
            [filteredTasks addObject:task];
        }

        //Finished tasks check
        if (checkEqualsDateComponents(finishedDateComponent, selectedDateComponent)) {
            [filteredTasks addObject:task];
        }

        //Intermediate tasks check

        NSTimeInterval startDateInterval = [calendar dateFromComponents:startDateComponent].timeIntervalSince1970;
        NSTimeInterval finishDateInterval = [calendar dateFromComponents:finishedDateComponent].timeIntervalSince1970;

        if (startDateInterval <= selectedDateInterval && finishDateInterval >= selectedDateInterval) {
            [filteredTasks addObject:task];
        }
    }

    return [filteredTasks arrayByRemovingDuplicates];
}

@end