import UIKit
import CoreData

class CoreDataFetchController<T : NSManagedObject> {
    weak var delegate: NSFetchedResultsControllerDelegate? = nil {
        didSet {
            fetchedResultsController.delegate = delegate
        }
    }

    let fetchedResultsController: NSFetchedResultsController

    init(fetchedResultsController: NSFetchedResultsController) {
        self.fetchedResultsController = fetchedResultsController
        fetchedResultsController.performFetch(nil)
    }

    init(let entityName: String, let managedObjectContext: NSManagedObjectContext, let sortDescriptors: [NSSortDescriptor], let predicate: NSPredicate? = nil, let sectionNameKeyPath: String? = nil, let cacheName: String? = nil) {
        let request = NSFetchRequest(entityName: entityName)
        request.sortDescriptors = sortDescriptors
        request.predicate = predicate

        fetchedResultsController = NSFetchedResultsController(fetchRequest: request, managedObjectContext: managedObjectContext, sectionNameKeyPath: sectionNameKeyPath, cacheName: cacheName)
        fetchedResultsController.performFetch(nil)
    }

    func numberOfRowsInSection(section: Int) -> Int {
        if let s = fetchedResultsController.sections as? [NSFetchedResultsSectionInfo] {
            return s[section].numberOfObjects
        } else {
            return 0
        }
    }

    func numberOfSections() -> Int {
        if let s = fetchedResultsController.sections as? [NSFetchedResultsSectionInfo] {
            return s.count
        } else {
            return 0
        }
    }

    func objectAtIndexPath(let indexPath: NSIndexPath) -> T {
        return fetchedResultsController.objectAtIndexPath(indexPath) as T
    }
}