ViewController.swift

//
//  ViewController.swift
//  Notes
//
//  Created by Bart Jacobs on 08/03/2017.
//  Copyright © 2017 Cocoacasts. All rights reserved.
//

import UIKit
import CoreData

class ViewController: UIViewController {

    // MARK: - Properties

    @IBOutlet var tableView: UITableView!

    // MARK: -

    fileprivate let coreDataManager = CoreDataManager(modelName: "Notes")

    // MARK: -

    fileprivate lazy var fetchedResultsController: NSFetchedResultsController<Note> = {
        // Initialize Fetch Request
        let fetchRequest: NSFetchRequest<Note> = Note.fetchRequest()

        // Add Sort Descriptors
        let sortDescriptor = NSSortDescriptor(key: "updatedAt", ascending: false)
        fetchRequest.sortDescriptors = [sortDescriptor]

        // Initialize Fetched Results Controller
        let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.coreDataManager.managedObjectContext, sectionNameKeyPath: nil, cacheName: nil)

        // Configure Fetched Results Controller
        fetchedResultsController.delegate = self

        return fetchedResultsController
    }()

    // MARK: - View Life Cycle

    override func viewDidLoad() {
        super.viewDidLoad()

        do {
            try fetchedResultsController.performFetch()
        } catch {
            let fetchError = error as NSError
            print("Unable to Save Note")
            print("\(fetchError), \(fetchError.localizedDescription)")
        }
    }

    // MARK: - Navigation

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        guard let identifier = segue.identifier else { return }

        switch identifier {
        case "SegueAddNoteViewController":
            guard let navigationController = segue.destination as? UINavigationController else { return }
            guard let viewController = navigationController.viewControllers.first as? AddNoteViewController else { return }

            // Configure View Controller
            viewController.delegate = self
        case "SegueNoteViewController":
            guard let indexPath = tableView.indexPathForSelectedRow else { return }
            guard let viewController = segue.destination as? NoteViewController else { return }

            // Fetch Note
            let note = fetchedResultsController.object(at: indexPath)

            // Configure View Controller
            viewController.note = note
        default:
            print("Unknown Segue")
        }
    }

}

extension ViewController: NSFetchedResultsControllerDelegate {

    func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
        tableView.beginUpdates()
    }

    func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
        tableView.endUpdates()
    }

    func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
        switch (type) {
        case .insert:
            if let indexPath = newIndexPath {
                tableView.insertRows(at: [indexPath], with: .fade)
            }
            break;
        case .delete:
            if let indexPath = indexPath {
                tableView.deleteRows(at: [indexPath], with: .fade)
            }
            break;
        case .update:
            if let indexPath = indexPath, let cell = tableView.cellForRow(at: indexPath) {
                configureCell(cell, at: indexPath)
            }
            break;
        case .move:
            if let indexPath = indexPath {
                tableView.deleteRows(at: [indexPath], with: .fade)
            }

            if let newIndexPath = newIndexPath {
                tableView.insertRows(at: [newIndexPath], with: .fade)
            }
            break;
        }
    }

}

extension ViewController: UITableViewDataSource {

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        guard let sections = fetchedResultsController.sections else {
            return 0
        }

        let sectionInfo = sections[section]
        return sectionInfo.numberOfObjects
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "NoteCell", for: indexPath)

        // Configure Cell
        configureCell(cell, at: indexPath)

        return cell
    }

    func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
        guard editingStyle == .delete else { return }

        // Fetch Note
        let note = fetchedResultsController.object(at: indexPath)

        // Delete Note
        fetchedResultsController.managedObjectContext.delete(note)
    }

    func configureCell(_ cell: UITableViewCell, at indexPath: IndexPath) {
        // Fetch Note
        let note = fetchedResultsController.object(at: indexPath)

        // Configure Cell
        cell.textLabel?.text = note.title
        cell.detailTextLabel?.text = note.content
    }

}

extension ViewController: UITableViewDelegate {

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath, animated: true)
    }

}

extension ViewController: AddNoteViewControllerDelegate {

    func controller(_ controller: AddNoteViewController, didAddNoteWithTitle title: String) {
        // Create Note
        let note = Note(context: coreDataManager.managedObjectContext)

        // Populate Note
        note.content = ""
        note.title = title
        note.updatedAt = NSDate()
        note.createdAt = NSDate()

        do {
            try note.managedObjectContext?.save()
        } catch {
            let saveError = error as NSError
            print("Unable to Save Note")
            print("\(saveError), \(saveError.localizedDescription)")
        }
    }

}