elpha-ios/elpha-ios/TimelinesViewController.swift

//
//  TimelineViewController.swift
//  elpha-ios
//
//  Created by Dwayne Harris on 10/28/18.
//  Copyright © 2018 Elpha. All rights reserved.
//

import CoreData
import UIKit

protocol TimelinesViewControllerDelegate: class {
    func didSelect(_ sender: Any, timeline: TimelineMO)
}

class TimelinesViewController: UIViewController {
    @IBOutlet var tableView: UITableView!
    
    weak var delegate: TimelinesViewControllerDelegate?
    var fetchedResultsController: NSFetchedResultsController<TimelineMO>?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        tableView.dataSource = self
        tableView.delegate = self
        
        tableView.layer.cornerRadius = 20
        tableView.layer.masksToBounds = true
        
        initializeFetchedResultsController()
    }
    
    func initializeFetchedResultsController() {
        let request = NSFetchRequest<TimelineMO>(entityName: "Timeline")
        request.sortDescriptors = [
            NSSortDescriptor(key: "order", ascending: true),
        ]
        
        fetchedResultsController = NSFetchedResultsController(
            fetchRequest: request,
            managedObjectContext: CoreDataManager.shared.context,
            sectionNameKeyPath: nil,
            cacheName: nil
        )
        
        fetchedResultsController!.delegate = self
        
        do {
            try fetchedResultsController!.performFetch()
        } catch {
            print("\(error)")
        }
    }
}

extension TimelinesViewController: NSFetchedResultsControllerDelegate {
    func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
        tableView.beginUpdates()
    }
    
    func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
        switch type {
        case NSFetchedResultsChangeType.insert:
            tableView.insertRows(at: [newIndexPath!], with: UITableView.RowAnimation.fade)
        case NSFetchedResultsChangeType.delete:
            tableView.deleteRows(at: [indexPath!], with: UITableView.RowAnimation.fade)
        case NSFetchedResultsChangeType.update:
            return
        case NSFetchedResultsChangeType.move:
            tableView.deleteRows(at: [indexPath!], with: UITableView.RowAnimation.fade)
            tableView.insertRows(at: [newIndexPath!], with: UITableView.RowAnimation.fade)
        }
    }
    
    func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
        tableView.endUpdates()
    }
}

extension TimelinesViewController: UITableViewDataSource, UITableViewDelegate {
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        guard let count = fetchedResultsController?.fetchedObjects?.count else {
            return 0
        }
        
        return count
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        guard let cell = tableView.dequeueReusableCell(withIdentifier: "TimelinesTableViewCell", for: indexPath) as? TimelinesTableViewCell else {
            fatalError("Unable to find reusable cell")
        }
        
        guard let timeline = fetchedResultsController?.object(at: indexPath) else {
            fatalError("CoreData error")
        }
        
        let selectedTimeline = AuthenticationManager.session?.timeline
        
        cell.timelineLabel.text = timeline.name
        
        if selectedTimeline == timeline {
            cell.accessoryType = UITableViewCell.AccessoryType.checkmark
        }
        
        switch TimelineCategory(rawValue: timeline.category!)! {
        case .home:
            cell.timelineImageView.image = UIImage(named: "Home")
        case .local:
            cell.timelineImageView.image = UIImage(named: "Users")
        case .federated:
            cell.timelineImageView.image = UIImage(named: "Globe")
        case .favorites:
            cell.timelineImageView.image = UIImage(named: "Star Regular")
        case .tag:
            cell.timelineImageView.image = UIImage(named: "Tag")
        }
        
        return cell
    }
    
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        guard let timeline = fetchedResultsController?.object(at: indexPath) else {
            fatalError("CoreData error")
        }
        
        delegate?.didSelect(self, timeline: timeline)
        
        dismiss(animated: true)
    }
}