elpha-ios/elpha-ios/InstancesTableViewController.swift

//
//  InstancesTableViewController.swift
//  elpha-ios
//
//  Created by Dwayne Harris on 8/29/18.
//  Copyright © 2018 Elpha. All rights reserved.
//

import CoreData
import UIKit

struct Instance {
    var id: String?
    var name: String?
    var addedAt: String?
    var updatedAt: String?
    var checkedAt: String?
    var uptime: Int?
    var up: Bool?
    var dead: Bool?
    var version: String?
    var ipv6: Bool?
    var httpsScore: Int?
    var httpsRank: String?
    var users: String?
    var statuses: String?
    var connections: Int?
    var openRegistrations: Bool?
    var thumbnail: String?
    var thumbnailProxy: String?
    var activeUsers: Int?
    var shortDescription: String?
    var fullDescription: String?
    var topic: String?
    var languages: [String]?
    var categories: [String]?
}

class InstancesTableViewController: UITableViewController, UIViewControllerPreviewingDelegate {
    @IBOutlet var mainNavigationItem: UINavigationItem!
    
    var loading: Bool = false {
        didSet {
            DispatchQueue.main.async {
                if self.loading {
                    UIApplication.shared.isNetworkActivityIndicatorVisible = true
                    self.refreshControl?.beginRefreshing()
                } else {
                    UIApplication.shared.isNetworkActivityIndicatorVisible = false
                    self.refreshControl?.endRefreshing()
                }
            }
        }
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        UINavigationBar.appearance().titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]
        
        mainNavigationItem.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .done, target: self, action: #selector(done))
        
        registerForPreviewing(with: self, sourceView: tableView)
        refreshControl?.addTarget(self, action: #selector(self.reloadInstances), for: .valueChanged)
        
        loadInstances()
    }
    
    @objc func done() {
        dismiss(animated: true, completion: nil)
    }
    
    @objc func reloadInstances() {
        loading = true
        
        InstancesDataManager.shared.reloadInstances() { error in
            self.loading = false
            
            guard error == nil else {
                return
            }
            
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }
    }
    
    func loadInstances() {
        loading = true
        
        InstancesDataManager.shared.loadInstances() { error in
            self.loading = false
            
            guard error == nil else {
                return
            }
            
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }
    }
    
    func getInstancesRequest() -> NSFetchRequest<ISInstanceMO> {
        let request = NSFetchRequest<ISInstanceMO>(entityName: "ISInstance")
        let sort = NSSortDescriptor(key: "users", ascending: false)
        request.sortDescriptors = [sort]
        
        return request
    }
    
    func getInstance(for indexPath: IndexPath) -> ISInstanceMO? {
        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
        
        do {
            let instances = try context.fetch(self.getInstancesRequest())
            return instances[indexPath.row]
        } catch {
            return nil
        }
    }
    
    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
        
        do {
            return try context.count(for: self.getInstancesRequest())
        } catch {
            return 0
        }
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
        
        guard let cell = tableView.dequeueReusableCell(withIdentifier: "InstancesTableViewCell", for: indexPath) as? InstancesTableViewCell else {
            fatalError("Unable to find reusable cell")
        }
        
        do {
            let instances = try context.fetch(self.getInstancesRequest())
            let instance = instances[indexPath.row]
            
            cell.instanceNameLabel.text = instance.name
            cell.statusesLabel.text = NumberFormatter.localizedString(from: NSNumber(value: instance.statuses), number: .decimal)
            cell.usersLabel.text = NumberFormatter.localizedString(from: NSNumber(value: instance.users), number: .decimal)
            
            if let thumbnail = instance.thumbnail {
                cell.thumbnailURL = thumbnail
            }
            
            if indexPath.row == instances.count - 1 && !loading && !InstancesDataManager.shared.finished {
                loadInstances()
            }
            
            return cell
        } catch {
            return cell
        }
    }
    
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "InstanceDetailSegue", let cell = segue.destination as? InstanceViewController {
            if let indexPath = tableView.indexPathForSelectedRow {
                cell.instance = getInstance(for: indexPath)
            }
        }
    }
    
    public func previewingContext(_ previewingContext: UIViewControllerPreviewing, viewControllerForLocation location: CGPoint) -> UIViewController? {
        guard let indexPath = tableView.indexPathForRow(at: location) else {
            return nil
        }
        
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        if let detailViewController = storyboard.instantiateViewController(withIdentifier: "InstanceViewController") as? InstanceViewController {
            detailViewController.instance = getInstance(for: indexPath)
            return detailViewController
        } else {
            return nil
        }
    }
    
    public func previewingContext(_ previewingContext: UIViewControllerPreviewing, commit viewControllerToCommit: UIViewController) {
        navigationController?.pushViewController(viewControllerToCommit, animated: true)
    }
}