IGListKit/Examples/Examples-macOS/IGListKitExamples/ViewControllers/UsersViewController.swift

/**
 Copyright (c) 2016-present, Facebook, Inc. All rights reserved.

 The examples provided by Facebook are for non-commercial testing and evaluation
 purposes only. Facebook reserves all rights not expressly granted.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

import Cocoa
import IGListKit

final class UsersViewController: NSViewController {

    @IBOutlet weak var tableView: NSTableView!

    // MARK: Data

    var users = [User]() {
        didSet {
            computeFilteredUsers()
        }
    }

    var searchTerm = "" {
        didSet {
            computeFilteredUsers()
        }
    }

    private func computeFilteredUsers() {
        guard !searchTerm.characters.isEmpty else {
            filteredUsers = users
            return
        }

        filteredUsers = users.filter({ $0.name.localizedCaseInsensitiveContains(self.searchTerm) })
    }

    fileprivate func delete(user: User) {
        guard let index = self.users.index(where: { $0.pk == user.pk }) else { return }

        self.users.remove(at: index)
    }

    // MARK: -
    // MARK: Diffing 

    var filteredUsers = [User]() {
        didSet {
            // get the difference between the old array of Users and the new array of Users
            let diff = ListDiff(oldArray: oldValue, newArray: filteredUsers, option: .equality)

            // this difference is used here to update the table view, but it can be used
            // to update collection views and other similar interface elements
            // this code can also be added to an extension of NSTableView ;)
            tableView.beginUpdates()
            tableView.insertRows(at: diff.inserts, withAnimation: .slideDown)
            tableView.removeRows(at: diff.deletes, withAnimation: .slideUp)
            tableView.reloadData(forRowIndexes: diff.updates, columnIndexes: .zero)
            diff.moves.forEach { move in
                self.tableView.moveRow(at: move.from, to: move.to)
            }
            tableView.endUpdates()
        }
    }

    // MARK: -

    private func loadSampleUsers() {
        guard let file = Bundle.main.url(forResource: "users", withExtension: "json") else { return }

        do {
            self.users = try UsersProvider(with: file).users
        } catch {
            NSAlert(error: error).runModal()
        }
    }

    // MARK: Interface

    override func viewDidLoad() {
        super.viewDidLoad()

        loadSampleUsers()
    }

    override func viewDidAppear() {
        super.viewDidAppear()

        view.window?.titleVisibility = .hidden
    }

    @IBAction func shuffle(_ sender: Any?) {
        users = users.shuffled
    }

    @IBAction func search(_ sender: NSSearchField) {
        searchTerm = sender.stringValue
    }

    @IBAction func delete(_ sender: Any?) {
        guard !tableView.selectedRowIndexes.isEmpty else { return }

        tableView.selectedRowIndexes.forEach({ self.delete(user: self.filteredUsers[$0]) })
    }

}

extension UsersViewController: NSTableViewDataSource {

    func numberOfRows(in tableView: NSTableView) -> Int {
        return filteredUsers.count
    }

}

extension UsersViewController: NSTableViewDelegate {

    private struct Storyboard {
        static let cellIdentifier = "cell"
    }

    func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
        guard let cell = tableView.make(withIdentifier: Storyboard.cellIdentifier, owner: tableView) as? NSTableCellView else {
            return nil
        }

        cell.textField?.stringValue = filteredUsers[row].name

        return cell
    }

    @available(OSX 10.11, *)
    func tableView(_ tableView: NSTableView, rowActionsForRow row: Int, edge: NSTableRowActionEdge) -> [NSTableViewRowAction] {
        let delete = NSTableViewRowAction(style: .destructive, title: "Delete") { _, row in
            guard row < self.filteredUsers.count else { return }

            self.delete(user: self.filteredUsers[row])
        }

        return [delete]
    }

}