metatext/View Controllers/InstancePickerViewController.swift

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// Copyright © 2021 Metabolist. All rights reserved.
import Combine
import UIKit
import WebKit
final class InstancePickerViewController: UIViewController {
private let selectionAction: (InstancePickerViewController, String) -> Void
private let webView: WKWebView
private let backButton: UIBarButtonItem
private let forwardButton: UIBarButtonItem
private var cancellables = Set<AnyCancellable>()
init(selectionAction: @escaping (InstancePickerViewController, String) -> Void) {
let webView = WKWebView()
webView.allowsBackForwardNavigationGestures = true
self.webView = webView
self.selectionAction = selectionAction
backButton = UIBarButtonItem(title: nil, image: UIImage(systemName: "chevron.backward"),
primaryAction: UIAction { _ in webView.goBack() })
forwardButton = UIBarButtonItem(title: nil, image: UIImage(systemName: "chevron.forward"),
primaryAction: UIAction { _ in webView.goForward() })
super.init(nibName: nil, bundle: nil)
}
@available(*, unavailable)
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func loadView() {
view = webView
webView.navigationDelegate = self
}
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.leftBarButtonItem = UIBarButtonItem(
systemItem: .done,
primaryAction: UIAction { [weak self] _ in self?.presentingViewController?.dismiss(animated: true) })
navigationItem.rightBarButtonItems = [forwardButton, backButton]
webView.publisher(for: \.canGoBack)
.sink { [weak self] in self?.backButton.isEnabled = $0 }
.store(in: &cancellables)
webView.publisher(for: \.canGoForward)
.sink { [weak self] in self?.forwardButton.isEnabled = $0 }
.store(in: &cancellables)
webView.publisher(for: \.title)
.sink { [weak self] in self?.navigationItem.title = $0 }
.store(in: &cancellables)
webView.load(.init(url: Self.url))
}
}
extension InstancePickerViewController: WKNavigationDelegate {
func webView(_ webView: WKWebView,
decidePolicyFor navigationAction: WKNavigationAction,
preferences: WKWebpagePreferences,
decisionHandler: @escaping (WKNavigationActionPolicy, WKWebpagePreferences) -> Void) {
if webView.url?.host == "joinmastodon.org",
let url = navigationAction.request.url,
let host = url.host,
host != "joinmastodon.org",
url.pathComponents == ["/", "about"] {
decisionHandler(.cancel, preferences)
selectionAction(self, host)
} else {
decisionHandler(.allow, preferences)
}
}
}
private extension InstancePickerViewController {
static let url = URL(string: "https://joinmastodon.org/communities")!
}