NetNewsWire/Mac/SafariExtension/SafariExtensionHandler.swift

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//
// SafariExtensionHandler.swift
// Subscribe to Feed
//
// Created by Daniel Jalkut on 6/11/18.
// Copyright © 2018 Ranchero Software. All rights reserved.
//
import SafariServices
class SafariExtensionHandler: SFSafariExtensionHandler {
// Safari App Extensions don't support any reasonable means of detecting whether a
// specific Safari page was loaded with the benefit of the extension's injected
// JavaScript. For this reason a condition can easily be reached where the toolbar
// icon is active for a page, but the expected supporting code is not loaded into
// the page. To detect this and disable our icon, we use a kind of "ping" trick
// to verify whether our code is installed.
// I tried to use a NSMapTable from String to the closure directly, but Swift
// complains that the object has to be a class type.
typealias ValidationHandler = (Bool, String) -> Void
class ValidationWrapper {
let validationHandler: ValidationHandler
init(validationHandler: @escaping ValidationHandler) {
self.validationHandler = validationHandler
}
}
// Maps from UUID to a validation wrapper
static var gPingPongMap = Dictionary<String, ValidationWrapper>()
static var validationQueue = DispatchQueue(label: "Toolbar Validation")
// Bottleneck for calling through to a validation handler we have saved, and removing it from the list.
static func callValidationHandler(forHandlerID handlerID: String, withShouldValidate shouldValidate: Bool) {
if let validationWrapper = gPingPongMap[handlerID] {
validationWrapper.validationHandler(shouldValidate, "")
gPingPongMap.removeValue(forKey: handlerID)
}
}
override func messageReceived(withName messageName: String, from page: SFSafariPage, userInfo: [String : Any]?) {
if (messageName == "subscribeToFeed") {
if var feedURLString = userInfo?["url"] as? String {
var openInDefaultBrowser = false
// Ask for the user's choice for whether to open the feed URL using whatever the system
// configured default is, or to always hard-code it to have NetNewsWire handle it itself.
if let appGroupID = Bundle.main.object(forInfoDictionaryKey: "AppGroup") as? String {
if let groupDefaults = UserDefaults(suiteName: appGroupID) {
openInDefaultBrowser = groupDefaults.bool(forKey: "subscribeToFeedsInDefaultBrowser")
}
}
if openInDefaultBrowser == false {
feedURLString = feedURLString.replacingOccurrences(of: "feed:", with: "x-netnewswire-feed:")
}
if let feedURL = URL(string: feedURLString) {
NSWorkspace.shared.open(feedURL)
}
}
}
else if (messageName == "pong") {
if let validationIDString = userInfo?["validationID"] as? String {
// Should we validate the button?
let shouldValidate = userInfo?["shouldValidate"] as? Bool ?? false
SafariExtensionHandler.callValidationHandler(forHandlerID: validationIDString, withShouldValidate:shouldValidate)
}
}
}
override func toolbarItemClicked(in window: SFSafariWindow) {
window.getActiveTab { (activeTab) in
activeTab?.getActivePage(completionHandler: { (activePage) in
activePage?.dispatchMessageToScript(withName: "toolbarButtonClicked", userInfo: nil)
})
}
}
override func validateToolbarItem(in window: SFSafariWindow, validationHandler: @escaping ((Bool, String) -> Void)) {
let uniqueValidationID = NSUUID().uuidString
SafariExtensionHandler.validationQueue.sync {
// Save it right away to eliminate any doubt of whether the handler gets deallocated while
// we are waiting for a callback from the getActiveTab or getActivatePage methods below.
let validationWrapper = ValidationWrapper(validationHandler: validationHandler)
SafariExtensionHandler.gPingPongMap[uniqueValidationID] = validationWrapper
// To avoid problems with validation handlers dispatched after we've, for example,
// switched to a new tab, we aggressively clear out the map of any pending validations,
// and focus only on the newest validation request we've been asked for.
for thisValidationID in SafariExtensionHandler.gPingPongMap.keys {
if thisValidationID != uniqueValidationID {
// Default to valid ... we'll know soon enough whether the latest state
// is actually still valid or not...
SafariExtensionHandler.callValidationHandler(forHandlerID: thisValidationID, withShouldValidate: true);
}
}
// See comments above where gPingPongMap is declared. Upon being asked to validate the
// toolbar icon for a specific page, we save the validationHandler and postpone calling
// it until we have either received a response from our installed JavaScript, or until
// a timeout period has elapsed
window.getActiveTab { (activeTab) in
guard let activeTab = activeTab else {
SafariExtensionHandler.callValidationHandler(forHandlerID: uniqueValidationID, withShouldValidate:false);
return
}
activeTab.getActivePage { (activePage) in
guard let activePage = activePage else {
SafariExtensionHandler.callValidationHandler(forHandlerID: uniqueValidationID, withShouldValidate:false);
return
}
activePage.getPropertiesWithCompletionHandler { (pageProperties) in
if let isActive = pageProperties?.isActive {
if isActive {
// Capture the uniqueValidationID to ensure it doesn't change out from under us on a future call
activePage.dispatchMessageToScript(withName: "ping", userInfo: ["validationID": uniqueValidationID])
let pongTimeoutInNanoseconds = Int(Double(NSEC_PER_SEC) * 0.5)
let timeoutDeadline = DispatchTime.now() + DispatchTimeInterval.nanoseconds(pongTimeoutInNanoseconds)
DispatchQueue.main.asyncAfter(deadline: timeoutDeadline, execute: { [timedOutValidationID = uniqueValidationID] in
SafariExtensionHandler.callValidationHandler(forHandlerID: timedOutValidationID, withShouldValidate:false)
})
}
}
}
}
}
}
}
}