Hacki/ios/Action Extension/ActionViewController.swift

//
//  ActionViewController.swift
//  Action Extension
//
//  Created by Jiaqi Feng on 5/22/22.
//

import UIKit
import MobileCoreServices
import UniformTypeIdentifiers

class ActionViewController: UIViewController {
    let hostAppBundleIdentifier = "com.jiaqi.hacki"
    let sharedKey = "ShareKey"
    var sharedText: [String] = []
    let urlContentType = kUTTypeURL as String
    @IBOutlet weak var imageView: UIImageView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        if let content = extensionContext!.inputItems[0] as? NSExtensionItem {
            if let contents = content.attachments {
                for (index, attachment) in (contents).enumerated() {
                    handleUrl(content: content, attachment: attachment, index: index)
                }
            }
        }
    }
    
    private func handleUrl (content: NSExtensionItem, attachment: NSItemProvider, index: Int) {
        attachment.loadItem(forTypeIdentifier: urlContentType, options: nil) { [weak self] data, error in
            
            if error == nil, let item = data as? URL, let this = self {
                this.sharedText.append(item.absoluteString)
                
                // If this is the last item, save imagesData in userDefaults and redirect to host app
                if index == (content.attachments?.count)! - 1 {
                    let userDefaults = UserDefaults(suiteName: "group.\(this.hostAppBundleIdentifier)")
                    userDefaults?.set(this.sharedText, forKey: this.sharedKey)
                    userDefaults?.synchronize()
                    print(this.sharedText)
                    this.redirectToHostApp()
                }
                
            } else {
                self?.dismissWithError()
            }
        }
    }
    
    private func dismissWithError() {
        print("[ERROR] Error loading data!")
        let alert = UIAlertController(title: "Error", message: "Error loading data", preferredStyle: .alert)
        
        let action = UIAlertAction(title: "Error", style: .cancel) { _ in
            self.dismiss(animated: true, completion: nil)
        }
        
        alert.addAction(action)
        present(alert, animated: true, completion: nil)
        extensionContext!.completeRequest(returningItems: [], completionHandler: nil)
    }
    
    private func redirectToHostApp() {
        let url = URL(string: "ShareMedia://dataUrl=\(sharedKey)#text")
        var responder = self as UIResponder?
        let selectorOpenURL = sel_registerName("openURL:")
        
        while (responder != nil) {
            if let application = responder as? UIApplication {
                application.performSelector(inBackground: selectorOpenURL, with: url)
            }
            
            responder = responder!.next
        }
        extensionContext!.completeRequest(returningItems: [], completionHandler: nil)
    }
    
    @IBAction func done() {
        // Return any edited content to the host app.
        // This template doesn't do anything, so we just echo the passed in items.
        self.extensionContext!.completeRequest(returningItems: self.extensionContext!.inputItems, completionHandler: nil)
    }
    
}