eqn.ios/Sources/Earthquake Network/Controllers/InApp/PurchaseProVersionViewController.swift

//
//  PurchaseProVersionViewController.swift
//  Earthquake Network
//
//  Created by Busi Andrea on 29/07/2020.
//  Copyright © 2020 Earthquake Network. All rights reserved.
//

import UIKit
import SafariServices
import StoreKit


class PurchaseProVersionViewController: UIViewController {
    
    @IBOutlet private weak var discountTextLabel: UILabel!
    @IBOutlet private weak var descriptionTextLabel: UILabel!
    @IBOutlet private weak var openPrivacyButton: UIButton!
    @IBOutlet private weak var openTermsButton: UIButton!
    @IBOutlet private weak var priceLabel: UILabel!
    @IBOutlet private weak var purchaseButton: UIButton!
    
    // MARK: - Internal
    
    private var products = [SKProduct]()
    private var proProduct: SKProduct?
    
    private var restoreTapped = false
    /// Time remaining (in hours) for discounted price. If zero, no discount available
    private var discountTimeRemaining: Int = 0
    
    // MARK: - View Lifecycle
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        NotificationCenter.default.addObserver(self, selector: #selector(handlePurchaseNotification(_:)),
                                               name: .IAPHelperPurchaseNotification,
                                               object: nil)
        
        configureUI()
        loadProducts()
        checkDiscountPrice()
    }
    
    // MARK: - Private
    
    private func configureUI() {
        let restoreButton = UIBarButtonItem(title: NSLocalizedString("purchase_pro_restore", comment: ""),
                                            style: .plain,
                                            target: self,
                                            action: #selector(restoreTapped(_:)))
        navigationItem.rightBarButtonItem = restoreButton
        
        purchaseButton.isEnabled = false
        descriptionTextLabel.text = NSLocalizedString("purchase_pro_description", comment: "")
        discountTextLabel.text = NSLocalizedString("purchase_pro_discount", comment: "")
        discountTextLabel.isHidden = true
    }
    
    private func updateUI() {
        // search for the Pro product
        let isDiscountEnabled = discountTimeRemaining > 0
        let identifier = isDiscountEnabled ? VersioneProProducts.Identifier.ProVersionDiscounted : VersioneProProducts.Identifier.ProVersionFullPrice
        guard let proProduct = products.first(where: { $0.productIdentifier.lowercased() == identifier.lowercased() }) else {
            return
        }
        
        self.proProduct = proProduct
        priceFormatter.locale = proProduct.priceLocale
        
        if isDiscountEnabled {
            discountTextLabel.isHidden = false
            let string = NSLocalizedString("purchase_pro_discount", comment: "")
            discountTextLabel.text = String(format: string, discountTimeRemaining)
        }
        
        priceLabel.text = priceFormatter.string(from: proProduct.price)
        purchaseButton.isEnabled = true
        
        if  UserDefaults.standard.bool(forKey: VersioneProProducts.Identifier.ProVersionFullPrice) ||
            UserDefaults.standard.bool(forKey: VersioneProProducts.Identifier.ProVersionDiscounted) ||
            UserDefaults.standard.bool(forKey: VersioneProProducts.Identifier.Subscription10kYearly) ||
            UserDefaults.standard.bool(forKey: VersioneProProducts.Identifier.Subscription10kYearlyDiscounted) ||
            UserDefaults.standard.bool(forKey: VersioneProProducts.Identifier.Subscription100kYearly) ||
            UserDefaults.standard.bool(forKey: VersioneProProducts.Identifier.Subscription100kYearlyDiscounted)  {
            
            purchaseButton.isEnabled = false
            priceLabel.text = "-"
        }
    }
    
    private func loadProducts() {
        VersioneProProducts.store.requestProducts { [weak self] success, products in
            guard let self = self, let products = products, success == true else { return }
            
            self.products = products
            self.updateUI()
        }
    }
    
    private func checkDiscountPrice() {
        EQNPurchaseUtility.offerTimeRemaining { (timeRemaining) in
            DispatchQueue.main.async {
                self.discountTimeRemaining = timeRemaining
                self.updateUI()
            }
        }
    }
    
    // MARK: - Actions
    
    @objc func restoreTapped(_ sender: Any) {
        restoreTapped = true
        VersioneProProducts.store.restorePurchases()
    }
    
    @IBAction func purchaseTapped(_ sender: UIButton) {
        guard let product = proProduct else { return }
        
        VersioneProProducts.store.buyProduct(product)
    }
    
    @IBAction func openExternalLinkTapped(_ sender: UIButton) {
        var linkUrl: URL?
        if sender == openPrivacyButton {
            linkUrl = URL(string: "\(EQNWebsiteAddress)/privacy/")
        } else if sender == openTermsButton {
            linkUrl = URL(string: "\(EQNWebsiteAddress)/terms-conditions/")

        }
        
        if let url = linkUrl {
            let controller = SFSafariViewController(url: url)
            present(controller, animated: true, completion: nil)
        }
    }
    
    // MARK: - Notifications
    
    @objc func handlePurchaseNotification(_ notification: Notification) {
        guard   let productId = notification.object as? String,
            products.contains(where: { $0.productIdentifier == productId }) else {
                print("[PurchasePro] Unable to find the product")
                return
        }
        
        if restoreTapped {
            restoreTapped = false
            let alert = UIAlertController(title: NSLocalizedString("purchase_pro_restore_alert_title", comment: ""),
                                          message: NSLocalizedString("purchase_pro_restore_alert_message", comment: ""),
                                          preferredStyle: .alert)
            alert.addAction(UIAlertAction(title: "OK", style: .default) { [weak self] _ in
                self?.navigationController?.popViewController(animated: true)
            })
            present(alert, animated: true)
        } else {
            navigationController?.popViewController(animated: true)
        }
    }
    
    // MARK: - Helper
    
    private var priceFormatter: NumberFormatter = {
        let formatter = NumberFormatter()
        formatter.formatterBehavior = .behavior10_4
        formatter.numberStyle = .currency
        return formatter
    }()
}