AboutViewController.swift

//
//  AboutViewController.swift
//  IFTTT SDK
//
//  Copyright © 2019 IFTTT. All rights reserved.
//

import UIKit
import SafariServices
import StoreKit

class AboutViewController: UIViewController {
    
    private let connection: Connection
    private let primaryService: Connection.Service
    private let secondaryService: Connection.Service
    private let activationFlow: ConnectionHandoffFlow
    
    init(connection: Connection, activationFlow: ConnectionHandoffFlow) {
        self.connection = connection
        self.primaryService = connection.primaryService
        self.secondaryService = connection.connectingService
        self.activationFlow = activationFlow
        
        super.init(nibName: nil, bundle: nil)
        
        modalTransitionStyle = .coverVertical
        modalPresentationStyle = .formSheet
    }
    
    @available(*, unavailable)
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        Analytics.shared.track(.Impression,
                               location: Location(type: "connect_button", identifier: connection.id),
                               object: AnalyticsObject.about)
    }
    
    private struct Constants {
        struct Color {
            static let mediumGrey = UIColor(hex: 0x666666)
            static let transparentWhite = UIColor(white: 1, alpha: 0.14)
        }
        
        struct Layout {
            static let serviceIconSize: CGFloat = 44
            
            static let serviceIconSpacing: CGFloat = 24
            
            /// The margins around all the page content
            static let pageMargins = UIEdgeInsets(top: 20, left: 30, bottom: 40, right: 30)
            
            /// The spacing between the close button and the page header
            static let closeButtonHeaderSpacing: CGFloat = 20
            
            /// The spacing between views in the header
            static let headerSpacing: CGFloat = 16
            
            /// The spacing between the header, body, and footer
            static let valuePropMargins: CGFloat = 36
            
            /// The spacing between items in the page body
            static let valuePropSpacing: CGFloat = 24
            
            /// The size of item icons in the page body
            static let valuePropIconSise: CGFloat = 24
            
            /// The spacing between the icon and title in body items
            static let ValuePropIconTextSpacing: CGFloat = 24
            
            /// The spacing between the download in app store button and the legal terms
            static let footerSpacing: CGFloat = 24
        }
        
        struct Text {
            /// The about page title
            static func titleText(connects primaryService: Connection.Service,
                                  with secondaryService: Connection.Service) -> NSAttributedString {
                let rawText = "about.title_full".localized(with: primaryService.shortName,
                                                           secondaryService.shortName)
                let iftttRemoved = rawText.replacingOccurrences(of: "IFTTT", with: "")
                
                let text = NSMutableAttributedString(string: iftttRemoved,
                                                     attributes: [.font : StyleGuide.Font.h3(weight: .demiBold)])
                let ifttt = NSAttributedString(string: "IFTTT",
                                               attributes: [.font : StyleGuide.Font.h3(weight: .heavy)])
                text.insert(ifttt, at: 0)
                return text
            }
            
            /// The text for legal terms
            static var legalTermsText: NSAttributedString {
                return LegalTermsText.string(withPrefix: "about.legal.full".localized,
                                             attributes: [.foregroundColor : Color.mediumGrey,
                                                          .font : StyleGuide.Font.body(weight: .demiBold)])
            }
        }
    }
    
    
    // MARK: - Header

    /// Dismisses the about page
    private lazy var closeButton = PillButton(Assets.About.close) {
        $0.imageView.tintColor = .white
        $0.onSelect { [weak self] in
            self?.dismiss(animated: true, completion: nil)
        }
        $0.backgroundColor = .clear
    }
    
    /// Aligns the close button to the top right
    private lazy var closeButtonContainer = UIStackView([closeButton]) {
        $0.axis = .vertical
        $0.alignment = .trailing
        $0.isLayoutMarginsRelativeArrangement = true
        $0.layoutMargins = UIEdgeInsets(top: 0,
                                        left: 0,
                                        bottom: Constants.Layout.closeButtonHeaderSpacing,
                                        right: 0)
    }
    
    private lazy var serviceIconsView = ServiceIconsView(primaryIcon: primaryService.templateIconURL,
                                                         secondaryIcon: secondaryService.templateIconURL,
                                                         primaryIconTapped: { [weak self] in
                                                            guard let self = self else { return }
                                                            Analytics.shared.track(.Click,
                                                                                   location: Location(type: "connect_button", identifier: self.connection.id),
                                                                                   object: AnalyticsObject.button(identifier: self.primaryService.name))
                                                            self.open(url: self.primaryService.url)
                                                         }, secondaryIconTapped: { [weak self] in
                                                            guard let self = self else { return }
                                                            Analytics.shared.track(.Click,
                                                                                   location: Location(type: "connect_button", identifier: self.connection.id),
                                                                                   object: AnalyticsObject.button(identifier: self.secondaryService.name))
                                                            self.open(url: self.secondaryService.url)
                                                         })
    
    /// The page title
    private lazy var titleLabel = UILabel(Constants.Text.titleText(connects: primaryService, with: secondaryService)) {
        $0.textColor = .white
        $0.textAlignment = .center
        $0.numberOfLines = 0
    }
    
    private var titleLabelSelectable: Selectable?
    
    /// Contains all the header components
    private lazy var headerView = UIStackView([serviceIconsView, titleLabel]) {
        $0.spacing = Constants.Layout.headerSpacing
        $0.axis = .vertical
        $0.alignment = .center
    }
    
    
    // MARK: - Page body
    
    private lazy var valuePropositionViews: [ValuePropositionView] = [
        ValuePropositionView(icon: Assets.About.connect, text: "about.connect".localized),
        ValuePropositionView(icon: Assets.About.control, text: "about.control".localized),
        ValuePropositionView(icon: Assets.About.security, text: "about.security".localized),
        ValuePropositionView(icon: Assets.About.manage, text: "about.manage".localized)
    ]
    
    private lazy var itemsStackView = UIStackView(valuePropositionViews) {
        $0.spacing = Constants.Layout.valuePropSpacing
        $0.axis = .vertical
        $0.alignment = .fill
        $0.isLayoutMarginsRelativeArrangement = true
        $0.layoutMargins = UIEdgeInsets(top: Constants.Layout.valuePropMargins,
                                        left: 0,
                                        bottom: Constants.Layout.valuePropMargins,
                                        right: 0)
    }
    
    
    // MARK: - Links
    
    private lazy var legalTermsView = LegalTermsView(text: Constants.Text.legalTermsText) { [weak self] url in
        Analytics.shared.track(.Click,
                               location: Location(type: "connect_button", identifier: self?.connection.id),
                               object: AnalyticsObject.privacyPolicy)
        self?.open(url: url)
    }
    
    private lazy var deepLinkConnectionButton = PillButton("about.connection-deep-link".localized) {
        $0.backgroundColor = Constants.Color.transparentWhite
        $0.label.textColor = .white
        $0.label.font = StyleGuide.Font.h5()
    }
    
    private lazy var downloadOnAppStoreButton: UIButton = {
        let button = UIButton(type: .custom)
        button.setImage(Assets.About.downloadOnAppStore, for: [])
        return button
    }()
    
    private lazy var footerView: UIStackView = {
        let views: [UIView]
        if ConnectionDeeplinkAction.isIftttAppAvailable {
            switch connection.status {
            case .enabled:
                views = [deepLinkConnectionButton, legalTermsView]
            case .initial, .disabled, .unknown:
                views = [legalTermsView]
            }
        } else {
            views = [downloadOnAppStoreButton, legalTermsView]
        }
        return UIStackView(views) {
            $0.axis = .vertical
            $0.alignment = .center
            $0.distribution = .fillEqually
            $0.spacing = Constants.Layout.footerSpacing
        }
    }()
    
    private func open(url: URL) {
        UIApplication.shared.open(url, options: [.universalLinksOnly: NSNumber(booleanLiteral: true)]) { [weak self] (opened) in
            guard let self = self else { return }
            if !opened {
                let controller = SFSafariViewController(url: url)
                self.present(controller, animated: true, completion: nil)
            }
        }
    }
    
    /// Acts as the delegate for displaying the IFTTT app store page
    private class StoreProductViewControllerDelegate: NSObject, SKStoreProductViewControllerDelegate {
        public func productViewControllerDidFinish(_ viewController: SKStoreProductViewController) {
            viewController.dismiss(animated: true, completion: nil)
        }
    }
    
    private var storeProductViewControllerDelegate = StoreProductViewControllerDelegate()
    
    /// Presents an App Store view for the IFTTT app
    @objc private func showAppStorePage() {
        let viewController = SKStoreProductViewController()
        let parameters: [String : Any] = [SKStoreProductParameterITunesItemIdentifier : API.iftttAppStoreId]
        viewController.loadProduct(withParameters: parameters, completionBlock: nil)
        viewController.delegate = storeProductViewControllerDelegate
        present(viewController, animated: true)
    }
    
    private func deepLinkToEditConnection() {
        Analytics.shared.track(.Click,
                               location: Location(type: "connect_button", identifier: connection.id),
                               object: AnalyticsObject.button(identifier: "manage"))
        
        guard let url = activationFlow.appHandoffUrl(userId: nil, action: .edit) else { return }
        
        UIApplication.shared.open(url, options: [:]) { didOpen in
            if !didOpen {
                // Fallback to opening in Safari
                let safari = SFSafariViewController(url: url)
                self.present(safari, animated: true, completion: nil)
            }
        }
    }
    
    
    // MARK: - Page structure
    
    /// Aligns all page components
    private lazy var primaryView = UIStackView([closeButtonContainer, headerView, itemsStackView, footerView]) {
        $0.axis = .vertical
        $0.alignment = .fill
        $0.isLayoutMarginsRelativeArrangement = true
        $0.layoutMargins = Constants.Layout.pageMargins
    }
    
    
    // MARK: - UIViewController
    
    override func loadView() {
        super.loadView()
        
        view.backgroundColor = .black
        
        let scrollView = UIScrollView()
        scrollView.addSubview(primaryView)
        
        primaryView.constrain.edges(to: scrollView)
        primaryView.constrain.width(to: scrollView)
        
        view.addSubview(scrollView)
        scrollView.constrain.edges(to: view)
        
        downloadOnAppStoreButton.addTarget(self, action: #selector(showAppStorePage), for: .touchUpInside)
        
        deepLinkConnectionButton.onSelect { [weak self] in
            self?.deepLinkToEditConnection()
        }
        
        titleLabelSelectable = Selectable(titleLabel, onSelect: { [weak self] in
            guard let self = self else { return }
            Analytics.shared.track(.Click,
                                   location: Location(type: "connect_button", identifier: self.connection.id),
                                   object: AnalyticsObject.button(identifier: self.connection.name))
            self.open(url: self.connection.url)
        })
    }
    
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return .lightContent
    }
}


// MARK: - Service icons header view

private extension AboutViewController {
    /// Presents the primary and secondary service icons with an arrow connecting the two
    final class ServiceIconsView: UIView {
        private var primaryIconSelectable: Selectable?
        private var secondaryIconSelectable: Selectable?
        
        init(primaryIcon: URL, secondaryIcon: URL, primaryIconTapped: @escaping VoidClosure, secondaryIconTapped: @escaping VoidClosure) {
            super.init(frame: .zero)
            
            let primaryIconView = UIImageView()
            let secondaryIconView = UIImageView()
            
            primaryIconView.constrain.square(length: Constants.Layout.serviceIconSize)
            secondaryIconView.constrain.square(length: Constants.Layout.serviceIconSize)
            
            let arrowIcon = UIImageView(image: Assets.About.connectArrow)
            
            let stackView = UIStackView([primaryIconView, arrowIcon, secondaryIconView]) { (view) in
                view.axis = .horizontal
                view.spacing = Constants.Layout.serviceIconSpacing
                view.alignment = .center
            }
            addSubview(stackView)
            stackView.constrain.edges(to: self)
            
            let serviceIconsDownloader = ServiceIconsNetworkController()
            serviceIconsDownloader.setImage(with: primaryIcon, for: primaryIconView)
            serviceIconsDownloader.setImage(with: secondaryIcon, for: secondaryIconView)
            
            primaryIconSelectable = Selectable(primaryIconView, onSelect: primaryIconTapped)
            secondaryIconSelectable = Selectable(secondaryIconView, onSelect: secondaryIconTapped)
        }
        
        @available(*, unavailable)
        required init?(coder aDecoder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }
    }
}


// MARK: - Value proposition view

private extension AboutViewController {
    final class ValuePropositionView: UIView {
        init(icon: UIImage?, text: String) {
            super.init(frame: .zero)
            
            let iconView = UIImageView(image: icon)
            iconView.tintColor = Constants.Color.mediumGrey
            iconView.contentMode = .scaleAspectFit
            iconView.constrain.square(length: Constants.Layout.valuePropIconSise)
            
            let label = UILabel(text) {
                $0.font = StyleGuide.Font.body(weight: .demiBold)
                $0.textColor = .white
                $0.textAlignment = .left
                $0.numberOfLines = 0
            }
            
            let stackView = UIStackView([iconView, label]) {
                $0.spacing = Constants.Layout.ValuePropIconTextSpacing
                $0.axis = .horizontal
                $0.alignment = .center
            }
            
            addSubview(stackView)
            stackView.constrain.edges(to: self)
            
            iconView.setContentHuggingPriority(.required, for: .horizontal)
        }
        
        @available(*, unavailable)
        required init?(coder aDecoder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }
    }
}


// MARK: - Legal terms view

private extension AboutViewController {
    final class LegalTermsView: UIView, UITextViewDelegate {
        
        /// One of the links was selected
        let onLinkSelected: ((URL) -> Void)?
        
        init(text: NSAttributedString, onLinkSelected: ((URL) -> Void)?) {
            self.onLinkSelected = onLinkSelected
            
            super.init(frame: .zero)
            
            let view = UITextView(frame: .zero)
            addSubview(view)
            view.constrain.edges(to: self)
            
            view.attributedText = text
            view.textAlignment = .center
            // This sets the color of the links
            // The should match the text
            view.tintColor = Constants.Color.mediumGrey
            view.isScrollEnabled = false
            view.isEditable = false
            view.backgroundColor = .clear
            
            view.delegate = self
        }
        
        @available(*, unavailable)
        required init?(coder aDecoder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }
        
        func textView(_ textView: UITextView, shouldInteractWith URL: URL, in characterRange: NSRange, interaction: UITextItemInteraction) -> Bool {
            updateLinkText(with: .white, textView: textView)
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) {
                self.updateLinkText(with: Constants.Color.mediumGrey, textView: textView)
                self.onLinkSelected?(URL)
            }
            return false
        }
        
        private func updateLinkText(with color: UIColor, textView: UITextView) {
            textView.linkTextAttributes = [
                NSAttributedString.Key.foregroundColor: color,
                NSAttributedString.Key.underlineStyle: NSUnderlineStyle.single.rawValue,
            ]
        }
    }
}