Show link preview suggestion if needed

Session.xcodeproj/project.pbxproj

@@ -562,6 +562,7 @@
 		C35E8AAE2485E51D00ACB629 /* IP2Country.swift in Sources */ = {isa = PBXBuildFile; fileRef = C35E8AAD2485E51D00ACB629 /* IP2Country.swift */; };
 		C3645350252449260045C478 /* VoiceMessageView.swift in Sources */ = {isa = PBXBuildFile; fileRef = C364534F252449260045C478 /* VoiceMessageView.swift */; };
 		C364535C252467900045C478 /* AudioUtilities.swift in Sources */ = {isa = PBXBuildFile; fileRef = C364535B252467900045C478 /* AudioUtilities.swift */; };
+		C374EEE225DA26740073A857 /* LinkPreviewModal.swift in Sources */ = {isa = PBXBuildFile; fileRef = C374EEE125DA26740073A857 /* LinkPreviewModal.swift */; };
 		C379DCF4256735770002D4EB /* VisibleMessage+Attachment.swift in Sources */ = {isa = PBXBuildFile; fileRef = C379DCF3256735770002D4EB /* VisibleMessage+Attachment.swift */; };
 		C37F5385255B94F6002AEA92 /* SelectRecipientViewController.h in Headers */ = {isa = PBXBuildFile; fileRef = C38EF34E255B6DC8007E1867 /* SelectRecipientViewController.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		C37F5396255B95BD002AEA92 /* OWSAnyTouchGestureRecognizer.h in Headers */ = {isa = PBXBuildFile; fileRef = C38EF302255B6DBE007E1867 /* OWSAnyTouchGestureRecognizer.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -1604,6 +1605,7 @@
 		C35E8AAD2485E51D00ACB629 /* IP2Country.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = IP2Country.swift; sourceTree = "<group>"; };
 		C364534F252449260045C478 /* VoiceMessageView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = VoiceMessageView.swift; sourceTree = "<group>"; };
 		C364535B252467900045C478 /* AudioUtilities.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AudioUtilities.swift; sourceTree = "<group>"; };
+		C374EEE125DA26740073A857 /* LinkPreviewModal.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LinkPreviewModal.swift; sourceTree = "<group>"; };
 		C379DCF3256735770002D4EB /* VisibleMessage+Attachment.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "VisibleMessage+Attachment.swift"; sourceTree = "<group>"; };
 		C379DCFD25673DBC0002D4EB /* TSAttachmentPointer+Conversion.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "TSAttachmentPointer+Conversion.swift"; sourceTree = "<group>"; };
 		C37F53E8255BA9BB002AEA92 /* Environment.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = Environment.h; sourceTree = "<group>"; };
@@ -2246,6 +2248,7 @@
 				B821494525D4D6FF009C0F2A /* URLModal.swift */,
 				B821494E25D4E163009C0F2A /* BodyTextView.swift */,
 				B82149B725D60393009C0F2A /* BlockedModal.swift */,
+				C374EEE125DA26740073A857 /* LinkPreviewModal.swift */,
 				B82149C025D605C6009C0F2A /* InfoBanner.swift */,
 				B8214A2A25D63EB9009C0F2A /* MessagesTableView.swift */,
 			);
@@ -5156,6 +5159,7 @@
 				C33100092558FF6D00070591 /* UserCell.swift in Sources */,
 				B8269D2925C7A4B400488AB4 /* InputView.swift in Sources */,
 				C3645350252449260045C478 /* VoiceMessageView.swift in Sources */,
+				C374EEE225DA26740073A857 /* LinkPreviewModal.swift in Sources */,
 				3496956F21A301A100DCFE74 /* OWSBackupLazyRestore.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Session/Conversations V2/ConversationVC.swift

@@ -354,6 +354,15 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, UITableViewD
         viewModel.loadAnotherPageOfMessages()
     }
 
+    func showLinkPreviewSuggestionModal() {
+        let linkPreviewModel = LinkPreviewModal() { [weak self] in
+            self?.snInputView.autoGenerateLinkPreview()
+        }
+        linkPreviewModel.modalPresentationStyle = .overFullScreen
+        linkPreviewModel.modalTransitionStyle = .crossDissolve
+        present(linkPreviewModel, animated: true, completion: nil)
+    }
+    
     // MARK: Convenience
     private func getTitle() -> String {
         if let thread = thread as? TSGroupThread {

Session/Conversations V2/Input View/InputView.swift

@@ -99,7 +99,7 @@ final class InputView : UIView, InputViewButtonDelegate, InputTextViewDelegate,
     // MARK: Updating
     func inputTextViewDidChangeSize(_ inputTextView: InputTextView) {
         invalidateIntrinsicContentSize()
-        doLinkPreviewThingies()
+        autoGenerateLinkPreviewIfPossible()
     }
 
     private func handleQuoteDraftChanged() {
@@ -117,20 +117,26 @@ final class InputView : UIView, InputViewButtonDelegate, InputTextViewDelegate,
         quoteView.pin(.bottom, to: .bottom, of: additionalContentContainer, withInset: -6)
     }
 
-    private func doLinkPreviewThingies() {
+    private func autoGenerateLinkPreviewIfPossible() {
         additionalContentContainer.subviews.forEach { $0.removeFromSuperview() }
         quoteDraftInfo = nil
-        // Suggest that the user enable link previews if they haven't already, and we haven't
+        // Suggest that the user enable link previews if they haven't already and we haven't
         // told them about link previews yet
         let text = inputTextView.text!
         let userDefaults = UserDefaults.standard
         if !OWSLinkPreview.allPreviewUrls(forMessageBodyText: text).isEmpty && !SSKPreferences.areLinkPreviewsEnabled
             && !userDefaults[.hasSeenLinkPreviewSuggestion] {
-            // TODO: Show suggestion
+            delegate.showLinkPreviewSuggestionModal()
             userDefaults[.hasSeenLinkPreviewSuggestion] = true
+            return
         }
         // Check that link previews are enabled
         guard SSKPreferences.areLinkPreviewsEnabled else { return }
+        // Proceed
+        autoGenerateLinkPreview()
+    }
+
+    func autoGenerateLinkPreview() {
         // Check that a valid URL is present
         guard let linkPreviewURL = OWSLinkPreview.previewUrl(forRawBodyText: text, selectedRange: inputTextView.selectedRange) else {
             return
@@ -189,6 +195,7 @@ final class InputView : UIView, InputViewButtonDelegate, InputTextViewDelegate,
 // MARK: Delegate
 protocol InputViewDelegate {
 
+    func showLinkPreviewSuggestionModal()
     func handleCameraButtonTapped()
     func handleLibraryButtonTapped()
     func handleGIFButtonTapped()

Session/Conversations V2/Views & Modals/LinkPreviewModal.swift

@@ -0,0 +1,66 @@
+
+final class LinkPreviewModal : Modal {
+    private let onLinkPreviewsEnabled: () -> Void
+
+    // MARK: Lifecycle
+    init(onLinkPreviewsEnabled: @escaping () -> Void) {
+        self.onLinkPreviewsEnabled = onLinkPreviewsEnabled
+        super.init(nibName: nil, bundle: nil)
+    }
+
+    required init?(coder: NSCoder) {
+        preconditionFailure("Use init(onLinkPreviewsEnabled:) instead.")
+    }
+
+    override init(nibName: String?, bundle: Bundle?) {
+        preconditionFailure("Use init(onLinkPreviewsEnabled:) instead.")
+    }
+
+    override func populateContentView() {
+        // Title
+        let titleLabel = UILabel()
+        titleLabel.textColor = Colors.text
+        titleLabel.font = .boldSystemFont(ofSize: Values.largeFontSize)
+        titleLabel.text = "Enable Link Previews?"
+        titleLabel.textAlignment = .center
+        // Message
+        let messageLabel = UILabel()
+        messageLabel.textColor = Colors.text
+        messageLabel.font = .systemFont(ofSize: Values.smallFontSize)
+        let message = "Session can show previews for URLs. This will make your messaging experience nicer, but to generate a preview Session needs to contact the website in question. You can always disable link previews in the in-app settings."
+        messageLabel.text = message
+        messageLabel.numberOfLines = 0
+        messageLabel.lineBreakMode = .byWordWrapping
+        messageLabel.textAlignment = .center
+        // Enable button
+        let enableButton = UIButton()
+        enableButton.set(.height, to: Values.mediumButtonHeight)
+        enableButton.layer.cornerRadius = Values.modalButtonCornerRadius
+        enableButton.backgroundColor = Colors.buttonBackground
+        enableButton.titleLabel!.font = .systemFont(ofSize: Values.smallFontSize)
+        enableButton.setTitleColor(Colors.text, for: UIControl.State.normal)
+        enableButton.setTitle("Enable", for: UIControl.State.normal)
+        enableButton.addTarget(self, action: #selector(enable), for: UIControl.Event.touchUpInside)
+        // Button stack view
+        let buttonStackView = UIStackView(arrangedSubviews: [ cancelButton, enableButton ])
+        buttonStackView.axis = .horizontal
+        buttonStackView.spacing = Values.mediumSpacing
+        buttonStackView.distribution = .fillEqually
+        // Main stack view
+        let mainStackView = UIStackView(arrangedSubviews: [ titleLabel, messageLabel, buttonStackView ])
+        mainStackView.axis = .vertical
+        mainStackView.spacing = Values.largeSpacing
+        contentView.addSubview(mainStackView)
+        mainStackView.pin(.leading, to: .leading, of: contentView, withInset: Values.largeSpacing)
+        mainStackView.pin(.top, to: .top, of: contentView, withInset: Values.largeSpacing)
+        contentView.pin(.trailing, to: .trailing, of: mainStackView, withInset: Values.largeSpacing)
+        contentView.pin(.bottom, to: .bottom, of: mainStackView, withInset: Values.largeSpacing)
+    }
+
+    // MARK: Interaction
+    @objc private func enable() {
+        SSKPreferences.areLinkPreviewsEnabled = true
+        presentingViewController?.dismiss(animated: true, completion: nil)
+        onLinkPreviewsEnabled()
+    }
+}