Added initial support for sharing URLs and text

Updated the share extension to load URL previews.
Updated the ThreadPickerVC to send plain text & URLs in the same way they are sent for normal messages.

Session/Meta/MainAppContext.m

@@ -160,6 +160,10 @@ NSString *const ReportedApplicationStateDidChangeNotification = @"ReportedApplic
     return [UIApplication sharedApplication].applicationState == UIApplicationStateActive;
 }
 
+- (BOOL)isShareExtension {
+    return NO;
+}
+
 - (BOOL)isRTL
 {
     static BOOL isRTL = NO;

SessionMessagingKit/Sending & Receiving/Attachments/SignalAttachment.swift

@@ -114,6 +114,9 @@ public class SignalAttachment: NSObject {
 
     @objc
     public var captionText: String?
+    
+    @objc
+    public var linkPreviewDraft: OWSLinkPreviewDraft?
 
     @objc
     public var data: Data {
@@ -292,6 +295,15 @@ public class SignalAttachment: NSObject {
             return nil
         }
     }
+    
+    @objc
+    public func text() -> String? {
+        guard let text = String(data: dataSource.data(), encoding: .utf8) else {
+            return nil
+        }
+        
+        return text
+    }
 
     // Returns the MIME type for this attachment or nil if no MIME type
     // can be identified.

SessionNotificationServiceExtension/NotificationServiceExtensionContext.swift

@@ -9,6 +9,7 @@ final class NotificationServiceExtensionContext : NSObject, AppContext {
     let appLaunchTime = Date()
     let isMainApp = false
     let isMainAppAndActive = false
+    var isShareExtension: Bool = false
 
     var openSystemSettingsAction: UIAlertAction?
     var wasWokenUpByPushNotification = true

SessionShareExtension/ShareAppExtensionContext.swift

@@ -13,6 +13,7 @@ final class ShareAppExtensionContext: NSObject, AppContext {
     let appLaunchTime = Date()
     let isMainApp = false
     let isMainAppAndActive = false
+    var isShareExtension: Bool = true
     
     var mainWindow: UIWindow?
     var wasWokenUpByPushNotification: Bool = false

SessionShareExtension/ThreadPickerVC.swift

@@ -147,19 +147,44 @@ final class ThreadPickerVC: UIViewController, UITableViewDataSource, UITableView
     }
     
     func attachmentApproval(_ attachmentApproval: AttachmentApprovalViewController, didApproveAttachments attachments: [SignalAttachment], messageText: String?) {
+        // Sharing a URL or plain text will populate the 'messageText' field so in those
+        // cases we should ignore the attachments
+        let isSharingUrl: Bool = (attachments.count == 1 && attachments[0].isUrl)
+        let isSharingText: Bool = (attachments.count == 1 && attachments[0].isText)
+        let finalAttachments: [SignalAttachment] = (isSharingUrl || isSharingText ? [] : attachments)
+        
         let message = VisibleMessage()
         message.sentTimestamp = NSDate.millisecondTimestamp()
         message.text = messageText
         
         let tsMessage = TSOutgoingMessage.from(message, associatedWith: selectedThread!)
-        Storage.write { transaction in
-            tsMessage.save(with: transaction)
-        }
+        Storage.write(
+            with: { transaction in
+                if isSharingUrl {
+                    message.linkPreview = VisibleMessage.LinkPreview.from(
+                        attachments[0].linkPreviewDraft,
+                        using: transaction
+                    )
+                }
+                else {
+                    tsMessage.save(with: transaction)
+                }
+            },
+            completion: {
+                if isSharingUrl {
+                    tsMessage.linkPreview = OWSLinkPreview.from(message.linkPreview)
+                    
+                    Storage.write { transaction in
+                        tsMessage.save(with: transaction)
+                    }
+                }
+            }
+        )
         
         shareVC!.dismiss(animated: true, completion: nil)
         
         ModalActivityIndicatorViewController.present(fromViewController: shareVC!, canCancel: false, message: "vc_share_sending_message".localized()) { activityIndicator in
-            MessageSender.sendNonDurably(message, with: attachments, in: self.selectedThread!)
+            MessageSender.sendNonDurably(message, with: finalAttachments, in: self.selectedThread!)
                 .done { [weak self] _ in
                     activityIndicator.dismiss { }
                     self?.shareVC?.shareViewWasCompleted()

SessionUtilitiesKit/General/AppContext.h

@@ -35,6 +35,7 @@ NSString *NSStringForUIApplicationState(UIApplicationState value);
 
 @property (nonatomic, readonly) BOOL isMainApp;
 @property (nonatomic, readonly) BOOL isMainAppAndActive;
+@property (nonatomic, readonly) BOOL isShareExtension;
 /// Whether the app was woken up by a silent push notification. This is important for determining whether attachments should be downloaded or not.
 @property (nonatomic) BOOL wasWokenUpByPushNotification;
 

SessionUtilitiesKit/Networking/ProxiedContentDownloader.swift

@@ -594,7 +594,7 @@ open class ProxiedContentDownloader: NSObject, URLSessionTaskDelegate, URLSessio
             removeAssetRequestFromQueue(assetRequest: assetRequest)
             return
         }
-        guard CurrentAppContext().isMainAppAndActive else {
+        guard CurrentAppContext().isMainAppAndActive || CurrentAppContext().isShareExtension else {
             // If app is not active, fail the asset request.
             assetRequest.state = .failed
             assetRequestDidFail(assetRequest: assetRequest)

SignalUtilitiesKit/Media Viewing & Editing/Attachment Approval/AttachmentApprovalViewController.swift

@@ -241,6 +241,12 @@ public class AttachmentApprovalViewController: UIPageViewController, UIPageViewC
         UIView.performWithoutAnimation {
             self.currentPageViewController?.view.layoutIfNeeded()
         }
+        
+        // If the first item is just text, or is a URL and LinkPreviews are disabled
+        // then just fill the 'message' box with it
+        if firstItem.attachment.isText || (firstItem.attachment.isUrl && OWSLinkPreview.previewURL(forRawBodyText: firstItem.attachment.text()) == nil) {
+            bottomToolView.attachmentTextToolbar.messageText = firstItem.attachment.text()
+        }
 
         setupLayout()
     }

SignalUtilitiesKit/Media Viewing & Editing/MediaMessageView.swift

@@ -5,6 +5,7 @@
 import Foundation
 import MediaPlayer
 import YYImage
+import NVActivityIndicatorView
 
 import SessionUIKit
 
@@ -52,6 +53,8 @@ public class MediaMessageView: UIView, OWSAudioPlayerDelegate {
 
     @objc
     public var contentView: UIView?
+    
+    private var linkPreviewInfo: (url: String, draft: OWSLinkPreviewDraft?)?
 
     // MARK: Initializers
 
@@ -89,6 +92,10 @@ public class MediaMessageView: UIView, OWSAudioPlayerDelegate {
             createVideoPreview()
         } else if attachment.isAudio {
             createAudioPreview()
+        } else if attachment.isUrl {
+            createUrlPreview()
+        } else if attachment.isText {
+            // Do nothing as we will just put the text in the 'message' input
         } else {
             createGenericPreview()
         }
@@ -118,6 +125,31 @@ public class MediaMessageView: UIView, OWSAudioPlayerDelegate {
 
         return stackView
     }
+    
+    private func wrapViewsInHorizontalStack(subviews: [UIView]) -> UIView {
+        assert(subviews.count > 0)
+
+        let stackView = UIView()
+
+        var lastView: UIView?
+        for subview in subviews {
+
+            stackView.addSubview(subview)
+            subview.autoVCenterInSuperview()
+
+            if lastView == nil {
+                subview.autoPinEdge(toSuperviewEdge: .left)
+            } else {
+                subview.autoPinEdge(.left, to: .right, of: lastView!, withOffset: stackSpacing())
+            }
+
+            lastView = subview
+        }
+
+        lastView?.autoPinEdge(toSuperviewEdge: .right)
+
+        return stackView
+    }
 
     private func stackSpacing() -> CGFloat {
         switch mode {
@@ -265,6 +297,120 @@ public class MediaMessageView: UIView, OWSAudioPlayerDelegate {
             videoPlayButton.autoSetDimension(.height, toSize: 72)
         }
     }
+    
+    private func createUrlPreview() {
+        // If link previews aren't enabled then use a fallback state
+        guard let linkPreviewURL: String = OWSLinkPreview.previewURL(forRawBodyText: attachment.text()) else {
+            createGenericPreview()
+            return
+        }
+        
+        linkPreviewInfo = (url: linkPreviewURL, draft: nil)
+        
+        var subviews = [UIView]()
+        
+        let color: UIColor = isLightMode ? .black : .white
+        let loadingView = NVActivityIndicatorView(frame: CGRect.zero, type: .circleStrokeSpin, color: color, padding: nil)
+        loadingView.set(.width, to: 24)
+        loadingView.set(.height, to: 24)
+        loadingView.startAnimating()
+        subviews.append(loadingView)
+        
+        let imageViewContainer = UIView()
+        imageViewContainer.clipsToBounds = true
+        imageViewContainer.contentMode = .center
+        imageViewContainer.alpha = 0
+        imageViewContainer.layer.cornerRadius = 8
+        subviews.append(imageViewContainer)
+        
+        let imageView = createHeroImageView(imageName: "FileLarge")
+        imageViewContainer.addSubview(imageView)
+        imageView.pin(to: imageViewContainer)
+
+        let titleLabel = UILabel()
+        titleLabel.text = linkPreviewURL
+        titleLabel.textColor = controlTintColor
+        titleLabel.font = labelFont()
+        titleLabel.textAlignment = .center
+        titleLabel.lineBreakMode = .byTruncatingMiddle
+        subviews.append(titleLabel)
+        
+        let stackView = wrapViewsInVerticalStack(subviews: subviews)
+        self.addSubview(stackView)
+        
+        titleLabel.autoPinWidthToSuperview(withMargin: 32)
+        
+        NSLayoutConstraint.activate([
+            imageView.widthAnchor.constraint(equalToConstant: 80),
+            imageView.heightAnchor.constraint(equalToConstant: 80)
+        ])
+        
+        // Build the link preview
+        OWSLinkPreview.tryToBuildPreviewInfo(previewUrl: linkPreviewURL).done { [weak self] draft in
+            // Loader
+            loadingView.alpha = 0
+            loadingView.stopAnimating()
+            
+            self?.linkPreviewInfo = (url: linkPreviewURL, draft: draft)
+            
+            // TODO: Look at refactoring this behaviour to consolidate attachment mutations
+            self?.attachment.linkPreviewDraft = draft
+            
+            let image: UIImage?
+
+            if let jpegImageData: Data = draft.jpegImageData, let loadedImage: UIImage = UIImage(data: jpegImageData) {
+                image = loadedImage
+                imageView.contentMode = .scaleAspectFill
+            }
+            else {
+                image = UIImage(named: "Link")?.withTint(isLightMode ? .black : .white)
+                imageView.contentMode = .center
+            }
+            
+            // Image view
+            (imageView as? UIImageView)?.image = image
+            imageViewContainer.alpha = 1
+            imageViewContainer.backgroundColor = isDarkMode ? .black : UIColor.black.withAlphaComponent(0.06)
+            
+            // Title
+            if let title = draft.title {
+                titleLabel.font = .boldSystemFont(ofSize: Values.smallFontSize)
+                titleLabel.text = title
+                titleLabel.textAlignment = .left
+                titleLabel.numberOfLines = 2
+            }
+            
+            guard let hStackView = self?.wrapViewsInHorizontalStack(subviews: subviews) else {
+                // TODO: Fallback
+                return
+            }
+            stackView.removeFromSuperview()
+            self?.addSubview(hStackView)
+            
+            // We want to center the stackView in it's superview while also ensuring
+            // it's superview is big enough to contain it.
+            hStackView.autoPinWidthToSuperview(withMargin: 32)
+            hStackView.autoVCenterInSuperview()
+            NSLayoutConstraint.autoSetPriority(UILayoutPriority.defaultLow) {
+                hStackView.autoPinHeightToSuperview()
+            }
+            hStackView.autoPinEdge(toSuperviewEdge: .top, withInset: 0, relation: .greaterThanOrEqual)
+            hStackView.autoPinEdge(toSuperviewEdge: .bottom, withInset: 0, relation: .greaterThanOrEqual)
+        }.catch { _ in
+            // TODO: Fallback
+            loadingView.stopAnimating()
+        }.retainUntilComplete()
+
+        // We want to center the stackView in it's superview while also ensuring
+        // it's superview is big enough to contain it.
+        stackView.autoPinWidthToSuperview()
+        stackView.autoVCenterInSuperview()
+        NSLayoutConstraint.autoSetPriority(UILayoutPriority.defaultLow) {
+            stackView.autoPinHeightToSuperview()
+        }
+        stackView.autoPinEdge(toSuperviewEdge: .top, withInset: 0, relation: .greaterThanOrEqual)
+        stackView.autoPinEdge(toSuperviewEdge: .bottom, withInset: 0, relation: .greaterThanOrEqual)
+    }
 
     private func createGenericPreview() {
         var subviews = [UIView]()