Add gif/alt badges to attachments

Closes #255, #338

Tusker/Views/Attachments/AttachmentView.swift

@@ -127,6 +127,15 @@ class AttachmentView: GIFImageView {
             }
         }
         
+        var badges: Badges = []
+        if attachment.description?.isEmpty == false {
+            badges.formUnion(.alt)
+        }
+        if attachment.kind == .gifv || attachment.url.pathExtension == "gif" {
+            badges.formUnion(.gif)
+        }
+        createBadgesView(badges)
+        
         switch attachment.kind {
         case .image:
             loadImage()
@@ -302,6 +311,64 @@ class AttachmentView: GIFImageView {
         }
     }
     
+    private func createBadgesView(_ badges: Badges) {
+        guard !badges.isEmpty else {
+            return
+        }
+        
+        let stack = UIStackView()
+        stack.axis = .horizontal
+        stack.spacing = 2
+        stack.translatesAutoresizingMaskIntoConstraints = false
+        
+        let font = UIFontMetrics(forTextStyle: .caption1).scaledFont(for: .systemFont(ofSize: 13, weight: .bold))
+        func makeBadgeView(text: String) {
+            let container = UIView()
+            container.backgroundColor = .secondarySystemBackground.resolvedColor(with: UITraitCollection(userInterfaceStyle: .dark))
+            
+            let label = UILabel()
+            label.font = font
+            label.adjustsFontForContentSizeCategory = true
+            label.textColor = .white
+            label.text = text
+            label.translatesAutoresizingMaskIntoConstraints = false
+            container.addSubview(label)
+            NSLayoutConstraint.activate([
+                label.leadingAnchor.constraint(equalTo: container.leadingAnchor, constant: 2),
+                label.trailingAnchor.constraint(equalTo: container.trailingAnchor, constant: -2),
+                label.topAnchor.constraint(equalTo: container.topAnchor, constant: 2),
+                label.bottomAnchor.constraint(equalTo: container.bottomAnchor, constant: -2),
+            ])
+            stack.addArrangedSubview(container)
+        }
+        
+        if badges.contains(.gif) {
+            makeBadgeView(text: "GIF")
+        }
+        if badges.contains(.alt) {
+            makeBadgeView(text: "ALT")
+        }
+        
+        let first = stack.arrangedSubviews.first!
+        first.layer.masksToBounds = true
+        first.layer.cornerRadius = 4
+        if stack.arrangedSubviews.count > 1 {
+            first.layer.maskedCorners = [.layerMinXMinYCorner, .layerMinXMaxYCorner]
+            let last = stack.arrangedSubviews.last!
+            last.layer.masksToBounds = true
+            last.layer.cornerRadius = 4
+            last.layer.maskedCorners = [.layerMaxXMinYCorner, .layerMaxXMaxYCorner]
+        }
+        
+        addSubview(stack)
+        NSLayoutConstraint.activate([
+            stack.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 4),
+            stack.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -4),
+        ])
+    }
+    
+    // MARK: Interaction
+    
     func showGallery() {
         if let delegate = delegate,
            let gallery = delegate.attachmentViewGallery(startingAt: index) {
@@ -328,6 +395,13 @@ fileprivate extension AttachmentView {
         case gifData(URL, Data)
         case cgImage(URL, CGImage)
     }
+    
+    struct Badges: OptionSet {
+        static let gif = Badges(rawValue: 1 << 0)
+        static let alt = Badges(rawValue: 1 << 1)
+        
+        let rawValue: Int
+    }
 }
 
 extension AttachmentView: UIContextMenuInteractionDelegate {