Fix images copied from Safari pasting as URLs

Closes #301

Tusker/Screens/Compose/ComposeUIState.swift

@@ -16,6 +16,7 @@ protocol ComposeUIStateDelegate: AnyObject {
     func presentAssetPickerSheet()
     func presentComposeDrawing()
     func selectDraft(_ draft: Draft)
+    func paste(itemProviders: [NSItemProvider])
 }
 
 class ComposeUIState: ObservableObject {

Tusker/Screens/Compose/ComposeView.swift

@@ -72,8 +72,24 @@ struct ComposeView: View {
         return attachmentIds.contains { uiState.attachmentsMissingDescriptions.contains($0) }
     }
     
+    private var validAttachmentCombination: Bool {
+        if !mastodonController.instanceFeatures.mastodonAttachmentRestrictions {
+            return true
+        } else if draft.attachments.contains(where: { $0.data.type == .video }) && draft.attachments.count > 1 {
+            return false
+        } else if draft.attachments.count > 4 {
+            return false
+        }
+        return true
+    }
+    
     private var postButtonEnabled: Bool {
-        draft.hasContent && charactersRemaining >= 0 && !isPosting && !requiresAttachmentDescriptions && (draft.poll == nil || draft.poll!.options.allSatisfy { !$0.text.isEmpty })
+        draft.hasContent
+        && charactersRemaining >= 0
+        && !isPosting
+        && !requiresAttachmentDescriptions
+        && validAttachmentCombination
+        && (draft.poll == nil || draft.poll!.options.allSatisfy { !$0.text.isEmpty })
     }
     
     var body: some View {

Tusker/Screens/Compose/MainComposeTextView.swift

@@ -83,7 +83,7 @@ struct MainComposeWrappedTextView: UIViewRepresentable {
     @Environment(\.isEnabled) var isEnabled: Bool
     
     func makeUIView(context: Context) -> UITextView {
-        let textView = WrappedTextView()
+        let textView = WrappedTextView(uiState: uiState)
         textView.delegate = context.coordinator
         textView.isEditable = true
         textView.backgroundColor = .clear
@@ -128,6 +128,16 @@ struct MainComposeWrappedTextView: UIViewRepresentable {
     
     class WrappedTextView: UITextView {
         private let formattingActions = [#selector(toggleBoldface(_:)), #selector(toggleItalics(_:))]
+        unowned var uiState: ComposeUIState
+        
+        init(uiState: ComposeUIState) {
+            self.uiState = uiState
+            super.init(frame: .zero, textContainer: nil)
+        }
+        
+        required init?(coder: NSCoder) {
+            fatalError("init(coder:) has not been implemented")
+        }
         
         override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
             if formattingActions.contains(action) {
@@ -154,6 +164,14 @@ struct MainComposeWrappedTextView: UIViewRepresentable {
             }
         }
         
+        override func paste(_ sender: Any?) {
+            if UIPasteboard.general.contains(pasteboardTypes: CompositionAttachment.readableTypeIdentifiersForItemProvider) {
+                uiState.delegate?.paste(itemProviders: UIPasteboard.general.itemProviders)
+            } else {
+                super.paste(sender)
+            }
+        }
+        
     }
     
     class Coordinator: NSObject, UITextViewDelegate, ComposeInput, ComposeTextViewCaretScrolling {