Add rich link previews for shared URLs

- Capture both URL and title when sharing links
- Create LinkPreviewView component with clickable cards
- Support markdown-style links [title](url)
- Auto-detect plain URLs in messages
- Add link metadata fetching on iOS
- Display clean preview cards with title, URL, and description

bitchat/Views/ContentView.swift

@@ -415,18 +415,33 @@ struct ContentView: View {
                                     .frame(maxWidth: .infinity, alignment: .leading)
                             } else {
                                 // Regular messages with natural text wrapping
-                                HStack(alignment: .top, spacing: 0) {
-                                    // Single text view for natural wrapping
-                                    Text(viewModel.formatMessageAsText(message, colorScheme: colorScheme))
-                                        .textSelection(.enabled)
-                                        .fixedSize(horizontal: false, vertical: true)
-                                        .frame(maxWidth: .infinity, alignment: .leading)
+                                VStack(alignment: .leading, spacing: 8) {
+                                    HStack(alignment: .top, spacing: 0) {
+                                        // Single text view for natural wrapping
+                                        Text(viewModel.formatMessageAsText(message, colorScheme: colorScheme))
+                                            .textSelection(.enabled)
+                                            .fixedSize(horizontal: false, vertical: true)
+                                            .frame(maxWidth: .infinity, alignment: .leading)
+                                        
+                                        // Delivery status indicator for private messages
+                                        if message.isPrivate && message.sender == viewModel.nickname,
+                                           let status = message.deliveryStatus {
+                                            DeliveryStatusView(status: status, colorScheme: colorScheme)
+                                                .padding(.leading, 4)
+                                        }
+                                    }
                                     
-                                    // Delivery status indicator for private messages
-                                    if message.isPrivate && message.sender == viewModel.nickname,
-                                       let status = message.deliveryStatus {
-                                        DeliveryStatusView(status: status, colorScheme: colorScheme)
-                                            .padding(.leading, 4)
+                                    // Check for links and show preview
+                                    if let markdownLink = message.content.extractMarkdownLink() {
+                                        LinkPreviewView(url: markdownLink.url, title: markdownLink.title)
+                                            .padding(.top, 4)
+                                    } else {
+                                        // Check for plain URLs
+                                        let urls = message.content.extractURLs()
+                                        ForEach(urls.prefix(3), id: \.url) { urlInfo in
+                                            LinkPreviewView(url: urlInfo.url, title: nil)
+                                                .padding(.top, 4)
+                                        }
                                     }
                                 }
                             }

bitchat/Views/LinkPreviewView.swift

@@ -0,0 +1,163 @@
+//
+// LinkPreviewView.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import SwiftUI
+#if os(iOS)
+import LinkPresentation
+#endif
+
+struct LinkPreviewView: View {
+    let url: URL
+    let title: String?
+    @Environment(\.colorScheme) var colorScheme
+    @State private var isLoadingMetadata = false
+    @State private var metadata: LinkMetadata?
+    
+    private var textColor: Color {
+        colorScheme == .dark ? Color.green : Color(red: 0, green: 0.5, blue: 0)
+    }
+    
+    private var backgroundColor: Color {
+        colorScheme == .dark ? Color.black : Color.white
+    }
+    
+    private var borderColor: Color {
+        textColor.opacity(0.3)
+    }
+    
+    var body: some View {
+        Button(action: {
+            #if os(iOS)
+            UIApplication.shared.open(url)
+            #else
+            NSWorkspace.shared.open(url)
+            #endif
+        }) {
+            VStack(alignment: .leading, spacing: 6) {
+                // Title
+                Text(metadata?.title ?? title ?? url.host ?? "Link")
+                    .font(.system(size: 14, weight: .medium, design: .monospaced))
+                    .foregroundColor(textColor)
+                    .lineLimit(2)
+                    .multilineTextAlignment(.leading)
+                
+                // URL
+                Text(url.absoluteString)
+                    .font(.system(size: 12, design: .monospaced))
+                    .foregroundColor(textColor.opacity(0.7))
+                    .lineLimit(1)
+                    .truncationMode(.middle)
+                
+                // Description if available
+                if let description = metadata?.description {
+                    Text(description)
+                        .font(.system(size: 12, design: .monospaced))
+                        .foregroundColor(textColor.opacity(0.8))
+                        .lineLimit(2)
+                        .multilineTextAlignment(.leading)
+                }
+            }
+            .padding(10)
+            .frame(maxWidth: .infinity, alignment: .leading)
+            .background(backgroundColor.opacity(0.05))
+            .overlay(
+                RoundedRectangle(cornerRadius: 8)
+                    .stroke(borderColor, lineWidth: 1)
+            )
+        }
+        .buttonStyle(.plain)
+        .onAppear {
+            loadMetadata()
+        }
+    }
+    
+    private func loadMetadata() {
+        #if os(iOS)
+        guard metadata == nil && !isLoadingMetadata else { return }
+        
+        isLoadingMetadata = true
+        let provider = LPMetadataProvider()
+        provider.startFetchingMetadata(for: url) { metadata, error in
+            DispatchQueue.main.async {
+                if let metadata = metadata {
+                    self.metadata = LinkMetadata(
+                        title: metadata.title,
+                        description: metadata.value(forKey: "_summary") as? String,
+                        imageURL: metadata.imageProvider?.value(forKey: "_URL") as? URL
+                    )
+                }
+                self.isLoadingMetadata = false
+            }
+        }
+        #endif
+    }
+}
+
+struct LinkMetadata {
+    let title: String?
+    let description: String?
+    let imageURL: URL?
+}
+
+// Helper to extract URLs from text
+extension String {
+    func extractURLs() -> [(url: URL, range: Range<String.Index>)] {
+        var urls: [(URL, Range<String.Index>)] = []
+        
+        // Check for markdown-style links [title](url)
+        let markdownPattern = #"\[([^\]]+)\]\(([^)]+)\)"#
+        if let regex = try? NSRegularExpression(pattern: markdownPattern) {
+            let matches = regex.matches(in: self, range: NSRange(location: 0, length: self.utf16.count))
+            for match in matches {
+                if let urlRange = Range(match.range(at: 2), in: self),
+                   let url = URL(string: String(self[urlRange])),
+                   let fullRange = Range(match.range, in: self) {
+                    urls.append((url, fullRange))
+                }
+            }
+        }
+        
+        // Also check for plain URLs
+        let types: NSTextCheckingResult.CheckingType = .link
+        if let detector = try? NSDataDetector(types: types.rawValue) {
+            let matches = detector.matches(in: self, range: NSRange(location: 0, length: self.utf16.count))
+            for match in matches {
+                if let range = Range(match.range, in: self),
+                   let url = match.url {
+                    // Don't add if this URL is already part of a markdown link
+                    let isPartOfMarkdown = urls.contains { $0.range.overlaps(range) }
+                    if !isPartOfMarkdown {
+                        urls.append((url, range))
+                    }
+                }
+            }
+        }
+        
+        return urls
+    }
+    
+    func extractMarkdownLink() -> (title: String, url: URL)? {
+        let pattern = #"\[([^\]]+)\]\(([^)]+)\)"#
+        if let regex = try? NSRegularExpression(pattern: pattern),
+           let match = regex.firstMatch(in: self, range: NSRange(location: 0, length: self.utf16.count)) {
+            if let titleRange = Range(match.range(at: 1), in: self),
+               let urlRange = Range(match.range(at: 2), in: self),
+               let url = URL(string: String(self[urlRange])) {
+                return (String(self[titleRange]), url)
+            }
+        }
+        return nil
+    }
+}
+
+#Preview {
+    VStack {
+        LinkPreviewView(url: URL(string: "https://example.com")!, title: "Example Website")
+            .padding()
+    }
+}