Make clicking links navigate

Gemini.xcodeproj/project.pbxproj

@@ -45,6 +45,7 @@
 		D664673A24BD0B8E00B0B741 /* Fonts.swift in Sources */ = {isa = PBXBuildFile; fileRef = D664673924BD0B8E00B0B741 /* Fonts.swift */; };
 		D69F00AC24BE9DD300E37622 /* GeminiDataTask.swift in Sources */ = {isa = PBXBuildFile; fileRef = D69F00AB24BE9DD300E37622 /* GeminiDataTask.swift */; };
 		D69F00AE24BEA29100E37622 /* GeminiResponse.swift in Sources */ = {isa = PBXBuildFile; fileRef = D69F00AD24BEA29100E37622 /* GeminiResponse.swift */; };
+		D69F00B024BEA84D00E37622 /* NavigationManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = D69F00AF24BEA84D00E37622 /* NavigationManager.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -190,6 +191,7 @@
 		D664673924BD0B8E00B0B741 /* Fonts.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Fonts.swift; sourceTree = "<group>"; };
 		D69F00AB24BE9DD300E37622 /* GeminiDataTask.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GeminiDataTask.swift; sourceTree = "<group>"; };
 		D69F00AD24BEA29100E37622 /* GeminiResponse.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GeminiResponse.swift; sourceTree = "<group>"; };
+		D69F00AF24BEA84D00E37622 /* NavigationManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NavigationManager.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -286,6 +288,7 @@
 			children = (
 				D626645E24BBF1C200DF9B88 /* AppDelegate.swift */,
 				D626646024BBF1C200DF9B88 /* ContentView.swift */,
+				D69F00AF24BEA84D00E37622 /* NavigationManager.swift */,
 				D626646224BBF1C300DF9B88 /* Assets.xcassets */,
 				D626646724BBF1C300DF9B88 /* Main.storyboard */,
 				D626646A24BBF1C300DF9B88 /* Info.plist */,
@@ -668,6 +671,7 @@
 			files = (
 				D626646124BBF1C200DF9B88 /* ContentView.swift in Sources */,
 				D626645F24BBF1C200DF9B88 /* AppDelegate.swift in Sources */,
+				D69F00B024BEA84D00E37622 /* NavigationManager.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

Gemini/AppDelegate.swift

@@ -14,11 +14,12 @@ class AppDelegate: NSObject, NSApplicationDelegate {
 
     var window: NSWindow!
 
-    let url = URL(string: "gemini://gemini.circumlunar.space/")!
+    let homePage = URL(string: "gemini://gemini.circumlunar.space/")!
+    private(set) lazy var navigationManager = NavigationManager(url: homePage)
     
     func applicationDidFinishLaunching(_ aNotification: Notification) {
         // Create the SwiftUI view that provides the window contents.
-        let contentView = ContentView(url: url)
+        let contentView = ContentView(navigator: navigationManager)
 
         // Create the window and set the content view.
         window = NSWindow(

Gemini/ContentView.swift

@@ -11,7 +11,7 @@ import GeminiRenderer
 import GeminiProtocol
 
 struct ContentView: View {
-    let url: URL
+    let navigator: NavigationManager
     @State var task: GeminiDataTask?
     @State var document: Document?
     @State var errorMessage: String?
@@ -19,12 +19,13 @@ struct ContentView: View {
     var body: some View {
         mainView
             .frame(minWidth: 480, maxWidth: .infinity, minHeight: 300, maxHeight: .infinity)
+            .onReceive(navigator.$currentURL, perform: self.urlChanged)
     }
     
     @ViewBuilder
     private var mainView: some View {
         if let document = document {
-            DocumentView(document: document)
+            DocumentView(document: document, changeURL: navigator.changeURL)
         } else if let errorMessage = errorMessage {
             VStack {
                 Text("An error occurred")
@@ -47,6 +48,7 @@ struct ContentView: View {
     }
     
     private func loadDocument() {
+        let url = navigator.currentURL
         task = try! GeminiDataTask(url: url, completion: { (response) in
             switch response {
             case let .failure(error):
@@ -58,13 +60,20 @@ struct ContentView: View {
                 }
                 self.document = GeminiParser.parse(text: text, baseURL: url)
             }
+            self.task = nil
         })
         task!.resume()
     }
+    
+    private func urlChanged(_ newValue: URL) {
+        self.task = nil
+        self.document = nil
+        self.errorMessage = nil
+    }
 }
 
 struct ContentView_Previews: PreviewProvider {
     static var previews: some View {
-        ContentView(url: URL(string: "gemini://gemini.circumlunar.space/")!)
+        ContentView(navigator: NavigationManager(url: URL(string: "gemini://localhost/overview.gmi")!))
     }
 }

Gemini/NavigationManager.swift

@@ -0,0 +1,22 @@
+//
+//  NavigationManager.swift
+//  Gemini
+//
+//  Created by Shadowfacts on 7/14/20.
+//
+
+import Foundation
+
+class NavigationManager: ObservableObject {
+    
+    @Published var currentURL: URL
+    
+    init(url: URL) {
+        self.currentURL = url
+    }
+    
+    func changeURL(_ url: URL) {
+        self.currentURL = url
+    }
+    
+}

GeminiRenderer/DocumentView.swift

@@ -11,17 +11,19 @@ import GeminiFormat
 public struct DocumentView: View {
     private let document: Document
     private let blocks: [RenderingBlock]
+    private let changeURL: ((URL) -> Void)?
     
-    public init(document: Document) {
+    public init(document: Document, changeURL: ((URL) -> Void)? = nil) {
         self.document = document
         self.blocks = document.renderingBlocks
+        self.changeURL = changeURL
     }
     
     public var body: some View {
         ScrollView(.vertical) {
             MaybeLazyVStack(alignment: .leading) {
                 ForEach(blocks.indices) { (index) in
-                    RenderingBlockView(block: blocks[index])
+                    RenderingBlockView(block: blocks[index], changeURL: changeURL)
                 }
             }.padding()
         }

GeminiRenderer/RenderingBlockView.swift

@@ -10,6 +10,12 @@ import GeminiFormat
 
 struct RenderingBlockView: View {
     let block: RenderingBlock
+    let changeURL: ((URL) -> Void)?
+    
+    init(block: RenderingBlock, changeURL: ((URL) -> Void)? = nil) {
+        self.block = block
+        self.changeURL = changeURL
+    }
     
     @ViewBuilder
     var body: some View {
@@ -20,11 +26,15 @@ struct RenderingBlockView: View {
                 .frame(maxWidth: .infinity, alignment: .leading)
         case let .link(url, text: linkText):
             let text = linkText ?? url.absoluteString
+            Button {
+                self.changeURL?(url)
+            } label: {
                 Text(verbatim: text)
                     .font(.documentBody)
                     .foregroundColor(.blue)
                     .underline()
                     .frame(maxWidth: .infinity, alignment: .leading)
+            }.buttonStyle(LinkButtonStyle())
         case let .preformatted(text, alt: _):
             ScrollView(.horizontal) {
                 Text(verbatim: text)