Make redirects work

Gemini/ContentView.swift

@@ -13,8 +13,7 @@ import GeminiProtocol
 struct ContentView: View {
     let navigator: NavigationManager
     @State var task: GeminiDataTask?
-    @State var document: Document?
-    @State var errorMessage: String?
+    @State var state: ViewState = .loading
     
     var body: some View {
         mainView
@@ -24,17 +23,18 @@ struct ContentView: View {
     
     @ViewBuilder
     private var mainView: some View {
-        if let document = document {
-            DocumentView(document: document, changeURL: navigator.changeURL)
-        } else if let errorMessage = errorMessage {
+        switch state {
+        case .loading:
+            loadingView
+                .onAppear(perform: self.loadDocument)
+        case let .error(message):
             VStack {
                 Text("An error occurred")
                     .font(.headline)
-                Text(errorMessage)
+                Text(message)
             }
-        } else {
-            loadingView
-                .onAppear(perform: self.loadDocument)
+        case let .document(doc):
+            DocumentView(document: doc, changeURL: navigator.changeURL)
         }
     }
     
@@ -50,25 +50,39 @@ struct ContentView: View {
     private func loadDocument() {
         let url = navigator.currentURL
         task = try! GeminiDataTask(url: url, completion: { (response) in
+            self.task = nil
             switch response {
             case let .failure(error):
-                self.errorMessage = error.localizedDescription
+                state = .error(error.localizedDescription)
             case let .success(response):
-                guard let text = response.bodyText else {
-                    self.errorMessage = "Response had no body text"
-                    return
+                if response.status.isRedirect {
+                    if let redirect = URL(string: response.meta) {
+                        navigator.changeURL(redirect)
+                        loadDocument()
+                    } else {
+                        state = .error("Invalid redirect URL: '\(response.meta)'")
+                    }
+                } else if response.status.isSuccess,
+                          let text = response.bodyText {
+                    state = .document(GeminiParser.parse(text: text, baseURL: url))
+                } else {
+                    state = .error("Unknown error: \(response.header)")
                 }
-                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
+        state = .loading
+    }
+}
+
+extension ContentView {
+    enum ViewState {
+        case loading
+        case document(Document)
+        case error(String)
     }
 }
 

GeminiProtocol/GeminiResponseHeader.swift

@@ -35,15 +35,15 @@ public extension GeminiResponseHeader {
         case certificateNotValid = 62
         
         // Status type helpers
-        var isInput: Bool                     { rawValue / 10 == 1 }
-        var isSuccess: Bool                   { rawValue / 10 == 2 }
-        var isRedirect: Bool                  { rawValue / 10 == 3 }
-        var isTemporaryFailure: Bool          { rawValue / 10 == 4 }
-        var isPermanentFailure: Bool          { rawValue / 10 == 5 }
-        var isClientCertificateRequired: Bool { rawValue / 10 == 6 }
+        public var isInput: Bool                     { rawValue / 10 == 1 }
+        public var isSuccess: Bool                   { rawValue / 10 == 2 }
+        public var isRedirect: Bool                  { rawValue / 10 == 3 }
+        public var isTemporaryFailure: Bool          { rawValue / 10 == 4 }
+        public var isPermanentFailure: Bool          { rawValue / 10 == 5 }
+        public var isClientCertificateRequired: Bool { rawValue / 10 == 6 }
         
         // Other helpers
-        var isFailure: Bool { isTemporaryFailure || isPermanentFailure }
+        public var isFailure: Bool { isTemporaryFailure || isPermanentFailure }
     }
 }