OAuth Support (#53)

Rips out the old auth method, adds OAuth support. Fixes #51.

Tested Platforms:
- [x] Linux
    - [x] Flatpak
    - [x] Native (Nix)
- [x] Android
- [ ] Windows
- [ ] MacOS

Reviewed-on: Nexus/nexus#53

lib/pages/chat.dart

@@ -18,6 +18,7 @@ class ChatPage extends ConsumerWidget {
       final showMembersByDefault = constraints.maxWidth > 1000;
       final initComplete = ref.watch(InitCompleteController.provider);
       final roomId = ref.watch(KeyController.provider(KeyController.roomKey));
+
       ref.read(EmojiController.provider);
 
       return SafeArea(

lib/pages/login.dart

@@ -1,99 +0,0 @@
-import "package:flutter/material.dart";
-import "package:flutter_hooks/flutter_hooks.dart";
-import "package:hooks_riverpod/hooks_riverpod.dart";
-import "package:nexus/controllers/client.dart";
-import "package:nexus/widgets/appbar.dart";
-import "package:nexus/helpers/required_validator_helper.dart";
-
-class LoginPage extends HookConsumerWidget {
-  final Uri homeserver;
-  const LoginPage({super.key, required this.homeserver});
-
-  @override
-  Widget build(BuildContext context, WidgetRef ref) {
-    final client = ref.watch(ClientController.provider.notifier);
-
-    final isLoading = useState(false);
-    final username = useTextEditingController();
-    final password = useTextEditingController();
-
-    final inputError = useState<String?>(null);
-    final formKey = useRef(GlobalKey<FormState>());
-
-    Future<void> tryLogin() async {
-      isLoading.value = true;
-
-      try {
-        if (formKey.value.currentState?.validate() != true) return;
-
-        final error = await client.login(
-          .new(
-            username: username.text,
-            password: password.text,
-            homeserverUrl: homeserver.origin,
-          ),
-        );
-
-        if (error != null) {
-          inputError.value = error;
-          isLoading.value = false;
-        } else {
-          if (context.mounted) Navigator.of(context).pop();
-        }
-      } finally {
-        isLoading.value = false;
-      }
-    }
-
-    return Scaffold(
-      appBar: Appbar(
-        leading: IconButton(
-          icon: Icon(Icons.arrow_back),
-          onPressed: Navigator.of(context).pop,
-        ),
-      ),
-      body: AlertDialog(
-        title: Text("Login to ${homeserver.host}"),
-        content: Form(
-          key: formKey.value,
-          child: Column(
-            mainAxisSize: .min,
-            crossAxisAlignment: .start,
-            children: [
-              TextFormField(
-                autofocus: true,
-                textInputAction: .next,
-                autovalidateMode: .onUserInteraction,
-                validator: requiredValidator,
-                decoration: .new(label: Text("Username")),
-                controller: username,
-              ),
-              SizedBox(height: 12),
-              TextFormField(
-                textInputAction: .done,
-                decoration: .new(
-                  label: Text("Password"),
-                  errorText: inputError.value,
-                  errorMaxLines: 5,
-                ),
-                autovalidateMode: .onUserInteraction,
-                validator: requiredValidator,
-                controller: password,
-                obscureText: true,
-                onFieldSubmitted: (_) => tryLogin(),
-                // Don't defocus on submit
-                onEditingComplete: () {},
-              ),
-            ],
-          ),
-        ),
-        actions: [
-          TextButton(
-            onPressed: isLoading.value ? null : tryLogin,
-            child: Text("Sign In"),
-          ),
-        ],
-      ),
-    );
-  }
-}

lib/pages/select_server.dart

@@ -1,11 +1,14 @@
+import "package:app_links/app_links.dart";
 import "package:flutter/material.dart";
 import "package:flutter_hooks/flutter_hooks.dart";
 import "package:flutter_svg/flutter_svg.dart";
 import "package:hooks_riverpod/hooks_riverpod.dart";
+import "package:nexus/controllers/auth_url.dart";
 import "package:nexus/controllers/client.dart";
+import "package:nexus/controllers/client_id.dart";
 import "package:nexus/helpers/launch_helper.dart";
+import "package:nexus/main.dart";
 import "package:nexus/models/homeserver.dart";
-import "package:nexus/pages/login.dart";
 import "package:nexus/widgets/appbar.dart";
 import "package:nexus/widgets/divider_text.dart";
 
@@ -32,7 +35,7 @@ class SelectServerPage extends HookConsumerWidget {
         final newUrl = newHomeserver == null
             ? null
             : await ref
-                  .watch(ClientController.provider.notifier)
+                  .read(ClientController.provider.notifier)
                   .discoverHomeserver(newHomeserver);
 
         if (context.mounted) {
@@ -47,11 +50,42 @@ class SelectServerPage extends HookConsumerWidget {
               ),
             );
           } else {
-            await Navigator.of(context).push(
-              MaterialPageRoute(builder: (_) => LoginPage(homeserver: newUrl)),
+            final codeResponse = await ref.watch(
+              AuthUrlController.provider(newUrl).future,
             );
+
+            await ref.watch(LaunchHelper.provider).launchUrl(codeResponse.url);
+
+            AppLinks().uriLinkStream.listen((encodedUri) async {
+              final code = encodedUri.queryParameters["code"];
+
+              if (code != null) {
+                await ref
+                    .watch(ClientController.provider.notifier)
+                    .exchangeToken(
+                      .new(
+                        homeserverUrl: newUrl,
+                        codeVerifier: codeResponse.codeVerifier,
+                        redirectUri: .new(
+                          scheme: "nexus.federated.nexus",
+                          path: "/",
+                        ),
+                        code: code,
+                        clientId: await ref.watch(
+                          ClientIdController.provider(newUrl).future,
+                        ),
+                      ),
+                    )
+                    .onError(showError);
+              }
+            });
+            // await Navigator.of(context).push(
+            //   MaterialPageRoute(builder: (_) => LoginPage(homeserver: newUrl)),
+            // );
           }
         }
+      } catch (error, stackTrace) {
+        showError(error, stackTrace);
       } finally {
         isLoading.value = false;
       }