Add block button to profiles

Fixes #152

lib/widgets/settings/block_user_field.dart

@@ -0,0 +1,66 @@
+import "package:flutter_hooks/flutter_hooks.dart";
+import "package:hooks_riverpod/hooks_riverpod.dart";
+import "package:material_ui/material_ui.dart";
+import "package:nexus/controllers/account_data.dart";
+import "package:nexus/controllers/client_state.dart";
+import "package:nexus/helpers/extensions/get_localpart.dart";
+import "package:nexus/helpers/hooks/saving.dart";
+import "package:nexus/main.dart";
+
+/// Blocks a user by their ID, hiding their messages and invites.
+class const BlockUserField({super.key}) extends HookConsumerWidget {
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final saving = Saving.use();
+    final controller = useTextEditingController();
+    final userId = useValueListenable(controller).text.trim();
+    final blocked = ref.watch(
+      AccountDataController.provider.select(
+        (data) => data.ignoredUserList.contains(userId),
+      ),
+    );
+    final ownId = ref.watch(
+      ClientStateController.provider.select((state) => state?.userId),
+    );
+
+    final error = userId.isEmpty || userId.isValidUserId
+        ? userId == ownId
+              ? "You can't block yourself"
+              : blocked
+              ? "Already blocked"
+              : null
+        : "Enter a user ID, like @user:example.com";
+    final canBlock = userId.isNotEmpty && error == null && !saving.active;
+
+    void block() {
+      if (!canBlock) return;
+      saving
+          .run(() async {
+            await ref
+                .read(AccountDataController.provider.notifier)
+                .setIgnored(userId, ignored: true);
+            if (context.mounted) controller.clear();
+          })
+          .onError(showError);
+    }
+
+    return Padding(
+      padding: EdgeInsets.symmetric(horizontal: 8).copyWith(top: 8),
+      child: TextField(
+        controller: controller,
+        enabled: !saving.active,
+        onSubmitted: (_) => block(),
+        decoration: .new(
+          labelText: "User ID",
+          hintText: "@user:example.com",
+          errorText: error,
+          suffixIcon: IconButton(
+            tooltip: "Block user",
+            icon: Icon(Icons.block),
+            onPressed: canBlock ? block : null,
+          ),
+        ),
+      ),
+    );
+  }
+}