add m.location support

Needs cross-platform testing. Currently only tested on Android.

lib/helpers/current_location_helper.dart

@@ -0,0 +1,82 @@
+import "dart:async";
+import "dart:io";
+
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:geolocator/geolocator.dart";
+import "package:latlong2/latlong.dart";
+import "package:nexus/controllers/portal.dart";
+import "package:nexus/models/location_exception.dart";
+
+class CurrentLocationHelper(final Ref ref) {
+  static const _timeLimit = Duration(seconds: 10);
+
+  /// The user's location and its accuracy in meters, or null if [askPermission]
+  /// is off and they haven't allowed it.
+  Future<(LatLng, double?)?> get({required bool askPermission}) async {
+    // geolocator talks to GeoClue directly, which Flatpak's sandbox blocks, so
+    // Linux uses the location portal, which also asks the user for permission
+    if (Platform.isLinux) {
+      // The portal can't say whether it's allowed without asking
+      if (!askPermission) return null;
+
+      try {
+        final portal = await ref.read(PortalController.provider.future);
+        final location = await portal.location
+            .createSession(accuracy: .exact)
+            .first
+            .timeout(_timeLimit);
+
+        return switch ((location.latitude, location.longitude)) {
+          (final latitude?, final longitude?) => (
+            LatLng(latitude, longitude),
+            location.accuracy,
+          ),
+          _ => throw LocationException.failed,
+        };
+      } on TimeoutException {
+        throw LocationException.timedOut;
+      } catch (_) {
+        throw LocationException.failed;
+      }
+    }
+
+    if (!await Geolocator.isLocationServiceEnabled()) {
+      if (!askPermission) return null;
+      throw LocationException.servicesOff;
+    }
+
+    var permission = await Geolocator.checkPermission();
+    if (permission == .denied && askPermission) {
+      permission = await Geolocator.requestPermission();
+    }
+    if (permission == .denied || permission == .deniedForever) {
+      if (!askPermission) return null;
+      throw LocationException.denied;
+    }
+
+    Position? position;
+    try {
+      position = await Geolocator.getCurrentPosition(
+        locationSettings: Platform.isAndroid
+            // Play services' location can hang without Google, like on microG,
+            // so this uses Android's own, as other apps do
+            ? AndroidSettings(forceLocationManager: true, timeLimit: _timeLimit)
+            : const LocationSettings(timeLimit: _timeLimit),
+      );
+    } on TimeoutException {
+      // A fix can take long indoors, but another app may have a recent one
+      position = await Geolocator.getLastKnownPosition(
+        forceAndroidLocationManager: true,
+      );
+    } catch (_) {
+      throw LocationException.failed;
+    }
+    if (position == null) throw LocationException.timedOut;
+
+    return (LatLng(position.latitude, position.longitude), position.accuracy);
+  }
+
+  static final provider = Provider<CurrentLocationHelper>(
+    CurrentLocationHelper.new,
+  );
+}

lib/helpers/extensions/build_event_options.dart

@@ -173,7 +173,9 @@ extension BuildEventOptions on Event {
           ),
         ),
 
-      if (content is MessageContent && sender == userId)
+      if (content is MessageContent &&
+          content is! LocationMessageContent &&
+          sender == userId)
         PopupMenuItem(
           onTap: () => onRelation(rowId, .edit),
           child: const ListTile(leading: Icon(Icons.edit), title: Text("Edit")),

lib/helpers/extensions/show_adaptive_sheet.dart

@@ -4,7 +4,10 @@ import "package:nexus/helpers/extensions/is_desktop.dart";
 extension ShowAdaptiveSheet on BuildContext {
   /// Shows the widget from [builder] in a dialog on desktop, or a bottom sheet
   /// on mobile. Use the context passed to [builder] to close it.
-  Future<T?> showAdaptiveSheet<T>(WidgetBuilder builder) => isDesktop
+  Future<T?> showAdaptiveSheet<T>(
+    WidgetBuilder builder, {
+    bool enableDrag = true,
+  }) => isDesktop
       ? showDialog<T>(
           context: this,
           builder: (context) => Dialog(
@@ -18,6 +21,7 @@ extension ShowAdaptiveSheet on BuildContext {
       : showModalBottomSheet<T>(
           context: this,
           isScrollControlled: true,
+          enableDrag: enableDrag,
           constraints: .new(maxHeight: MediaQuery.sizeOf(this).height - 80),
           builder: (context) => SafeArea(child: builder(context)),
         );