keep message drafts on room switches

this is for you courge

lib/controllers/attachment.dart

@@ -7,7 +7,9 @@ import "package:nexus/models/content/message.dart";
 import "package:nexus/models/composer_params.dart";
 import "package:path/path.dart";
 
-class AttachmentController(final ComposerParams composer)
+typedef AttachmentParams = ({ComposerParams composer, int? editingRowId});
+
+class AttachmentController(final AttachmentParams params)
     extends Notifier<(String, MessageContent?)?> {
   @override
   Null build() => null;
@@ -19,7 +21,7 @@ class AttachmentController(final ComposerParams composer)
     final isEncrypted = ref.read(
       RoomsController.provider.select(
         (value) =>
-            value[composer.roomId]
+            value[params.composer.roomId]
                 ?.state[EventType.encryption.type]
                 ?.isNotEmpty ==
             true,
@@ -35,10 +37,10 @@ class AttachmentController(final ComposerParams composer)
 
   void set((String, MessageContent?)? attachment) => state = attachment;
 
-  static final provider = NotifierProvider.family
-      .autoDispose<
+  static final provider =
+      NotifierProvider.family<
         AttachmentController,
         (String, MessageContent?)?,
-        ComposerParams
+        AttachmentParams
       >(AttachmentController.new);
 }

lib/controllers/bot_command_draft.dart

@@ -95,10 +95,14 @@ class BotCommandDraftController(final ComposerParams composer)
     }
   }
 
+  void set(BotCommandDraft? draft) => state = draft;
+
   void clear() => state = null;
 
-  static final provider = NotifierProvider.autoDispose
-      .family<BotCommandDraftController, BotCommandDraft?, ComposerParams>(
-        BotCommandDraftController.new,
-      );
+  static final provider =
+      NotifierProvider.family<
+        BotCommandDraftController,
+        BotCommandDraft?,
+        ComposerParams
+      >(BotCommandDraftController.new);
 }

lib/controllers/composer_draft.dart

@@ -0,0 +1,93 @@
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/attachment.dart";
+import "package:nexus/controllers/bot_command_draft.dart";
+import "package:nexus/controllers/rooms.dart";
+import "package:nexus/helpers/extensions/get_filename.dart";
+import "package:nexus/helpers/extensions/is_media.dart";
+import "package:nexus/helpers/extensions/with_latest_edit.dart";
+import "package:nexus/models/composer_draft.dart";
+import "package:nexus/models/composer_params.dart";
+import "package:nexus/models/content/message.dart";
+import "package:nexus/models/relation_type.dart";
+
+class ComposerDraftController(final ComposerParams composer)
+    extends Notifier<ComposerDraft> {
+  @override
+  ComposerDraft build() => const .new();
+
+  BotCommandDraftController get _botCommand =>
+      ref.read(BotCommandDraftController.provider(composer).notifier);
+
+  void update(ComposerDraft Function(ComposerDraft draft) update) =>
+      state = update(state);
+
+  void relate(int rowId, RelationType type) {
+    if (type == .reply) {
+      _restoreBeforeEdit();
+      state = state.copyWith(relatedEvent: rowId, relationType: .reply);
+      return;
+    }
+
+    // Keeps the changes made so far
+    if (state.isEditing && state.relatedEvent == rowId) return;
+
+    final event = ref
+        .read(RoomsController.provider)[composer.roomId]
+        ?.withLatestEdit(rowId);
+    final content = event?.content;
+    final text =
+        event?.localContent?.editSource ??
+        switch (content) {
+          TextMessageContent(:final body) ||
+          ImageMessageContent(:final body) ||
+          VideoMessageContent(:final body) ||
+          AudioMessageContent(:final body) ||
+          FileMessageContent(:final body) => body,
+          _ => "",
+        };
+
+    state = ComposerDraft(
+      text: text,
+      relatedEvent: rowId,
+      relationType: .edit,
+      beforeEdit:
+          state.beforeEdit ??
+          (
+            draft: state,
+            botCommand: ref.read(BotCommandDraftController.provider(composer)),
+          ),
+    );
+    ref
+        .read(
+          AttachmentController.provider((
+            composer: composer,
+            editingRowId: rowId,
+          )).notifier,
+        )
+        .set(
+          content is MessageContent && content.isMedia
+              ? (content.filename ?? content.body ?? "Attachment", content)
+              : null,
+        );
+    _botCommand.clear();
+  }
+
+  void dismiss() {
+    if (state.isEditing) return _restoreBeforeEdit();
+    state = state.copyWith(relatedEvent: null);
+  }
+
+  void _restoreBeforeEdit() {
+    if (state.beforeEdit case (:final draft, :final botCommand)) {
+      state = draft;
+      _botCommand.set(botCommand);
+    }
+  }
+
+  static final provider =
+      NotifierProvider.family<
+        ComposerDraftController,
+        ComposerDraft,
+        ComposerParams
+      >(ComposerDraftController.new);
+}

lib/controllers/room_chat.dart

@@ -404,7 +404,10 @@ class RoomChatController(final ChatParams info)
       roomId: info.roomId,
       threadRoot: info.threadRoot,
     );
-    final attachmentProvider = AttachmentController.provider(composer);
+    final attachmentProvider = AttachmentController.provider((
+      composer: composer,
+      editingRowId: relationType == .edit ? relatedEventRowId : null,
+    ));
     final attachment = ref.read(attachmentProvider)?.$2;
     ref.invalidate(attachmentProvider);
 
@@ -418,11 +421,13 @@ class RoomChatController(final ChatParams info)
             ? latestContent
             : null);
 
-    // Replaces each formatted tag, like "@id#name#", with its ID
+    // Replaces each formatted tag, like ":id#name#", with its ID
     final taggedMessage = tags.fold(
       text,
       (message, tag) => message.replaceAllMapped(
-        RegExp(r"@+(" + RegExp.escape(tag.id) + r")(#[^#]*#)?"),
+        RegExp(
+          "${RegExp.escape(tag.triggerCharacter)}(${RegExp.escape(tag.id)})(#[^#]*#)?",
+        ),
         (match) => match.group(1)!,
       ),
     );