add pick default reaction

lib/stores/accounts_store.dart

@@ -10,6 +10,7 @@ class AccountsStore extends _AccountsStore with _$AccountsStore {}
 
 abstract class _AccountsStore with Store {
   ReactionDisposer _saveReactionDisposer;
+  ReactionDisposer _pickDefaultsDisposer;
 
   _AccountsStore() {
     // persistently save settings each time they are changed
@@ -24,10 +25,98 @@ abstract class _AccountsStore with Store {
       ],
       (_) => save(),
     );
+
+    // check if there's a default profile and if not, select one
+    _pickDefaultsDisposer = reaction(
+        (_) => [
+              users.forEach((k, submap) =>
+                  MapEntry(k, submap.forEach((k2, v2) => MapEntry(k2, v2)))),
+              tokens.forEach((k, submap) =>
+                  MapEntry(k, submap.forEach((k2, v2) => MapEntry(k2, v2)))),
+            ], (_) {
+      if (users.isEmpty) {
+        // if empty clear def users
+        _defaultAccount = null;
+        _defaultAccounts = ObservableMap();
+        return;
+      }
+
+      // == SET LOCAL DEFAULTS ==
+
+      // go through instances
+      for (final instanceUrl in users.keys) {
+        // if this instance is already in defaults
+        if (_defaultAccounts.keys.contains(instanceUrl)) {
+          // if this account wasn't removed, skip
+          if (users[instanceUrl].keys.contains(_defaultAccounts[instanceUrl])) {
+            continue;
+          }
+          // if every account was removed,
+          if (users[instanceUrl].isEmpty) {
+            _defaultAccounts.remove(instanceUrl);
+            continue;
+          }
+          _defaultAccounts[instanceUrl] = users[instanceUrl].entries.first.key;
+        } else {
+          // select first account in this instance, if any
+          if (users[instanceUrl].isEmpty) {
+            continue;
+          }
+
+          _defaultAccounts[instanceUrl] = users[instanceUrl].entries.first.key;
+        }
+      }
+
+      // clean up
+      for (final instance in _defaultAccounts.keys) {
+        if (!users.keys.contains(instance)) {
+          _defaultAccounts.remove(instance);
+        }
+      }
+
+      // == SET GLOBAL DEFAULT ==
+
+      if (_defaultAccount == null) {
+        // select first account of first instance
+        for (final instance in users.keys) {
+          if (users[instance].isNotEmpty) {
+            _defaultAccount = '$instance@${users[instance].keys.first}';
+          }
+        }
+        return;
+      }
+      final instance = _defaultAccount.split('@')[1];
+      final username = _defaultAccount.split('@')[0];
+
+      final containsDefaultInstance = users.keys.contains(instance);
+
+      // if default instance is even added
+      if (containsDefaultInstance && users[instance].isNotEmpty) {
+        if (users[instance].containsKey(username)) return;
+        // select new profile
+        final newDefault = users[instance].entries.first;
+        _defaultAccount = '${newDefault.value.name}@${newDefault.key}';
+        return;
+      } else {
+        // if default instance is not even added
+        // select first account of first instance
+
+        for (final user in users.entries) {
+          if (user.value.entries.isEmpty) continue;
+
+          final newDefault = user.value.entries.first;
+          _defaultAccount = '${newDefault.value.name}@${newDefault.key}';
+          return;
+        }
+        _defaultAccount = null;
+        return;
+      }
+    });
   }
 
   void dispose() {
     _saveReactionDisposer();
+    _pickDefaultsDisposer();
   }
 
   void load() async {
@@ -122,11 +211,13 @@ abstract class _AccountsStore with Store {
         return tokens[instanceUrl][_defaultAccounts[instanceUrl]];
       }).value;
 
+  /// sets globally default account
   @action
   void setDefaultAccount(String instanceUrl, String username) {
     _defaultAccount = '$username@$instanceUrl';
   }
 
+  /// sets default account for given instance
   @action
   void setDefaultAccountFor(String instanceUrl, String username) {
     _defaultAccounts[instanceUrl] = username;
@@ -167,15 +258,6 @@ abstract class _AccountsStore with Store {
     final userData =
         await lemmy.getSite(auth: token.raw).then((value) => value.myUser);
 
-    // first account for this instance
-    if (users[instanceUrl].isEmpty) {
-      // first account ever
-      if (hasNoAccount) {
-        setDefaultAccount(instanceUrl, userData.name);
-      }
-
-      setDefaultAccountFor(instanceUrl, userData.name);
-    }
     users[instanceUrl][userData.name] = userData;
     tokens[instanceUrl][userData.name] = token;
   }