Allow editing messages via sed expressions

This reuses the Neochat code to edit your most recent message by
sed expressions, but if you reply to one of your messages, it will
try to edit that message instead.

src/UserSettingsPage.cpp

@@ -72,6 +72,7 @@ UserSettings::load(std::optional<QString> profile)
       settings.value(QStringLiteral("user/timeline/enlarge_emoji_only_msg"), false).toBool();
     markdown_       = settings.value(QStringLiteral("user/markdown_enabled"), true).toBool();
     invertEnterKey_ = settings.value(QStringLiteral("user/invert_enter_key"), false).toBool();
+    sedEditing_     = settings.value(QStringLiteral("user/sed_editing"), false).toBool();
     bubbles_        = settings.value(QStringLiteral("user/bubbles_enabled"), false).toBool();
     smallAvatars_   = settings.value(QStringLiteral("user/small_avatars_enabled"), false).toBool();
     animateImagesOnHover_ =
@@ -342,6 +343,17 @@ UserSettings::setInvertEnterKey(bool state)
     save();
 }
 
+void
+UserSettings::setSedEditing(bool state)
+{
+    if (state == sedEditing_)
+        return;
+
+    sedEditing_ = state;
+    emit sedEditingChanged(state);
+    save();
+}
+
 void
 UserSettings::setBubbles(bool state)
 {
@@ -910,6 +922,7 @@ UserSettings::save()
     settings.setValue(QStringLiteral("scrollbars_in_roomlist"), scrollbarsInRoomlist_);
     settings.setValue(QStringLiteral("markdown_enabled"), markdown_);
     settings.setValue(QStringLiteral("invert_enter_key"), invertEnterKey_);
+    settings.setValue(QStringLiteral("sed_editing"), sedEditing_);
     settings.setValue(QStringLiteral("bubbles_enabled"), bubbles_);
     settings.setValue(QStringLiteral("small_avatars_enabled"), smallAvatars_);
     settings.setValue(QStringLiteral("animate_images_on_hover"), animateImagesOnHover_);
@@ -1023,6 +1036,8 @@ UserSettingsModel::data(const QModelIndex &index, int role) const
             return tr("Send messages as Markdown");
         case InvertEnterKey:
             return tr("Use shift+enter to send and enter to start a new line");
+        case SedEditing:
+            return tr("Allow editing your last message with sed expressions");
         case Bubbles:
             return tr("Enable message bubbles");
         case SmallAvatars:
@@ -1177,6 +1192,8 @@ UserSettingsModel::data(const QModelIndex &index, int role) const
             return i->markdown();
         case InvertEnterKey:
             return i->invertEnterKey();
+        case SedEditing:
+            return i->sedEditing();
         case Bubbles:
             return i->bubbles();
         case SmallAvatars:
@@ -1341,6 +1358,11 @@ UserSettingsModel::data(const QModelIndex &index, int role) const
             return tr(
               "Invert the behavior of the enter key in the text input, making it send the message "
               "when shift+enter is pressed and starting a new line when enter is pressed.");
+        case SedEditing:
+            return tr("If you send a message that is a valid sed expression (e.g. s/foo/bar), try "
+                      "to apply it to your last sent message as an edit instead of sending it as a "
+                      "regular message. If the sed expression cannot be applied to your last "
+                      "message, it will be sent as a normal message.");
         case Bubbles:
             return tr(
               "Messages get a bubble background. This also triggers some layout changes (WIP).");
@@ -1512,6 +1534,7 @@ UserSettingsModel::data(const QModelIndex &index, int role) const
         case ScrollbarsInRoomlist:
         case Markdown:
         case InvertEnterKey:
+        case SedEditing:
         case Bubbles:
         case SmallAvatars:
         case AnimateImagesOnHover:
@@ -1762,6 +1785,13 @@ UserSettingsModel::setData(const QModelIndex &index, const QVariant &value, int
             } else
                 return false;
         }
+        case SedEditing: {
+            if (value.userType() == QMetaType::Bool) {
+                i->setSedEditing(value.toBool());
+                return true;
+            } else
+                return false;
+        }
         case Bubbles: {
             if (value.userType() == QMetaType::Bool) {
                 i->setBubbles(value.toBool());
@@ -2221,6 +2251,9 @@ UserSettingsModel::UserSettingsModel(QObject *p)
     connect(s.get(), &UserSettings::invertEnterKeyChanged, this, [this]() {
         emit dataChanged(index(InvertEnterKey), index(InvertEnterKey), {Value});
     });
+    connect(s.get(), &UserSettings::sedEditingChanged, this, [this]() {
+        emit dataChanged(index(SedEditing), index(SedEditing), {Value});
+    });
     connect(s.get(), &UserSettings::bubblesChanged, this, [this]() {
         emit dataChanged(index(Bubbles), index(Bubbles), {Value});
     });

src/UserSettingsPage.h

@@ -31,6 +31,7 @@ class UserSettings final : public QObject
     Q_PROPERTY(bool markdown READ markdown WRITE setMarkdown NOTIFY markdownChanged)
     Q_PROPERTY(
       bool invertEnterKey READ invertEnterKey WRITE setInvertEnterKey NOTIFY invertEnterKeyChanged)
+    Q_PROPERTY(bool sedEditing READ sedEditing WRITE setSedEditing NOTIFY sedEditingChanged)
     Q_PROPERTY(bool bubbles READ bubbles WRITE setBubbles NOTIFY bubblesChanged)
     Q_PROPERTY(bool smallAvatars READ smallAvatars WRITE setSmallAvatars NOTIFY smallAvatarsChanged)
     Q_PROPERTY(bool animateImagesOnHover READ animateImagesOnHover WRITE setAnimateImagesOnHover
@@ -172,6 +173,7 @@ public:
     void setScrollbarsInRoomlist(bool state);
     void setMarkdown(bool state);
     void setInvertEnterKey(bool state);
+    void setSedEditing(bool state);
     void setBubbles(bool state);
     void setSmallAvatars(bool state);
     void setAnimateImagesOnHover(bool state);
@@ -244,6 +246,7 @@ public:
     int privacyScreenTimeout() const { return privacyScreenTimeout_; }
     bool markdown() const { return markdown_; }
     bool invertEnterKey() const { return invertEnterKey_; }
+    bool sedEditing() const { return sedEditing_; }
     bool bubbles() const { return bubbles_; }
     bool smallAvatars() const { return smallAvatars_; }
     bool animateImagesOnHover() const { return animateImagesOnHover_; }
@@ -315,6 +318,7 @@ signals:
     void startInTrayChanged(bool state);
     void markdownChanged(bool state);
     void invertEnterKeyChanged(bool state);
+    void sedEditingChanged(bool state);
     void bubblesChanged(bool state);
     void smallAvatarsChanged(bool state);
     void animateImagesOnHoverChanged(bool state);
@@ -384,6 +388,7 @@ private:
     bool scrollbarsInRoomlist_;
     bool markdown_;
     bool invertEnterKey_;
+    bool sedEditing_;
     bool bubbles_;
     bool smallAvatars_;
     bool animateImagesOnHover_;
@@ -491,6 +496,7 @@ class UserSettingsModel : public QAbstractListModel
         ReadReceipts,
         Markdown,
         InvertEnterKey,
+        SedEditing,
         Bubbles,
         SmallAvatars,
 

src/timeline/InputBar.cpp

@@ -450,15 +450,67 @@ InputBar::generateRelations() const
 void
 InputBar::message(const QString &msg, MarkdownOverride useMarkdown, bool rainbowify)
 {
+    auto trimmed                = msg.trimmed();
     mtx::events::msg::Text text = {};
-    text.body                   = msg.trimmed().toStdString();
+    text.body                   = trimmed.toStdString();
+
+    // we don't want to have unexpected behavior if somebody was genuinely trying to edit a message
+    // to be a regex
+    if (UserSettings::instance()->sedEditing() && room->edit().isEmpty()) [[unlikely]] {
+        // The bulk of this logic was shamelessly stolen from Neochat. Thanks to Carl Schwan for
+        // letting us have this :)
+        static const QRegularExpression sed("^s/([^/]*)/([^/]*)(/g)?$");
+        auto match = sed.match(trimmed);
+
+        if (match.hasMatch()) {
+            const QString regex       = match.captured(1);
+            const QString replacement = match.captured(2).toHtmlEscaped();
+            const QString flags       = match.captured(3);
+
+            std::optional<mtx::events::collections::TimelineEvents> event;
+            if (!room->reply().isEmpty()) {
+                auto ev = room->eventById(room->reply());
+                if (ev && room->data(*ev, TimelineModel::IsEditable).toBool())
+                    event = ev;
+            } else {
+                for (int i = 0; i < room->rowCount(); ++i) {
+                    const auto idx = room->index(i);
+                    if (room->data(idx, TimelineModel::IsEditable).toBool()) {
+                        event = room->eventById(room->data(idx, TimelineModel::EventId).toString());
+                        break;
+                    }
+                }
+            }
+
+            if (event) {
+                auto other = room->data(*event, TimelineModel::FormattedBody).toString();
+                const auto original{other};
+                if (flags == "/g")
+                    other.replace(regex, replacement);
+                else
+                    other.replace(other.indexOf(regex), regex.size(), replacement);
+
+                // don't bother sending a pointless edit
+                if (original != other) {
+                    text.formatted_body = other.toStdString();
+                    text.format         = "org.matrix.custom.html";
+                    text.relations.relations.push_back(
+                      {.rel_type = mtx::common::RelationType::Replace,
+                       .event_id =
+                         room->data(*event, TimelineModel::EventId).toString().toStdString()});
+                    room->sendMessageEvent(text, mtx::events::EventType::RoomMessage);
+                    return;
+                }
+            }
+        }
+    }
 
     if ((ChatPage::instance()->userSettings()->markdown() &&
          useMarkdown == MarkdownOverride::NOT_SPECIFIED) ||
         useMarkdown == MarkdownOverride::ON) {
         text.formatted_body = utils::markdownToHtml(msg, rainbowify).toStdString();
         // Remove markdown links by completer
-        text.body = replaceMatrixToMarkdownLink(msg.trimmed()).toStdString();
+        text.body = replaceMatrixToMarkdownLink(trimmed).toStdString();
 
         // Don't send formatted_body, when we don't need to
         // Specifically, if it includes no html tag and no newlines (which behave differently in
@@ -473,7 +525,7 @@ InputBar::message(const QString &msg, MarkdownOverride useMarkdown, bool rainbow
         // disable all markdown extensions
         text.formatted_body = utils::markdownToHtml(msg, rainbowify, true).toStdString();
         // keep everything as it was
-        text.body = msg.trimmed().toStdString();
+        text.body = trimmed.toStdString();
 
         // always send formatted
         text.format = "org.matrix.custom.html";
@@ -484,9 +536,9 @@ InputBar::message(const QString &msg, MarkdownOverride useMarkdown, bool rainbow
         auto related = room->relatedInfo(room->reply());
 
         // Skip reply fallbacks to users who would cause a room ping with the fallback.
-        // This should be fine, since in some cases the reply fallback can be omitted now and the
-        // alternative is worse! On Element Android this applies to any substring, but that is their
-        // bug to fix.
+        // This should be fine, since in some cases the reply fallback can be omitted now and
+        // the alternative is worse! On Element Android this applies to any substring, but that
+        // is their bug to fix.
         if (!related.quoted_user.startsWith("@room:")) {
             QString body;
             bool firstLine = true;