Refactor input stuff

This is the start of a significant refactoring of everything related to sending messages, which is roughly:
- the chatbox
- action handling
- message sending on the c++ side
- autocompletion of users/rooms/emojis/commands/things i forgot

Notable changes so far include:
- ChatBox is now a ColumnLayout. As part of this, i removed the height animations for now. <del>as far as i can tell, they were broken anyway.</del> I'll readd them later
- Actions were refactored to live outside of the message sending function and are now each an object; it's mostly a wrapper around a function that is executed when the action is invoked
- Everything that used to live in ChatBoxHelper is now in NeoChatRoom; that means that the exact input status (text, message being replied to, message being edited, attachment) is now saved between room switching).
- To edit/reply an event, set `NeoChatRoom::chatBox{edit,reply}Id` to the desired event id, `NeoChatRoom::chatBox{reply,edit}{User,Message}` will then be updated automatically
- Attachments behave equivalently with `NeoChatRoom::chatBoxAttachmentPath`
- Error message reporting from ActionsHandler has been fixed (same fix as in !517) and moved to NeoChatRoom


Broken at the moment:
- [x] Any kind of autocompletion
- [x] Mentions
- [x] Fancy effects
- [x] sed-style edits
- [x] last-user-message edits and replies
- [x] Some of the actions, probably
- [x] Replies from notifications
- [x] Lots of keyboard shortcuts
- [x] Custom emojis
- [x] ChatBox height animations

TODO:
- [x] User / room mentions based on QTextCursors instead of the hack we currently use
- [x] Refactor autocompletion stuff
- [x] ???
- [x] Profit

src/chatdocumenthandler.h

@@ -4,30 +4,33 @@
 #pragma once
 
 #include <QObject>
+
 #include <QTextCursor>
 
+#include "userlistmodel.h"
+
 class QTextDocument;
 class QQuickTextDocument;
 class NeoChatRoom;
-class Controller;
+class SyntaxHighlighter;
+class CompletionModel;
 
 class ChatDocumentHandler : public QObject
 {
     Q_OBJECT
     Q_PROPERTY(QQuickTextDocument *document READ document WRITE setDocument NOTIFY documentChanged)
     Q_PROPERTY(int cursorPosition READ cursorPosition WRITE setCursorPosition NOTIFY cursorPositionChanged)
-    Q_PROPERTY(int selectionStart READ selectionStart WRITE setSelectionStart NOTIFY selectionStartChanged)
-    Q_PROPERTY(int selectionEnd READ selectionEnd WRITE setSelectionEnd NOTIFY selectionEndChanged)
+    Q_PROPERTY(CompletionModel *completionModel READ completionModel NOTIFY completionModelChanged)
 
-    Q_PROPERTY(NeoChatRoom *room READ room WRITE setRoom NOTIFY roomChanged)
+    Q_PROPERTY(NeoChatRoom *room READ room NOTIFY roomChanged)
 
 public:
     enum AutoCompletionType {
         User,
+        Room,
         Emoji,
         Command,
         None,
-        Ignore,
     };
     Q_ENUM(AutoCompletionType)
 
@@ -39,44 +42,34 @@ public:
     [[nodiscard]] int cursorPosition() const;
     void setCursorPosition(int position);
 
-    [[nodiscard]] int selectionStart() const;
-    void setSelectionStart(int position);
-
-    [[nodiscard]] int selectionEnd() const;
-    void setSelectionEnd(int position);
-
     [[nodiscard]] NeoChatRoom *room() const;
     void setRoom(NeoChatRoom *room);
 
-    /// This function will look at the current QTextCursor and determine if there
-    /// is the possibility to autocomplete it.
-    Q_INVOKABLE QVariantMap getAutocompletionInfo(bool isAutocompleting);
-    Q_INVOKABLE void replaceAutoComplete(const QString &word);
+    Q_INVOKABLE void complete(int index);
 
+    void updateCompletions();
+    CompletionModel *completionModel() const;
 Q_SIGNALS:
     void documentChanged();
     void cursorPositionChanged();
-    void selectionStartChanged();
-    void selectionEndChanged();
     void roomChanged();
-    void joinRoom(QString roomName);
+    void completionModelChanged();
 
 private:
-    [[nodiscard]] QTextCursor textCursor() const;
-    [[nodiscard]] QTextDocument *textDocument() const;
+    int completionStartIndex() const;
 
     QQuickTextDocument *m_document;
 
-    NeoChatRoom *m_room;
+    NeoChatRoom *m_room = nullptr;
+    bool completionVisible = false;
 
     int m_cursorPosition;
-    int m_selectionStart;
-    int m_selectionEnd;
 
-    int m_autoCompleteBeginPosition = -1;
-    int m_autoCompleteEndPosition = -1;
+    SyntaxHighlighter *m_highlighter = nullptr;
 
-    QString m_lastState;
+    AutoCompletionType m_completionType = None;
+
+    CompletionModel *m_completionModel = nullptr;
 };
 
 Q_DECLARE_METATYPE(ChatDocumentHandler::AutoCompletionType);