Kordophone/src/transcript/transcript-view.vala

using Adw;
using Gtk;
using Gee;

public class TranscriptView : Adw.Bin
{
    public MessageListModel? model {
        get {
            return _model;
        }
        set {
            if (_model != null) {
                _model.disconnect(messages_changed_handler_id);
                _model.unwatch_updates();
            }

            _model = value;

            if (value != null) {
                reset_for_conversation_change();

                weak TranscriptView self = this;
                messages_changed_handler_id = value.messages_changed.connect(() => {
                    self.reload_messages();
                });

                value.load_messages();
                value.watch_updates();
            } else {
                transcript_drawing_area.set_messages(new ArrayList<Message>());
            }
        }
    }

    public string title {
        get { return title_label.label; }
        set { title_label.label = value; }
    }

    private MessageListModel? _model = null;
    private Adw.ToolbarView container;
    private Label title_label = new Label("Messages");

    private Overlay overlay = new Overlay();
    private TranscriptDrawingArea transcript_drawing_area = new TranscriptDrawingArea();
    private ScrolledWindow scrolled_window = new ScrolledWindow();
    private ulong messages_changed_handler_id = 0;
    private bool needs_reload = false;

    private Graphene.Point _hovering_text_view_origin = Graphene.Point() { x = 0, y = 0 };
    private TextView _hovering_text_view = new TextView();

    private VisibleTextLayout? hovered_text_bubble = null;
    private VisibleTextLayout? locked_text_bubble = null;

    public TranscriptView() {
        container = new Adw.ToolbarView();
        set_child(container);
        
        // Set minimum width for the transcript view
        set_size_request(330, -1);

        overlay.set_child(transcript_drawing_area);

        weak TranscriptView self = this;
        overlay.get_child_position.connect((child, out allocation) => {
            allocation = Gtk.Allocation() { x = 0, y = 0, width = 0, height = 0 };
            if (self.hovered_text_bubble != null) {
                var rect = self.hovered_text_bubble.rect;
                allocation.x = (int)(rect.origin.x + self._hovering_text_view_origin.x);
                allocation.y = (int)(rect.origin.y - self._hovering_text_view_origin.y);
                allocation.width = (int)rect.size.width;
                allocation.height = (int)rect.size.height;

                return true;
            }

            return true; 
        });

        scrolled_window.set_child(overlay);
        scrolled_window.add_css_class("flipped-y-axis");
        transcript_drawing_area.viewport = scrolled_window.vadjustment;
        container.set_content(scrolled_window);

        // Connect to the adjustment's value_changed signal
        scrolled_window.vadjustment.value_changed.connect(() => {
            transcript_drawing_area.viewport = scrolled_window.vadjustment;
        });

        var header_bar = new Adw.HeaderBar();
        title_label.single_line_mode = true;
        title_label.ellipsize = Pango.EllipsizeMode.END;
        header_bar.set_title_widget(title_label);
        container.add_top_bar(header_bar);

        // This is an invisible text view that's used to handle selection.
        _hovering_text_view.add_css_class("hovering-text-view");
        _hovering_text_view.add_css_class("flipped-y-axis");
        _hovering_text_view.set_editable(false);
        _hovering_text_view.set_wrap_mode(Gtk.WrapMode.WORD_CHAR);
        overlay.add_overlay(_hovering_text_view);

        // When the selection changes, lock the text bubble so that if the cursor moves to another bubble we don't clear it. 
        _hovering_text_view.buffer.mark_set.connect((location, end) => {
            self.lock_text_bubble(self.hovered_text_bubble);
        });

        // When the mouse hovers over a text bubble, configure the hovering text view to show the text of the bubble.
        transcript_drawing_area.on_text_bubble_hover.connect((visible_text_layout) => {
            if (visible_text_layout != null) {
                configure_hovering_text_view(visible_text_layout);
            }
        });

        // This is triggered when another bubble is currently locked, and the user clicks on a new bubble.
        transcript_drawing_area.on_text_bubble_click.connect((visible_text_layout) => {
            if (visible_text_layout != null) {
                locked_text_bubble = null;
                configure_hovering_text_view(visible_text_layout);
            }
        });

        Repository.get_instance().attachment_downloaded.connect((attachment_guid) => {
            debug("Attachment downloaded: %s", attachment_guid);

            // See if this attachment is part of this transcript. 
            bool contains_attachment = false;
            foreach (var message in _model.messages) {
                foreach (var attachment in message.attachments) {
                    if (attachment.guid == attachment_guid) {
                        contains_attachment = true;
                        break;
                    }
                }
            }

            if (contains_attachment && !needs_reload) {
                debug("Queueing reload of messages for attachment download");

                needs_reload = true;
                GLib.Idle.add(() => {
                    if (needs_reload) {
                        debug("Reloading messages for attachment download");
                        model.load_messages();
                        needs_reload = false;
                    }

                    return false;
                }, GLib.Priority.HIGH);
            }
        });
    }

    private void reset_for_conversation_change() {
        locked_text_bubble = null;
        hovered_text_bubble = null;
        _hovering_text_view.buffer.text = "";
        overlay.queue_allocate();

        // Reset scroll position by updating the existing adjustment
        scrolled_window.vadjustment.value = 0;
        scrolled_window.vadjustment.upper = 0;
        scrolled_window.vadjustment.page_size = 0;
    }

    private void lock_text_bubble(VisibleTextLayout? visible_text_layout) {
        if (visible_text_layout != null) {
            locked_text_bubble = visible_text_layout;
            configure_hovering_text_view(visible_text_layout);
        }
    }

    private void configure_hovering_text_view(VisibleTextLayout? visible_text_layout) {
        hovered_text_bubble = visible_text_layout;

        if (locked_text_bubble == null) {
            _hovering_text_view_origin = visible_text_layout.text_bubble.get_text_origin();
            _hovering_text_view.buffer.text = visible_text_layout.text_bubble.message.text;
            overlay.queue_allocate();
        }
    }

    private void reload_messages() {
        transcript_drawing_area.show_sender = _model.is_group_chat;
        transcript_drawing_area.set_messages(_model.messages);
    }
}