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 scroll position
                scrolled_window.vadjustment = new Gtk.Adjustment(0, 0, 0, 0, 0, 0);

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

                value.load_messages();
            } 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 TranscriptDrawingArea transcript_drawing_area = new TranscriptDrawingArea();
    private ScrolledWindow scrolled_window = new ScrolledWindow();
    private ulong messages_changed_handler_id = 0;
    private bool needs_reload = false;

    public TranscriptView() {
        container = new Adw.ToolbarView();
        set_child(container);

        scrolled_window.set_child(transcript_drawing_area);
        scrolled_window.add_css_class("message-list-scroller");
        container.set_content(scrolled_window);

        var header_bar = new Adw.HeaderBar();
        header_bar.set_title_widget(title_label);
        container.add_top_bar(header_bar);

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