ppub-viewer/src/Window.vala

using Adw;
using Gtk;

namespace PpubViewer {

    public class ViewerWindow : Adw.ApplicationWindow {

        private Adw.HeaderBar header_bar;
        private Box box;
        private Flap flap;
        private DocumentView.DocumentViewManager document_view;

        private Button back_button;
        private Button forward_button;
        private Button properties_button;

        private Button menu_button;
        private PopoverMenu menu;
        private ZoomSpinButton zoom_spin;

        private Ppub.Publication publication;
        private NavigationHistoryItem current_page = null;
        private WindowTitle window_title;

        public ViewerWindow(Adw.Application app) {
            application = app;
            header_bar = new Adw.HeaderBar ();
            window_title = new WindowTitle("PPUB Viewer", "");
            flap = new Flap();
            box = new Box (Orientation.VERTICAL, 0);
            box.append (header_bar);
            box.append (flap);
            content = box;
            header_bar.show_end_title_buttons = true;
            default_width = 900;
            default_height = 700;
            header_bar.title_widget = window_title;
            flap.separator = new Separator(Orientation.VERTICAL);

            properties_button = new Button.from_icon_name("sidebar-show-symbolic");
            header_bar.pack_start(properties_button);

            header_bar.pack_start(new Separator(Orientation.VERTICAL));

            back_button = new Button.from_icon_name("go-previous-symbolic");
            back_button.sensitive = false;
            back_button.clicked.connect(go_back);
            header_bar.pack_start(back_button);
            forward_button = new Button.from_icon_name("go-next-symbolic");
            forward_button.sensitive = false;
            forward_button.clicked.connect(go_forward);
            header_bar.pack_start(forward_button);

            //  menu = new PopoverMenu.from_model(null);
            //  header_bar.pack_end(menu);
            //  menu_button = new Button.from_icon_name("open-menu-symbolic");
            //  menu_button.clicked.connect(() => menu.popup());
            //  header_bar.pack_end(menu_button);

            var zoom_squeezer = new Squeezer();
            zoom_squeezer.transition_type = SqueezerTransitionType.CROSSFADE;
            zoom_spin = new ZoomSpinButton(false);
            var zoom_spin_small = new ZoomSpinButton(true);
            zoom_spin_small.adjustment = zoom_spin.adjustment;
            zoom_squeezer.add(zoom_spin);
            zoom_squeezer.add(zoom_spin_small);
            zoom_spin.zoom_level_changed.connect(change_zoom);
            header_bar.pack_end(zoom_squeezer);

            document_view = new DocumentView.DocumentViewManager();
            document_view.link_clicked.connect(link_clicked);
            flap.content = document_view;

            properties_button.clicked.connect(() => {
                flap.reveal_flap = !flap.reveal_flap;
            });

        }

        public void load_ppub(File file) throws Error {
            publication = new Ppub.Publication(file.get_path());
            var asset = publication.get_default_asset ();

            window_title.title = publication.metadata.title ?? "Untitled PPUB";
            window_title.subtitle = publication.metadata.author_name ?? "";
            title = window_title.title + " - PPUB Viewer";

            var scroller = new ScrolledWindow();
            scroller.add_css_class("background");
            scroller.hscrollbar_policy = PolicyType.NEVER;
            var pane = new PropertiesPane(publication.metadata, false);
            scroller.child = pane;
            pane.link_clicked.connect(property_link_clicked);

            flap.flap = scroller;
            navigate(asset.name);   
        }

        public void navigate(string file) {

            if(current_page == null) {
                current_page = new NavigationHistoryItem();
                current_page.file_name = file;
                current_page.scroll_position = 0;
            }
            else {
                current_page = current_page.add_next(file, document_view.get_scroll_position());
            }

            load_document(file);
        }

        public void go_back() {
            current_page.scroll_position = document_view.get_scroll_position();
            current_page = current_page.previous;
            load_document(current_page.file_name);
        }

        public void go_forward() {
            current_page.scroll_position = document_view.get_scroll_position();
            current_page = current_page.next;
            load_document(current_page.file_name);
        }


        public void load_document(string file) {

            back_button.sensitive = current_page.previous != null;
            forward_button.sensitive = current_page.next != null;            

            document_view.load_asset(publication, publication.get_asset(file));

            Idle.add_once(() => {
                document_view.set_scroll_position(current_page.scroll_position);
                return false;
            });
        }

        private void link_clicked(string url) {

            var asset = publication.get_asset(Uri.unescape_string(url));
            if(asset != null) {
                navigate(asset.name);
                return;
            }

            Uri uri;

            try{
                uri = Uri.parse(url, UriFlags.PARSE_RELAXED);
            }
            catch {
                var dialog = new Adw.MessageDialog(this, "Unrecognised link",  @"Could not determine how to handle the link <i>$url</i>.");
                dialog.body_use_markup = true;
                dialog.add_response("close", "Close");
                dialog.present();
                dialog.response.connect(() => dialog.close());
                return;
            }

            var app = AppInfo.get_default_for_uri_scheme(uri.get_scheme());
            if(app == null) {
                var dialog = new Adw.MessageDialog(this, "No application",  @"Could not find an application to handle the URI <i>$uri</i>.");
                dialog.body_use_markup = true;
                dialog.add_response("close", "Close");
                dialog.present();
                dialog.response.connect(() => dialog.close());
                return;
            }

            var uris = new List<string>();
            uris.append(uri.to_string());

            var dialog = new Adw.MessageDialog(this, "Open external link?", @"Do you want to open the external link <i>$uri</i>?");
            dialog.body_use_markup = true;
            dialog.add_response("cancel", @"Cancel");
            dialog.add_response("open", @"Open in $(app.get_display_name())");
            dialog.present();

            dialog.response.connect(id => {
                if(id == "open") {
                    app.launch_uris(uris, null);
                }
                dialog.close();
            });
            
        }

        private void property_link_clicked(string file) {
            link_clicked(file);
            if(flap.folded) {
                flap.reveal_flap = false;
            }
        }

        private void change_zoom(int percent) {
            document_view.set_zoom_percentage(percent);
        }

        public override void size_allocate(int width, int height, int baseline) {
            base.size_allocate(width, height, baseline);
            document_view.reflow();
        }

    }

}