/*

See LICENSE.txt for this sample’s licensing information.

Abstract:

This class handles presenting the Menu Bar template example.

*/

class MenuBarController extends DocumentController {

    fetchDocument(documentURL, loadingDocument) {

        this._documentLoader.fetch({

            url: documentURL,

            success: (menuBarDocument) => {

                const menuBarElem = menuBarDocument.getElementsByTagName("menuBar").item(0);

                menuBarElem.addEventListener("select", (event) => {

                    this.selectMenuItem(event.target);

                });

                // Pre-load the document for the initial focused menu item or first item,

                // before presenting the menuBarTemplate on navigation stack.

                // NOTE: Pre-loading is optional

                const initialMenuItemElem = this.findInitialMenuItem(menuBarElem);

                const initialMenuItemController = this.selectMenuItem(initialMenuItemElem, true, () => {

                    this.handleDocument(menuBarDocument, loadingDocument);

                });

            },

            error: (xhr) => {

                const alertDocument = createLoadErrorAlertDocument(documentURL, xhr, false);

                this.handleDocument(alertDocument, loadingDocument);

            }

        });

    }

    findInitialMenuItem(menuBarElem) {

        let highlightIndex = 0;

        const menuItemElems = menuBarElem.childNodes;

        for (let i = 0; i < menuItemElems.length; i++) {

            if (menuItemElems.item(i).hasAttribute("autoHighlight")) {

                highlightIndex = i;

                break;

            }

        }

        return menuItemElems.item(highlightIndex);

    }

    selectMenuItem(menuItemElem, isInitialItem, doneCallback) {

        const menuBarElem = menuItemElem.parentNode;

        const menuBarFeature = menuBarElem.getFeature("MenuBarDocument");

        const existingDocument = menuBarFeature.getDocument(menuItemElem);

        if (!existingDocument) {

            const controllerOptions = resolveControllerFromElement(menuItemElem);

            if (controllerOptions) {

                if (!isInitialItem) {

                    menuBarFeature.setDocument(createLoadingDocument(), menuItemElem);

                }

                controllerOptions.documentLoader = this._documentLoader;

                const controllerClass = controllerOptions.type;

                const controller = new controllerClass(controllerOptions);

                controller.handleDocument = (document) => {

                    if (isInitialItem) {

                        menuBarFeature.setDocument(document, menuItemElem);

                    } else {

                        // Force timeout to convey intent of displaying loading while the

                        // content is being loaded from server

                        setTimeout(function() {

                            // Override the presentation of controller since this controller

                            // is child of menuBar and doesn't get pushed on the navigation stack

                            menuBarFeature.setDocument(document, menuItemElem);

                        }, 1000);

                    }

                    doneCallback && doneCallback();

                };

            }

        }

    }

}

registerAttributeName('menuBarDocumentURL', MenuBarController);