+const undoLog: string[] = [];
+
+const UI = {
+ addTask: function (description: string): Element {
+ const now = clock.now();
+ undoLog.push(`State ${now} deleted`);
+ return <Element>log.recordAndApply(`${now} Create ${description}`);
+ },
+ edit: function (createTimestamp: string, newDescription: string, oldDescription: string) {
+ undoLog.push(`Edit ${createTimestamp} ${oldDescription}`);
+ return log.recordAndApply(`${clock.now()} Edit ${createTimestamp} ${newDescription}`);
+ },
+ setPriority: function (createTimestamp: string, newPriority: number, oldPriority: number) {
+ undoLog.push(`Priority ${createTimestamp} ${oldPriority}`);
+ return log.recordAndApply(`${clock.now()} Priority ${createTimestamp} ${newPriority}`);
+ },
+ setState: function (createTimestamp: string, newState: string, oldState: string) {
+ undoLog.push(`State ${createTimestamp} ${oldState}`);
+ return log.recordAndApply(`${clock.now()} State ${createTimestamp} ${newState}`);
+ },
+ undo: function () {
+ if (undoLog.length > 0) {
+ return log.recordAndApply(`${clock.now()} ${undoLog.pop()}`);
+ }
+ },
+};
+
+function BrowserUI() {
+ return {
+ addTask: function (event: KeyboardEvent) {
+ const input = <HTMLInputElement>document.getElementById("taskName");
+ if (input.value) {
+ const task = UI.addTask(input.value);
+ if (task && task instanceof HTMLElement) task.focus();
+ input.value = "";
+ if (event.getModifierState("Control")) {
+ this.setPriority(task, null, document.getElementsByClassName("task")[0]);
+ }
+ }
+ },
+
+ beginEdit: function (event: Event) {
+ const task = document.activeElement;
+ if (!task) return;
+ const input = document.createElement("input");
+ const oldDescription = task.textContent!;
+ task.setAttribute("data-description", oldDescription);
+ input.value = oldDescription;
+ input.addEventListener("blur", this.completeEdit, { once: true });
+ task.textContent = "";
+ task.appendChild(input);
+ input.focus();
+ input.select();
+ event.preventDefault();
+ },
+
+ completeEdit: function (event: Event) {
+ const input = event.target as HTMLInputElement;
+ const task = input.parentElement!;
+ const oldDescription = task.getAttribute("data-description")!;
+ const newDescription = input.value;
+ input.removeEventListener("blur", this.completeEdit);
+ task.removeChild(task.children[0]);
+ task.removeAttribute("data-description");
+ task.focus();
+ if (newDescription === oldDescription) {
+ task.textContent = oldDescription;
+ } else {
+ UI.edit(task.getAttribute("data-created")!, newDescription, oldDescription);
+ }
+ },
+
+ firstVisibleTask: function () {
+ for (const task of document.getElementsByClassName("task")) {
+ if (task instanceof HTMLElement && task.getAttribute("data-state")! === "todo") {
+ return task;
+ }
+ }
+ },
+
+ focusTaskNameInput: function (event: Event) {