feat: Use a state machine for appointment flow

pkg/lib/client.go

@@ -71,22 +71,7 @@ func NewClient(ctx context.Context, discordWebhook string, headless, disableGpu,
  }, cancel, nil
 }
 
-func isLocationAvailable(ctx context.Context, apptType AppointmentType, location Location, timeout time.Duration) (bool, error) {
- // Navigate to the main page.
- if _, err := chromedp.RunResponse(ctx, chromedp.Navigate(makeApptUrl)); err != nil {
- return false, err
- }
-
- // Click the "Make Appointment" button once it is visible.
- if _, err := chromedp.RunResponse(ctx, chromedp.Click(makeApptButtonSelector, chromedp.NodeVisible, chromedp.ByQuery)); err != nil {
- return false, err
- }
-
- // Click the appointment type button.
- if _, err := chromedp.RunResponse(ctx, chromedp.Click(apptType.ToSelector(), chromedp.NodeVisible, chromedp.ByQuery)); err != nil {
- return false, err
- }
-
+func isLocationAvailable(ctx context.Context, apptType AppointmentType, location Location) (bool, error) {
  // Wait for the location and read the node.
  var nodes []*cdp.Node
  if err := chromedp.Run(ctx,
@@ -121,7 +106,7 @@ func findAvailableAppointmentDates(ctx context.Context) ([]time.Time, error) {
  // Wait for the time select element to appear.
  chromedp.WaitVisible(appointmentTimeSelectSelector, chromedp.ByQuery),
 
- // Extract the HTML for the calendar.
+ // Extract the HTML for the calendar widget.
  chromedp.InnerHTML(appointmentCalendarSelector, &calendarHtml, chromedp.ByQuery),
  ); err != nil {
  return nil, err
@@ -132,7 +117,10 @@ func findAvailableAppointmentDates(ctx context.Context) ([]time.Time, error) {
  return nil, fmt.Errorf("failed to parse HTML: %w", err)
  }
 
- // Find the available dates.
+ // Find the available dates by parsing the HTML.
+ // TODO(aksiksi): Figure out how to also parse appointment times.
+ // Also, it would be cool if we could advance the month in the calendar widget to see
+ // all appointment slots.
  var availableDates []time.Time
  doc.Find(appointmentDayButtonSelector).Each(func(i int, s *goquery.Selection) {
  // Extract the day, month, and year from the DOM node.
@@ -174,38 +162,76 @@ func findAvailableAppointmentDates(ctx context.Context) ([]time.Time, error) {
  return availableDates, nil
 }
 
+// appointmentFlowState represents the current state of the appointment workflow for a single location.
+type appointmentFlowState int
+
+const (
+ appointmentFlowStateStart appointmentFlowState = iota
+ appointmentFlowStateMainPage
+ appointmentFlowStateAppointmentType
+ appointmentFlowStateLocationsPage
+ appointmentFlowStateLocationCalendar
+)
+
 // findAvailableAppointments finds all available appointment dates for the given location.
 //
+// This function uses a simple state machine to navigate the appointment flow.
+//
 // NOTE: Currently does not parse the appointment time slots - just dates. Also, this does not look at
 // later months.
-func findAvailableAppointments(ctx context.Context, apptType AppointmentType, location Location, timeout time.Duration) (appointments []*Appointment, _ error) {
- isAvailable, err := isLocationAvailable(ctx, apptType, location, timeout)
- if err != nil {
- return nil, err
- }
- if !isAvailable {
- return nil, nil
- }
+func findAvailableAppointments(ctx context.Context, apptType AppointmentType, location Location) (appointments []*Appointment, _ error) {
+ state := appointmentFlowStateStart
 
- // At this point, we are on the locations page.
- // Click the location button.
- if _, err := chromedp.RunResponse(ctx, chromedp.Click(location.ToSelector()), chromedp.Sleep(3*time.Second)); err != nil {
- return nil, err
- }
-
- availableDates, err := findAvailableAppointmentDates(ctx)
- if err != nil {
- return nil, err
- }
-
- for _, d := range availableDates {
- appointments = append(appointments, &Appointment{
- Location: location,
- Time: d,
- })
+ for {
+ switch state {
+ case appointmentFlowStateStart:
+ // Navigate to the main page.
+ if _, err := chromedp.RunResponse(ctx, chromedp.Navigate(makeApptUrl)); err != nil {
+ return nil, err
+ }
+ state = appointmentFlowStateMainPage
+ case appointmentFlowStateMainPage:
+ // Click the "Make Appointment" button once it is visible.
+ if _, err := chromedp.RunResponse(ctx, chromedp.Click(makeApptButtonSelector, chromedp.NodeVisible, chromedp.ByQuery)); err != nil {
+ return nil, err
+ }
+ state = appointmentFlowStateAppointmentType
+ case appointmentFlowStateAppointmentType:
+ // Click the appointment type button.
+ if _, err := chromedp.RunResponse(ctx, chromedp.Click(apptType.ToSelector(), chromedp.NodeVisible, chromedp.ByQuery)); err != nil {
+ return nil, err
+ }
+ state = appointmentFlowStateLocationsPage
+ case appointmentFlowStateLocationsPage:
+ // Check if the location is available.
+ isAvailable, err := isLocationAvailable(ctx, apptType, location)
+ if err != nil {
+ return nil, err
+ }
+ // If it isn't, it means no appointments are available.
+ if !isAvailable {
+ return nil, nil
+ }
+ // At this point, we are on the locations page. Click the location button.
+ if _, err := chromedp.RunResponse(ctx, chromedp.Click(location.ToSelector())); err != nil {
+ return nil, err
+ }
+ state = appointmentFlowStateLocationCalendar
+ case appointmentFlowStateLocationCalendar:
+ // Find available dates for this location by parsing the calendar HTML.
+ availableDates, err := findAvailableAppointmentDates(ctx)
+ if err != nil {
+ return nil, err
+ }
+ for _, d := range availableDates {
+ appointments = append(appointments, &Appointment{
+ Location: location,
+ Time: d,
+ })
+ }
+ return appointments, nil
+ }
  }
-
- return appointments, nil
 }
 
 func (c Client) sendDiscordMessage(appointment Appointment) error {
@@ -261,7 +287,7 @@ func (c Client) RunForLocations(apptType AppointmentType, locations []Location,
  location := location
  ctx := locationCtxs[i]
  go func() {
- appointments, err := findAvailableAppointments(ctx, apptType, location, timeout)
+ appointments, err := findAvailableAppointments(ctx, apptType, location)
  resultChan <- locationResult{
  idx: i,
  appointments: appointments,