Cancel event on conflict

app.go

@@ -234,7 +234,7 @@ func collectResources(config apiserver.Configuration) error {
 		log.Error("Booking", "updating bookings: %v", err)
 	}
 
-	if err := bc.Cancel(cancelledBookings); err != nil {
+	if err := bc.CancelSlice(cancelledBookings); err != nil {
 		log.Error("Booking", "cancelling bookings: %v", err)
 	}
 
@@ -307,15 +307,28 @@ func bookInEWS(book model.Booking, config apiserver.Configuration) {
 		Location:  asset.ProviderID,
 		Attendees: []string{asset.ProviderID},
 	}
-	booking, err := ewsHelper.CreateAppointment(app)
-	if err != nil {
+	a, err := ewsHelper.CreateAppointment(app)
+	book.ExchangeUID = a.ExchangeUID
+	book.ExchangeIDInResourceMailbox = a.ExchangeIDInResourceMailbox
+	if errors.Is(err, ews.ErrDeclined) {
+		bc := booking.NewClient(*config.BookingAppURL)
+		if err := ewsHelper.CancelEvent(book); err != nil {
+			log.Error("ews", "cancelling conflicting event: %v", err)
+			return
+		}
+		if err := bc.Cancel(book.ElionaID, "conflict"); err != nil {
+			log.Error("booking", "cancelling conflicting appointment: %v", err)
+			return
+		}
+		log.Debug("ews", "booking for %v was conflicting; cancelled", book.OrganizerEmail)
+	} else if err != nil {
 		log.Error("ews", "creating appointment: %v", err)
 		return
 	}
 	log.Debug("ews", "created a booking for %v", book.OrganizerEmail)
 	b := appdb.Booking{
-		ExchangeID:  null.StringFrom(booking.ExchangeIDInResourceMailbox),
-		ExchangeUID: null.StringFrom(booking.ExchangeUID),
+		ExchangeID:  null.StringFrom(book.ExchangeIDInResourceMailbox),
+		ExchangeUID: null.StringFrom(book.ExchangeUID),
 		BookingID:   null.Int32From(book.ElionaID),
 	}
 	if err := conf.UpsertBooking(b); err != nil {

booking/booking.go

@@ -98,18 +98,18 @@ func (c *client) book(bookings bookingRequest) (bookingResponse, error) {
 	return respBody, nil
 }
 
-func (c *client) Cancel(bookings []model.Booking) error {
+func (c *client) CancelSlice(bookings []model.Booking) error {
 	for _, b := range bookings {
-		err := c.cancel(b.ElionaID)
+		err := c.Cancel(b.ElionaID, "cancelled")
 		if err != nil {
 			return err
 		}
 	}
 	return nil
 }
 
-func (c *client) cancel(elionaID int32) error {
-	req, err := http.NewRequest(http.MethodDelete, fmt.Sprintf("%s/sync/bookings/%v", c.BaseURL, elionaID), nil)
+func (c *client) Cancel(elionaID int32, reason string) error {
+	req, err := http.NewRequest(http.MethodDelete, fmt.Sprintf("%s/sync/bookings/%v?reason=%v", c.BaseURL, elionaID, reason), nil)
 	if err != nil {
 		return err
 	}

ews/ews.go

@@ -21,6 +21,7 @@ import (
 	"encoding/base64"
 	"encoding/hex"
 	"encoding/xml"
+	"errors"
 	"ews/apiserver"
 	"ews/model"
 	"fmt"
@@ -33,6 +34,10 @@ import (
 	"golang.org/x/oauth2/clientcredentials"
 )
 
+var ErrDeclined = errors.New("resource has declined invitation")
+
+var errNotFound = errors.New("entity not found")
+
 type EWSHelper struct {
 	Client       *http.Client
 	EwsURL       string
@@ -431,15 +436,24 @@ func (h *EWSHelper) CreateAppointment(appointment Appointment) (booking model.Bo
 	if err != nil {
 		return model.Booking{}, fmt.Errorf("getting UID from ItemID: %v", err)
 	}
+	booking.ExchangeUID = uid
+
+	// Let's give the server some time to process the invitation. Sometimes it's
+	// instant, sometimes 2 seconds aren't enough. This should be long enough
+	// time.
+	time.Sleep(15 * time.Second)
+
 	resourceEventID, _, err := h.findEventUIDInMailbox(appointment.Location, uid)
-	if err != nil {
-		return model.Booking{}, fmt.Errorf("finding resource event ID: %v", err)
+	if errors.Is(err, errNotFound) {
+		// The resource has probably declined the invitation.
+		return booking, ErrDeclined
+	} else if err != nil {
+		return booking, fmt.Errorf("finding resource event ID: %v", err)
 	}
 
-	return model.Booking{
-		ExchangeIDInResourceMailbox: resourceEventID,
-		ExchangeUID:                 uid,
-	}, nil
+	booking.ExchangeIDInResourceMailbox = resourceEventID
+
+	return booking, nil
 }
 
 func formatAttendees(attendees []string) string {
@@ -701,7 +715,7 @@ func (h *EWSHelper) findEventUIDInMailbox(mailbox, uid string) (itemID string, c
 	}
 
 	if len(response.Body.FindItemResponse.ResponseMessages.FindItemResponseMessage.RootFolder.Items.CalendarItem) == 0 {
-		return "", "", fmt.Errorf("event not found. response: %v", string(respBody))
+		return "", "", errNotFound
 	}
 
 	item := response.Body.FindItemResponse.ResponseMessages.FindItemResponseMessage.RootFolder.Items.CalendarItem[0].ItemId