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-rw-r--r--lib/calendar/calendar.go201
1 files changed, 201 insertions, 0 deletions
diff --git a/lib/calendar/calendar.go b/lib/calendar/calendar.go
new file mode 100644
index 00000000..d53aec5b
--- /dev/null
+++ b/lib/calendar/calendar.go
@@ -0,0 +1,201 @@
+package calendar
+
+import (
+ "bytes"
+ "fmt"
+ "io"
+ "net/mail"
+ "regexp"
+ "strings"
+ "time"
+
+ ics "github.com/arran4/golang-ical"
+)
+
+type Reply struct {
+ MimeType string
+ Params map[string]string
+ CalendarText io.ReadWriter
+ PlainText io.ReadWriter
+ Organizers []string
+}
+
+func (cr *Reply) AddOrganizer(o string) {
+ cr.Organizers = append(cr.Organizers, o)
+}
+
+// CreateReply parses a ics request and return a ics reply (RFC 2446, Section 3.2.3)
+func CreateReply(reader io.Reader, from *mail.Address, partstat string) (*Reply, error) {
+
+ cr := Reply{
+ MimeType: "text/calendar",
+ Params: map[string]string{
+ "charset": "UTF-8",
+ "method": "REPLY",
+ },
+ CalendarText: &bytes.Buffer{},
+ PlainText: &bytes.Buffer{},
+ }
+
+ var (
+ status ics.ParticipationStatus
+ action string
+ )
+
+ switch partstat {
+ case "accept":
+ status = ics.ParticipationStatusAccepted
+ action = "accepted"
+ case "accept-tentative":
+ status = ics.ParticipationStatusTentative
+ action = "tentatively accepted"
+ case "decline":
+ status = ics.ParticipationStatusDeclined
+ action = "declined"
+ default:
+ return nil, fmt.Errorf("participation status %s is not implemented", partstat)
+ }
+
+ name := from.Name
+ if name == "" {
+ name = from.Address
+ }
+ fmt.Fprintf(cr.PlainText, "%s has %s this invitation.", name, action)
+
+ invite, err := parse(reader)
+ if err != nil {
+ return nil, err
+ }
+
+ if ok := invite.request(); !ok {
+ return nil, fmt.Errorf("no reply is requested")
+ }
+
+ // update invite as a reply
+ reply := invite
+ reply.SetMethod(ics.MethodReply)
+ reply.SetProductId("aerc")
+
+ // check all events
+ for _, vevent := range reply.Events() {
+ e := event{vevent}
+
+ // check if we should answer
+ if err := e.isReplyRequested(from.Address); err != nil {
+ return nil, err
+ }
+
+ // make sure we send our reply to the meeting organizer
+ if organizer := e.GetProperty(ics.ComponentPropertyOrganizer); organizer != nil {
+ cr.AddOrganizer(organizer.Value)
+ }
+
+ // update attendee participation status
+ e.updateAttendees(status, from.Address)
+
+ // update timestamp
+ e.SetDtStampTime(time.Now())
+
+ // remove any subcomponents of event
+ e.Components = nil
+ }
+
+ // keep only timezone and event components
+ reply.clean()
+
+ if len(reply.Events()) == 0 {
+ return nil, fmt.Errorf("no events to respond to")
+ }
+
+ if err := reply.SerializeTo(cr.CalendarText); err != nil {
+ return nil, err
+ }
+ return &cr, nil
+}
+
+type calendar struct {
+ *ics.Calendar
+}
+
+func parse(reader io.Reader) (*calendar, error) {
+ // fix capitalized mailto for parsing of ics file
+ var sb strings.Builder
+ io.Copy(&sb, reader)
+ re := regexp.MustCompile("MAILTO:(.+@)")
+ str := re.ReplaceAllString(sb.String(), "mailto:${1}")
+
+ // parse calendar
+ invite, err := ics.ParseCalendar(strings.NewReader(str))
+ if err != nil {
+ return nil, err
+ }
+ return &calendar{invite}, nil
+}
+
+func (cal *calendar) request() (ok bool) {
+ ok = false
+ for i := range cal.CalendarProperties {
+ if cal.CalendarProperties[i].IANAToken == string(ics.PropertyMethod) {
+ if cal.CalendarProperties[i].Value == string(ics.MethodRequest) {
+ ok = true
+ return
+ }
+ }
+ }
+ return
+}
+
+func (cal *calendar) clean() {
+ var clean []ics.Component
+ for _, comp := range cal.Components {
+ switch comp.(type) {
+ case *ics.VTimezone, *ics.VEvent:
+ clean = append(clean, comp)
+ default:
+ continue
+ }
+ }
+ cal.Components = clean
+}
+
+type event struct {
+ *ics.VEvent
+}
+
+func (e *event) isReplyRequested(from string) error {
+ var present bool = false
+ var rsvp bool = false
+ for _, a := range e.Attendees() {
+ if a.Email() == from {
+ present = true
+ if r, ok := a.ICalParameters[string(ics.ParameterRsvp)]; ok {
+ if len(r) > 0 && strings.ToLower(r[0]) == "true" {
+ rsvp = true
+ }
+ }
+ }
+ }
+ if !present {
+ return fmt.Errorf("we are not invited")
+ }
+ if !rsvp {
+ return fmt.Errorf("we don't have to rsvp")
+ }
+ return nil
+}
+
+func (e *event) updateAttendees(status ics.ParticipationStatus, from string) {
+ var clean []ics.IANAProperty
+ for _, prop := range e.Properties {
+ if prop.IANAToken == string(ics.ComponentPropertyAttendee) {
+ att := ics.Attendee{prop}
+ if att.Email() != from {
+ continue
+ }
+ prop.ICalParameters[string(ics.ParameterParticipationStatus)] = []string{string(status)}
+ delete(prop.ICalParameters, string(ics.ParameterRsvp))
+ }
+ clean = append(clean, prop)
+ }
+ e.Properties = clean
+}