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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
_, err := io.Copy(&sb, reader)
if err != nil {
return nil, fmt.Errorf("failed to copy calendar data: %w", err)
}
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
from = strings.ToLower(from)
for _, a := range e.Attendees() {
if strings.ToLower(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{IANAProperty: 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
}
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