pim: invite, and a way to say what you mean

pim/invite makes an event and, when it names attendees, sends the
invitation -- which on a caldav server with auto-schedule is the same
act. -p writes the object to standard output instead, so it can go to
upas/marshal as iMIP, into a directory an ical/fs is serving, or
nowhere in particular. There is no separate verb for inviting because
to a calendar there is no separate thing.

It writes the tree's own key: value form rather than icalendar. The
first version spelled SUMMARY: by hand and got "lunch, then a walk"
wrong: a comma is a separator there and wants escaping. Parsing with
go-ical and generating by hand is the wrong asymmetry, so calfs grew
Compose, and now the same shape the tree emits is the shape it accepts.
The one UID we ever mint -- as organiser we own the event -- is minted
there too.

pim/invites lists what is waiting for an answer, which is what makes
pim/rsvp usable: it walks the date tree rather than every event, since
an invitation you never answered last March is not news.

agenda and show take -d date now, via seconds(1), which parses a human
date where date(1) only formats one.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/pim/lib/cal/backend.go b/pim/lib/cal/backend.go
index 6ed488c..91f793a 100644
--- a/pim/lib/cal/backend.go
+++ b/pim/lib/cal/backend.go
@@ -1,6 +1,10 @@
 package cal
 
-import "time"
+import (
+	"time"
+
+	"github.com/emersion/go-ical"
+)
 
 // A Backend supplies a calendar's events and, where the protocol allows
 // it, accepts changes back.
@@ -49,6 +53,17 @@ type Identity interface {
 	Me() []string
 }
 
+// Creator is implemented by a backend that can add an event.
+//
+// It takes a whole object rather than fields, because that is what the
+// protocols underneath take: CalDAV PUTs an entire icalendar object and
+// JMAP patches a whole JSCalendar one. Building an event field by field
+// and hoping the server knows when you have finished is a shape that
+// fits neither.
+type Creator interface {
+	Create(c *ical.Calendar) error
+}
+
 // RSVPer is implemented by a backend that can answer an invitation.
 //
 // Accepting is two writes: update your own copy, and tell the organiser.