# Astro::App::Satpass2 source file. Invoke as (e.g.)
# satpass2> source eg/pass_vcalendar
#
# Do satellite pass calculations, displaying the results in vCalendar
# format. The output may be redirected to a .vcal file. The start and
# end dates for the pass calculation can be passed as arguments to the
# 'source' statement, and default to 'today noon' and '+8' respectively.
# This whole thing (less the comments) could be wrapped up as a macro
# if desired.

#	CAVEAT: My ancient Palm desktop software appears not to properly
#	handle the switch between normal and daylight-saving  time
#	(a.k.a. summer time), in that predictions made before the switch
#	for events after the switch get assigned the wrong time, even
#	though the UT event time is correct in the emitted file. I have
#	not changed the event times to local time eg/flare_vcalendar
#	because the vcalendar standard specifies UT.

localize formatter

# We intend to use date(units='z') to format the event begin and end. We
# truncate the time to the previous minute.

formatter date_format %Y%m%dT%H%M00Z

# We intend to use time() to format the individual event times.

formatter time_format %I:%M:%S

# The individual pass events get concatenated to the summary, with no newline.

formatter template pass <<'EOD'
BEGIN:VCALENDAR
[%- FOR pass IN data %]
[%- events = pass.events %]
[%- CALL events.fixed_width( 0 ) %]
[%- first = events.first %]
[%- punct = ' -' %]
BEGIN:VEVENT
DTSTART:[% first.date( units = 'zulu' ) %]
DALARM:[% first.date( delta = -360, units = 'zulu' ) %]
DALARM:[% first.date( delta = -60, units = 'zulu' ) %]
SUMMARY:[% first.name %]
    [%- FOREACH evt IN events %][% punct %]
	[%- evt_name = evt.event %]
	[%- end_date = evt.date( delta = 30, units = 'z' ) %]
	[%= evt_name %]
	[%- IF 'apls' == evt_name %]
            [%- appulse = evt.appulse %]
            [%= appulse.angle %]
	    [%= appulse.name %]
	[%- END %]
	[%= evt.time %] Az
	[%= evt.azimuth( places = 0, bearing = 2 ) %]
	[%- IF 'rise' != evt_name and 'set' != evt_name %] Ele
	    [%= evt.elevation( places = 0 ) %]
	[%- END %]
        [%- punct = ';' %]
    [%- END %]
DTEND:[% end_date %]
END:VEVENT
[%- END %]
END:VCALENDAR
EOD

# Do the pass calculation. I do not know that the vcal format requires
# the data to be chronological, but ...

pass -chronological "${1:-today noon}" "${2:-+8}"