# Astro::App::Satpass2 source file. Invoke as (e.g.)
# satpass2> source eg/flare_vcalendar
#
# Do iridium flare calculations, displaying the results in vCalendar
# format. The output may be redirected to a .vcal file. Any arguments
# passed to the source statement will in turn be passed to the flare
# command.
#
# 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

# Template to provide output in vCalendar format.

formatter template flare <<'EOD'
BEGIN:VCALENDAR
[%- FOREACH item IN data %]
[%- CALL item.fixed_width( 0 ) %]
BEGIN:VEVENT
DTSTART:[% item.date( units = 'z' ) %]
DALARM:[% item.date( delta = -360, units = 'z' ) %]
DALARM:[% item.date( delta = -60, units = 'z' ) %]
SUMMARY:[% item.name( units = 'title_case', width = '' ) %]
    [%= item.time %] Az [% item.azimuth(
    places = 0, bearing = 2 ) %] Ele [% item.elevation(
    places = 0 ) %] Mag [% item.magnitude %]
    [%- IF 'day' == item.type %]
	[%= item.appulse.angle %] deg from Sun
    [%- ELSE =%]
	night
    [%- END %]
DTEND:[% item.date( delta = 60, units = 'z' ) %]
END:VEVENT
[%- END %]
END:VCALENDAR
EOD

# Do the flare calculation.

flare "$@"