#!/usr/bin/perl

use v5.36;
use utf8;
use open qw(:std :encoding(UTF-8));
use Feature::Compat::Try;

use FindBin qw($Bin);
use lib "$Bin/../lib";

use IO::Interactive::Tiny;
use Log::Any qw($log);
use Log::Any::Adapter;
use URI;
use DateTime;
use Path::Tiny;
use Text::Xslate;
use POSIX qw(locale_h);    # resolve LC_TIME
use locale;
use DateTime::TimeZone;

use Object::Groupware::DAV;
use Object::Groupware::Calendar;

if ( IO::Interactive::Tiny::is_interactive() ) {
	Log::Any::Adapter->set( 'Screen', default_level => 'info' );
}
else {
	use Log::Any::Adapter ( 'Stderr', default_level => 'info' );
}

# set defaults and parse command-line options
my ($BASE_URI, $CALENDAR_URI, $SKELDIR, $OUTPUT_FILE, $CALENDAR_LANG,
	$CALENDAR_TIME_ZONE, %GROUPWARE_OPTIONS
);
$BASE_URI     = $ENV{CAL_DAV_URL_BASE};
$CALENDAR_URI = $ENV{CAL_DAV_URL_CALENDAR};
$SKELDIR      = $ENV{SKELDIR} || "$Bin/../templates";
$BASE_URI ||= shift @ARGV
	if @ARGV;
$CALENDAR_URI ||= shift @ARGV
	if @ARGV;
$OUTPUT_FILE = shift @ARGV
	if @ARGV;
$CALENDAR_LANG = $ENV{CAL_LANG} || setlocale(LC_TIME);
$CALENDAR_TIME_ZONE
	= DateTime::TimeZone->new( name => ( $ENV{CAL_TIME_ZONE} || 'local' ), );

# extend DateTime locale with form LONGER
#  * omit year and second
#  * unabbreviate weekday and month
#  * interpose time preposition in combined date and time, where known
my %at = (
	C  => " 'at' ",
	ar => " 'في' ",
	da => " 'kl.' ",
	de => " 'um' ",
	en => " 'at' ",
	es => " 'a las' ",
	fr => " 'à' ",
	he => " 'בשעה' ",
	it => " 'alle' ",
	ja => "'に'",
	no => " 'kl.' ",
	ru => " 'в' ",
	zh => "'在'",
);
my $dt_locale = DateTime::Locale->load($CALENDAR_LANG);
my ( $locale, $lang ) = $dt_locale->code =~ /^((\w+)(?:-\w+)?)/;
my $dt             = DateTime->now( locale => $dt_locale );
my %dt_locale_data = $dt_locale->locale_data;
$dt_locale_data{code} = "${locale}-LONGER";
$dt_locale_data{name} .= ' nouns unabbreviated';
$dt_locale_data{date_format_medium} = $dt->locale->format_for('MMMMEd');
$dt_locale_data{date_format_medium} ||= $dt->locale->format_for('MMMEd');
$dt_locale_data{date_format_medium} =~ s/\bMMM\b/MMMM/;
$dt_locale_data{date_format_medium} =~ s/\bMMM\b/MMMM/;
$dt_locale_data{date_format_medium} =~ s/\bE\b/EEEE/;
$dt_locale_data{time_format_medium} = $dt->locale->format_for('Hm');
$dt_locale_data{datetime_format_medium}
	=~ s/^\{1\}\K,? (?=\{0\}$)/$at{$lang}/
	if $at{$lang};
%GROUPWARE_OPTIONS = (
	dt_locale    => DateTime::Locale::FromData->new( \%dt_locale_data ),
	dt_time_zone => $CALENDAR_TIME_ZONE,
);
$log->infof(
	'Will use locale %s and time zone %s',
	$GROUPWARE_OPTIONS{dt_locale}->code,
	$GROUPWARE_OPTIONS{dt_time_zone}->name,
);

# resolve calendar URIs
my ( $base_uri, $calendar_uri, $calendar );
$base_uri = URI->new($BASE_URI)
	if ($BASE_URI);
$base_uri
	or $log->fatal('required base URI not provided') && exit 2;
$base_uri->scheme
	or $base_uri->scheme('file');

if ( $base_uri->scheme eq 'http' or $base_uri->scheme eq 'https' ) {
	$log->infof( 'will use base URI %s', $base_uri );
	$calendar_uri = URI->new( $CALENDAR_URI || $base_uri );
	$calendar_uri and $calendar_uri->authority
		or $log->fatal('bad calendar URI: must be an internet URI') && exit 2;
	$base_uri->eq($calendar_uri) and $calendar_uri = undef
		or $log->infof( 'will use calendar URI %s', $calendar_uri );

	my $session = Object::Groupware::DAV->new(
		user => $ENV{CAL_DAV_USER},
		pass => $ENV{CAL_DAV_PASS},
		uri  => $base_uri,
		%GROUPWARE_OPTIONS,
	);
	$calendar = $session->get($calendar_uri);
}
elsif ( $base_uri->scheme eq 'file' ) {
	defined $base_uri->file
		or $log->fatal('bad base URI: cannot open file') && exit 2;
	$log->infof( 'will use base URI %s', $base_uri );

	# parse local calendar data
	$log->debug('parse local calendar data...');
	my $path = path( $base_uri->file );
	if ( $path->is_file ) {
		$calendar = Object::Groupware::Calendar->new(
			filename => "$path",
			%GROUPWARE_OPTIONS,
		);
	}
	else {
		my $data;
		$path->visit( sub { $data .= $_->slurp_raw if $_->is_file } );
		$calendar = Object::Groupware::Calendar->new(
			data => $data,
			%GROUPWARE_OPTIONS,
		);
	}
}

# select subset of calendar events
$log->debug('serialize calendar events...');
my $start;
if ( $ENV{CAL_DAV_NOW} ) {
	try { require DateTimeX::Easy }
	catch ($e) {
		$log->fatalf( 'failed parsing CAL_DAV_NOW: %s', $e ) && exit 2
	}
	$start = DateTimeX::Easy->new( $ENV{CAL_DAV_NOW} );
	$log->fatalf(
		'failed parsing CAL_DAV_NOW: unknown start time "%s"',
		$ENV{CAL_DAV_NOW}
		)
		&& exit 2
		unless defined $start;
}
$start ||= DateTime->now;
my $end    = $start->clone->add( months => 6 );
my $span   = DateTime::Span->from_datetimes( start => $start, end => $end );
my @events = $calendar->events($span);

# serialize calendar view
my $output_path;
if ($OUTPUT_FILE) {
	$output_path = path($OUTPUT_FILE);
	$output_path->parent->mkpath;
	$output_path->remove;
}

my %vars;
for (@events) {
	next unless $_->summary;
	push @{ $vars{events} }, $_;
}

my %tmpl;
$tmpl{list} = path($SKELDIR)->child('list.md')->slurp_utf8;

my $template = Text::Xslate->new(
	path   => \%tmpl,
	syntax => 'TTerse',
	type   => 'text',
);

my $content = $template->render( 'list', \%vars );

if ($output_path) {
	$output_path->append_utf8($content);
}
else {
	print $content;
}

1;