#!/usr/bin/perl

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

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

use POSIX qw(locale_h);
use locale;
use Net::Netrc;
use List::Util qw(first);

use IO::Interactive::Tiny;
use Log::Any qw($log);
use Log::Any::Adapter;

use URI;
use IO::Prompter;
use Cal::DAV;
use DateTime;
use Path::Tiny;
use Text::Xslate;

use Object::Groupware::Calendar;

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

# set defaults and parse command-line options
my ( $BASE_URI, $CALENDAR_URI, $SKELDIR, $OUTPUT_FILE );
$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;

# use system locale to format DateTime objects parsed from iCal data
DateTime->DefaultLocale( setlocale(LC_TIME) );

# 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 );

	# resolve credentials
	$log->debug('resolve credentials...');
	my ( $mach, $user, $pass );
	( $user, $pass ) = split ':', $base_uri->userinfo
		if $base_uri->userinfo;
	$user ||= $ENV{CAL_DAV_USER};
	$pass ||= $ENV{CAL_DAV_PASS};
	$mach = Net::Netrc->lookup( $base_uri->host, $user )
		if !$user or !$pass;
	if ($mach) {
		$user ||= $mach->login;
		$pass ||= $mach->password;
		$log->infof(
			'will use .netrc provided credentials for user %s',
			$user
		);
	}
	elsif ( IO::Interactive::Tiny::is_interactive() ) {
		$log->warn(
			'will ask for missing info - this will fail in headless mode');
		$user ||= prompt 'Enter your username';
		$pass ||= prompt 'Enter your password', -echo => '*';
	}
	$log->debugf( 'resolved credentials for user %s', $user );

	# fetch and parse CalDAV calendar data
	$log->debug('fetch and parse CalDAV calendar data...');
	my $session = Cal::DAV->new(
		user => $user,
		pass => $pass,
		url  => $base_uri,
	);
	$session->get($calendar_uri)
		if $calendar_uri;
	$calendar = Object::Groupware::Calendar->new( data => $session->cal );
}
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" );
	}
	else {
		my $data;
		$path->visit( sub { $data .= $_->slurp_raw if $_->is_file } );
		$calendar = Object::Groupware::Calendar->new( data => $data );
	}
}
if ( $log->is_trace ) {
	use DDP;
	p $calendar;
}

# TODO: if list is empty and no calendar uri was explicitly supplied,
# warn on stdout with list of abailable collections using this sequence:
#  1. PROPFIND on base-URL for {DAV:}current-user-principal
#  2. PROPFIND for calendar-home-set property in caldav namespace
#  3. PROPFIND with depth: 1
# as documented at <https://stackoverflow.com/a/11673483>

# 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;