use strict;
use warnings;
use XML::Simple;
use Data::Dumper;
use Time::Piece;

my $xml = XMLin( 'depart.xml', 

		ForceArray => ['flightStatus'], 	# To force the flightstatuses into an arrayref
		GroupTags => { 				# To eliminate unnecessary levels in the structure
			airlines => 'airline',
			airports => 'airport',
			equipments => 'equipment',
			flightStatuses => 'flightStatus'});

# just to illustrate that you can easily extract the data
my $airports = $xml->{appendix}{airports};
my $equipments = $xml->{appendix}{equipments};
my $airlines = $xml->{appendix}{airlines};
my @flightstatuses = @{$xml->{flightStatuses}}; # make it a normal array from flightstatuses

print "Airports\n";
print "--------\n";
print Dumper $airports;

print "Airlines\n";
print "--------\n";
print Dumper $airlines;

print "Equipments\n";
print "----------\n";
print Dumper $equipments;

print "Flightstatuses\n";
print "----------\n";
print Dumper (\@flightstatuses);

# examples of obtaining an element of a flightstatus that i use in the sorting

# take the first element
my $flightstatus = $flightstatuses[0];

# obtain departure and arrival times
my $departuretime = $flightstatus->{departureDate}{dateUtc};
my $arrivaltime = $flightstatus->{arrivalDate}{dateUtc};

print $departuretime, "\n";
print $arrivaltime, "\n";

# printed after conversion (remark: didn't take the '000Z' in my conversion)
print Time::Piece->strptime($departuretime, '%Y-%m-%dT%H:%M:%S.000Z'), "\n";
print Time::Piece->strptime($arrivaltime, '%Y-%m-%dT%H:%M:%S.000Z'), "\n";

# transform the times into epoch, needed for sort function (strictly, it is not, because a Time::Piece
# object will stringify to epoch  
my $departuretime_epoch = Time::Piece->strptime($departuretime, '%Y-%m-%dT%H:%M:%S.000Z')->epoch;
my $arrivaltime_epoch = Time::Piece->strptime($arrivaltime, '%Y-%m-%dT%H:%M:%S.000Z')->epoch;

print $departuretime_epoch , "\n";
print $arrivaltime_epoch, "\n";

# the classic example of the camel cookbook to sort with mapping where the mappings shown in the examples are used.
my @sorted_by_arrival = map {$_->[1]}								 # map back to original array
	  		sort {$a->[0] cmp $b->[0]}						 # classical compare of two values
		        map {[Time::Piece->strptime($_->{arrivalDate}{dateUtc}, '%Y-%m-%dT%H:%M:%S.000Z')->epoch, $_]} # make a intermediate array with on first place the value used to sort
		        @flightstatuses;

my @sorted_by_departure = map {$_->[1]}								 # map back to original array
	  		  sort {$a->[0] cmp $b->[0]}						 # classical compare of two values
		          map {[Time::Piece->strptime($_->{departureDate}{dateUtc}, '%Y-%m-%dT%H:%M:%S.000Z')->epoch, $_]} # make a intermediate array with on first place the value used to sort
		          @flightstatuses;


# mapping to be able to print the results
my @sorted_by_arrival_id = map {$_->{'flightId'}} @sorted_by_arrival;
my @sorted_by_departure_id = map {$_->{'flightId'}} @sorted_by_departure;

print join " ", @sorted_by_arrival_id, "\n";
print join " ", @sorted_by_departure_id, "\n";