File Coverage

blib/lib/Weather/Meteo.pm

Criterion	Covered	Total	%
statement	32	74	43.2
branch	5	30	16.6
condition	1	8	12.5
subroutine	8	10	80.0
pod	3	3	100.0
total	49	125	39.2

package Weather::Meteo;

use strict;
use warnings;

use Carp;
use JSON::MaybeXS;
use LWP::UserAgent;
use URI;

use constant FIRST_YEAR => 1940;

=head1 NAME

Weather::Meteo - Interface to L for historical weather data

=head1 VERSION

Version 0.05

=cut

our $VERSION = '0.05';

=head1 SYNOPSIS

      use Weather::Meteo;

      my $meteo = Weather::Meteo->new();
      my $weather = $meteo->weather({ latitude => 0.1, longitude => 0.2, date => '2022-12-25' });

=head1 DESCRIPTION

Weather::Meteo provides an interface to open-meteo.com
for historical weather data from 1940.

=head1 METHODS

=head2 new

    my $meteo = Weather::Meteo->new();
    my $ua = LWP::UserAgent->new();
    $ua->env_proxy(1);
    $meteo = Weather::Meteo->new(ua => $ua);

    my $weather = $meteo->weather({ latitude => 51.34, longitude => 1.42, date => '2022-12-25' });
    my @snowfall = @{$weather->{'hourly'}->{'snowfall'}};

    print 'Number of cms of snow: ', $snowfall[1], "\n";

=cut

sub new {
	my($class, %args) = @_;

	if(!defined($class)) {
		# Weather::Meteo::new() used rather than Weather::Meteo->new()
		$class = __PACKAGE__;
	} elsif(ref($class)) {
		# clone the given object
		return bless { %{$class}, %args }, ref($class);
	}

	my $ua = $args{ua};
	if(!defined($ua)) {
		$ua = LWP::UserAgent->new(agent => __PACKAGE__ . "/$VERSION");
		$ua->default_header(accept_encoding => 'gzip,deflate');
	}
	my $host = $args{host} || 'archive-api.open-meteo.com';

	return bless { ua => $ua, host => $host }, $class;
}

=head2 weather

    use Geo::Location::Point;

    my $ramsgate = Geo::Location::Point->new({ latitude => 51.34, longitude => 1.42 });
    # Print snowfall at 1AM on Christmas morning in Ramsgate
    $weather = $meteo->weather($ramsgate, '2022-12-25');
    @snowfall = @{$weather->{'hourly'}->{'snowfall'}};

    print 'Number of cms of snow: ', $snowfall[1], "\n";

=cut

sub weather {
	my $self = shift;
	my %param;

	if(ref($_[0]) eq 'HASH') {
		%param = %{$_[0]};
	} elsif((@_ == 2) && (ref($_[0]) =~ /::/) && ($_[0]->can('latitude'))) {
		my $location = $_[0];
		$param{latitude} = $location->latitude();
		$param{longitude} = $location->longitude();
		$param{'date'} = $_[1];
	} elsif(ref($_[0])) {
		Carp::croak('Usage: weather(latitude => $latitude, longitude => $logitude, date => "YYYY-MM-DD")');
		return;
	} elsif(@_ % 2 == 0) {
		%param = @_;
	}

	my $latitude = $param{latitude};
	my $longitude = $param{longitude};
	my $date = $param{'date'};

	if(!defined($latitude)) {
		Carp::croak('Usage: weather(latitude => $latitude, longitude => $logitude, date => "YYYY-MM-DD")');
		return;
	}

	if($date =~ /^(\d{4})-/) {
		my $year = $1;

		return if($1 < FIRST_YEAR);
	} else {
		Carp::carp("'$date' is not a valid date");
		return;
	}

	my $uri = URI->new("https://$self->{host}/v1/archive");
	my %query_parameters = (
		'latitude' => $latitude,
		'longitude' => $longitude,
		'start_date' => $date,
		'end_date' => $date,
		'hourly' => 'temperature_2m,rain,snowfall,weathercode',
		'daily' => 'weathercode,temperature_2m_max,temperature_2m_min,rain_sum,snowfall_sum,precipitation_hours',
		'timezone' => 'Europe/London',	# FIXME
			# https://stackoverflow.com/questions/16086962/how-to-get-a-time-zone-from-a-location-using-latitude-and-longitude-coordinates
		'windspeed_unit' => 'mph',
		'precipitation_unit' => 'inch'
	);

	$uri->query_form(%query_parameters);
	my $url = $uri->as_string();

	$url =~ s/%2C/,/g;

	my $res = $self->{ua}->get($url);

	if($res->is_error()) {
		Carp::croak("$url API returned error: ", $res->status_line());
		return;
	}
	# $res->content_type('text/plain');	# May be needed to decode correctly

	my $json = JSON::MaybeXS->new()->utf8();
	if(my $rc = $json->decode($res->decoded_content())) {
		if($rc->{'error'}) {
			# TODO: print error code
			return;
		}
		if(defined($rc->{'hourly'})) {
			return $rc;	# No support for list context, yet
		}
	}

	# my @results = @{ $data || [] };
	# wantarray ? @results : $results[0];
}

=head2 ua

Accessor method to get and set UserAgent object used internally. You
can call I for example, to get the proxy information from
environment variables:

    $meteo->ua()->env_proxy(1);

You can also set your own User-Agent object:

    use LWP::UserAgent::Throttled;

    my $ua = LWP::UserAgent::Throttled->new();
    $ua->throttle('open-meteo.com' => 1);
    $meteo->ua($ua);

=cut

sub ua {
	my $self = shift;
	if (@_) {
		$self->{ua} = shift;
	}
	$self->{ua};
}

=head1 AUTHOR

Nigel Horne, C<<  >>

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

Lots of thanks to the folks at L.

=head1 BUGS

=head1 SEE ALSO

Open Meteo API: L

=head1 SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc Weather::Meteo

You can also look for information at:

=over 4

=item * MetaCPAN

L

=item * RT: CPAN's request tracker

L

=item * CPANTS

L

=item * CPAN Testers' Matrix

L

=item * CPAN Testers Dependencies

L

=back

=head1 LICENSE AND COPYRIGHT

Copyright 2023 Nigel Horne.

This program is released under the following licence: GPL2

=cut

1;