package Bio::EnsEMBL::Utils::Net;

=pod

=head1 LICENSE

  Copyright (c) 1999-2013 The European Bioinformatics Institute and
  Genome Research Limited.  All rights reserved.

  This software is distributed under a modified Apache license.
  For license details, please see

    http://www.ensembl.org/info/about/code_licence.html

=head1 CONTACT

  Please email comments or questions to the public Ensembl
  developers list at <dev@ensembl.org>.

  Questions may also be sent to the Ensembl help desk at
  <helpdesk@ensembl.org>.

=cut

=pod

=head1 NAME

Bio::EnsEMBL::Utils::Net

=head1 SYNOPSIS

  use Bio::EnsEMBL::Utils::Net qw/do_GET do_FTP/;

  #Doing a HTTP get
  my $google_contents = do_GET('http://www.google.co.uk/');
  
  #Doing a FTP request; delegates onto LWP
  my $ftp_contents = do_GET('ftp://ftp.ensembl.org/pub/current_README');

=head1 DESCRIPTION

A collection of subroutines aimed to helping network based operations. The code
will use HTTP::Tiny for all HTTP operations if available. Otherwise it
will delegate to LWP. LWP is currently the only supported target for FTP.

=head1 METHODS

See subroutines.

=head1 VERSION

$Revision: 1.1 $

=cut

use strict;
use warnings;

use base qw/Exporter/;
use Time::HiRes;

our @EXPORT_OK;

@EXPORT_OK = qw(
  do_GET
  do_FTP
);

use Bio::EnsEMBL::Utils::Exception qw(throw);

our $HTTP_TINY = 0;
our $LWP = 0;
eval {
  require HTTP::Tiny;
  $HTTP_TINY = 1;
};
eval {
  require LWP::UserAgent;
  $LWP = 1;
};

=head2 do_GET

  Arg [1]     : string $url The URL to fetch including all parameters
  Arg [2]     : int; $total_attempts The number of times to try the URL 
                before throwing an exception
  Arg [3]     : number; $sleep Amount of time to sleep between attempts. 
                Delegates onto Time::HiRes so floating point numbers are 
                supported
  Description : Performs a HTTP GET method call to return the specified remote
                resource.
  Returntype  : Scalar of the contents of the remote URL. Do not use to
                retrieve very large amounts of data.
  Example     : my $contents = do_GET('http://www.google.co.uk/');
  Exceptions  : If we could not retrieve the resource after the specified 
                number of attempts.
  Status      : Stable

=cut

sub do_GET {
  my ($url, $total_attempts, $sleep) = @_;
  return _retry_sleep(sub {
    if($HTTP_TINY) {
      return _get_http_tiny($url);
    }
    elsif($LWP) {
      return _get_lwp($url);
    }
    else {
      throw "Cannot continue. You do not have HTTP::Tiny or LWP available."
    }
  }, $total_attempts, $sleep);
}

=head2 do_FTP

  Arg [1]     : string $uri
  Arg [2]     : int; $total_attempts The number of times to try the URI 
                before throwing an exception
  Arg [3]     : number; $sleep Amount of time to sleep between attempts. 
                Delegates onto Time::HiRes so floating point numbers are 
                supported
  Description : Performs a FTP fetch using a non-authenticated connection (
                however some servers will allow you to encode this in the URI).
  Returntype  : Scalar of the contents of the remote URL. Do not use to
                retrieve very large amounts of data.
  Example     : my $contents = do_GET('http://www.google.co.uk/');
  Exceptions  : If we could not retrieve the resource after the specified 
                number of attempts.
  Status      : Stable

=cut

sub do_FTP {
  my ($url, $total_attempts, $sleep) = @_;
  return _retry_sleep(sub {
    return _get_lwp($url);
  }, $total_attempts, $sleep);
}

sub _retry_sleep {
  my ($callback, $total_attempts, $sleep) = @_;
  $total_attempts ||= 1;
  $sleep ||= 0;
  my $response;
  my $retries = 0;
  my $fail = 1;
  while($retries <= $total_attempts) {
    $response = $callback->();
    if(defined $response) {
      $fail = 0;
      last;
    }
    $retries++;
    Time::HiRes::sleep($sleep);
  }
  if($fail) {
    throw "Could request remote resource after $total_attempts attempts";
  }
  return $response;
}

sub _get_http_tiny {
  my ($url) = @_;
  my $response = HTTP::Tiny->new->get($url);
  return unless $response->{success};
  return $response->{content} if length $response->{content};
  return;
}

sub _get_lwp {
  my ($url) = @_;
  throw "Cannot perform action as LWP::UserAgent is not available" unless $LWP;
  my $ua = LWP::UserAgent->new();
  $ua->env_proxy;
  my $response = $ua->get($url);
  return $response->decoded_content if $response->is_success;
  return;
}

1;