Add GithubPulls input plugin.

This can be used with declarative projects to build PRs.

The github_authorization section should contain verbatim Authorization header contents keyed by repo owner for private repos

src/lib/Hydra/Plugin/GithubPulls.pm

@@ -0,0 +1,62 @@
+package Hydra::Plugin::GithubPulls;
+
+use strict;
+use parent 'Hydra::Plugin';
+use HTTP::Request;
+use LWP::UserAgent;
+use JSON;
+use Hydra::Helper::CatalystUtils;
+use File::Temp;
+
+sub supportedInputTypes {
+    my ($self, $inputTypes) = @_;
+    $inputTypes->{'githubpulls'} = 'Open GitHub Pull Requests';
+}
+
+sub _iterate {
+    my ($url, $auth, $pulls, $ua) = @_;
+    my $req = HTTP::Request->new('GET', $url);
+    $req->header('Accept' => 'application/vnd.github.v3+json');
+    $req->header('Authorization' => $auth) if defined $auth;
+    my $res = $ua->request($req);
+    my $content = $res->decoded_content;
+    die "Error pulling from the github pulls API: $content\n"
+        unless $res->is_success;
+    my $pulls_list = decode_json $content;
+    # TODO Stream out the json instead
+    foreach my $pull (@$pulls_list) {
+        $pulls->{$pull->{number}} = $pull;
+    }
+    # TODO Make Link header parsing more robust!!!
+    my @links = split ',', $res->header("Link");
+    my $next = "";
+    foreach my $link (@links) {
+        my ($url, $rel) = split ";", $link;
+        if (trim($rel) eq 'rel="next"') {
+            $next = substr trim($url), 1, -1;
+            last;
+        }
+    }
+    _iterate($next, $auth, $pulls, $ua) unless $next eq "";
+}
+
+sub fetchInput {
+    my ($self, $type, $name, $value, $project, $jobset) = @_;
+    return undef if $type ne "githubpulls";
+    # TODO Allow filtering of some kind here?
+    (my $owner, my $repo) = split ' ', $value;
+    my $auth = $self->{config}->{github_authorization}->{$owner};
+    my %pulls;
+    my $ua = LWP::UserAgent->new();
+    _iterate("https://api.github.com/repos/$owner/$repo/pulls?per_page=100", $auth, \%pulls, $ua);
+    my $tempdir = File::Temp->newdir("github-pulls" . "XXXXX", TMPDIR => 1);
+    my $filename = "$tempdir/github-pulls.json";
+    open(my $fh, ">", $filename) or die "Cannot open $filename for writing: $!";
+    print $fh encode_json \%pulls;
+    close $fh;
+    my $storePath = `nix-store --add "$filename"`
+        or die "cannot copy path $filename to the Nix store.\n";
+    return { storePath => $storePath };
+}
+
+1;