#!/usr/bin/perl -w

use strict;
use LWP::Simple;
use LWP::UserAgent;
use Getopt::Long;
use Pod::Usage;
use Digest::SHA1 qw /sha1_hex/;

my %opt = (
);

GetOptions(
        'review-num|review|r=i' => \$opt{review_num},
        'diff-num|diff|d=i' => \$opt{diff_num},
        'help|?' => \$opt{help},
        man => \$opt{man}
) or pod2usage(2);
pod2usage(1) if ($opt{help});
if (not defined $opt{review_num}) {
	print STDERR "$0: Error: review number (-r) is required\n";
	pod2usage(2);
}
pod2usage(-exitstatus => 0, -verbose => 2) if $opt{man};


my $reviewboard_server ="reviewboard.asterisk.org"; 
my $base_url="https://reviewboard.asterisk.org";

my $diff_num;
my $diff_num_str = "";
if (defined $opt{diff_num}) {
	$diff_num = $opt{diff_num};
	print STDERR "$diff_num\n";
	$diff_num_str = "/$diff_num";
	exit 1;
}
my $review_num = $opt{review_num};
my $review_url = "$base_url/r/$review_num";
my $diff_page_url = "$review_url/diff$diff_num_str";
my $diff_url = "$diff_page_url/raw";

my $content = get($diff_page_url);
die "$0: Failed to get reviewboard page $diff_page_url\n" unless defined $content;

# Simple lines-based parsing will do hor now
my @page = split(/\n/, $content);
$content =~ m{<h1 id="summary" class="editable">([^<]*)</h1>};
my $summary = $1;
$content =~ m{<a id="submitter" href="/users/([^/]*)/">([^<]*)</a>};
my ($user_name, $full_name) = ($1, $2);
$content =~ m{<span id="branch" class="editable">([^<]*)</span>};
my $branch = $1;
$content =~ m{var gRevision = '(\d+)';};
$diff_num = $1;

my $ua = LWP::UserAgent->new;
my $response = $ua->get($diff_url);

#my $raw_diff = get($diff_url);
die "$0: Failed to get raw diff $diff_url".($response->status_live)."\n"
	unless $response->is_success;
my $raw_diff = $response->content;
my $date = $response->header('Date');

my $checksum = sha1_hex("${review_num}::${diff_num}::${user_name}::${date}");
#my @head = head($diff_page_url);
##my $date = $head[2];
#my $date = join '>|<', @head;

# Fix patch-level from -p0 to -p1
# Alternatively you could use git-am -p0
$raw_diff =~ m{\n--- [^\n]*\s\(revision (\d+)\)};
my $revision = $1;
$raw_diff =~ s{\n--- }   {$&a/}g;
$raw_diff =~ s{\n\+\+\+ }{$&b/}g;

print 
"From $checksum $date
From: $full_name <$user_name\@$reviewboard_server>
Date: $date
Subject: [PATCH] $summary

Review: $review_num
Diff: $diff_num
Svn-Branch: $branch
Svn-Revision: $revision
Origin: $diff_page_url

<fill in further description>

$raw_diff

-- 
$0
"

__END__

=head1 NAME
rb-patch

=head1 SYNOPSIS

rb-patch -r I<NUM>

Options:
  -r --review  number of reivewboard review to fetch. Required.
  -d --diff    number of the diff to fetch. Default: last one.
  --help       brief help message
  --man        full documentation

=head1 OPTIONS

=over

=item B<--review> I<num>

Fetch ReviewBoard review number I<num>. This parameter is required.

=item B<--diff> I<num>

Fetch diff no. I<num> rather than the last one.

=item B<--help>

Print a brief help message and exits.

=item B<--man>

Prints the manual page and exits.

=back

=head1 DESCRIPTION

This script is intended, in the long run, to convert a review-board review
to a mailbox that could be merged into a git repository through git-am(1).

At the moment, however, it only fetches latest review. Use:

  git checkout -b test-branch
  ../asterisk-tools/rb-patch -r I<num> >patch
  git am patch

=cut