#!/usr/bin/env perl

# core-cpan-diff: Compare CPAN modules with their equivalent in core

# Originally based on App::DualLivedDiff by Steffen Mueller.
 
use strict;
use warnings;

use 5.010;

use Getopt::Long;
use File::Temp ();
use File::Path ();
use File::Spec;
use Archive::Extract;
use IO::Uncompress::Gunzip ();
use File::Compare ();
use ExtUtils::Manifest;

BEGIN { die "Must be run from root of perl source tree\n" unless -d 'Porting' }
use lib 'Porting';
use Maintainers ();

# if running from blead, we may be doing -Ilib, which means when we
# 'chdir /tmp/foo', Archive::Extract may not find Archive::Tar etc.
# So preload the things we need, and tell it to check %INC first:

use Archive::Tar;
use IPC::Open3;
use IO::Select;
$Module::Load::Conditional::CHECK_INC_HASH = 1;
# stop Archive::Extract whinging about lack of Archive::Zip
$Archive::Extract::WARN = 0;


# Files, which if they exist in CPAN but not in perl, will not generate
# an 'Only in CPAN' listing
#
our %IGNORABLE = map { ($_ => 1) }
	qw(.cvsignore .dualLivedDiffConfig .gitignore
	      ANNOUNCE Announce Artistic AUTHORS BENCHMARK BUGS Build.PL
	      CHANGELOG ChangeLog CHANGES Changes COPYING Copying CREDITS
	      GOALS HISTORY INSTALL INSTALL.SKIP LICENSE Makefile.PL
	      MANIFEST MANIFEST.SKIP META.yml NEW NOTES ppport.h README
	      SIGNATURE THANKS TODO Todo VERSION WHATSNEW);

# where, under the cache dir, to untar stuff to

use constant UNTAR_DIR => 'untarred';

use constant DIFF_CMD  => 'diff';
use constant WGET_CMD  => 'wget';

sub usage {
    print STDERR "\n@_\n\n" if @_;
    print STDERR <<HERE;
Usage: $0 [opts] [ -d | -v | -x ] [ -a | module ... ]

-a/--all      Scan all dual-life modules.

-c/--cachedir Where to save downloaded CPAN tarball files
              (defaults to /tmp/something/ with deletion after each run).

-d/--diff     Display file differences using diff(1), rather than just
              listing which files have changed.
              The diff(1) command is assumed to be in your PATH.

--diffopts    Options to pass to the diff command. Defaults to '-u'.

-f|force      Force download from CPAN of new 02packages.details.txt file
              (with --crosscheck only).

-o/--output   File name to write output to (defaults to STDOUT).

-r/--reverse  Reverses the diff (perl to CPAN).

-u/--upstream only print modules with the given upstream (defaults to all)

-v/--verbose  List the fate of *all* files in the tarball, not just those
              that differ or are missing.

-x|crosscheck List the distributions whose current CPAN version differs from
              that in blead (i.e. the DISTRIBUTION field in Maintainers.pl).

By default (i.e. without the --crosscheck option),  for each listed module
(or with -a, all CPAN modules listed in Maintainers.pl), grab the tarball
from CPAN associated with that module, and compare the files in it with
those in the perl source tree.

Must be run from the root of the perl source tree.
Module names must match the keys of %Modules in Maintainers.pl.
HERE
    exit(1);
}


sub run {
    my $scan_all;
    my $diff_opts;
    my $reverse    = 0;
    my @wanted_upstreams;
    my $cache_dir;
    my $use_diff;
    my $output_file;
    my $verbose;
    my $force;
    my $do_crosscheck;

    GetOptions(
	'a|all'        => \$scan_all,
	'c|cachedir=s' => \$cache_dir,
	'd|diff'       => \$use_diff,
	'diffopts:s'   => \$diff_opts,
	'f|force'      => \$force,
	'h|help'       => \&usage,
	'o|output=s'   => \$output_file,
	'r|reverse'    => \$reverse,
	'u|upstream=s@'=> \@wanted_upstreams,
	'v|verbose'    => \$verbose,
	'x|crosscheck' => \$do_crosscheck,
    ) or usage;


    my @modules;

    usage("Cannot mix -a with module list") if $scan_all && @ARGV;

    if ($do_crosscheck) {
	usage("can't use -r, -d, --diffopts, -v with --crosscheck")
	    if ($reverse || $use_diff || $diff_opts || $verbose);
    }
    else {
	$diff_opts = '-u' unless defined $diff_opts;
	usage("can't use -f without --crosscheck") if $force;
    }

    @modules = $scan_all
	        ? grep $Maintainers::Modules{$_}{CPAN},
		    (sort {lc $a cmp lc $b } keys %Maintainers::Modules)
	        : @ARGV;
    usage("No modules specified") unless @modules;


    my $outfh;
    if (defined $output_file) {
	open $outfh, '>', $output_file
	    or die "ERROR: could not open file '$output_file' for writing: $!\n";
    }
    else {
	open $outfh, ">&STDOUT"
			    or die "ERROR: can't dup STDOUT: $!\n";
    }

    if (defined $cache_dir) {
	die "ERROR: no such directory: '$cache_dir'\n" unless -d $cache_dir;
    }

    if ($do_crosscheck) {
	do_crosscheck($outfh, $cache_dir, $force, \@modules);
    }
    else {
	do_compare(\@modules, $outfh, $output_file, $cache_dir, $verbose, $use_diff,
	    $reverse, $diff_opts, \@wanted_upstreams);
    }
}



# compare a list of modules against their CPAN equivalents

sub do_compare {
    my ($modules, $outfh, $output_file, $cache_dir, $verbose,
		$use_diff, $reverse, $diff_opts, $wanted_upstreams) = @_;


    # first, make sure we have a directory where they can all be untarred,
    # and if its a permanent directory, clear any previous content
    my $untar_dir;
    if ($cache_dir) {
	$untar_dir = File::Spec->catdir($cache_dir, UNTAR_DIR); 
	if (-d $untar_dir) {
	    File::Path::rmtree($untar_dir)
		    or die "failed to remove $untar_dir\n";
	}
	mkdir $untar_dir
	    or die "mkdir $untar_dir: $!\n";
    }
    else {
	$untar_dir = File::Temp::tempdir( CLEANUP => 1 );
    }

    my %ignorable = map { ($_ => 1) } @Maintainers::IGNORABLE;

    my %seen_dist;
    for my $module (@$modules) {
	warn "Processing $module ...\n" if defined $output_file;

	my $m = $Maintainers::Modules{$module} 
	    or die "ERROR: No such module in Maintainers.pl: '$module'\n";

	unless ($m->{CPAN}) {
	    print $outfh "WARNING: $module is not dual-life; skipping\n";
	    next;
	}

	my $dist = $m->{DISTRIBUTION};
	die "ERROR: $module has no DISTRIBUTION entry\n" unless defined $dist;

	if ($seen_dist{$dist}) {
	    warn "WARNING: duplicate entry for $dist in $module\n"
	}

	my $upstream = $m->{UPSTREAM} || 'UNKNOWN';
	next if @$wanted_upstreams and ! ($upstream ~~ $wanted_upstreams);
	print $outfh "\n$module - ".$Maintainers::Modules{$module}->{DISTRIBUTION}."\n" unless $use_diff;
	print $outfh "  upstream is: ".($m->{UPSTREAM} || 'UNKNOWN!')."\n";

	$seen_dist{$dist}++;

	my $cpan_dir;
	eval {
	    $cpan_dir = get_distribution($cache_dir, $untar_dir, $module, $dist)
	};
	if ($@) {
	    print $outfh "  ", $@;
	    print $outfh "  (skipping)\n";
	    next;
	}

	my @perl_files = Maintainers::get_module_files($module);

	my $manifest = File::Spec->catfile($cpan_dir, 'MANIFEST');
	die "ERROR: no such file: $manifest\n" unless  -f $manifest;

	my $cpan_files = ExtUtils::Manifest::maniread($manifest);
	my @cpan_files = sort keys %$cpan_files;

	my ($excluded, $map) =  get_map($m, $module, \@perl_files);

	my %perl_unseen;
	@perl_unseen{@perl_files} = ();
	my %perl_files = %perl_unseen;

	foreach my $cpan_file (@cpan_files) {
	    my $mapped_file = cpan_to_perl($excluded, $map, $cpan_file);
	    unless (defined $mapped_file) {
	        print $outfh "  Excluded:  $cpan_file\n" if $verbose;
	        next;
	    }

	    if (exists $perl_files{$mapped_file}) {
	        delete $perl_unseen{$mapped_file};
	    }
	    else {
	        # some CPAN files foo are stored in core as foo.packed,
	        # which are then unpacked by 'make test_prep'
	        my $packed_file = "$mapped_file.packed";
	        if (exists $perl_files{$packed_file} ) {
	            if (! -f $mapped_file and -f $packed_file) {
	                print $outfh <<EOF;
WARNING: $mapped_file not found, but .packed variant exists.
Perhaps you need to run 'make test_prep'?
EOF
	                next;
	            }
	            delete $perl_unseen{$packed_file};
	        }
	        else {
	            if ($ignorable{$cpan_file}) {
	                print $outfh "  Ignored:   $cpan_file\n" if $verbose;
	                next;
	            }

	            unless ($use_diff) {
	                print $outfh "  CPAN only: $cpan_file",
	                    ($cpan_file eq $mapped_file) ? "\n"
				: " (expected $mapped_file)\n";
	            }
	            next;
	        }
	    }


	    my $abs_cpan_file = File::Spec->catfile($cpan_dir, $cpan_file);

	    # should never happen
	    die "ERROR: can't find file $abs_cpan_file\n" unless -f $abs_cpan_file;

	    # might happen if the FILES entry in Maintainers.pl is wrong
	    unless (-f $mapped_file) {
	        print $outfh "WARNING: perl file not found: $mapped_file\n";
	        next;
	    }

			my $relative_mapped_file = $mapped_file;
			$relative_mapped_file =~ s/^(cpan|dist|ext)\/.*?\///;

	    if (File::Compare::compare($abs_cpan_file, $mapped_file)) {


	         if ($use_diff) {
	            file_diff($outfh, $abs_cpan_file, $mapped_file,
	                                $reverse, $diff_opts);
	        }
	        else {
	            if ($cpan_file eq $relative_mapped_file) {
	                print $outfh "  Modified:  $relative_mapped_file\n";
	            }
	            else {
	                print $outfh "  Modified:  $cpan_file $relative_mapped_file\n";
	            }
	        }
	    }
	    elsif ($verbose) {
	            if ($cpan_file eq $relative_mapped_file) {
	                print $outfh "  Unchanged: $cpan_file\n";
	            }
	            else {
	                print $outfh "  Unchanged: $cpan_file $relative_mapped_file\n";
	            }
	    }
	}
	for (sort keys %perl_unseen) {
	    print $outfh "  Perl only: $_\n" unless $use_diff;
	}
    }
}

# given FooBar-1.23_45.tar.gz, return FooBar

sub distro_base {
    my $d = shift;
    $d =~ s/\.tar\.gz$//;
    $d =~ s/\.gip$//;
    $d =~ s/[\d\-_\.]+$//;
    return $d;
}

# process --crosscheck action:
# ie list all distributions whose CPAN versions differ from that listed in
# Maintainers.pl

sub do_crosscheck {
    my ($outfh, $cache_dir, $force, $modules) = @_;

    my $file = '02packages.details.txt';
    my $download_dir = $cache_dir || File::Temp::tempdir( CLEANUP => 1 );
    my $path = File::Spec->catfile($download_dir, $file);
    my $gzfile = "$path.gz";

    # grab 02packages.details.txt

    my $url = 'http://www.cpan.org/modules/02packages.details.txt.gz';

    if (! -f $gzfile or $force) {
	unlink $gzfile;
	my_getstore($url, $gzfile);
    }
    unlink $path;
    IO::Uncompress::Gunzip::gunzip($gzfile, $path)
	or die "ERROR: failed to ungzip $gzfile: $IO::Uncompress::Gunzip::GunzipError\n";

    # suck in the data from it
    
    open my $fh, '<', $path
	or die "ERROR: open: $file: $!\n";

    my %distros;
    my %modules;

    while (<$fh>) {
	next if 1../^$/;
	chomp;
	my @f = split ' ', $_;
	if (@f != 3) {
	    warn "WARNING: $file:$.: line doesn't have three fields (skipping)\n";
	    next;
	}
	my $distro = $f[2];
	$distro =~ s{^[A-Z]/[A-Z]{2}/}{}; # strip leading A/AB/
	$modules{$f[0]} = $distro;

	(my $short_distro = $distro) =~ s{^.*/}{};

	$distros{distro_base($short_distro)}{$distro} = 1;
    }

    for my $module (@$modules) {
	my $m = $Maintainers::Modules{$module} 
	    or die "ERROR: No such module in Maintainers.pl: '$module'\n";

	unless ($m->{CPAN}) {
	    print $outfh "\nWARNING: $module is not dual-life; skipping\n";
	    next;
	}

	# given an entry like
	#   Foo::Bar 1.23 foo-bar-1.23.tar.gz,
	# first compare the module name against Foo::Bar, and failing that,
	# against foo-bar

	my $pdist = $m->{DISTRIBUTION};
	die "ERROR: $module has no DISTRIBUTION entry\n" unless defined $pdist;

	my $cdist = $modules{$module};
	(my $short_pdist = $pdist) =~ s{^.*/}{};

	unless (defined $cdist) {
	    my $d = $distros{distro_base($short_pdist)};
	    unless (defined $d) {
	        print $outfh "\n$module: Can't determine current CPAN entry\n";
	        next;
	    }
	    if (keys %$d > 1) {
	        print $outfh "\n$module: (found more than one CPAN candidate):\n";
	        print $outfh "    perl: $pdist\n";
	        print $outfh "    CPAN: $_\n" for sort keys %$d;
	        next;
	    }
	    $cdist = (keys %$d)[0];
	}

	if ($cdist ne $pdist) {
	    print $outfh "\n$module:\n    Perl: $pdist\n    CPAN: $cdist\n";
	}
    }
}



# get the EXCLUDED and MAP entries for this module, or
# make up defauts if they don't exist

sub get_map {
    my ($m, $module_name, $perl_files) = @_;

    my ($excluded, $map) = @$m{qw(EXCLUDED MAP)};

    $excluded ||= [];

    return $excluded, $map if $map;

    # all files under ext/foo-bar (plus maybe some under t/lib)???

    my $ext;
    for (@$perl_files) {
	if (m{^((?:ext|dist|cpan)/[^/]+/)}) {
	    if (defined $ext and $ext ne $1) {
	        # more than one ext/$ext/
	        undef $ext;
	        last;
	    }
	    $ext = $1;
	}
	elsif (m{^t/lib/}) {
	    next;
	}
	else {
	    undef $ext;
	    last;
	}
    }
    
    if (defined $ext) {
	    $map = { '' => $ext },
    }
    else {
	(my $base = $module_name) =~ s{::}{/}g;
	$base ="lib/$base";
	$map = {
	    'lib/'	=> 'lib/',
	    ''	=> "$base/",
	};
    }
    return $excluded, $map;
}


# Given an exclude list and a mapping hash, convert a CPAN filename
# (eg 't/bar.t') to the equivalent perl filename (eg 'lib/Foo/Bar/t/bar.t').
# Returns an empty list for an excluded file

sub cpan_to_perl {
    my ($excluded, $map, $cpan_file) = @_;

    for my $exclude (@$excluded) {
	# may be a simple string to match exactly, or a pattern
	if (ref $exclude) {
	    return if $cpan_file =~ $exclude;
	}
	else {
	    return if $cpan_file eq $exclude;
	}
    }

    my $perl_file = $cpan_file;

    # try longest prefix first, then alphabetically on tie-break
    for my $prefix (sort { length($b) <=> length($a) || $a cmp $b } keys %$map)
    {
	last if $perl_file =~ s/^\Q$prefix/$map->{$prefix}/;
    }
    return $perl_file;
}



# do LWP::Simple::getstore, possibly without LWP::Simple being available

my $lwp_simple_available;

sub my_getstore {
    my ($url, $file) = @_;
    unless (defined $lwp_simple_available) {
	eval { require LWP::Simple };
	$lwp_simple_available = $@ eq '';
    }
    if ($lwp_simple_available) {
	return LWP::Simple::is_success(LWP::Simple::getstore($url, $file));
    }
    else {
	return system(WGET_CMD, "-O", $file, $url) == 0;
    }
}


# download and unpack a distribution
# Returns the full pathname of the extracted directory
# (eg '/tmp/XYZ/Foo_bar-1.23')

# cache_dir: where to dowenload the .tar.gz file to
# untar_dir: where to untar or unzup the file 
# module:    name of module
# dist:      name of the distribution

sub get_distribution {
    my ($cache_dir, $untar_dir, $module, $dist) = @_;

    $dist =~ m{.+/([^/]+)$}
	or die "ERROR: $module: invalid DISTRIBUTION name (no AUTHOR/ prefix): $dist\n";
    my $filename = $1;

    my $download_dir = $cache_dir || File::Temp::tempdir( CLEANUP => 1 );
    my $download_file = File::Spec->catfile($download_dir, $filename);

    # download distribution

    if (-f $download_file and ! -s $download_file ) {
	# wget can leave a zero-length file on failed download
	unlink $download_file;
    }

    unless (-f $download_file) {
	# not cached
	$dist =~ /^([A-Z])([A-Z])/
	    or die "ERROR: $module: invalid DISTRIBUTION name (not /^[A-Z]{2}/): $dist\n";

	my $url = "http://www.cpan.org/modules/by-authors/id/$1/$1$2/$dist";
	my_getstore($url, $download_file)
	    or die "ERROR: Could not fetch '$url'\n";
    }

    # extract distribution

    my $ae = Archive::Extract->new( archive => $download_file);
    $ae->extract( to => $untar_dir )
	or die "ERROR: failed to extract distribution '$download_file to temp. dir: " . $ae->error() . "\n";

    # get the name of the extracted distribution dir

    my $path = File::Spec->catfile($untar_dir, $filename);

    $path =~ s/\.tar\.gz$// or
    $path =~ s/\.zip$// or
      die "ERROR: downloaded file does not have a recognised suffix: $path\n";

    die "ERROR: Extracted tarball does not appear as $path\n" unless -d $path;

    return $path;
}


# produce the diff of a single file
sub file_diff {
    my $outfh     = shift;
    my $cpan_file = shift;
    my $perl_file = shift;
    my $reverse   = shift;
    my $diff_opts = shift;


    my @cmd = (DIFF_CMD, split ' ', $diff_opts);
    if ($reverse) {
	push @cmd, $perl_file, $cpan_file;
    }
    else {
	push @cmd, $cpan_file, $perl_file;
    }
    my $result = `@cmd`;

    $result =~ s{^(--- |\+\+\+ )/tmp/[^/]+/}{$1}gm;

    print $outfh $result;
}


run();