#!/usr/bin/perl
# These two should go upon release to make the script Perl 5.005 compatible
use strict;
use warnings;

=head1 NAME

make_patchnum.pl - make patchnum

=head1 SYNOPSIS

  miniperl make_patchnum.pl

  perl make_patchnum.pl

=head1 DESCRITPTION

This program creates the files holding the information
about locally applied patches to the source code. The created
files are  C<git_version.h> and C<lib/Config_git.pl>.

=item C<lib/Config_git.pl>

Contains status information from git in a form meant to be processed
by the tied hash logic of Config.pm. It is actually optional,
although -V will look strange without it.

C<git_version.h> contains similar information in a C header file
format, designed to be used by patchlevel.h. This file is obtained
from stock_git_version.h if miniperl is not available, and then
later on replaced by the version created by this script.

=head1 AUTHOR

Yves Orton, Kenichi Ishigaki, Max Maischein

=head1 COPYRIGHT

Same terms as Perl itself.

=cut

BEGIN {
    my $root=".";
    while (!-e "$root/perl.c" and length($root)<100) {
        if ($root eq '.') {
            $root="..";
        } else {
            $root.="/..";
        }
    }
    die "Can't find toplevel" if !-e "$root/perl.c";
    sub path_to { "$root/$_[0]" } # use $_[0] if this'd be placed in toplevel.
}

sub read_file {
    my $file = path_to(@_);
    return "" unless -e $file;
    open my $fh, '<', $file
        or die "Failed to open for read '$file':$!";
    return do { local $/; <$fh> };
}

sub write_file {
    my ($file, $content) = @_;
    $file= path_to($file);
    open my $fh, '>', $file
        or die "Failed to open for write '$file':$!";
    print $fh $content;
    close $fh;
}

sub backtick {
    my $command = shift;
    if (wantarray) {
        my @result= `$command`;
        chomp @result;
        return @result;
    } else {
        my $result= `$command`;
        $result="" if ! defined $result;
        chomp $result;
        return $result;
    }
}

sub write_files {
    my %content= map { /WARNING: '([^']+)'/ || die "Bad mojo!"; $1 => $_ } @_;
    my @files= sort keys %content;
    my $files= join " and ", map { "'$_'" } @files;
    foreach my $file (@files) {
        if (read_file($file) ne $content{$file}) {
            print "Updating $files\n";
            write_file($_,$content{$_}) for @files;
            return 1;
        }
    }
    print "Reusing $files\n";
    return 0;
}

my $unpushed_commits = '/*no-op*/';
my ($read, $branch, $snapshot_created, $commit_id, $describe)= ("") x 5;
my ($changed, $extra_info, $commit_title, $new_patchnum, $status)= ("") x 5;
if (my $patch_file= read_file(".patch")) {
    ($branch, $snapshot_created, $commit_id, $describe) = split /\s+/, $patch_file;
    $extra_info = "git_snapshot_date='$snapshot_created'";
    $commit_title = "Snapshot of:";
}
elsif (-d path_to('.git')) {
    # git branch | awk 'BEGIN{ORS=""} /\*/ { print $2 }'
    ($branch) = map { /\* ([^(]\S*)/ ? $1 : () } backtick('git branch');
    my ($remote,$merge);
    if (length $branch) {
        $merge= backtick("git config branch.$branch.merge");
        $merge =~ s!^refs/heads/!!;
        $remote= backtick("git config branch.$branch.remote");
    }
    $commit_id = backtick("git rev-parse HEAD");
    $describe = backtick("git describe");
    my $commit_created = backtick(qq{git log -1 --pretty="format:%ci"});
    $new_patchnum = "describe: $describe";
    $extra_info = "git_commit_date='$commit_created'";
    if (length $branch && length $remote) {
        # git cherry $remote/$branch | awk 'BEGIN{ORS=","} /\+/ {print $2}' | sed -e 's/,$//'
        my $unpushed_commit_list =
            join ",", map { (split /\s/, $_)[1] }
            grep {/\+/} backtick("git cherry $remote/$merge");
        # git cherry $remote/$branch | awk 'BEGIN{ORS="\t\\\\\n"} /\+/ {print ",\"" $2 "\""}'
        $unpushed_commits =
            join "", map { ',"'.(split /\s/, $_)[1]."\"\t\\\n" }
            grep {/\+/} backtick("git cherry $remote/$merge");
        if (length $unpushed_commits) {
            $commit_title = "Local Commit:";
            my $ancestor = backtick("git rev-parse $remote/$merge");
            $extra_info = "$extra_info
git_ancestor='$ancestor'
git_remote_branch='$remote/$merge'
git_unpushed='$unpushed_commit_list'";
        }
    }
    if ($changed) {
        $changed = 'true';
        $commit_title =  "Derived from:";
        $status='"uncommitted-changes"'
    } else {
        $status='/*clean-working-directory*/'
    }
    $commit_title ||= "Commit id:";
}

# we extract the filename out of the warning header, so dont mess with that
exit(write_files(<<"EOF_HEADER", <<"EOF_CONFIG"));
/**************************************************************************
* WARNING: 'git_version.h' is automatically generated by make_patchnum.pl
*          DO NOT EDIT DIRECTLY - edit make_patchnum.pl instead
***************************************************************************/
#define PERL_GIT_UNCOMMITTED_CHANGES $status
#define PERL_PATCHNUM "$describe"
#define PERL_GIT_UNPUSHED_COMMITS\t\t\\
$unpushed_commits/*leave-this-comment*/
EOF_HEADER
######################################################################
# WARNING: 'lib/Config_git.pl' is generated by make_patchnum.pl
#          DO NOT EDIT DIRECTLY - edit make_patchnum.pl instead
######################################################################
\$Config::Git_Data=<<'ENDOFGIT';
git_commit_id='$commit_id'
git_describe='$describe'
git_branch='$branch'
git_uncommitted_changes='$changed'
git_commit_id_title='$commit_title'
$extra_info
ENDOFGIT
EOF_CONFIG
# ex: set ts=8 sts=4 sw=4 et ft=perl: