#!/usr/bin/perl -w

use Git;
my $git = Git->repository();

sub add_remote_config {
        my ($hash, $name, $what, $value) = @_;
        if ($what eq 'url') {
                if (exists $hash->{$name}{'URL'}) {
                        print STDERR "Warning: more than one remote.$name.url\n";
                }
                $hash->{$name}{'URL'} = $value;
        }
        elsif ($what eq 'fetch') {
                $hash->{$name}{'FETCH'} ||= [];
                push @{$hash->{$name}{'FETCH'}}, $value;
        }
        if (!exists $hash->{$name}{'SOURCE'}) {
                $hash->{$name}{'SOURCE'} = 'config';
        }
}

sub add_remote_remotes {
        my ($hash, $file, $name) = @_;

        if (exists $hash->{$name}) {
                $hash->{$name}{'WARNING'} = 'ignored due to config';
                return;
        }

        my $fh;
        if (!open($fh, '<', $file)) {
                print STDERR "Warning: cannot open $file\n";
                return;
        }
        my $it = { 'SOURCE' => 'remotes' };
        $hash->{$name} = $it;
        while (<$fh>) {
                chomp;
                if (/^URL:\s*(.*)$/) {
                        # Having more than one is Ok -- it is used for push.
                        if (! exists $it->{'URL'}) {
                                $it->{'URL'} = $1;
                        }
                }
                elsif (/^Push:\s*(.*)$/) {
                        ; # later
                }
                elsif (/^Pull:\s*(.*)$/) {
                        $it->{'FETCH'} ||= [];
                        push @{$it->{'FETCH'}}, $1;
                }
                elsif (/^\#/) {
                        ; # ignore
                }
                else {
                        print STDERR "Warning: funny line in $file: $_\n";
                }
        }
        close($fh);
}

sub list_remote {
        my ($git) = @_;
        my %seen = ();
        my @remotes = eval {
                $git->command(qw(config --get-regexp), '^remote\.');
        };
        for (@remotes) {
                if (/^remote\.([^.]*)\.(\S*)\s+(.*)$/) {
                        add_remote_config(\%seen, $1, $2, $3);
                }
        }

        my $dir = $git->repo_path() . "/remotes";
        if (opendir(my $dh, $dir)) {
                local $_;
                while ($_ = readdir($dh)) {
                        chomp;
                        next if (! -f "$dir/$_" || ! -r _);
                        add_remote_remotes(\%seen, "$dir/$_", $_);
                }
        }

        return \%seen;
}

sub add_branch_config {
        my ($hash, $name, $what, $value) = @_;
        if ($what eq 'remote') {
                if (exists $hash->{$name}{'REMOTE'}) {
                        print STDERR "Warning: more than one branch.$name.remote\n";
                }
                $hash->{$name}{'REMOTE'} = $value;
        }
        elsif ($what eq 'merge') {
                $hash->{$name}{'MERGE'} ||= [];
                push @{$hash->{$name}{'MERGE'}}, $value;
        }
}

sub list_branch {
        my ($git) = @_;
        my %seen = ();
        my @branches = eval {
                $git->command(qw(config --get-regexp), '^branch\.');
        };
        for (@branches) {
                if (/^branch\.([^.]*)\.(\S*)\s+(.*)$/) {
                        add_branch_config(\%seen, $1, $2, $3);
                }
        }

        return \%seen;
}

my $remote = list_remote($git);
my $branch = list_branch($git);

sub update_ls_remote {
        my ($harder, $info) = @_;

        return if (($harder == 0) ||
                   (($harder == 1) && exists $info->{'LS_REMOTE'}));

        my @ref = map {
                s|^[0-9a-f]{40}\s+refs/heads/||;
                $_;
        } $git->command(qw(ls-remote --heads), $info->{'URL'});
        $info->{'LS_REMOTE'} = \@ref;
}

sub list_wildcard_mapping {
        my ($forced, $ours, $ls) = @_;
        my %refs;
        for (@$ls) {
                $refs{$_} = 01; # bit #0 to say "they have"
        }
        for ($git->command('for-each-ref', "refs/remotes/$ours")) {
                chomp;
                next unless (s|^[0-9a-f]{40}\s[a-z]+\srefs/remotes/$ours/||);
                next if ($_ eq 'HEAD');
                $refs{$_} ||= 0;
                $refs{$_} |= 02; # bit #1 to say "we have"
        }
        my (@new, @stale, @tracked);
        for (sort keys %refs) {
                my $have = $refs{$_};
                if ($have == 1) {
                        push @new, $_;
                }
                elsif ($have == 2) {
                        push @stale, $_;
                }
                elsif ($have == 3) {
                        push @tracked, $_;
                }
        }
        return \@new, \@stale, \@tracked;
}

sub list_mapping {
        my ($name, $info) = @_;
        my $fetch = $info->{'FETCH'};
        my $ls = $info->{'LS_REMOTE'};
        my (@new, @stale, @tracked);

        for (@$fetch) {
                next unless (/(\+)?([^:]+):(.*)/);
                my ($forced, $theirs, $ours) = ($1, $2, $3);
                if ($theirs eq 'refs/heads/*' &&
                    $ours =~ /^refs\/remotes\/(.*)\/\*$/) {
                        # wildcard mapping
                        my ($w_new, $w_stale, $w_tracked)
                                = list_wildcard_mapping($forced, $1, $ls);
                        push @new, @$w_new;
                        push @stale, @$w_stale;
                        push @tracked, @$w_tracked;
                }
                elsif ($theirs =~ /\*/ || $ours =~ /\*/) {
                        print STDERR "Warning: unrecognized mapping in remotes.$name.fetch: $_\n";
                }
                elsif ($theirs =~ s|^refs/heads/||) {
                        if (!grep { $_ eq $theirs } @$ls) {
                                push @stale, $theirs;
                        }
                        elsif ($ours ne '') {
                                push @tracked, $theirs;
                        }
                }
        }
        return \@new, \@stale, \@tracked;
}

sub show_mapping {
        my ($name, $info) = @_;
        my ($new, $stale, $tracked) = list_mapping($name, $info);
        if (@$new) {
                print "  New remote branches (next fetch will store in remotes/$name)\n";
                print "    @$new\n";
        }
        if (@$stale) {
                print "  Stale tracking branches in remotes/$name (you'd better remove them)\n";
                print "    @$stale\n";
        }
        if (@$tracked) {
                print "  Tracked remote branches\n";
                print "    @$tracked\n";
        }
}

sub show_remote {
        my ($name, $ls_remote) = @_;
        if (!exists $remote->{$name}) {
                print STDERR "No such remote $name\n";
                return;
        }
        my $info = $remote->{$name};
        update_ls_remote($ls_remote, $info);

        print "* remote $name\n";
        print "  URL: $info->{'URL'}\n";
        for my $branchname (sort keys %$branch) {
                next if ($branch->{$branchname}{'REMOTE'} ne $name);
                my @merged = map {
                        s|^refs/heads/||;
                        $_;
                } split(' ',"@{$branch->{$branchname}{'MERGE'}}");
                next unless (@merged);
                print "  Remote branch(es) merged with 'git pull' while on branch $branchname\n";
                print "    @merged\n";
        }
        if ($info->{'LS_REMOTE'}) {
                show_mapping($name, $info);
        }
}

sub add_remote {
        my ($name, $url) = @_;
        if (exists $remote->{$name}) {
                print STDERR "remote $name already exists.\n";
                exit(1);
        }
        $git->command('config', "remote.$name.url", $url);
        $git->command('config', "remote.$name.fetch",
                      "+refs/heads/*:refs/remotes/$name/*");
}

if (!@ARGV) {
        for (sort keys %$remote) {
                print "$_\n";
        }
}
elsif ($ARGV[0] eq 'show') {
        my $ls_remote = 1;
        my $i;
        for ($i = 1; $i < @ARGV; $i++) {
                if ($ARGV[$i] eq '-n') {
                        $ls_remote = 0;
                }
                else {
                        last;
                }
        }
        if ($i >= @ARGV) {
                print STDERR "Usage: git remote show <remote>\n";
                exit(1);
        }
        for (; $i < @ARGV; $i++) {
                show_remote($ARGV[$i], $ls_remote);
        }
}
elsif ($ARGV[0] eq 'add') {
        if (@ARGV != 3) {
                print STDERR "Usage: git remote add <name> <url>\n";
                exit(1);
        }
        add_remote($ARGV[1], $ARGV[2]);
}
else {
        print STDERR "Usage: git remote\n";
        print STDERR "       git remote add <name> <url>\n";
        print STDERR "       git remote show <name>\n";
        exit(1);
}