#!/usr/bin/env perl
# Copyright (C) 2006, Eric Wong <normalperson@yhbt.net>
# License: GPL v2 or later
use warnings;
use strict;
use vars qw/    $AUTHOR $VERSION
                $sha1 $sha1_short $_revision
                $_q $_authors %users/;
$AUTHOR = 'Eric Wong <normalperson@yhbt.net>';
$VERSION = '@@GIT_VERSION@@';

$ENV{GIT_DIR} ||= '.git';
$Git::SVN::default_repo_id = 'git-svn';
$Git::SVN::default_ref_id = $ENV{GIT_SVN_ID} || 'git-svn';

$Git::SVN::Log::TZ = $ENV{TZ};
$ENV{TZ} = 'UTC';
$| = 1; # unbuffer STDOUT

sub fatal (@) { print STDERR @_; exit 1 }
require SVN::Core; # use()-ing this causes segfaults for me... *shrug*
require SVN::Ra;
require SVN::Delta;
if ($SVN::Core::VERSION lt '1.1.0') {
        fatal "Need SVN::Core 1.1.0 or better (got $SVN::Core::VERSION)\n";
}
push @Git::SVN::Ra::ISA, 'SVN::Ra';
push @SVN::Git::Editor::ISA, 'SVN::Delta::Editor';
push @SVN::Git::Fetcher::ISA, 'SVN::Delta::Editor';
use Carp qw/croak/;
use IO::File qw//;
use File::Basename qw/dirname basename/;
use File::Path qw/mkpath/;
use Getopt::Long qw/:config gnu_getopt no_ignore_case auto_abbrev pass_through/;
use IPC::Open3;
use Git;

BEGIN {
        my $s;
        foreach (qw/command command_oneline command_noisy command_output_pipe
                    command_input_pipe command_close_pipe/) {
                $s .= "*SVN::Git::Editor::$_ = *SVN::Git::Fetcher::$_ = ".
                      "*Git::SVN::Migration::$_ = ".
                      "*Git::SVN::Log::$_ = *Git::SVN::$_ = *$_ = *Git::$_; ";
        }
        eval $s;
}

my ($SVN);

my $_optimize_commits = 1 unless $ENV{GIT_SVN_NO_OPTIMIZE_COMMITS};
$sha1 = qr/[a-f\d]{40}/;
$sha1_short = qr/[a-f\d]{4,40}/;
my ($_stdin, $_help, $_edit,
        $_repack, $_repack_nr, $_repack_flags,
        $_message, $_file,
        $_template, $_shared,
        $_version,
        $_merge, $_strategy, $_dry_run,
        $_prefix);

my %remote_opts = ( 'username=s' => \$Git::SVN::Prompt::_username,
                    'config-dir=s' => \$Git::SVN::Ra::config_dir,
                    'no-auth-cache' => \$Git::SVN::Prompt::_no_auth_cache );
my %fc_opts = ( 'follow-parent|follow' => \$Git::SVN::_follow_parent,
                'authors-file|A=s' => \$_authors,
                'repack:i' => \$_repack,
                'no-metadata' => \$Git::SVN::_no_metadata,
                'quiet|q' => \$_q,
                'repack-flags|repack-args|repack-opts=s' => \$_repack_flags,
                %remote_opts );

my ($_trunk, $_tags, $_branches);
my %multi_opts = ( 'trunk|T=s' => \$_trunk,
                'tags|t=s' => \$_tags,
                'branches|b=s' => \$_branches );
my %init_opts = ( 'template=s' => \$_template, 'shared' => \$_shared );
my %cmt_opts = ( 'edit|e' => \$_edit,
                'rmdir' => \$SVN::Git::Editor::_rmdir,
                'find-copies-harder' => \$SVN::Git::Editor::_find_copies_harder,
                'l=i' => \$SVN::Git::Editor::_rename_limit,
                'copy-similarity|C=i'=> \$SVN::Git::Editor::_cp_similarity
);

my %cmd = (
        fetch => [ \&cmd_fetch, "Download new revisions from SVN",
                        { 'revision|r=s' => \$_revision, %fc_opts } ],
        init => [ \&cmd_init, "Initialize a repo for tracking" .
                          " (requires URL argument)",
                          \%init_opts ],
        dcommit => [ \&cmd_dcommit,
                     'Commit several diffs to merge with upstream',
                        { 'merge|m|M' => \$_merge,
                          'strategy|s=s' => \$_strategy,
                          'dry-run|n' => \$_dry_run,
                        %cmt_opts, %fc_opts } ],
        'set-tree' => [ \&cmd_set_tree,
                        "Set an SVN repository to a git tree-ish",
                        { 'stdin|' => \$_stdin, %cmt_opts, %fc_opts, } ],
        'show-ignore' => [ \&cmd_show_ignore, "Show svn:ignore listings",
                        { 'revision|r=i' => \$_revision } ],
        'multi-init' => [ \&cmd_multi_init,
                        'Initialize multiple trees (like git-svnimport)',
                        { %multi_opts, %init_opts, %remote_opts,
                         'revision|r=i' => \$_revision,
                         'prefix=s' => \$_prefix,
                        } ],
        'multi-fetch' => [ \&cmd_multi_fetch,
                        'Fetch multiple trees (like git-svnimport)',
                        \%fc_opts ],
        'migrate' => [ sub { },
                       # no-op, we automatically run this anyways,
                       'Migrate configuration/metadata/layout from
                        previous versions of git-svn',
                        \%remote_opts ],
        'log' => [ \&Git::SVN::Log::cmd_show_log, 'Show commit logs',
                        { 'limit=i' => \$Git::SVN::Log::limit,
                          'revision|r=s' => \$_revision,
                          'verbose|v' => \$Git::SVN::Log::verbose,
                          'incremental' => \$Git::SVN::Log::incremental,
                          'oneline' => \$Git::SVN::Log::oneline,
                          'show-commit' => \$Git::SVN::Log::show_commit,
                          'non-recursive' => \$Git::SVN::Log::non_recursive,
                          'authors-file|A=s' => \$_authors,
                          'color' => \$Git::SVN::Log::color,
                          'pager=s' => \$Git::SVN::Log::pager,
                        } ],
        'commit-diff' => [ \&cmd_commit_diff,
                           'Commit a diff between two trees',
                        { 'message|m=s' => \$_message,
                          'file|F=s' => \$_file,
                          'revision|r=s' => \$_revision,
                        %cmt_opts } ],
);

my $cmd;
for (my $i = 0; $i < @ARGV; $i++) {
        if (defined $cmd{$ARGV[$i]}) {
                $cmd = $ARGV[$i];
                splice @ARGV, $i, 1;
                last;
        }
};

my %opts = %{$cmd{$cmd}->[2]} if (defined $cmd);

read_repo_config(\%opts);
my $rv = GetOptions(%opts, 'help|H|h' => \$_help, 'version|V' => \$_version,
                    'minimize-connections' => \$Git::SVN::Migration::_minimize,
                    'id|i=s' => \$Git::SVN::default_ref_id,
                    'svn-remote|remote|R=s' => \$Git::SVN::default_repo_id);
exit 1 if (!$rv && $cmd ne 'log');

usage(0) if $_help;
version() if $_version;
usage(1) unless defined $cmd;
load_authors() if $_authors;
unless ($cmd =~ /^(?:init|multi-init|commit-diff)$/) {
        Git::SVN::Migration::migration_check();
}
eval {
        Git::SVN::verify_remotes_sanity();
        $cmd{$cmd}->[0]->(@ARGV);
};
fatal $@ if $@;
exit 0;

####################### primary functions ######################
sub usage {
        my $exit = shift || 0;
        my $fd = $exit ? \*STDERR : \*STDOUT;
        print $fd <<"";
git-svn - bidirectional operations between a single Subversion tree and git
Usage: $0 <command> [options] [arguments]\n

        print $fd "Available commands:\n" unless $cmd;

        foreach (sort keys %cmd) {
                next if $cmd && $cmd ne $_;
                print $fd '  ',pack('A17',$_),$cmd{$_}->[1],"\n";
                foreach (keys %{$cmd{$_}->[2]}) {
                        # prints out arguments as they should be passed:
                        my $x = s#[:=]s$## ? '<arg>' : s#[:=]i$## ? '<num>' : '';
                        print $fd ' ' x 21, join(', ', map { length $_ > 1 ?
                                                        "--$_" : "-$_" }
                                                split /\|/,$_)," $x\n";
                }
        }
        print $fd <<"";
\nGIT_SVN_ID may be set in the environment or via the --id/-i switch to an
arbitrary identifier if you're tracking multiple SVN branches/repositories in
one git repository and want to keep them separate.  See git-svn(1) for more
information.

        exit $exit;
}

sub version {
        print "git-svn version $VERSION (svn $SVN::Core::VERSION)\n";
        exit 0;
}

sub do_git_init_db {
        unless (-d $ENV{GIT_DIR}) {
                my @init_db = ('init');
                push @init_db, "--template=$_template" if defined $_template;
                push @init_db, "--shared" if defined $_shared;
                command_noisy(@init_db);
        }
}

sub cmd_init {
        my $url = shift or die "SVN repository location required " .
                                "as a command-line argument\n";
        if (my $repo_path = shift) {
                unless (-d $repo_path) {
                        mkpath([$repo_path]);
                }
                chdir $repo_path or croak $!;
                $ENV{GIT_DIR} = $repo_path . "/.git";
        }
        do_git_init_db();

        Git::SVN->init($url);
}

sub cmd_fetch {
        if (@_) {
                die "Additional fetch arguments are no longer supported.\n",
                    "Use --follow-parent if you have moved/copied directories
                    instead.\n";
        }
        my $gs = Git::SVN->new;
        $gs->fetch(parse_revision_argument());
        if ($gs->{last_commit} && !verify_ref('refs/heads/master^0')) {
                command_noisy(qw(update-ref refs/heads/master),
                              $gs->{last_commit});
        }
}

sub cmd_set_tree {
        my (@commits) = @_;
        if ($_stdin || !@commits) {
                print "Reading from stdin...\n";
                @commits = ();
                while (<STDIN>) {
                        if (/\b($sha1_short)\b/o) {
                                unshift @commits, $1;
                        }
                }
        }
        my @revs;
        foreach my $c (@commits) {
                my @tmp = command('rev-parse',$c);
                if (scalar @tmp == 1) {
                        push @revs, $tmp[0];
                } elsif (scalar @tmp > 1) {
                        push @revs, reverse(command('rev-list',@tmp));
                } else {
                        fatal "Failed to rev-parse $c\n";
                }
        }
        my $gs = Git::SVN->new;
        my ($r_last, $cmt_last) = $gs->last_rev_commit;
        $gs->fetch;
        if (defined $gs->{last_rev} && $r_last != $gs->{last_rev}) {
                fatal "There are new revisions that were fetched ",
                      "and need to be merged (or acknowledged) ",
                      "before committing.\nlast rev: $r_last\n",
                      " current: $gs->{last_rev}\n";
        }
        $gs->set_tree($_) foreach @revs;
        print "Done committing ",scalar @revs," revisions to SVN\n";
}

sub cmd_dcommit {
        my $head = shift;
        my $gs = Git::SVN->new;
        $head ||= 'HEAD';
        my @refs = command(qw/rev-list --no-merges/, $gs->refname."..$head");
        my $last_rev;
        foreach my $d (reverse @refs) {
                if (!verify_ref("$d~1")) {
                        fatal "Commit $d\n",
                              "has no parent commit, and therefore ",
                              "nothing to diff against.\n",
                              "You should be working from a repository ",
                              "originally created by git-svn\n";
                }
                unless (defined $last_rev) {
                        (undef, $last_rev, undef) = cmt_metadata("$d~1");
                        unless (defined $last_rev) {
                                fatal "Unable to extract revision information ",
                                      "from commit $d~1\n";
                        }
                }
                if ($_dry_run) {
                        print "diff-tree $d~1 $d\n";
                } else {
                        my %ed_opts = ( r => $last_rev,
                                        log => get_commit_entry($d)->{log},
                                        ra => $gs->ra,
                                        tree_a => "$d~1",
                                        tree_b => $d,
                                        editor_cb => sub {
                                               print "Committed r$_[0]\n";
                                               $last_rev = $_[0]; },
                                        svn_path => $gs->{path} );
                        if (!SVN::Git::Editor->new(\%ed_opts)->apply_diff) {
                                print "No changes\n$d~1 == $d\n";
                        }
                }
        }
        return if $_dry_run;
        $gs->fetch;
        # we always want to rebase against the current HEAD, not any
        # head that was passed to us
        my @diff = command('diff-tree', 'HEAD', $gs->refname, '--');
        my @finish;
        if (@diff) {
                @finish = qw/rebase/;
                push @finish, qw/--merge/ if $_merge;
                push @finish, "--strategy=$_strategy" if $_strategy;
                print STDERR "W: HEAD and ", $gs->refname, " differ, ",
                             "using @finish:\n", "@diff";
        } else {
                print "No changes between current HEAD and ",
                      $gs->refname, "\nResetting to the latest ",
                      $gs->refname, "\n";
                @finish = qw/reset --mixed/;
        }
        command_noisy(@finish, $gs->refname);
}

sub cmd_show_ignore {
        my $gs = Git::SVN->new;
        my $r = (defined $_revision ? $_revision : $gs->ra->get_latest_revnum);
        $gs->traverse_ignore(\*STDOUT, '', $r);
}

sub cmd_multi_init {
        my $url = shift;
        unless (defined $_trunk || defined $_branches || defined $_tags) {
                usage(1);
        }
        do_git_init_db();
        $_prefix = '' unless defined $_prefix;
        $url =~ s#/+$## if defined $url;
        if (defined $_trunk) {
                my $trunk_ref = $_prefix . 'trunk';
                # try both old-style and new-style lookups:
                my $gs_trunk = eval { Git::SVN->new($trunk_ref) };
                unless ($gs_trunk) {
                        my ($trunk_url, $trunk_path) =
                                              complete_svn_url($url, $_trunk);
                        $gs_trunk = Git::SVN->init($trunk_url, $trunk_path,
                                                   undef, $trunk_ref);
                }
        }
        return unless defined $_branches || defined $_tags;
        my $ra = $url ? Git::SVN::Ra->new($url) : undef;
        complete_url_ls_init($ra, $_branches, '--branches/-b', $_prefix);
        complete_url_ls_init($ra, $_tags, '--tags/-t', $_prefix . 'tags/');
}

sub cmd_multi_fetch {
        my $remotes = Git::SVN::read_all_remotes();
        foreach my $repo_id (sort keys %$remotes) {
                my $url = $remotes->{$repo_id}->{url} or next;
                my $fetch = $remotes->{$repo_id}->{fetch} or next;
                Git::SVN::fetch_all($repo_id, $url, $fetch);
        }
}

# this command is special because it requires no metadata
sub cmd_commit_diff {
        my ($ta, $tb, $url) = @_;
        my $usage = "Usage: $0 commit-diff -r<revision> ".
                    "<tree-ish> <tree-ish> [<URL>]\n";
        fatal($usage) if (!defined $ta || !defined $tb);
        my $svn_path;
        if (!defined $url) {
                my $gs = eval { Git::SVN->new };
                if (!$gs) {
                        fatal("Needed URL or usable git-svn --id in ",
                              "the command-line\n", $usage);
                }
                $url = $gs->{url};
                $svn_path = $gs->{path};
        }
        unless (defined $_revision) {
                fatal("-r|--revision is a required argument\n", $usage);
        }
        if (defined $_message && defined $_file) {
                fatal("Both --message/-m and --file/-F specified ",
                      "for the commit message.\n",
                      "I have no idea what you mean\n");
        }
        if (defined $_file) {
                $_message = file_to_s($_file);
        } else {
                $_message ||= get_commit_entry($tb)->{log};
        }
        my $ra ||= Git::SVN::Ra->new($url);
        $svn_path ||= $ra->{svn_path};
        my $r = $_revision;
        if ($r eq 'HEAD') {
                $r = $ra->get_latest_revnum;
        } elsif ($r !~ /^\d+$/) {
                die "revision argument: $r not understood by git-svn\n";
        }
        my %ed_opts = ( r => $r,
                        log => $_message,
                        ra => $ra,
                        tree_a => $ta,
                        tree_b => $tb,
                        editor_cb => sub { print "Committed r$_[0]\n" },
                        svn_path => $svn_path );
        if (!SVN::Git::Editor->new(\%ed_opts)->apply_diff) {
                print "No changes\n$ta == $tb\n";
        }
}

########################### utility functions #########################

sub parse_revision_argument {
        if (!defined $_revision || $_revision eq 'BASE:HEAD') {
                return (undef, undef);
        }
        return ($1, $2) if ($_revision =~ /^(\d+):(\d+)$/);
        return ($_revision, $_revision) if ($_revision =~ /^\d+$/);
        return (undef, $1) if ($_revision =~ /^BASE:(\d+)$/);
        return ($1, undef) if ($_revision =~ /^(\d+):HEAD$/);
        die "revision argument: $_revision not understood by git-svn\n",
            "Try using the command-line svn client instead\n";
}

sub complete_svn_url {
        my ($url, $path) = @_;
        $path =~ s#/+$##;
        if ($path !~ m#^[a-z\+]+://#) {
                if (!defined $url || $url !~ m#^[a-z\+]+://#) {
                        fatal("E: '$path' is not a complete URL ",
                              "and a separate URL is not specified\n");
                }
                return ($url, $path);
        }
        return ($path, '');
}

sub complete_url_ls_init {
        my ($ra, $repo_path, $switch, $pfx) = @_;
        unless ($repo_path) {
                print STDERR "W: $switch not specified\n";
                return;
        }
        $repo_path =~ s#/+$##;
        if ($repo_path =~ m#^[a-z\+]+://#) {
                $ra = Git::SVN::Ra->new($repo_path);
                $repo_path = '';
        } else {
                $repo_path =~ s#^/+##;
                unless ($ra) {
                        fatal("E: '$repo_path' is not a complete URL ",
                              "and a separate URL is not specified\n");
                }
        }
        my $r = defined $_revision ? $_revision : $ra->get_latest_revnum;
        my ($dirent, undef, undef) = $ra->get_dir($repo_path, $r);
        my $url = $ra->{url};
        foreach my $d (sort keys %$dirent) {
                next if ($dirent->{$d}->kind != $SVN::Node::dir);
                my $path =  "$repo_path/$d";
                my $ref = "$pfx$d";
                my $gs = eval { Git::SVN->new($ref) };
                # don't try to init already existing refs
                unless ($gs) {
                        print "init $url/$path => $ref\n";
                        Git::SVN->init($url, $path, undef, $ref);
                }
        }
}

sub verify_ref {
        my ($ref) = @_;
        eval { command_oneline([ 'rev-parse', '--verify', $ref ],
                               { STDERR => 0 }); };
}

sub get_tree_from_treeish {
        my ($treeish) = @_;
        # $treeish can be a symbolic ref, too:
        my $type = command_oneline(qw/cat-file -t/, $treeish);
        my $expected;
        while ($type eq 'tag') {
                ($treeish, $type) = command(qw/cat-file tag/, $treeish);
        }
        if ($type eq 'commit') {
                $expected = (grep /^tree /, command(qw/cat-file commit/,
                                                    $treeish))[0];
                ($expected) = ($expected =~ /^tree ($sha1)$/o);
                die "Unable to get tree from $treeish\n" unless $expected;
        } elsif ($type eq 'tree') {
                $expected = $treeish;
        } else {
                die "$treeish is a $type, expected tree, tag or commit\n";
        }
        return $expected;
}

sub get_commit_entry {
        my ($treeish) = shift;
        my %log_entry = ( log => '', tree => get_tree_from_treeish($treeish) );
        my $commit_editmsg = "$ENV{GIT_DIR}/COMMIT_EDITMSG";
        my $commit_msg = "$ENV{GIT_DIR}/COMMIT_MSG";
        open my $log_fh, '>', $commit_editmsg or croak $!;

        my $type = command_oneline(qw/cat-file -t/, $treeish);
        if ($type eq 'commit' || $type eq 'tag') {
                my ($msg_fh, $ctx) = command_output_pipe('cat-file',
                                                         $type, $treeish);
                my $in_msg = 0;
                while (<$msg_fh>) {
                        if (!$in_msg) {
                                $in_msg = 1 if (/^\s*$/);
                        } elsif (/^git-svn-id: /) {
                                # skip this for now, we regenerate the
                                # correct one on re-fetch anyways
                                # TODO: set *:merge properties or like...
                        } else {
                                print $log_fh $_ or croak $!;
                        }
                }
                command_close_pipe($msg_fh, $ctx);
        }
        close $log_fh or croak $!;

        if ($_edit || ($type eq 'tree')) {
                my $editor = $ENV{VISUAL} || $ENV{EDITOR} || 'vi';
                # TODO: strip out spaces, comments, like git-commit.sh
                system($editor, $commit_editmsg);
        }
        rename $commit_editmsg, $commit_msg or croak $!;
        open $log_fh, '<', $commit_msg or croak $!;
        { local $/; chomp($log_entry{log} = <$log_fh>); }
        close $log_fh or croak $!;
        unlink $commit_msg;
        \%log_entry;
}

sub s_to_file {
        my ($str, $file, $mode) = @_;
        open my $fd,'>',$file or croak $!;
        print $fd $str,"\n" or croak $!;
        close $fd or croak $!;
        chmod ($mode &~ umask, $file) if (defined $mode);
}

sub file_to_s {
        my $file = shift;
        open my $fd,'<',$file or croak "$!: file: $file\n";
        local $/;
        my $ret = <$fd>;
        close $fd or croak $!;
        $ret =~ s/\s*$//s;
        return $ret;
}

# '<svn username> = real-name <email address>' mapping based on git-svnimport:
sub load_authors {
        open my $authors, '<', $_authors or die "Can't open $_authors $!\n";
        my $log = $cmd eq 'log';
        while (<$authors>) {
                chomp;
                next unless /^(\S+?|\(no author\))\s*=\s*(.+?)\s*<(.+)>\s*$/;
                my ($user, $name, $email) = ($1, $2, $3);
                if ($log) {
                        $Git::SVN::Log::rusers{"$name <$email>"} = $user;
                } else {
                        $users{$user} = [$name, $email];
                }
        }
        close $authors or croak $!;
}

# convert GetOpt::Long specs for use by git-config
sub read_repo_config {
        return unless -d $ENV{GIT_DIR};
        my $opts = shift;
        foreach my $o (keys %$opts) {
                my $v = $opts->{$o};
                my ($key) = ($o =~ /^([a-z\-]+)/);
                $key =~ s/-//g;
                my $arg = 'git-config';
                $arg .= ' --int' if ($o =~ /[:=]i$/);
                $arg .= ' --bool' if ($o !~ /[:=][sfi]$/);
                if (ref $v eq 'ARRAY') {
                        chomp(my @tmp = `$arg --get-all svn.$key`);
                        @$v = @tmp if @tmp;
                } else {
                        chomp(my $tmp = `$arg --get svn.$key`);
                        if ($tmp && !($arg =~ / --bool/ && $tmp eq 'false')) {
                                $$v = $tmp;
                        }
                }
        }
}

sub extract_metadata {
        my $id = shift or return (undef, undef, undef);
        my ($url, $rev, $uuid) = ($id =~ /^git-svn-id:\s(\S+?)\@(\d+)
                                                        \s([a-f\d\-]+)$/x);
        if (!defined $rev || !$uuid || !$url) {
                # some of the original repositories I made had
                # identifiers like this:
                ($rev, $uuid) = ($id =~/^git-svn-id:\s(\d+)\@([a-f\d\-]+)/);
        }
        return ($url, $rev, $uuid);
}

sub cmt_metadata {
        return extract_metadata((grep(/^git-svn-id: /,
                command(qw/cat-file commit/, shift)))[-1]);
}

package Git::SVN;
use strict;
use warnings;
use vars qw/$default_repo_id $default_ref_id $_no_metadata $_follow_parent/;
use Carp qw/croak/;
use File::Path qw/mkpath/;
use IPC::Open3;

# properties that we do not log:
my %SKIP_PROP;
BEGIN {
        %SKIP_PROP = map { $_ => 1 } qw/svn:wc:ra_dav:version-url
                                        svn:special svn:executable
                                        svn:entry:committed-rev
                                        svn:entry:last-author
                                        svn:entry:uuid
                                        svn:entry:committed-date/;
}

sub fetch_all {
        my ($repo_id, $url, $fetch) = @_;
        my @gs;
        my $ra = Git::SVN::Ra->new($url);
        my $head = $ra->get_latest_revnum;
        my $base = $head;
        my $new_remote;
        foreach my $p (sort keys %$fetch) {
                my $gs = Git::SVN->new($fetch->{$p}, $repo_id, $p);
                my $lr = $gs->last_rev;
                if (defined $lr) {
                        $base = $lr if ($lr < $base);
                } else {
                        $new_remote = 1;
                }
                push @gs, $gs;
        }
        $base = 0 if $new_remote;
        return if (++$base > $head);
        $ra->gs_fetch_loop_common($base, $head, @gs);
}

sub read_all_remotes {
        my $r = {};
        foreach (grep { s/^svn-remote\.// } command(qw/config -l/)) {
                if (m!^(.+)\.fetch=\s*(.*)\s*:\s*refs/remotes/(.+)\s*$!) {
                        $r->{$1}->{fetch}->{$2} = $3;
                } elsif (m!^(.+)\.url=\s*(.*)\s*$!) {
                        $r->{$1}->{url} = $2;
                }
        }
        $r;
}

sub verify_remotes_sanity {
        return unless -d $ENV{GIT_DIR};
        my %seen;
        foreach (command(qw/config -l/)) {
                if (m!^svn-remote\.(?:.+)\.fetch=.*:refs/remotes/(\S+)\s*$!) {
                        if ($seen{$1}) {
                                die "Remote ref refs/remote/$1 is tracked by",
                                    "\n  \"$_\"\nand\n  \"$seen{$1}\"\n",
                                    "Please resolve this ambiguity in ",
                                    "your git configuration file before ",
                                    "continuing\n";
                        }
                        $seen{$1} = $_;
                }
        }
}

# we allow more chars than remotes2config.sh...
sub sanitize_remote_name {
        my ($name) = @_;
        $name =~ tr{A-Za-z0-9:,/+-}{.}c;
        $name;
}

sub find_existing_remote {
        my ($url, $remotes) = @_;
        my $existing;
        foreach my $repo_id (keys %$remotes) {
                my $u = $remotes->{$repo_id}->{url} or next;
                next if $u ne $url;
                $existing = $repo_id;
                last;
        }
        $existing;
}

sub init_remote_config {
        my ($self, $url) = @_;
        $url =~ s!/+$!!; # strip trailing slash
        my $r = read_all_remotes();
        my $existing = find_existing_remote($url, $r);
        if ($existing) {
                print STDERR "Using existing ",
                             "[svn-remote \"$existing\"]\n";
                $self->{repo_id} = $existing;
        } else {
                my $min_url = Git::SVN::Ra->new($url)->minimize_url;
                $existing = find_existing_remote($min_url, $r);
                if ($existing) {
                        print STDERR "Using existing ",
                                     "[svn-remote \"$existing\"]\n";
                        $self->{repo_id} = $existing;
                }
                if ($min_url ne $url) {
                        print STDERR "Using higher level of URL: ",
                                     "$url => $min_url\n";
                        my $old_path = $self->{path};
                        $self->{path} = $url;
                        $self->{path} =~ s!^\Q$min_url\E/*!!;
                        if (length $old_path) {
                                $self->{path} .= "/$old_path";
                        }
                        $url = $min_url;
                }
        }
        my $orig_url;
        if (!$existing) {
                # verify that we aren't overwriting anything:
                $orig_url = eval {
                        command_oneline('config', '--get',
                                        "svn-remote.$self->{repo_id}.url")
                };
                if ($orig_url && ($orig_url ne $url)) {
                        die "svn-remote.$self->{repo_id}.url already set: ",
                            "$orig_url\nwanted to set to: $url\n";
                }
        }
        my ($xrepo_id, $xpath) = find_ref($self->refname);
        if (defined $xpath) {
                die "svn-remote.$xrepo_id.fetch already set to track ",
                    "$xpath:refs/remotes/", $self->refname, "\n";
        }
        command_noisy('config',
                      "svn-remote.$self->{repo_id}.url", $url);
        command_noisy('config', '--add',
                      "svn-remote.$self->{repo_id}.fetch",
                      "$self->{path}:".$self->refname);
        $self->{url} = $url;
}

sub init {
        my ($class, $url, $path, $repo_id, $ref_id) = @_;
        my $self = _new($class, $repo_id, $ref_id, $path);
        if (defined $url) {
                $self->init_remote_config($url);
        }
        $self;
}

sub find_ref {
        my ($ref_id) = @_;
        foreach (command(qw/config -l/)) {
                next unless m!^svn-remote\.(.+)\.fetch=
                              \s*(.*)\s*:\s*refs/remotes/(.+)\s*$!x;
                my ($repo_id, $path, $ref) = ($1, $2, $3);
                if ($ref eq $ref_id) {
                        $path = '' if ($path =~ m#^\./?#);
                        return ($repo_id, $path);
                }
        }
        (undef, undef, undef);
}

sub new {
        my ($class, $ref_id, $repo_id, $path) = @_;
        if (defined $ref_id && !defined $repo_id && !defined $path) {
                ($repo_id, $path) = find_ref($ref_id);
                if (!defined $repo_id) {
                        die "Could not find a \"svn-remote.*.fetch\" key ",
                            "in the repository configuration matching: ",
                            "refs/remotes/$ref_id\n";
                }
        }
        my $self = _new($class, $repo_id, $ref_id, $path);
        if (!defined $self->{path} || !length $self->{path}) {
                my $fetch = command_oneline('config', '--get',
                                            "svn-remote.$repo_id.fetch",
                                            ":refs/remotes/$ref_id\$") or
                     die "Failed to read \"svn-remote.$repo_id.fetch\" ",
                         "\":refs/remotes/$ref_id\$\" in config\n";
                ($self->{path}, undef) = split(/\s*:\s*/, $fetch);
        }
        $self->{url} = command_oneline('config', '--get',
                                       "svn-remote.$repo_id.url") or
                  die "Failed to read \"svn-remote.$repo_id.url\" in config\n";
        if (-z $self->{db_path} && ::verify_ref($self->refname.'^0')) {
                $self->rebuild;
        }
        $self;
}

sub refname { "refs/remotes/$_[0]->{ref_id}" }

sub ra {
        my ($self) = shift;
        Git::SVN::Ra->new($self->{url});
}

sub rel_path {
        my ($self) = @_;
        my $repos_root = $self->ra->{repos_root};
        return $self->{path} if ($self->{url} eq $repos_root);
        my $url = $self->{url} .
                  (length $self->{path} ? "/$self->{path}" : $self->{path});
        $url =~ s!^\Q$repos_root\E/*!!g;
        $url;
}

sub traverse_ignore {
        my ($self, $fh, $path, $r) = @_;
        $path =~ s#^/+##g;
        my $ra = $self->ra;
        my ($dirent, undef, $props) = $ra->get_dir($path, $r);
        my $p = $path;
        $p =~ s#^\Q$ra->{svn_path}\E/##;
        print $fh length $p ? "\n# $p\n" : "\n# /\n";
        if (my $s = $props->{'svn:ignore'}) {
                $s =~ s/[\r\n]+/\n/g;
                chomp $s;
                if (length $p == 0) {
                        $s =~ s#\n#\n/$p#g;
                        print $fh "/$s\n";
                } else {
                        $s =~ s#\n#\n/$p/#g;
                        print $fh "/$p/$s\n";
                }
        }
        foreach (sort keys %$dirent) {
                next if $dirent->{$_}->kind != $SVN::Node::dir;
                $self->traverse_ignore($fh, "$path/$_", $r);
        }
}

sub last_rev { ($_[0]->last_rev_commit)[0] }
sub last_commit { ($_[0]->last_rev_commit)[1] }

# returns the newest SVN revision number and newest commit SHA1
sub last_rev_commit {
        my ($self) = @_;
        if (defined $self->{last_rev} && defined $self->{last_commit}) {
                return ($self->{last_rev}, $self->{last_commit});
        }
        my $c = ::verify_ref($self->refname.'^0');
        if ($c) {
                my $rev = (::cmt_metadata($c))[1];
                if (defined $rev) {
                        ($self->{last_rev}, $self->{last_commit}) = ($rev, $c);
                        return ($rev, $c);
                }
        }
        my $offset = -41; # from tail
        my $rl;
        open my $fh, '<', $self->{db_path} or
                                 croak "$self->{db_path} not readable: $!\n";
        seek $fh, $offset, 2;
        $rl = readline $fh;
        defined $rl or return (undef, undef);
        chomp $rl;
        while ($c ne $rl && tell $fh != 0) {
                $offset -= 41;
                seek $fh, $offset, 2;
                $rl = readline $fh;
                defined $rl or return (undef, undef);
                chomp $rl;
        }
        my $rev = tell $fh;
        croak $! if ($rev < 0);
        $rev =  ($rev - 41) / 41;
        close $fh or croak $!;
        ($self->{last_rev}, $self->{last_commit}) = ($rev, $c);
        return ($rev, $c);
}

sub get_fetch_range {
        my ($self, $min, $max) = @_;
        $max ||= $self->ra->get_latest_revnum;
        $min ||= $self->last_rev || 0;
        (++$min, $max);
}

sub tmp_index_do {
        my ($self, $sub) = @_;
        my $old_index = $ENV{GIT_INDEX_FILE};
        $ENV{GIT_INDEX_FILE} = $self->{index};
        my @ret = &$sub;
        if ($old_index) {
                $ENV{GIT_INDEX_FILE} = $old_index;
        } else {
                delete $ENV{GIT_INDEX_FILE};
        }
        wantarray ? @ret : $ret[0];
}

sub assert_index_clean {
        my ($self, $treeish) = @_;

        $self->tmp_index_do(sub {
                command_noisy('read-tree', $treeish) unless -e $self->{index};
                my $x = command_oneline('write-tree');
                my ($y) = (command(qw/cat-file commit/, $treeish) =~
                           /^tree ($::sha1)/mo);
                if ($y ne $x) {
                        unlink $self->{index} or croak $!;
                        command_noisy('read-tree', $treeish);
                }
                $x = command_oneline('write-tree');
                if ($y ne $x) {
                        ::fatal "trees ($treeish) $y != $x\n",
                                "Something is seriously wrong...\n";
                }
        });
}

sub get_commit_parents {
        my ($self, $log_entry) = @_;
        my (%seen, @ret, @tmp);
        # legacy support for 'set-tree'; this is only used by set_tree_cb:
        if (my $ip = $self->{inject_parents}) {
                if (my $commit = delete $ip->{$log_entry->{revision}}) {
                        push @tmp, $commit;
                }
        }
        if (my $cur = ::verify_ref($self->refname.'^0')) {
                push @tmp, $cur;
        }
        push @tmp, $_ foreach (@{$log_entry->{parents}}, @tmp);
        while (my $p = shift @tmp) {
                next if $seen{$p};
                $seen{$p} = 1;
                push @ret, $p;
                # MAXPARENT is defined to 16 in commit-tree.c:
                last if @ret >= 16;
        }
        if (@tmp) {
                die "r$log_entry->{revision}: No room for parents:\n\t",
                    join("\n\t", @tmp), "\n";
        }
        @ret;
}

sub full_url {
        my ($self) = @_;
        $self->{url} . (length $self->{path} ? '/' . $self->{path} : '');
}

sub do_git_commit {
        my ($self, $log_entry) = @_;
        my $lr = $self->last_rev;
        if (defined $lr && $lr >= $log_entry->{revision}) {
                die "Last fetched revision of ", $self->refname,
                    " was r$lr, but we are about to fetch: ",
                    "r$log_entry->{revision}!\n";
        }
        if (my $c = $self->rev_db_get($log_entry->{revision})) {
                croak "$log_entry->{revision} = $c already exists! ",
                      "Why are we refetching it?\n";
        }
        my $author = $log_entry->{author};
        my ($name, $email) = (defined $::users{$author} ? @{$::users{$author}}
                           : ($author, "$author\@".$self->ra->uuid));
        $ENV{GIT_AUTHOR_NAME} = $ENV{GIT_COMMITTER_NAME} = $name;
        $ENV{GIT_AUTHOR_EMAIL} = $ENV{GIT_COMMITTER_EMAIL} = $email;
        $ENV{GIT_AUTHOR_DATE} = $ENV{GIT_COMMITTER_DATE} = $log_entry->{date};

        my $tree = $log_entry->{tree};
        if (!defined $tree) {
                $tree = $self->tmp_index_do(sub {
                                            command_oneline('write-tree') });
        }
        die "Tree is not a valid sha1: $tree\n" if $tree !~ /^$::sha1$/o;

        my @exec = ('git-commit-tree', $tree);
        foreach ($self->get_commit_parents($log_entry)) {
                push @exec, '-p', $_;
        }
        defined(my $pid = open3(my $msg_fh, my $out_fh, '>&STDERR', @exec))
                                                                   or croak $!;
        print $msg_fh $log_entry->{log} or croak $!;
        unless ($_no_metadata) {
                print $msg_fh "\ngit-svn-id: ", $self->full_url, '@',
                              $log_entry->{revision}, ' ',
                              $self->ra->uuid, "\n" or croak $!;
        }
        $msg_fh->flush == 0 or croak $!;
        close $msg_fh or croak $!;
        chomp(my $commit = do { local $/; <$out_fh> });
        close $out_fh or croak $!;
        waitpid $pid, 0;
        croak $? if $?;
        if ($commit !~ /^$::sha1$/o) {
                die "Failed to commit, invalid sha1: $commit\n";
        }

        command_noisy('update-ref',$self->refname, $commit);
        $self->rev_db_set($log_entry->{revision}, $commit);

        $self->{last_rev} = $log_entry->{revision};
        $self->{last_commit} = $commit;
        print "r$log_entry->{revision} = $commit ($self->{ref_id})\n";
        return $commit;
}

sub revisions_eq {
        my ($self, $r0, $r1) = @_;
        return 1 if $r0 == $r1;
        my $nr = 0;
        $self->ra->get_log([$self->{path}], $r0, $r1,
                           0, 0, 1, sub { $nr++ });
        return 0 if ($nr > 1);
        return 1;
}

sub match_paths {
        my ($self, $paths) = @_;
        return 1 if $paths->{'/'};
        $self->{path_regex} ||= qr/^\/\Q$self->{path}\E\/?/;
        grep /$self->{path_regex}/, keys %$paths and return 1;
        my $c = '';
        foreach (split m#/#, $self->rel_path) {
                $c .= "/$_";
                return 1 if $paths->{$c};
        }
        return 0;
}

sub find_parent_branch {
        my ($self, $paths, $rev) = @_;
        return undef unless $_follow_parent;
        unless (defined $paths) {
                $self->ra->get_log([$self->{path}], $rev, $rev, 0, 1, 1,
                                   sub { $paths = dup_changed_paths($_[0]) });
        }
        return undef unless defined $paths;

        # look for a parent from another branch:
        my @b_path_components = split m#/#, $self->rel_path;
        my @a_path_components;
        my $i;
        while (@b_path_components) {
                $i = $paths->{'/'.join('/', @b_path_components)};
                last if $i;
                unshift(@a_path_components, pop(@b_path_components));
        }
        goto not_found unless defined $i;
        my $branch_from = $i->{copyfrom_path} or goto not_found;
        if (@a_path_components) {
                print STDERR "branch_from: $branch_from => ";
                $branch_from .= '/'.join('/', @a_path_components);
                print STDERR $branch_from, "\n";
        }
        my $r = $i->{copyfrom_rev};
        my $repos_root = $self->ra->{repos_root};
        my $url = $self->ra->{url};
        my $new_url = $repos_root . $branch_from;
        print STDERR  "Found possible branch point: ",
                      "$new_url => ", $self->full_url, ", $r\n";
        $branch_from =~ s#^/##;
        my $remotes = read_all_remotes();
        my $gs;
        foreach my $repo_id (keys %$remotes) {
                my $u = $remotes->{$repo_id}->{url} or next;
                next if $url ne $u;
                my $fetch = $remotes->{$repo_id}->{fetch};
                foreach my $f (keys %$fetch) {
                        next if $f ne $branch_from;
                        $gs = Git::SVN->new($fetch->{$f}, $repo_id, $f);
                        last;
                }
                last if $gs;
        }
        unless ($gs) {
                my $ref_id = $self->{ref_id};
                $ref_id =~ s/\@\d+$//;
                $ref_id .= "\@$r";
                # just grow a tail if we're not unique enough :x
                $ref_id .= '-' while find_ref($ref_id);
                print STDERR "Initializing parent: $ref_id\n";
                $gs = Git::SVN->init($new_url, '', $ref_id, $ref_id);
        }
        my ($r0, $parent) = $gs->find_rev_before($r, 1);
        if ($_follow_parent && (!defined $r0 || !defined $parent)) {
                $gs->fetch(0, $r);
                ($r0, $parent) = $gs->last_rev_commit;
        }
        if (defined $r0 && defined $parent && $gs->revisions_eq($r0, $r)) {
                print STDERR "Found branch parent: ($self->{ref_id}) $parent\n";
                $self->assert_index_clean($parent);
                my $ed;
                if ($self->ra->can_do_switch) {
                        print STDERR "Following parent with do_switch\n";
                        # do_switch works with svn/trunk >= r22312, but that
                        # is not included with SVN 1.4.3 (the latest version
                        # at the moment), so we can't rely on it
                        $self->{last_commit} = $parent;
                        $ed = SVN::Git::Fetcher->new($self);
                        $gs->ra->gs_do_switch($r0, $rev, $gs,
                                              $self->full_url, $ed)
                          or die "SVN connection failed somewhere...\n";
                } else {
                        print STDERR "Following parent with do_update\n";
                        $ed = SVN::Git::Fetcher->new($self);
                        $self->ra->gs_do_update($rev, $rev, $self, $ed)
                          or die "SVN connection failed somewhere...\n";
                }
                print STDERR "Successfully followed parent\n";
                $ed->{new_fetch} = 1;
                return $self->make_log_entry($rev, [$parent], $ed);
        }
not_found:
        print STDERR "Branch parent for path: '/",
                     $self->rel_path, "' @ r$rev not found:\n";
        return undef unless $paths;
        print STDERR "Changed paths:\n";
        foreach my $x (sort keys %$paths) {
                my $p = $paths->{$x};
                print STDERR "\t$p->{action}\t$x";
                if ($p->{copyfrom_path}) {
                        print STDERR "(from $p->{copyfrom_path}: ",
                                     "$p->{copyfrom_rev})";
                }
                print STDERR "\n";
        }
        print STDERR '-'x72, "\n";
        return undef;
}

sub do_fetch {
        my ($self, $paths, $rev) = @_;
        my $ed;
        my ($last_rev, @parents);
        if ($self->{last_commit}) {
                $ed = SVN::Git::Fetcher->new($self);
                $last_rev = $self->{last_rev};
                $ed->{c} = $self->{last_commit};
                @parents = ($self->{last_commit});
        } else {
                $last_rev = $rev;
                if (my $log_entry = $self->find_parent_branch($paths, $rev)) {
                        return $log_entry;
                }
                $ed = SVN::Git::Fetcher->new($self);
                $ed->{new_fetch} = 1;
        }
        unless ($self->ra->gs_do_update($last_rev, $rev, $self, $ed)) {
                die "SVN connection failed somewhere...\n";
        }
        $self->make_log_entry($rev, \@parents, $ed);
}

sub get_untracked {
        my ($self, $ed) = @_;
        my @out;
        my $h = $ed->{empty};
        foreach (sort keys %$h) {
                my $act = $h->{$_} ? '+empty_dir' : '-empty_dir';
                push @out, "  $act: " . uri_encode($_);
                warn "W: $act: $_\n";
        }
        foreach my $t (qw/dir_prop file_prop/) {
                $h = $ed->{$t} or next;
                foreach my $path (sort keys %$h) {
                        my $ppath = $path eq '' ? '.' : $path;
                        foreach my $prop (sort keys %{$h->{$path}}) {
                                next if $SKIP_PROP{$prop};
                                my $v = $h->{$path}->{$prop};
                                my $t_ppath_prop = "$t: " .
                                                    uri_encode($ppath) . ' ' .
                                                    uri_encode($prop);
                                if (defined $v) {
                                        push @out, "  +$t_ppath_prop " .
                                                   uri_encode($v);
                                } else {
                                        push @out, "  -$t_ppath_prop";
                                }
                        }
                }
        }
        foreach my $t (qw/absent_file absent_directory/) {
                $h = $ed->{$t} or next;
                foreach my $parent (sort keys %$h) {
                        foreach my $path (sort @{$h->{$parent}}) {
                                push @out, "  $t: " .
                                           uri_encode("$parent/$path");
                                warn "W: $t: $parent/$path ",
                                     "Insufficient permissions?\n";
                        }
                }
        }
        \@out;
}

sub parse_svn_date {
        my $date = shift || return '+0000 1970-01-01 00:00:00';
        my ($Y,$m,$d,$H,$M,$S) = ($date =~ /^(\d{4})\-(\d\d)\-(\d\d)T
                                            (\d\d)\:(\d\d)\:(\d\d).\d+Z$/x) or
                                         croak "Unable to parse date: $date\n";
        "+0000 $Y-$m-$d $H:$M:$S";
}

sub check_author {
        my ($author) = @_;
        if (!defined $author || length $author == 0) {
                $author = '(no author)';
        }
        if (defined $::_authors && ! defined $::users{$author}) {
                die "Author: $author not defined in $::_authors file\n";
        }
        $author;
}

sub make_log_entry {
        my ($self, $rev, $parents, $ed) = @_;
        my $untracked = $self->get_untracked($ed);

        return undef if (! $ed->{new_fetch} && ! $ed->{nr} && ! @$untracked);

        open my $un, '>>', "$self->{dir}/unhandled.log" or croak $!;
        print $un "r$rev\n" or croak $!;
        print $un $_, "\n" foreach @$untracked;
        my %log_entry = ( parents => $parents || [], revision => $rev,
                          log => '');
        my $rp = $self->ra->rev_proplist($rev);
        foreach (sort keys %$rp) {
                my $v = $rp->{$_};
                if (/^svn:(author|date|log)$/) {
                        $log_entry{$1} = $v;
                } else {
                        print $un "  rev_prop: ", uri_encode($_), ' ',
                                  uri_encode($v), "\n";
                }
        }
        close $un or croak $!;

        $log_entry{date} = parse_svn_date($log_entry{date});
        $log_entry{author} = check_author($log_entry{author});
        $log_entry{log} .= "\n";
        \%log_entry;
}

sub fetch {
        my ($self, $min_rev, $max_rev, @parents) = @_;
        my ($last_rev, $last_commit) = $self->last_rev_commit;
        my ($base, $head) = $self->get_fetch_range($min_rev, $max_rev);
        return if ($base > $head);
        $self->ra->gs_fetch_loop_common($base, $head, $self);
}

sub set_tree_cb {
        my ($self, $log_entry, $tree, $rev, $date, $author) = @_;
        # TODO: enable and test optimized commits:
        if (0 && $rev == ($self->{last_rev} + 1)) {
                $log_entry->{revision} = $rev;
                $log_entry->{author} = $author;
                $self->do_git_commit($log_entry, "$rev=$tree");
        } else {
                $self->{inject_parents} = { $rev => $tree };
                $self->fetch(undef, undef);
        }
}

sub set_tree {
        my ($self, $tree) = (shift, shift);
        my $log_entry = ::get_commit_entry($tree);
        unless ($self->{last_rev}) {
                fatal("Must have an existing revision to commit\n");
        }
        my %ed_opts = ( r => $self->{last_rev},
                        log => $log_entry->{log},
                        ra => $self->ra,
                        tree_a => $self->{last_commit},
                        tree_b => $tree,
                        editor_cb => sub {
                               $self->set_tree_cb($log_entry, $tree, @_) },
                        svn_path => $self->{path} );
        if (!SVN::Git::Editor->new(\%ed_opts)->apply_diff) {
                print "No changes\nr$self->{last_rev} = $tree\n";
        }
}

sub rebuild {
        my ($self) = @_;
        print "Rebuilding $self->{db_path} ...\n";
        my ($rev_list, $ctx) = command_output_pipe("rev-list", $self->refname);
        my $latest;
        my $full_url = $self->full_url;
        my $svn_uuid;
        while (<$rev_list>) {
                chomp;
                my $c = $_;
                die "Non-SHA1: $c\n" unless $c =~ /^$::sha1$/o;
                my ($url, $rev, $uuid) = ::cmt_metadata($c);

                # ignore merges (from set-tree)
                next if (!defined $rev || !$uuid);

                # if we merged or otherwise started elsewhere, this is
                # how we break out of it
                if ((defined $svn_uuid && ($uuid ne $svn_uuid)) ||
                    ($full_url && $url && ($url ne $full_url))) {
                        next;
                }
                $latest ||= $rev;
                $svn_uuid ||= $uuid;

                $self->rev_db_set($rev, $c);
                print "r$rev = $c\n";
        }
        command_close_pipe($rev_list, $ctx);
        print "Done rebuilding $self->{db_path}\n";
}

# rev_db:
# Tie::File seems to be prone to offset errors if revisions get sparse,
# it's not that fast, either.  Tie::File is also not in Perl 5.6.  So
# one of my favorite modules is out :<  Next up would be one of the DBM
# modules, but I'm not sure which is most portable...  So I'll just
# go with something that's plain-text, but still capable of
# being randomly accessed.  So here's my ultra-simple fixed-width
# database.  All records are 40 characters + "\n", so it's easy to seek
# to a revision: (41 * rev) is the byte offset.
# A record of 40 0s denotes an empty revision.
# And yes, it's still pretty fast (faster than Tie::File).

sub rev_db_set {
        my ($self, $rev, $commit) = @_;
        length $commit == 40 or croak "arg3 must be a full SHA1 hexsum\n";
        open my $fh, '+<', $self->{db_path} or croak $!;
        my $offset = $rev * 41;
        # assume that append is the common case:
        seek $fh, 0, 2 or croak $!;
        my $pos = tell $fh;
        if ($pos < $offset) {
                print $fh (('0' x 40),"\n") x (($offset - $pos) / 41)
                  or croak $!;
        }
        seek $fh, $offset, 0 or croak $!;
        print $fh $commit,"\n" or croak $!;
        close $fh or croak $!;
}

sub rev_db_get {
        my ($self, $rev) = @_;
        my $ret;
        my $offset = $rev * 41;
        open my $fh, '<', $self->{db_path} or croak $!;
        if (seek $fh, $offset, 0) {
                $ret = readline $fh;
                if (defined $ret) {
                        chomp $ret;
                        $ret = undef if ($ret =~ /^0{40}$/);
                }
        }
        close $fh or croak $!;
        $ret;
}

sub find_rev_before {
        my ($self, $rev, $eq_ok) = @_;
        --$rev unless $eq_ok;
        while ($rev > 0) {
                if (my $c = $self->rev_db_get($rev)) {
                        return ($rev, $c);
                }
                --$rev;
        }
        return (undef, undef);
}

sub _new {
        my ($class, $repo_id, $ref_id, $path) = @_;
        unless (defined $repo_id && length $repo_id) {
                $repo_id = $Git::SVN::default_repo_id;
        }
        unless (defined $ref_id && length $ref_id) {
                $_[2] = $ref_id = $Git::SVN::default_ref_id;
        }
        $_[1] = $repo_id = sanitize_remote_name($repo_id);
        my $dir = "$ENV{GIT_DIR}/svn/$ref_id";
        $_[3] = $path = '' unless (defined $path);
        mkpath([$dir]);
        unless (-f "$dir/.rev_db") {
                open my $fh, '>>', "$dir/.rev_db" or croak $!;
                close $fh or croak $!;
        }
        bless { ref_id => $ref_id, dir => $dir, index => "$dir/index",
                path => $path,
                db_path => "$dir/.rev_db", repo_id => $repo_id }, $class;
}

sub uri_encode {
        my ($f) = @_;
        $f =~ s#([^a-zA-Z0-9\*!\:_\./\-])#uc sprintf("%%%02x",ord($1))#eg;
        $f
}

package Git::SVN::Prompt;
use strict;
use warnings;
require SVN::Core;
use vars qw/$_no_auth_cache $_username/;

sub simple {
        my ($cred, $realm, $default_username, $may_save, $pool) = @_;
        $may_save = undef if $_no_auth_cache;
        $default_username = $_username if defined $_username;
        if (defined $default_username && length $default_username) {
                if (defined $realm && length $realm) {
                        print STDERR "Authentication realm: $realm\n";
                        STDERR->flush;
                }
                $cred->username($default_username);
        } else {
                username($cred, $realm, $may_save, $pool);
        }
        $cred->password(_read_password("Password for '" .
                                       $cred->username . "': ", $realm));
        $cred->may_save($may_save);
        $SVN::_Core::SVN_NO_ERROR;
}

sub ssl_server_trust {
        my ($cred, $realm, $failures, $cert_info, $may_save, $pool) = @_;
        $may_save = undef if $_no_auth_cache;
        print STDERR "Error validating server certificate for '$realm':\n";
        if ($failures & $SVN::Auth::SSL::UNKNOWNCA) {
                print STDERR " - The certificate is not issued by a trusted ",
                      "authority. Use the\n",
                      "   fingerprint to validate the certificate manually!\n";
        }
        if ($failures & $SVN::Auth::SSL::CNMISMATCH) {
                print STDERR " - The certificate hostname does not match.\n";
        }
        if ($failures & $SVN::Auth::SSL::NOTYETVALID) {
                print STDERR " - The certificate is not yet valid.\n";
        }
        if ($failures & $SVN::Auth::SSL::EXPIRED) {
                print STDERR " - The certificate has expired.\n";
        }
        if ($failures & $SVN::Auth::SSL::OTHER) {
                print STDERR " - The certificate has an unknown error.\n";
        }
        printf STDERR
                "Certificate information:\n".
                " - Hostname: %s\n".
                " - Valid: from %s until %s\n".
                " - Issuer: %s\n".
                " - Fingerprint: %s\n",
                map $cert_info->$_, qw(hostname valid_from valid_until
                                       issuer_dname fingerprint);
        my $choice;
prompt:
        print STDERR $may_save ?
              "(R)eject, accept (t)emporarily or accept (p)ermanently? " :
              "(R)eject or accept (t)emporarily? ";
        STDERR->flush;
        $choice = lc(substr(<STDIN> || 'R', 0, 1));
        if ($choice =~ /^t$/i) {
                $cred->may_save(undef);
        } elsif ($choice =~ /^r$/i) {
                return -1;
        } elsif ($may_save && $choice =~ /^p$/i) {
                $cred->may_save($may_save);
        } else {
                goto prompt;
        }
        $cred->accepted_failures($failures);
        $SVN::_Core::SVN_NO_ERROR;
}

sub ssl_client_cert {
        my ($cred, $realm, $may_save, $pool) = @_;
        $may_save = undef if $_no_auth_cache;
        print STDERR "Client certificate filename: ";
        STDERR->flush;
        chomp(my $filename = <STDIN>);
        $cred->cert_file($filename);
        $cred->may_save($may_save);
        $SVN::_Core::SVN_NO_ERROR;
}

sub ssl_client_cert_pw {
        my ($cred, $realm, $may_save, $pool) = @_;
        $may_save = undef if $_no_auth_cache;
        $cred->password(_read_password("Password: ", $realm));
        $cred->may_save($may_save);
        $SVN::_Core::SVN_NO_ERROR;
}

sub username {
        my ($cred, $realm, $may_save, $pool) = @_;
        $may_save = undef if $_no_auth_cache;
        if (defined $realm && length $realm) {
                print STDERR "Authentication realm: $realm\n";
        }
        my $username;
        if (defined $_username) {
                $username = $_username;
        } else {
                print STDERR "Username: ";
                STDERR->flush;
                chomp($username = <STDIN>);
        }
        $cred->username($username);
        $cred->may_save($may_save);
        $SVN::_Core::SVN_NO_ERROR;
}

sub _read_password {
        my ($prompt, $realm) = @_;
        print STDERR $prompt;
        STDERR->flush;
        require Term::ReadKey;
        Term::ReadKey::ReadMode('noecho');
        my $password = '';
        while (defined(my $key = Term::ReadKey::ReadKey(0))) {
                last if $key =~ /[\012\015]/; # \n\r
                $password .= $key;
        }
        Term::ReadKey::ReadMode('restore');
        print STDERR "\n";
        STDERR->flush;
        $password;
}

package main;

{
        my $kill_stupid_warnings = $SVN::Node::none.$SVN::Node::file.
                                $SVN::Node::dir.$SVN::Node::unknown.
                                $SVN::Node::none.$SVN::Node::file.
                                $SVN::Node::dir.$SVN::Node::unknown.
                                $SVN::Auth::SSL::CNMISMATCH.
                                $SVN::Auth::SSL::NOTYETVALID.
                                $SVN::Auth::SSL::EXPIRED.
                                $SVN::Auth::SSL::UNKNOWNCA.
                                $SVN::Auth::SSL::OTHER;
}

package SVN::Git::Fetcher;
use vars qw/@ISA/;
use strict;
use warnings;
use Carp qw/croak/;
use IO::File qw//;
use Digest::MD5;

# file baton members: path, mode_a, mode_b, pool, fh, blob, base
sub new {
        my ($class, $git_svn) = @_;
        my $self = SVN::Delta::Editor->new;
        bless $self, $class;
        $self->{c} = $git_svn->{last_commit} if exists $git_svn->{last_commit};
        $self->{empty} = {};
        $self->{dir_prop} = {};
        $self->{file_prop} = {};
        $self->{absent_dir} = {};
        $self->{absent_file} = {};
        $self->{gii} = $git_svn->tmp_index_do(sub { Git::IndexInfo->new });
        $self;
}

sub set_path_strip {
        my ($self, $path) = @_;
        $self->{path_strip} = qr/^\Q$path\E\/?/;
}

sub open_root {
        { path => '' };
}

sub open_directory {
        my ($self, $path, $pb, $rev) = @_;
        { path => $path };
}

sub git_path {
        my ($self, $path) = @_;
        if ($self->{path_strip}) {
                $path =~ s!$self->{path_strip}!! or
                  die "Failed to strip path '$path' ($self->{path_strip})\n";
        }
        $path;
}

sub delete_entry {
        my ($self, $path, $rev, $pb) = @_;

        my $gpath = $self->git_path($path);
        return undef if ($gpath eq '');

        # remove entire directories.
        if (command('ls-tree', $self->{c}, '--', $gpath) =~ /^040000 tree/) {
                my ($ls, $ctx) = command_output_pipe(qw/ls-tree
                                                     -r --name-only -z/,
                                                     $self->{c}, '--', $gpath);
                local $/ = "\0";
                while (<$ls>) {
                        chomp;
                        $self->{gii}->remove($_);
                        print "\tD\t$_\n" unless $self->{q};
                }
                print "\tD\t$gpath/\n" unless $self->{q};
                command_close_pipe($ls, $ctx);
                $self->{empty}->{$path} = 0
        } else {
                $self->{gii}->remove($gpath);
                print "\tD\t$gpath\n" unless $self->{q};
        }
        undef;
}

sub open_file {
        my ($self, $path, $pb, $rev) = @_;
        my $gpath = $self->git_path($path);
        my ($mode, $blob) = (command('ls-tree', $self->{c}, '--', $gpath)
                             =~ /^(\d{6}) blob ([a-f\d]{40})\t/);
        unless (defined $mode && defined $blob) {
                die "$path was not found in commit $self->{c} (r$rev)\n";
        }
        { path => $path, mode_a => $mode, mode_b => $mode, blob => $blob,
          pool => SVN::Pool->new, action => 'M' };
}

sub add_file {
        my ($self, $path, $pb, $cp_path, $cp_rev) = @_;
        my ($dir, $file) = ($path =~ m#^(.*?)/?([^/]+)$#);
        delete $self->{empty}->{$dir};
        { path => $path, mode_a => 100644, mode_b => 100644,
          pool => SVN::Pool->new, action => 'A' };
}

sub add_directory {
        my ($self, $path, $cp_path, $cp_rev) = @_;
        my ($dir, $file) = ($path =~ m#^(.*?)/?([^/]+)$#);
        delete $self->{empty}->{$dir};
        $self->{empty}->{$path} = 1;
        { path => $path };
}

sub change_dir_prop {
        my ($self, $db, $prop, $value) = @_;
        $self->{dir_prop}->{$db->{path}} ||= {};
        $self->{dir_prop}->{$db->{path}}->{$prop} = $value;
        undef;
}

sub absent_directory {
        my ($self, $path, $pb) = @_;
        $self->{absent_dir}->{$pb->{path}} ||= [];
        push @{$self->{absent_dir}->{$pb->{path}}}, $path;
        undef;
}

sub absent_file {
        my ($self, $path, $pb) = @_;
        $self->{absent_file}->{$pb->{path}} ||= [];
        push @{$self->{absent_file}->{$pb->{path}}}, $path;
        undef;
}

sub change_file_prop {
        my ($self, $fb, $prop, $value) = @_;
        if ($prop eq 'svn:executable') {
                if ($fb->{mode_b} != 120000) {
                        $fb->{mode_b} = defined $value ? 100755 : 100644;
                }
        } elsif ($prop eq 'svn:special') {
                $fb->{mode_b} = defined $value ? 120000 : 100644;
        } else {
                $self->{file_prop}->{$fb->{path}} ||= {};
                $self->{file_prop}->{$fb->{path}}->{$prop} = $value;
        }
        undef;
}

sub apply_textdelta {
        my ($self, $fb, $exp) = @_;
        my $fh = IO::File->new_tmpfile;
        $fh->autoflush(1);
        # $fh gets auto-closed() by SVN::TxDelta::apply(),
        # (but $base does not,) so dup() it for reading in close_file
        open my $dup, '<&', $fh or croak $!;
        my $base = IO::File->new_tmpfile;
        $base->autoflush(1);
        if ($fb->{blob}) {
                defined (my $pid = fork) or croak $!;
                if (!$pid) {
                        open STDOUT, '>&', $base or croak $!;
                        print STDOUT 'link ' if ($fb->{mode_a} == 120000);
                        exec qw/git-cat-file blob/, $fb->{blob} or croak $!;
                }
                waitpid $pid, 0;
                croak $? if $?;

                if (defined $exp) {
                        seek $base, 0, 0 or croak $!;
                        my $md5 = Digest::MD5->new;
                        $md5->addfile($base);
                        my $got = $md5->hexdigest;
                        die "Checksum mismatch: $fb->{path} $fb->{blob}\n",
                            "expected: $exp\n",
                            "     got: $got\n" if ($got ne $exp);
                }
        }
        seek $base, 0, 0 or croak $!;
        $fb->{fh} = $dup;
        $fb->{base} = $base;
        [ SVN::TxDelta::apply($base, $fh, undef, $fb->{path}, $fb->{pool}) ];
}

sub close_file {
        my ($self, $fb, $exp) = @_;
        my $hash;
        my $path = $self->git_path($fb->{path});
        if (my $fh = $fb->{fh}) {
                seek($fh, 0, 0) or croak $!;
                my $md5 = Digest::MD5->new;
                $md5->addfile($fh);
                my $got = $md5->hexdigest;
                die "Checksum mismatch: $path\n",
                    "expected: $exp\n    got: $got\n" if ($got ne $exp);
                seek($fh, 0, 0) or croak $!;
                if ($fb->{mode_b} == 120000) {
                        read($fh, my $buf, 5) == 5 or croak $!;
                        $buf eq 'link ' or die "$path has mode 120000",
                                               "but is not a link\n";
                }
                defined(my $pid = open my $out,'-|') or die "Can't fork: $!\n";
                if (!$pid) {
                        open STDIN, '<&', $fh or croak $!;
                        exec qw/git-hash-object -w --stdin/ or croak $!;
                }
                chomp($hash = do { local $/; <$out> });
                close $out or croak $!;
                close $fh or croak $!;
                $hash =~ /^[a-f\d]{40}$/ or die "not a sha1: $hash\n";
                close $fb->{base} or croak $!;
        } else {
                $hash = $fb->{blob} or die "no blob information\n";
        }
        $fb->{pool}->clear;
        $self->{gii}->update($fb->{mode_b}, $hash, $path) or croak $!;
        print "\t$fb->{action}\t$path\n" if $fb->{action} && ! $self->{q};
        undef;
}

sub abort_edit {
        my $self = shift;
        $self->{nr} = $self->{gii}->{nr};
        delete $self->{gii};
        $self->SUPER::abort_edit(@_);
}

sub close_edit {
        my $self = shift;
        $self->{git_commit_ok} = 1;
        $self->{nr} = $self->{gii}->{nr};
        delete $self->{gii};
        $self->SUPER::close_edit(@_);
}

package SVN::Git::Editor;
use vars qw/@ISA $_rmdir $_cp_similarity $_find_copies_harder $_rename_limit/;
use strict;
use warnings;
use Carp qw/croak/;
use IO::File;
use Digest::MD5;

sub new {
        my ($class, $opts) = @_;
        foreach (qw/svn_path r ra tree_a tree_b log editor_cb/) {
                die "$_ required!\n" unless (defined $opts->{$_});
        }

        my $pool = SVN::Pool->new;
        my $mods = generate_diff($opts->{tree_a}, $opts->{tree_b});
        my $types = check_diff_paths($opts->{ra}, $opts->{svn_path},
                                     $opts->{r}, $mods);

        # $opts->{ra} functions should not be used after this:
        my @ce  = $opts->{ra}->get_commit_editor($opts->{log},
                                                $opts->{editor_cb}, $pool);
        my $self = SVN::Delta::Editor->new(@ce, $pool);
        bless $self, $class;
        foreach (qw/svn_path r tree_a tree_b/) {
                $self->{$_} = $opts->{$_};
        }
        $self->{url} = $opts->{ra}->{url};
        $self->{mods} = $mods;
        $self->{types} = $types;
        $self->{pool} = $pool;
        $self->{bat} = { '' => $self->open_root($self->{r}, $self->{pool}) };
        $self->{rm} = { };
        $self->{path_prefix} = length $self->{svn_path} ?
                               "$self->{svn_path}/" : '';
        return $self;
}

sub generate_diff {
        my ($tree_a, $tree_b) = @_;
        my @diff_tree = qw(diff-tree -z -r);
        if ($_cp_similarity) {
                push @diff_tree, "-C$_cp_similarity";
        } else {
                push @diff_tree, '-C';
        }
        push @diff_tree, '--find-copies-harder' if $_find_copies_harder;
        push @diff_tree, "-l$_rename_limit" if defined $_rename_limit;
        push @diff_tree, $tree_a, $tree_b;
        my ($diff_fh, $ctx) = command_output_pipe(@diff_tree);
        local $/ = "\0";
        my $state = 'meta';
        my @mods;
        while (<$diff_fh>) {
                chomp $_; # this gets rid of the trailing "\0"
                if ($state eq 'meta' && /^:(\d{6})\s(\d{6})\s
                                        $::sha1\s($::sha1)\s
                                        ([MTCRAD])\d*$/xo) {
                        push @mods, {   mode_a => $1, mode_b => $2,
                                        sha1_b => $3, chg => $4 };
                        if ($4 =~ /^(?:C|R)$/) {
                                $state = 'file_a';
                        } else {
                                $state = 'file_b';
                        }
                } elsif ($state eq 'file_a') {
                        my $x = $mods[$#mods] or croak "Empty array\n";
                        if ($x->{chg} !~ /^(?:C|R)$/) {
                                croak "Error parsing $_, $x->{chg}\n";
                        }
                        $x->{file_a} = $_;
                        $state = 'file_b';
                } elsif ($state eq 'file_b') {
                        my $x = $mods[$#mods] or croak "Empty array\n";
                        if (exists $x->{file_a} && $x->{chg} !~ /^(?:C|R)$/) {
                                croak "Error parsing $_, $x->{chg}\n";
                        }
                        if (!exists $x->{file_a} && $x->{chg} =~ /^(?:C|R)$/) {
                                croak "Error parsing $_, $x->{chg}\n";
                        }
                        $x->{file_b} = $_;
                        $state = 'meta';
                } else {
                        croak "Error parsing $_\n";
                }
        }
        command_close_pipe($diff_fh, $ctx);
        \@mods;
}

sub check_diff_paths {
        my ($ra, $pfx, $rev, $mods) = @_;
        my %types;
        $pfx .= '/' if length $pfx;

        sub type_diff_paths {
                my ($ra, $types, $path, $rev) = @_;
                my @p = split m#/+#, $path;
                my $c = shift @p;
                unless (defined $types->{$c}) {
                        $types->{$c} = $ra->check_path($c, $rev);
                }
                while (@p) {
                        $c .= '/' . shift @p;
                        next if defined $types->{$c};
                        $types->{$c} = $ra->check_path($c, $rev);
                }
        }

        foreach my $m (@$mods) {
                foreach my $f (qw/file_a file_b/) {
                        next unless defined $m->{$f};
                        my ($dir) = ($m->{$f} =~ m#^(.*?)/?(?:[^/]+)$#);
                        if (length $pfx.$dir && ! defined $types{$dir}) {
                                type_diff_paths($ra, \%types, $pfx.$dir, $rev);
                        }
                }
        }
        \%types;
}

sub split_path {
        return ($_[0] =~ m#^(.*?)/?([^/]+)$#);
}

sub repo_path {
        my ($self, $path) = @_;
        $self->{path_prefix}.(defined $path ? $path : '');
}

sub url_path {
        my ($self, $path) = @_;
        $self->{url} . '/' . $self->repo_path($path);
}

sub rmdirs {
        my ($self) = @_;
        my $rm = $self->{rm};
        delete $rm->{''}; # we never delete the url we're tracking
        return unless %$rm;

        foreach (keys %$rm) {
                my @d = split m#/#, $_;
                my $c = shift @d;
                $rm->{$c} = 1;
                while (@d) {
                        $c .= '/' . shift @d;
                        $rm->{$c} = 1;
                }
        }
        delete $rm->{$self->{svn_path}};
        delete $rm->{''}; # we never delete the url we're tracking
        return unless %$rm;

        my ($fh, $ctx) = command_output_pipe(qw/ls-tree --name-only -r -z/,
                                             $self->{tree_b});
        local $/ = "\0";
        while (<$fh>) {
                chomp;
                my @dn = split m#/#, $_;
                while (pop @dn) {
                        delete $rm->{join '/', @dn};
                }
                unless (%$rm) {
                        close $fh;
                        return;
                }
        }
        command_close_pipe($fh, $ctx);

        my ($r, $p, $bat) = ($self->{r}, $self->{pool}, $self->{bat});
        foreach my $d (sort { $b =~ tr#/#/# <=> $a =~ tr#/#/# } keys %$rm) {
                $self->close_directory($bat->{$d}, $p);
                my ($dn) = ($d =~ m#^(.*?)/?(?:[^/]+)$#);
                print "\tD+\t$d/\n" unless $::_q;
                $self->SUPER::delete_entry($d, $r, $bat->{$dn}, $p);
                delete $bat->{$d};
        }
}

sub open_or_add_dir {
        my ($self, $full_path, $baton) = @_;
        my $t = $self->{types}->{$full_path};
        if (!defined $t) {
                die "$full_path not known in r$self->{r} or we have a bug!\n";
        }
        if ($t == $SVN::Node::none) {
                return $self->add_directory($full_path, $baton,
                                                undef, -1, $self->{pool});
        } elsif ($t == $SVN::Node::dir) {
                return $self->open_directory($full_path, $baton,
                                                $self->{r}, $self->{pool});
        }
        print STDERR "$full_path already exists in repository at ",
                "r$self->{r} and it is not a directory (",
                ($t == $SVN::Node::file ? 'file' : 'unknown'),"/$t)\n";
        exit 1;
}

sub ensure_path {
        my ($self, $path) = @_;
        my $bat = $self->{bat};
        my $repo_path = $self->repo_path($path);
        return $bat->{''} unless (length $repo_path);
        my @p = split m#/+#, $repo_path;
        my $c = shift @p;
        $bat->{$c} ||= $self->open_or_add_dir($c, $bat->{''});
        while (@p) {
                my $c0 = $c;
                $c .= '/' . shift @p;
                $bat->{$c} ||= $self->open_or_add_dir($c, $bat->{$c0});
        }
        return $bat->{$c};
}

sub A {
        my ($self, $m) = @_;
        my ($dir, $file) = split_path($m->{file_b});
        my $pbat = $self->ensure_path($dir);
        my $fbat = $self->add_file($self->repo_path($m->{file_b}), $pbat,
                                        undef, -1);
        print "\tA\t$m->{file_b}\n" unless $::_q;
        $self->chg_file($fbat, $m);
        $self->close_file($fbat,undef,$self->{pool});
}

sub C {
        my ($self, $m) = @_;
        my ($dir, $file) = split_path($m->{file_b});
        my $pbat = $self->ensure_path($dir);
        my $fbat = $self->add_file($self->repo_path($m->{file_b}), $pbat,
                                $self->url_path($m->{file_a}), $self->{r});
        print "\tC\t$m->{file_a} => $m->{file_b}\n" unless $::_q;
        $self->chg_file($fbat, $m);
        $self->close_file($fbat,undef,$self->{pool});
}

sub delete_entry {
        my ($self, $path, $pbat) = @_;
        my $rpath = $self->repo_path($path);
        my ($dir, $file) = split_path($rpath);
        $self->{rm}->{$dir} = 1;
        $self->SUPER::delete_entry($rpath, $self->{r}, $pbat, $self->{pool});
}

sub R {
        my ($self, $m) = @_;
        my ($dir, $file) = split_path($m->{file_b});
        my $pbat = $self->ensure_path($dir);
        my $fbat = $self->add_file($self->repo_path($m->{file_b}), $pbat,
                                $self->url_path($m->{file_a}), $self->{r});
        print "\tR\t$m->{file_a} => $m->{file_b}\n" unless $::_q;
        $self->chg_file($fbat, $m);
        $self->close_file($fbat,undef,$self->{pool});

        ($dir, $file) = split_path($m->{file_a});
        $pbat = $self->ensure_path($dir);
        $self->delete_entry($m->{file_a}, $pbat);
}

sub M {
        my ($self, $m) = @_;
        my ($dir, $file) = split_path($m->{file_b});
        my $pbat = $self->ensure_path($dir);
        my $fbat = $self->open_file($self->repo_path($m->{file_b}),
                                $pbat,$self->{r},$self->{pool});
        print "\t$m->{chg}\t$m->{file_b}\n" unless $::_q;
        $self->chg_file($fbat, $m);
        $self->close_file($fbat,undef,$self->{pool});
}

sub T { shift->M(@_) }

sub change_file_prop {
        my ($self, $fbat, $pname, $pval) = @_;
        $self->SUPER::change_file_prop($fbat, $pname, $pval, $self->{pool});
}

sub chg_file {
        my ($self, $fbat, $m) = @_;
        if ($m->{mode_b} =~ /755$/ && $m->{mode_a} !~ /755$/) {
                $self->change_file_prop($fbat,'svn:executable','*');
        } elsif ($m->{mode_b} !~ /755$/ && $m->{mode_a} =~ /755$/) {
                $self->change_file_prop($fbat,'svn:executable',undef);
        }
        my $fh = IO::File->new_tmpfile or croak $!;
        if ($m->{mode_b} =~ /^120/) {
                print $fh 'link ' or croak $!;
                $self->change_file_prop($fbat,'svn:special','*');
        } elsif ($m->{mode_a} =~ /^120/ && $m->{mode_b} !~ /^120/) {
                $self->change_file_prop($fbat,'svn:special',undef);
        }
        defined(my $pid = fork) or croak $!;
        if (!$pid) {
                open STDOUT, '>&', $fh or croak $!;
                exec qw/git-cat-file blob/, $m->{sha1_b} or croak $!;
        }
        waitpid $pid, 0;
        croak $? if $?;
        $fh->flush == 0 or croak $!;
        seek $fh, 0, 0 or croak $!;

        my $md5 = Digest::MD5->new;
        $md5->addfile($fh) or croak $!;
        seek $fh, 0, 0 or croak $!;

        my $exp = $md5->hexdigest;
        my $pool = SVN::Pool->new;
        my $atd = $self->apply_textdelta($fbat, undef, $pool);
        my $got = SVN::TxDelta::send_stream($fh, @$atd, $pool);
        die "Checksum mismatch\nexpected: $exp\ngot: $got\n" if ($got ne $exp);
        $pool->clear;

        close $fh or croak $!;
}

sub D {
        my ($self, $m) = @_;
        my ($dir, $file) = split_path($m->{file_b});
        my $pbat = $self->ensure_path($dir);
        print "\tD\t$m->{file_b}\n" unless $::_q;
        $self->delete_entry($m->{file_b}, $pbat);
}

sub close_edit {
        my ($self) = @_;
        my ($p,$bat) = ($self->{pool}, $self->{bat});
        foreach (sort { $b =~ tr#/#/# <=> $a =~ tr#/#/# } keys %$bat) {
                $self->close_directory($bat->{$_}, $p);
        }
        $self->SUPER::close_edit($p);
        $p->clear;
}

sub abort_edit {
        my ($self) = @_;
        $self->SUPER::abort_edit($self->{pool});
}

sub DESTROY {
        my $self = shift;
        $self->SUPER::DESTROY(@_);
        $self->{pool}->clear;
}

# this drives the editor
sub apply_diff {
        my ($self) = @_;
        my $mods = $self->{mods};
        my %o = ( D => 1, R => 0, C => -1, A => 3, M => 3, T => 3 );
        foreach my $m (sort { $o{$a->{chg}} <=> $o{$b->{chg}} } @$mods) {
                my $f = $m->{chg};
                if (defined $o{$f}) {
                        $self->$f($m);
                } else {
                        fatal("Invalid change type: $f\n");
                }
        }
        $self->rmdirs if $_rmdir;
        if (@$mods == 0) {
                $self->abort_edit;
        } else {
                $self->close_edit;
        }
        return scalar @$mods;
}

package Git::SVN::Ra;
use vars qw/@ISA $config_dir/;
use strict;
use warnings;
my ($can_do_switch);
my $RA;

BEGIN {
        # enforce temporary pool usage for some simple functions
        my $e;
        foreach (qw/get_latest_revnum rev_proplist get_file
                    check_path get_dir get_uuid get_repos_root/) {
                $e .= "sub $_ {
                        my \$self = shift;
                        my \$pool = SVN::Pool->new;
                        my \@ret = \$self->SUPER::$_(\@_,\$pool);
                        \$pool->clear;
                        wantarray ? \@ret : \$ret[0]; }\n";
        }
        eval $e;
}

sub new {
        my ($class, $url) = @_;
        $url =~ s!/+$!!;
        return $RA if ($RA && $RA->{url} eq $url);

        SVN::_Core::svn_config_ensure($config_dir, undef);
        my ($baton, $callbacks) = SVN::Core::auth_open_helper([
            SVN::Client::get_simple_provider(),
            SVN::Client::get_ssl_server_trust_file_provider(),
            SVN::Client::get_simple_prompt_provider(
              \&Git::SVN::Prompt::simple, 2),
            SVN::Client::get_ssl_client_cert_prompt_provider(
              \&Git::SVN::Prompt::ssl_client_cert, 2),
            SVN::Client::get_ssl_client_cert_pw_prompt_provider(
              \&Git::SVN::Prompt::ssl_client_cert_pw, 2),
            SVN::Client::get_username_provider(),
            SVN::Client::get_ssl_server_trust_prompt_provider(
              \&Git::SVN::Prompt::ssl_server_trust),
            SVN::Client::get_username_prompt_provider(
              \&Git::SVN::Prompt::username, 2),
          ]);
        my $config = SVN::Core::config_get_config($config_dir);
        my $self = SVN::Ra->new(url => $url, auth => $baton,
                              config => $config,
                              pool => SVN::Pool->new,
                              auth_provider_callbacks => $callbacks);
        $self->{svn_path} = $url;
        $self->{repos_root} = $self->get_repos_root;
        $self->{svn_path} =~ s#^\Q$self->{repos_root}\E/*##;
        $RA = bless $self, $class;
}

sub DESTROY {
        # do not call the real DESTROY since we store ourselves in $RA
}

sub get_log {
        my ($self, @args) = @_;
        my $pool = SVN::Pool->new;
        splice(@args, 3, 1) if ($SVN::Core::VERSION le '1.2.0');
        my $ret = $self->SUPER::get_log(@args, $pool);
        $pool->clear;
        $ret;
}

sub get_commit_editor {
        my ($self, $log, $cb, $pool) = @_;
        my @lock = $SVN::Core::VERSION ge '1.2.0' ? (undef, 0) : ();
        $self->SUPER::get_commit_editor($log, $cb, @lock, $pool);
}

sub uuid {
        my ($self) = @_;
        $self->{uuid} ||= $self->get_uuid;
}

sub gs_do_update {
        my ($self, $rev_a, $rev_b, $gs, $editor) = @_;
        my $new = ($rev_a == $rev_b);
        my $path = $gs->{path};

        my $ta = $self->check_path($path, $rev_a);
        my $tb = $new ? $ta : $self->check_path($path, $rev_b);
        return 1 if ($tb != $SVN::Node::dir && $ta != $SVN::Node::dir);
        if ($ta == $SVN::Node::none) {
                $rev_a = $rev_b;
                $new = 1;
        }

        my $pool = SVN::Pool->new;
        $editor->set_path_strip($path);
        my (@pc) = split m#/#, $path;
        my $reporter = $self->do_update($rev_b, (@pc ? shift @pc : ''),
                                        1, $editor, $pool);
        my @lock = $SVN::Core::VERSION ge '1.2.0' ? (undef) : ();

        # Since we can't rely on svn_ra_reparent being available, we'll
        # just have to do some magic with set_path to make it so
        # we only want a partial path.
        my $sp = '';
        my $final = join('/', @pc);
        while (@pc) {
                $reporter->set_path($sp, $rev_b, 0, @lock, $pool);
                $sp .= '/' if length $sp;
                $sp .= shift @pc;
        }
        die "BUG: '$sp' != '$final'\n" if ($sp ne $final);

        $reporter->set_path($sp, $rev_a, $new, @lock, $pool);

        $reporter->finish_report($pool);
        $pool->clear;
        $editor->{git_commit_ok};
}

# this requires SVN 1.4.3 or later (do_switch didn't work before 1.4.3, and
# svn_ra_reparent didn't work before 1.4)
sub gs_do_switch {
        my ($self, $rev_a, $rev_b, $gs, $url_b, $editor) = @_;
        my $path = $gs->{path};
        my $pool = SVN::Pool->new;

        my $full_url = $self->{url};
        my $old_url = $full_url;
        $full_url .= "/$path" if length $path;
        my ($ra, $reparented);
        if ($old_url ne $full_url) {
                if ($old_url !~ m#^svn(\+ssh)?://#) {
                        SVN::_Ra::svn_ra_reparent($self->{session}, $full_url,
                                                  $pool);
                        $self->{url} = $full_url;
                        $reparented = 1;
                } else {
                        $ra = Git::SVN::Ra->new($full_url);
                }
        }
        $ra ||= $self;
        my $reporter = $ra->do_switch($rev_b, '', 1, $url_b, $editor, $pool);
        my @lock = $SVN::Core::VERSION ge '1.2.0' ? (undef) : ();
        $reporter->set_path('', $rev_a, 0, @lock, $pool);
        $reporter->finish_report($pool);

        if ($reparented) {
                SVN::_Ra::svn_ra_reparent($self->{session}, $old_url, $pool);
                $self->{url} = $old_url;
        }

        $pool->clear;
        $editor->{git_commit_ok};
}

sub gs_fetch_loop_common {
        my ($self, $base, $head, @gs) = @_;
        my $inc = 1000;
        my ($min, $max) = ($base, $head < $base + $inc ? $head : $base + $inc);
        my @paths = @gs == 1 ? ($gs[0]->{path}) : ('');
        foreach my $gs (@gs) {
                if (my $last_commit = $gs->last_commit) {
                        $gs->assert_index_clean($last_commit);
                }
        }
        while (1) {
                my @revs;
                my $err;
                my $err_handler = $SVN::Error::handler;
                $SVN::Error::handler = sub {
                        ($err) = @_;
                        skip_unknown_revs($err);
                };
                $self->get_log(\@paths, $min, $max, 0, 1, 1,
                    sub { push @revs, [ dup_changed_paths($_[0]), $_[1] ]; });
                $SVN::Error::handler = $err_handler;

                if (! @revs && $err && $max >= $head) {
                        print STDERR "Branch probably deleted:\n  ",
                                     $err->expanded_message,
                                     "\nWill attempt to follow revisions ",
                                     "r$min .. r$max ",
                                     "committed before the deletion\n";
                        @revs = map { [ undef, $_ ] } ($min .. $max);
                }
                foreach (@revs) {
                        my ($paths, $r) = @$_;
                        foreach my $gs (@gs) {
                                if ($paths) {
                                        $gs->match_paths($paths) or next;
                                }
                                my $lr = $gs->last_rev;
                                next if defined $lr && $lr >= $r;
                                next if defined $gs->rev_db_get($r);
                                if (my $log_entry = $gs->do_fetch($paths, $r)) {
                                        $gs->do_git_commit($log_entry);
                                }
                        }
                }
                last if $max >= $head;
                $min = $max + 1;
                $max += $inc;
                $max = $head if ($max > $head);
        }
}

sub minimize_url {
        my ($self) = @_;
        return $self->{url} if ($self->{url} eq $self->{repos_root});
        my $url = $self->{repos_root};
        my @components = split(m!/!, $self->{svn_path});
        my $c = '';
        do {
                $url .= "/$c" if length $c;
                eval { (ref $self)->new($url)->get_latest_revnum };
        } while ($@ && ($c = shift @components));
        $url;
}

sub can_do_switch {
        my $self = shift;
        unless (defined $can_do_switch) {
                my $pool = SVN::Pool->new;
                my $rep = eval {
                        $self->do_switch(1, '', 0, $self->{url},
                                         SVN::Delta::Editor->new, $pool);
                };
                if ($@) {
                        $can_do_switch = 0;
                } else {
                        $rep->abort_report($pool);
                        $can_do_switch = 1;
                }
                $pool->clear;
        }
        $can_do_switch;
}

sub skip_unknown_revs {
        my ($err) = @_;
        my $errno = $err->apr_err();
        # Maybe the branch we're tracking didn't
        # exist when the repo started, so it's
        # not an error if it doesn't, just continue
        #
        # Wonderfully consistent library, eh?
        # 160013 - svn:// and file://
        # 175002 - http(s)://
        # 175007 - http(s):// (this repo required authorization, too...)
        #   More codes may be discovered later...
        if ($errno == 175007 || $errno == 175002 || $errno == 160013) {
                return;
        }
        die "Error from SVN, ($errno): ", $err->expanded_message,"\n";
}

# svn_log_changed_path_t objects passed to get_log are likely to be
# overwritten even if only the refs are copied to an external variable,
# so we should dup the structures in their entirety.  Using an externally
# passed pool (instead of our temporary and quickly cleared pool in
# Git::SVN::Ra) does not help matters at all...
sub dup_changed_paths {
        my ($paths) = @_;
        return undef unless $paths;
        my %ret;
        foreach my $p (keys %$paths) {
                my $i = $paths->{$p};
                my %s = map { $_ => $i->$_ }
                              qw/copyfrom_path copyfrom_rev action/;
                $ret{$p} = \%s;
        }
        \%ret;
}

package Git::SVN::Log;
use strict;
use warnings;
use POSIX qw/strftime/;
use vars qw/$TZ $limit $color $pager $non_recursive $verbose $oneline
            %rusers $show_commit $incremental/;
my $l_fmt;

sub cmt_showable {
        my ($c) = @_;
        return 1 if defined $c->{r};
        if ($c->{l} && $c->{l}->[-1] eq "...\n" &&
                                $c->{a_raw} =~ /\@([a-f\d\-]+)>$/) {
                my @log = command(qw/cat-file commit/, $c->{c});
                shift @log while ($log[0] ne "\n");
                shift @log;
                @{$c->{l}} = grep !/^git-svn-id: /, @log;

                (undef, $c->{r}, undef) = ::extract_metadata(
                                (grep(/^git-svn-id: /, @log))[-1]);
        }
        return defined $c->{r};
}

sub log_use_color {
        return 1 if $color;
        my ($dc, $dcvar);
        $dcvar = 'color.diff';
        $dc = `git-config --get $dcvar`;
        if ($dc eq '') {
                # nothing at all; fallback to "diff.color"
                $dcvar = 'diff.color';
                $dc = `git-config --get $dcvar`;
        }
        chomp($dc);
        if ($dc eq 'auto') {
                my $pc;
                $pc = `git-config --get color.pager`;
                if ($pc eq '') {
                        # does not have it -- fallback to pager.color
                        $pc = `git-config --bool --get pager.color`;
                }
                else {
                        $pc = `git-config --bool --get color.pager`;
                        if ($?) {
                                $pc = 'false';
                        }
                }
                chomp($pc);
                if (-t *STDOUT || (defined $pager && $pc eq 'true')) {
                        return ($ENV{TERM} && $ENV{TERM} ne 'dumb');
                }
                return 0;
        }
        return 0 if $dc eq 'never';
        return 1 if $dc eq 'always';
        chomp($dc = `git-config --bool --get $dcvar`);
        return ($dc eq 'true');
}

sub git_svn_log_cmd {
        my ($r_min, $r_max) = @_;
        my $gs = Git::SVN->_new;
        my @cmd = (qw/log --abbrev-commit --pretty=raw --default/,
                   $gs->refname);
        push @cmd, '-r' unless $non_recursive;
        push @cmd, qw/--raw --name-status/ if $verbose;
        push @cmd, '--color' if log_use_color();
        return @cmd unless defined $r_max;
        if ($r_max == $r_min) {
                push @cmd, '--max-count=1';
                if (my $c = $gs->rev_db_get($r_max)) {
                        push @cmd, $c;
                }
        } else {
                my ($c_min, $c_max);
                $c_max = $gs->rev_db_get($r_max);
                $c_min = $gs->rev_db_get($r_min);
                if (defined $c_min && defined $c_max) {
                        if ($r_max > $r_max) {
                                push @cmd, "$c_min..$c_max";
                        } else {
                                push @cmd, "$c_max..$c_min";
                        }
                } elsif ($r_max > $r_min) {
                        push @cmd, $c_max;
                } else {
                        push @cmd, $c_min;
                }
        }
        return @cmd;
}

# adapted from pager.c
sub config_pager {
        $pager ||= $ENV{GIT_PAGER} || $ENV{PAGER};
        if (!defined $pager) {
                $pager = 'less';
        } elsif (length $pager == 0 || $pager eq 'cat') {
                $pager = undef;
        }
}

sub run_pager {
        return unless -t *STDOUT;
        pipe my $rfd, my $wfd or return;
        defined(my $pid = fork) or ::fatal "Can't fork: $!\n";
        if (!$pid) {
                open STDOUT, '>&', $wfd or
                                     ::fatal "Can't redirect to stdout: $!\n";
                return;
        }
        open STDIN, '<&', $rfd or ::fatal "Can't redirect stdin: $!\n";
        $ENV{LESS} ||= 'FRSX';
        exec $pager or ::fatal "Can't run pager: $! ($pager)\n";
}

sub tz_to_s_offset {
        my ($tz) = @_;
        $tz =~ s/(\d\d)$//;
        return ($1 * 60) + ($tz * 3600);
}

sub get_author_info {
        my ($dest, $author, $t, $tz) = @_;
        $author =~ s/(?:^\s*|\s*$)//g;
        $dest->{a_raw} = $author;
        my $au;
        if ($::_authors) {
                $au = $rusers{$author} || undef;
        }
        if (!$au) {
                ($au) = ($author =~ /<([^>]+)\@[^>]+>$/);
        }
        $dest->{t} = $t;
        $dest->{tz} = $tz;
        $dest->{a} = $au;
        # Date::Parse isn't in the standard Perl distro :(
        if ($tz =~ s/^\+//) {
                $t += tz_to_s_offset($tz);
        } elsif ($tz =~ s/^\-//) {
                $t -= tz_to_s_offset($tz);
        }
        $dest->{t_utc} = $t;
}

sub process_commit {
        my ($c, $r_min, $r_max, $defer) = @_;
        if (defined $r_min && defined $r_max) {
                if ($r_min == $c->{r} && $r_min == $r_max) {
                        show_commit($c);
                        return 0;
                }
                return 1 if $r_min == $r_max;
                if ($r_min < $r_max) {
                        # we need to reverse the print order
                        return 0 if (defined $limit && --$limit < 0);
                        push @$defer, $c;
                        return 1;
                }
                if ($r_min != $r_max) {
                        return 1 if ($r_min < $c->{r});
                        return 1 if ($r_max > $c->{r});
                }
        }
        return 0 if (defined $limit && --$limit < 0);
        show_commit($c);
        return 1;
}

sub show_commit {
        my $c = shift;
        if ($oneline) {
                my $x = "\n";
                if (my $l = $c->{l}) {
                        while ($l->[0] =~ /^\s*$/) { shift @$l }
                        $x = $l->[0];
                }
                $l_fmt ||= 'A' . length($c->{r});
                print 'r',pack($l_fmt, $c->{r}),' | ';
                print "$c->{c} | " if $show_commit;
                print $x;
        } else {
                show_commit_normal($c);
        }
}

sub show_commit_changed_paths {
        my ($c) = @_;
        return unless $c->{changed};
        print "Changed paths:\n", @{$c->{changed}};
}

sub show_commit_normal {
        my ($c) = @_;
        print '-' x72, "\nr$c->{r} | ";
        print "$c->{c} | " if $show_commit;
        print "$c->{a} | ", strftime("%Y-%m-%d %H:%M:%S %z (%a, %d %b %Y)",
                                 localtime($c->{t_utc})), ' | ';
        my $nr_line = 0;

        if (my $l = $c->{l}) {
                while ($l->[$#$l] eq "\n" && $#$l > 0
                                          && $l->[($#$l - 1)] eq "\n") {
                        pop @$l;
                }
                $nr_line = scalar @$l;
                if (!$nr_line) {
                        print "1 line\n\n\n";
                } else {
                        if ($nr_line == 1) {
                                $nr_line = '1 line';
                        } else {
                                $nr_line .= ' lines';
                        }
                        print $nr_line, "\n";
                        show_commit_changed_paths($c);
                        print "\n";
                        print $_ foreach @$l;
                }
        } else {
                print "1 line\n";
                show_commit_changed_paths($c);
                print "\n";

        }
        foreach my $x (qw/raw diff/) {
                if ($c->{$x}) {
                        print "\n";
                        print $_ foreach @{$c->{$x}}
                }
        }
}

sub cmd_show_log {
        my (@args) = @_;
        my ($r_min, $r_max);
        my $r_last = -1; # prevent dupes
        if (defined $TZ) {
                $ENV{TZ} = $TZ;
        } else {
                delete $ENV{TZ};
        }
        if (defined $::_revision) {
                if ($::_revision =~ /^(\d+):(\d+)$/) {
                        ($r_min, $r_max) = ($1, $2);
                } elsif ($::_revision =~ /^\d+$/) {
                        $r_min = $r_max = $::_revision;
                } else {
                        ::fatal "-r$::_revision is not supported, use ",
                                "standard \'git log\' arguments instead\n";
                }
        }

        config_pager();
        @args = (git_svn_log_cmd($r_min, $r_max), @args);
        my $log = command_output_pipe(@args);
        run_pager();
        my (@k, $c, $d);
        my $esc_color = qr/(?:\033\[(?:(?:\d+;)*\d*)?m)*/;
        while (<$log>) {
                if (/^${esc_color}commit ($::sha1_short)/o) {
                        my $cmt = $1;
                        if ($c && cmt_showable($c) && $c->{r} != $r_last) {
                                $r_last = $c->{r};
                                process_commit($c, $r_min, $r_max, \@k) or
                                                                goto out;
                        }
                        $d = undef;
                        $c = { c => $cmt };
                } elsif (/^${esc_color}author (.+) (\d+) ([\-\+]?\d+)$/o) {
                        get_author_info($c, $1, $2, $3);
                } elsif (/^${esc_color}(?:tree|parent|committer) /o) {
                        # ignore
                } elsif (/^${esc_color}:\d{6} \d{6} $::sha1_short/o) {
                        push @{$c->{raw}}, $_;
                } elsif (/^${esc_color}[ACRMDT]\t/) {
                        # we could add $SVN->{svn_path} here, but that requires
                        # remote access at the moment (repo_path_split)...
                        s#^(${esc_color})([ACRMDT])\t#$1   $2 #o;
                        push @{$c->{changed}}, $_;
                } elsif (/^${esc_color}diff /o) {
                        $d = 1;
                        push @{$c->{diff}}, $_;
                } elsif ($d) {
                        push @{$c->{diff}}, $_;
                } elsif (/^${esc_color}    (git-svn-id:.+)$/o) {
                        ($c->{url}, $c->{r}, undef) = ::extract_metadata($1);
                } elsif (s/^${esc_color}    //o) {
                        push @{$c->{l}}, $_;
                }
        }
        if ($c && defined $c->{r} && $c->{r} != $r_last) {
                $r_last = $c->{r};
                process_commit($c, $r_min, $r_max, \@k);
        }
        if (@k) {
                my $swap = $r_max;
                $r_max = $r_min;
                $r_min = $swap;
                process_commit($_, $r_min, $r_max) foreach reverse @k;
        }
out:
        close $log;
        print '-' x72,"\n" unless $incremental || $oneline;
}

package Git::SVN::Migration;
# these version numbers do NOT correspond to actual version numbers
# of git nor git-svn.  They are just relative.
#
# v0 layout: .git/$id/info/url, refs/heads/$id-HEAD
#
# v1 layout: .git/$id/info/url, refs/remotes/$id
#
# v2 layout: .git/svn/$id/info/url, refs/remotes/$id
#
# v3 layout: .git/svn/$id, refs/remotes/$id
#            - info/url may remain for backwards compatibility
#            - this is what we migrate up to this layout automatically,
#            - this will be used by git svn init on single branches
#
# v4 layout: .git/svn/$repo_id/$id, refs/remotes/$repo_id/$id
#            - this is only created for newly multi-init-ed
#              repositories.  Similar in spirit to the
#              --use-separate-remotes option in git-clone (now default)
#            - we do not automatically migrate to this (following
#              the example set by core git)
use strict;
use warnings;
use Carp qw/croak/;
use File::Path qw/mkpath/;
use File::Basename qw/dirname basename/;
use vars qw/$_minimize/;

sub migrate_from_v0 {
        my $git_dir = $ENV{GIT_DIR};
        return undef unless -d $git_dir;
        my ($fh, $ctx) = command_output_pipe(qw/rev-parse --symbolic --all/);
        my $migrated = 0;
        while (<$fh>) {
                chomp;
                my ($id, $orig_ref) = ($_, $_);
                next unless $id =~ s#^refs/heads/(.+)-HEAD$#$1#;
                next unless -f "$git_dir/$id/info/url";
                my $new_ref = "refs/remotes/$id";
                if (::verify_ref("$new_ref^0")) {
                        print STDERR "W: $orig_ref is probably an old ",
                                     "branch used by an ancient version of ",
                                     "git-svn.\n",
                                     "However, $new_ref also exists.\n",
                                     "We will not be able ",
                                     "to use this branch until this ",
                                     "ambiguity is resolved.\n";
                        next;
                }
                print STDERR "Migrating from v0 layout...\n" if !$migrated;
                print STDERR "Renaming ref: $orig_ref => $new_ref\n";
                command_noisy('update-ref', $new_ref, $orig_ref);
                command_noisy('update-ref', '-d', $orig_ref, $orig_ref);
                $migrated++;
        }
        command_close_pipe($fh, $ctx);
        print STDERR "Done migrating from v0 layout...\n" if $migrated;
        $migrated;
}

sub migrate_from_v1 {
        my $git_dir = $ENV{GIT_DIR};
        my $migrated = 0;
        return $migrated unless -d $git_dir;
        my $svn_dir = "$git_dir/svn";

        # just in case somebody used 'svn' as their $id at some point...
        return $migrated if -d $svn_dir && ! -f "$svn_dir/info/url";

        print STDERR "Migrating from a git-svn v1 layout...\n";
        mkpath([$svn_dir]);
        print STDERR "Data from a previous version of git-svn exists, but\n\t",
                     "$svn_dir\n\t(required for this version ",
                     "($::VERSION) of git-svn) does not. exist\n";
        my ($fh, $ctx) = command_output_pipe(qw/rev-parse --symbolic --all/);
        while (<$fh>) {
                my $x = $_;
                next unless $x =~ s#^refs/remotes/##;
                chomp $x;
                next unless -f "$git_dir/$x/info/url";
                my $u = eval { ::file_to_s("$git_dir/$x/info/url") };
                next unless $u;
                my $dn = dirname("$git_dir/svn/$x");
                mkpath([$dn]) unless -d $dn;
                if ($x eq 'svn') { # they used 'svn' as GIT_SVN_ID:
                        mkpath(["$git_dir/svn/svn"]);
                        print STDERR " - $git_dir/$x/info => ",
                                        "$git_dir/svn/$x/info\n";
                        rename "$git_dir/$x/info", "$git_dir/svn/$x/info" or
                               croak "$!: $x";
                        # don't worry too much about these, they probably
                        # don't exist with repos this old (save for index,
                        # and we can easily regenerate that)
                        foreach my $f (qw/unhandled.log index .rev_db/) {
                                rename "$git_dir/$x/$f", "$git_dir/svn/$x/$f";
                        }
                } else {
                        print STDERR " - $git_dir/$x => $git_dir/svn/$x\n";
                        rename "$git_dir/$x", "$git_dir/svn/$x" or
                               croak "$!: $x";
                }
                $migrated++;
        }
        command_close_pipe($fh, $ctx);
        print STDERR "Done migrating from a git-svn v1 layout\n";
        $migrated;
}

sub read_old_urls {
        my ($l_map, $pfx, $path) = @_;
        my @dir;
        foreach (<$path/*>) {
                if (-r "$_/info/url") {
                        $pfx .= '/' if $pfx && $pfx !~ m!/$!;
                        my $ref_id = $pfx . basename $_;
                        my $url = ::file_to_s("$_/info/url");
                        $l_map->{$ref_id} = $url;
                } elsif (-d $_) {
                        push @dir, $_;
                }
        }
        foreach (@dir) {
                my $x = $_;
                $x =~ s!^\Q$ENV{GIT_DIR}\E/svn/!!o;
                read_old_urls($l_map, $x, $_);
        }
}

sub migrate_from_v2 {
        my @cfg = command(qw/config -l/);
        return if grep /^svn-remote\..+\.url=/, @cfg;
        my %l_map;
        read_old_urls(\%l_map, '', "$ENV{GIT_DIR}/svn");
        my $migrated = 0;

        foreach my $ref_id (sort keys %l_map) {
                Git::SVN->init($l_map{$ref_id}, '', $ref_id, $ref_id);
                $migrated++;
        }
        $migrated;
}

sub minimize_connections {
        my $r = Git::SVN::read_all_remotes();
        my $new_urls = {};
        my $root_repos = {};
        foreach my $repo_id (keys %$r) {
                my $url = $r->{$repo_id}->{url} or next;
                my $fetch = $r->{$repo_id}->{fetch} or next;
                my $ra = Git::SVN::Ra->new($url);

                # skip existing cases where we already connect to the root
                if (($ra->{url} eq $ra->{repos_root}) ||
                    (Git::SVN::sanitize_remote_name($ra->{repos_root}) eq
                     $repo_id)) {
                        $root_repos->{$ra->{url}} = $repo_id;
                        next;
                }

                my $root_ra = Git::SVN::Ra->new($ra->{repos_root});
                my $root_path = $ra->{url};
                $root_path =~ s#^\Q$ra->{repos_root}\E/*##;
                foreach my $path (keys %$fetch) {
                        my $ref_id = $fetch->{$path};
                        my $gs = Git::SVN->new($ref_id, $repo_id, $path);

                        # make sure we can read when connecting to
                        # a higher level of a repository
                        my ($last_rev, undef) = $gs->last_rev_commit;
                        if (!defined $last_rev) {
                                $last_rev = eval {
                                        $root_ra->get_latest_revnum;
                                };
                                next if $@;
                        }
                        my $new = $root_path;
                        $new .= length $path ? "/$path" : '';
                        eval {
                                $root_ra->get_log([$new], $last_rev, $last_rev,
                                                  0, 0, 1, sub { });
                        };
                        next if $@;
                        $new_urls->{$ra->{repos_root}}->{$new} =
                                { ref_id => $ref_id,
                                  old_repo_id => $repo_id,
                                  old_path => $path };
                }
        }

        my @emptied;
        foreach my $url (keys %$new_urls) {
                # see if we can re-use an existing [svn-remote "repo_id"]
                # instead of creating a(n ugly) new section:
                my $repo_id = $root_repos->{$url} ||
                              Git::SVN::sanitize_remote_name($url);

                my $fetch = $new_urls->{$url};
                foreach my $path (keys %$fetch) {
                        my $x = $fetch->{$path};
                        Git::SVN->init($url, $path, $repo_id, $x->{ref_id});
                        my $pfx = "svn-remote.$x->{old_repo_id}";

                        my $old_fetch = quotemeta("$x->{old_path}:".
                                                  "refs/remotes/$x->{ref_id}");
                        command_noisy(qw/config --unset/,
                                      "$pfx.fetch", '^'. $old_fetch . '$');
                        delete $r->{$x->{old_repo_id}}->
                               {fetch}->{$x->{old_path}};
                        if (!keys %{$r->{$x->{old_repo_id}}->{fetch}}) {
                                command_noisy(qw/config --unset/,
                                              "$pfx.url");
                                push @emptied, $x->{old_repo_id}
                        }
                }
        }
        if (@emptied) {
                my $file = $ENV{GIT_CONFIG} || $ENV{GIT_CONFIG_LOCAL} ||
                           "$ENV{GIT_DIR}/config";
                print STDERR <<EOF;
The following [svn-remote] sections in your config file ($file) are empty
and can be safely removed:
EOF
                print STDERR "[svn-remote \"$_\"]\n" foreach @emptied;
        }
}

sub migration_check {
        migrate_from_v0();
        migrate_from_v1();
        migrate_from_v2();
        minimize_connections() if $_minimize;
}

package Git::IndexInfo;
use strict;
use warnings;
use Git qw/command_input_pipe command_close_pipe/;

sub new {
        my ($class) = @_;
        my ($gui, $ctx) = command_input_pipe(qw/update-index -z --index-info/);
        bless { gui => $gui, ctx => $ctx, nr => 0}, $class;
}

sub remove {
        my ($self, $path) = @_;
        if (print { $self->{gui} } '0 ', 0 x 40, "\t", $path, "\0") {
                return ++$self->{nr};
        }
        undef;
}

sub update {
        my ($self, $mode, $hash, $path) = @_;
        if (print { $self->{gui} } $mode, ' ', $hash, "\t", $path, "\0") {
                return ++$self->{nr};
        }
        undef;
}

sub DESTROY {
        my ($self) = @_;
        command_close_pipe($self->{gui}, $self->{ctx});
}

__END__

Data structures:

$log_entry hashref as returned by libsvn_log_entry()
{
        log => 'whitespace-formatted log entry
',                                              # trailing newline is preserved
        revision => '8',                        # integer
        date => '2004-02-24T17:01:44.108345Z',  # commit date
        author => 'committer name'
};


# this is generated by generate_diff();
@mods = array of diff-index line hashes, each element represents one line
        of diff-index output

diff-index line ($m hash)
{
        mode_a => first column of diff-index output, no leading ':',
        mode_b => second column of diff-index output,
        sha1_b => sha1sum of the final blob,
        chg => change type [MCRADT],
        file_a => original file name of a file (iff chg is 'C' or 'R')
        file_b => new/current file name of a file (any chg)
}
;

# retval of read_url_paths{,_all}();
$l_map = {
        # repository root url
        'https://svn.musicpd.org' => {
                # repository path               # GIT_SVN_ID
                'mpd/trunk'             =>      'trunk',
                'mpd/tags/0.11.5'       =>      'tags/0.11.5',
        },
}

Notes:
        I don't trust the each() function on unless I created %hash myself
        because the internal iterator may not have started at base.