#!/usr/bin/perl -w

# This tool is copyright (c) 2005, Matthias Urlichs.
# It is released under the Gnu Public License, version 2.
#
# The basic idea is to aggregate CVS check-ins into related changes.
# Fortunately, "cvsps" does that for us; all we have to do is to parse
# its output.
#
# Checking out the files is done by a single long-running CVS connection
# / server process.
#
# The head revision is on branch "origin" by default.
# You can change that with the '-o' option.

use strict;
use warnings;
use Getopt::Std;
use File::Path qw(mkpath);
use File::Basename qw(basename dirname);
use Time::Local;
use IO::Socket;
use IO::Pipe;
use POSIX qw(strftime dup2);

$SIG{'PIPE'}="IGNORE";
$ENV{'TZ'}="UTC";

our($opt_h,$opt_o,$opt_v,$opt_d,$opt_p,$opt_C);

sub usage() {
        print STDERR <<END;
Usage: ${\basename $0}     # fetch/update GIT from CVS
           [ -o branch-for-HEAD ] [ -h ] [ -v ] [ -d CVSROOT ]
       [ -p opts-for-cvsps ] [ -C GIT_repository ]
       [ CVS_module ]
END
        exit(1);
}

getopts("hqvo:d:p:C:") or usage();
usage if $opt_h;

@ARGV <= 1 or usage();

if($opt_d) {
        $ENV{"CVSROOT"} = $opt_d;
} elsif(-f 'CVS/Root') {
        open my $f, '<', 'CVS/Root' or die 'Failed to open CVS/Root';
        $opt_d = <$f>;
        chomp $opt_d;
        close $f;
        $ENV{"CVSROOT"} = $opt_d;
} elsif($ENV{"CVSROOT"}) {
        $opt_d = $ENV{"CVSROOT"};
} else {
        die "CVSROOT needs to be set";
}
$opt_o ||= "origin";
my $git_tree = $opt_C;
$git_tree ||= ".";

my $cvs_tree;
if ($#ARGV == 0) {
        $cvs_tree = $ARGV[0];
} elsif (-f 'CVS/Repository') {
        open my $f, '<', 'CVS/Repository' or 
            die 'Failed to open CVS/Repository';
        $cvs_tree = <$f>;
        chomp $cvs_tree;
        close $f
} else {
        usage();
}

select(STDERR); $|=1; select(STDOUT);


package CVSconn;
# Basic CVS dialog.
# We're only interested in connecting and downloading, so ...

use POSIX qw(strftime dup2);

sub new {
        my($what,$repo,$subdir) = @_;
        $what=ref($what) if ref($what);

        my $self = {};
        $self->{'buffer'} = "";
        bless($self,$what);

        $repo =~ s#/+$##;
        $self->{'fullrep'} = $repo;
        $self->conn();

        $self->{'subdir'} = $subdir;
        $self->{'lines'} = undef;

        return $self;
}

sub conn {
        my $self = shift;
        my $repo = $self->{'fullrep'};
        if($repo =~ s/^:pserver:(?:(.*?)(?::(.*?))?@)?([^:\/]*)(?::(\d*))?//) {
                my($user,$pass,$serv,$port) = ($1,$2,$3,$4);
                $user="anonymous" unless defined $user;
                my $rr2 = "-";
                unless($port) {
                        $rr2 = ":pserver:$user\@$serv:$repo";
                        $port=2401;
                }
                my $rr = ":pserver:$user\@$serv:$port$repo";

                unless($pass) {
                        open(H,$ENV{'HOME'}."/.cvspass") and do {
                                # :pserver:cvs@mea.tmt.tele.fi:/cvsroot/zmailer Ah<Z
                                while(<H>) {
                                        chomp;
                                        s/^\/\d+\s+//;
                                        my ($w,$p) = split(/\s/,$_,2);
                                        if($w eq $rr or $w eq $rr2) {
                                                $pass = $p;
                                                last;
                                        }
                                }
                        };
                }
                $pass="A" unless $pass;

                my $s = IO::Socket::INET->new(PeerHost => $serv, PeerPort => $port);
                die "Socket to $serv: $!\n" unless defined $s;
                $s->write("BEGIN AUTH REQUEST\n$repo\n$user\n$pass\nEND AUTH REQUEST\n")
                        or die "Write to $serv: $!\n";
                $s->flush();

                my $rep = <$s>;

                if($rep ne "I LOVE YOU\n") {
                        $rep="<unknown>" unless $rep;
                        die "AuthReply: $rep\n";
                }
                $self->{'socketo'} = $s;
                $self->{'socketi'} = $s;
        } else { # local: Fork off our own cvs server.
                my $pr = IO::Pipe->new();
                my $pw = IO::Pipe->new();
                my $pid = fork();
                die "Fork: $!\n" unless defined $pid;
                my $cvs = 'cvs';
                $cvs = $ENV{CVS_SERVER} if exists $ENV{CVS_SERVER};
                unless($pid) {
                        $pr->writer();
                        $pw->reader();
                        dup2($pw->fileno(),0);
                        dup2($pr->fileno(),1);
                        $pr->close();
                        $pw->close();
                        exec($cvs,"server");
                }
                $pw->writer();
                $pr->reader();
                $self->{'socketo'} = $pw;
                $self->{'socketi'} = $pr;
        }
        $self->{'socketo'}->write("Root $repo\n");

        # Trial and error says that this probably is the minimum set
        $self->{'socketo'}->write("Valid-responses ok error Valid-requests Mode M Mbinary E F Checked-in Created Updated Merged Removed\n");

        $self->{'socketo'}->write("valid-requests\n");
        $self->{'socketo'}->flush();

        chomp(my $rep=$self->readline());
        if($rep !~ s/^Valid-requests\s*//) {
                $rep="<unknown>" unless $rep;
                die "Expected Valid-requests from server, but got: $rep\n";
        }
        chomp(my $res=$self->readline());
        die "validReply: $res\n" if $res ne "ok";

        $self->{'socketo'}->write("UseUnchanged\n") if $rep =~ /\bUseUnchanged\b/;
        $self->{'repo'} = $repo;
}

sub readline {
        my($self) = @_;
        return $self->{'socketi'}->getline();
}

sub _file {
        # Request a file with a given revision.
        # Trial and error says this is a good way to do it. :-/
        my($self,$fn,$rev) = @_;
        $self->{'socketo'}->write("Argument -N\n") or return undef;
        $self->{'socketo'}->write("Argument -P\n") or return undef;
        # $self->{'socketo'}->write("Argument -ko\n") or return undef;
        # -ko: Linus' version doesn't use it
        $self->{'socketo'}->write("Argument -r\n") or return undef;
        $self->{'socketo'}->write("Argument $rev\n") or return undef;
        $self->{'socketo'}->write("Argument --\n") or return undef;
        $self->{'socketo'}->write("Argument $self->{'subdir'}/$fn\n") or return undef;
        $self->{'socketo'}->write("Directory .\n") or return undef;
        $self->{'socketo'}->write("$self->{'repo'}\n") or return undef;
        # $self->{'socketo'}->write("Sticky T1.0\n") or return undef;
        $self->{'socketo'}->write("co\n") or return undef;
        $self->{'socketo'}->flush() or return undef;
        $self->{'lines'} = 0;
        return 1;
}
sub _line {
        # Read a line from the server.
        # ... except that 'line' may be an entire file. ;-)
        my($self) = @_;
        die "Not in lines" unless defined $self->{'lines'};

        my $line;
        my $res="";
        while(defined($line = $self->readline())) {
                # M U gnupg-cvs-rep/AUTHORS
                # Updated gnupg-cvs-rep/
                # /daten/src/rsync/gnupg-cvs-rep/AUTHORS
                # /AUTHORS/1.1///T1.1
                # u=rw,g=rw,o=rw
                # 0
                # ok

                if($line =~ s/^(?:Created|Updated) //) {
                        $line = $self->readline(); # path
                        $line = $self->readline(); # Entries line
                        my $mode = $self->readline(); chomp $mode;
                        $self->{'mode'} = $mode;
                        defined (my $cnt = $self->readline())
                                or die "EOF from server after 'Changed'\n";
                        chomp $cnt;
                        die "Duh: Filesize $cnt" if $cnt !~ /^\d+$/;
                        $line="";
                        $res="";
                        while($cnt) {
                                my $buf;
                                my $num = $self->{'socketi'}->read($buf,$cnt);
                                die "Server: Filesize $cnt: $num: $!\n" if not defined $num or $num<=0;
                                $res .= $buf;
                                $cnt -= $num;
                        }
                } elsif($line =~ s/^ //) {
                        $res .= $line;
                } elsif($line =~ /^M\b/) {
                        # output, do nothing
                } elsif($line =~ /^Mbinary\b/) {
                        my $cnt;
                        die "EOF from server after 'Mbinary'" unless defined ($cnt = $self->readline());
                        chomp $cnt;
                        die "Duh: Mbinary $cnt" if $cnt !~ /^\d+$/ or $cnt<1;
                        $line="";
                        while($cnt) {
                                my $buf;
                                my $num = $self->{'socketi'}->read($buf,$cnt);
                                die "S: Mbinary $cnt: $num: $!\n" if not defined $num or $num<=0;
                                $res .= $buf;
                                $cnt -= $num;
                        }
                } else {
                        chomp $line;
                        if($line eq "ok") {
                                # print STDERR "S: ok (".length($res).")\n";
                                return $res;
                        } elsif($line =~ s/^E //) {
                                # print STDERR "S: $line\n";
                        } else {
                                die "Unknown: $line\n";
                        }
                }
        }
}
sub file {
        my($self,$fn,$rev) = @_;
        my $res;

        if ($self->_file($fn,$rev)) {
                $res = $self->_line();
                return $res if defined $res;
        }

        # retry
        $self->conn();
        $self->_file($fn,$rev)
                or die "No file command send\n";
        $res = $self->_line();
        die "No input: $fn $rev\n" unless defined $res;
        return $res;
}


package main;

my $cvs = CVSconn->new($opt_d, $cvs_tree);


sub pdate($) {
        my($d) = @_;
        m#(\d{2,4})/(\d\d)/(\d\d)\s(\d\d):(\d\d)(?::(\d\d))?#
                or die "Unparseable date: $d\n";
        my $y=$1; $y-=1900 if $y>1900;
        return timegm($6||0,$5,$4,$3,$2-1,$y);
}

sub pmode($) {
        my($mode) = @_;
        my $m = 0;
        my $mm = 0;
        my $um = 0;
        for my $x(split(//,$mode)) {
                if($x eq ",") {
                        $m |= $mm&$um;
                        $mm = 0;
                        $um = 0;
                } elsif($x eq "u") { $um |= 0700;
                } elsif($x eq "g") { $um |= 0070;
                } elsif($x eq "o") { $um |= 0007;
                } elsif($x eq "r") { $mm |= 0444;
                } elsif($x eq "w") { $mm |= 0222;
                } elsif($x eq "x") { $mm |= 0111;
                } elsif($x eq "=") { # do nothing
                } else { die "Unknown mode: $mode\n";
                }
        }
        $m |= $mm&$um;
        return $m;
}

my $tmpcv = "/var/cache/cvs";

sub getwd() {
        my $pwd = `pwd`;
        chomp $pwd;
        return $pwd;
}

-d $git_tree
        or mkdir($git_tree,0777)
        or die "Could not create $git_tree: $!";
chdir($git_tree);

my $last_branch = "";
my $orig_branch = "";
my %branch_date;

my $git_dir = $ENV{"GIT_DIR"} || ".git";
$git_dir = getwd()."/".$git_dir unless $git_dir =~ m#^/#;
$ENV{"GIT_DIR"} = $git_dir;
unless(-d $git_dir) {
        system("git-init-db");
        die "Cannot init the GIT db at $git_tree: $?\n" if $?;
        system("git-read-tree");
        die "Cannot init an empty tree: $?\n" if $?;

        $last_branch = $opt_o;
        $orig_branch = "";
} else {
        -f "$git_dir/refs/head/$opt_o"
                or die "Branch '$opt_o' does not exist.\n".
                       "Either use the correct '-o branch' option,\n".
                       "or import to a new repository.\n";

        $last_branch = basename(readlink("$git_dir/HEAD"));
        unless($last_branch) {
                warn "Cannot read the last branch name: $! -- assuming 'master'\n";
                $last_branch = "master";
        }
        $orig_branch = $last_branch;

        # Get the last import timestamps
        opendir(D,"$git_dir/refs/heads");
        while(defined(my $head = readdir(D))) {
                next if $head =~ /^\./;
                open(F,"$git_dir/refs/heads/$head")
                        or die "Bad head branch: $head: $!\n";
                chomp(my $ftag = <F>);
                close(F);
                open(F,"git-cat-file commit $ftag |");
                while(<F>) {
                        next unless /^author\s.*\s(\d+)\s[-+]\d{4}$/;
                        $branch_date{$head} = $1;
                        last;
                }
                close(F);
        }
        closedir(D);
}

-d $git_dir
        or die "Could not create git subdir ($git_dir).\n";

my $pid = open(CVS,"-|");
die "Cannot fork: $!\n" unless defined $pid;
unless($pid) {
        my @opt;
        @opt = split(/,/,$opt_p) if defined $opt_p;
        exec("cvsps",@opt,"-x","-A","--cvs-direct",'--root',$opt_d,$cvs_tree);
        die "Could not start cvsps: $!\n";
}


## cvsps output:
#---------------------
#PatchSet 314
#Date: 1999/09/18 13:03:59
#Author: wkoch
#Branch: STABLE-BRANCH-1-0
#Ancestor branch: HEAD
#Tag: (none)
#Log:
#    See ChangeLog: Sat Sep 18 13:03:28 CEST 1999  Werner Koch
#Members:
#       README:1.57->1.57.2.1
#       VERSION:1.96->1.96.2.1
#
#---------------------

my $state = 0;

my($patchset,$date,$author,$branch,$ancestor,$tag,$logmsg);
my(@old,@new);
my $commit = sub {
        my $pid;
        while(@old) {
                my @o2;
                if(@old > 55) {
                        @o2 = splice(@old,0,50);
                } else {
                        @o2 = @old;
                        @old = ();
                }
                system("git-update-cache","--force-remove","--",@o2);
                die "Cannot remove files: $?\n" if $?;
        }
        while(@new) {
                my @n2;
                if(@new > 55) {
                        @n2 = splice(@new,0,50);
                } else {
                        @n2 = @new;
                        @new = ();
                }
                system("git-update-cache","--add","--",@n2);
                die "Cannot add files: $?\n" if $?;
        }

        $pid = open(C,"-|");
        die "Cannot fork: $!" unless defined $pid;
        unless($pid) {
                exec("git-write-tree");
                die "Cannot exec git-write-tree: $!\n";
        }
        chomp(my $tree = <C>);
        length($tree) == 40
                or die "Cannot get tree id ($tree): $!\n";
        close(C)
                or die "Error running git-write-tree: $?\n";
        print "Tree ID $tree\n" if $opt_v;

        my $parent = "";
        if(open(C,"$git_dir/refs/heads/$last_branch")) {
                chomp($parent = <C>);
                close(C);
                length($parent) == 40
                        or die "Cannot get parent id ($parent): $!\n";
                print "Parent ID $parent\n" if $opt_v;
        }

        my $pr = IO::Pipe->new();
        my $pw = IO::Pipe->new();
        $pid = fork();
        die "Fork: $!\n" unless defined $pid;
        unless($pid) {
                $pr->writer();
                $pw->reader();
                dup2($pw->fileno(),0);
                dup2($pr->fileno(),1);
                $pr->close();
                $pw->close();

                my @par = ();
                @par = ("-p",$parent) if $parent;
                exec("env",
                        "GIT_AUTHOR_NAME=$author",
                        "GIT_AUTHOR_EMAIL=$author",
                        "GIT_AUTHOR_DATE=".strftime("+0000 %Y-%m-%d %H:%M:%S",gmtime($date)),
                        "GIT_COMMITTER_NAME=$author",
                        "GIT_COMMITTER_EMAIL=$author",
                        "GIT_COMMITTER_DATE=".strftime("+0000 %Y-%m-%d %H:%M:%S",gmtime($date)),
                        "git-commit-tree", $tree,@par);
                die "Cannot exec git-commit-tree: $!\n";
        }
        $pw->writer();
        $pr->reader();

        # compatibility with git2cvs
        substr($logmsg,32767) = "" if length($logmsg) > 32767;
        $logmsg =~ s/[\s\n]+\z//;

        print $pw "$logmsg\n"
                or die "Error writing to git-commit-tree: $!\n";
        $pw->close();

        print "Committed patch $patchset ($branch)\n" if $opt_v;
        chomp(my $cid = <$pr>);
        length($cid) == 40
                or die "Cannot get commit id ($cid): $!\n";
        print "Commit ID $cid\n" if $opt_v;
        $pr->close();

        waitpid($pid,0);
        die "Error running git-commit-tree: $?\n" if $?;

        open(C,">$git_dir/refs/heads/$branch")
                or die "Cannot open branch $branch for update: $!\n";
        print C "$cid\n"
                or die "Cannot write branch $branch for update: $!\n";
        close(C)
                or die "Cannot write branch $branch for update: $!\n";

        if($tag) {
                open(C,">$git_dir/refs/tags/$tag")
                        or die "Cannot create tag $tag: $!\n";
                print C "$cid\n"
                        or die "Cannot write tag $branch: $!\n";
                close(C)
                        or die "Cannot write tag $branch: $!\n";
                print "Created tag '$tag' on '$branch'\n" if $opt_v;
        }
};

while(<CVS>) {
        chomp;
        if($state == 0 and /^-+$/) {
                $state = 1;
        } elsif($state == 0) {
                $state = 1;
                redo;
        } elsif(($state==0 or $state==1) and s/^PatchSet\s+//) {
                $patchset = 0+$_;
                $state=2;
        } elsif($state == 2 and s/^Date:\s+//) {
                $date = pdate($_);
                unless($date) {
                        print STDERR "Could not parse date: $_\n";
                        $state=0;
                        next;
                }
                $state=3;
        } elsif($state == 3 and s/^Author:\s+//) {
                s/\s+$//;
                $author = $_;
                $state = 4;
        } elsif($state == 4 and s/^Branch:\s+//) {
                s/\s+$//;
                $branch = $_;
                $state = 5;
        } elsif($state == 5 and s/^Ancestor branch:\s+//) {
                s/\s+$//;
                $ancestor = $_;
                $ancestor = $opt_o if $ancestor eq "HEAD";
                $state = 6;
        } elsif($state == 5) {
                $ancestor = undef;
                $state = 6;
                redo;
        } elsif($state == 6 and s/^Tag:\s+//) {
                s/\s+$//;
                if($_ eq "(none)") {
                        $tag = undef;
                } else {
                        $tag = $_;
                }
                $state = 7;
        } elsif($state == 7 and /^Log:/) {
                $logmsg = "";
                $state = 8;
        } elsif($state == 8 and /^Members:/) {
                $branch = $opt_o if $branch eq "HEAD";
                if(defined $branch_date{$branch} and $branch_date{$branch} >= $date) {
                        # skip
                        print "skip patchset $patchset: $date before $branch_date{$branch}\n";
                        $state = 11;
                        next;
                }
                if($ancestor) {
                        if(-f "$git_dir/refs/heads/$branch") {
                                print STDERR "Branch $branch already exists!\n";
                                $state=11;
                                next;
                        }
                        unless(open(H,"$git_dir/refs/heads/$ancestor")) {
                                print STDERR "Branch $ancestor does not exist!\n";
                                $state=11;
                                next;
                        }
                        chomp(my $id = <H>);
                        close(H);
                        unless(open(H,"> $git_dir/refs/heads/$branch")) {
                                print STDERR "Could not create branch $branch: $!\n";
                                $state=11;
                                next;
                        }
                        print H "$id\n"
                                or die "Could not write branch $branch: $!";
                        close(H)
                                or die "Could not write branch $branch: $!";
                }
                if(($ancestor || $branch) ne $last_branch) {
                        print "Switching from $last_branch to $branch\n" if $opt_v;
                        system("git-read-tree","-m","-u","$last_branch","$branch");
                        die "read-tree failed: $?\n" if $?;
                }
                if($branch ne $last_branch) {
                        unlink("$git_dir/HEAD");
                        symlink("refs/heads/$branch","$git_dir/HEAD");
                        $last_branch = $branch;
                }
                $state = 9;
        } elsif($state == 8) {
                $logmsg .= "$_\n";
        } elsif($state == 9 and /^\s+(\S+):(INITIAL|\d(?:\.\d+)+)->(\d(?:\.\d+)+)\s*$/) {
#       VERSION:1.96->1.96.2.1
                my $init = ($2 eq "INITIAL");
                my $fn = $1;
                my $rev = $3;
                $fn =~ s#^/+##;
                my $data = $cvs->file($fn,$rev);
                print "".($init ? "New" : "Update")." $fn: ".length($data)." bytes.\n";
                mkpath(dirname($fn),$opt_v);
                open(F,"> ./$fn")
                        or die "Cannot create '$fn': $!\n";
                print F $data
                        or die "Cannot write to '$fn': $!\n";
                close(F)
                        or die "Cannot write to '$fn': $!\n";
                chmod(pmode($cvs->{'mode'}), $fn);
                push(@new,$fn); # may be resurrected!
        } elsif($state == 9 and /^\s+(\S+):\d(?:\.\d+)+->(\d(?:\.\d+)+)\(DEAD\)\s*$/) {
                my $fn = $1;
                $fn =~ s#^/+##;
                push(@old,$fn);
        } elsif($state == 9 and /^\s*$/) {
                $state = 10;
        } elsif(($state == 9 or $state == 10) and /^-+$/) {
                &$commit();
                $state = 1;
        } elsif($state == 11 and /^-+$/) {
                $state = 1;
        } elsif(/^-+$/) { # end of unknown-line processing
                $state = 1;
        } elsif($state != 11) { # ignore stuff when skipping
                print "* UNKNOWN LINE * $_\n";
        }
}
&$commit() if $branch and $state != 11;

# Now switch back to the branch we were in before all of this happened
if($orig_branch) {
        print "DONE; switching back to $orig_branch\n" if $opt_v;
} else {
        $orig_branch = "master";
        print "DONE; creating $orig_branch branch\n" if $opt_v;
        system("cp","$git_dir/refs/heads/$opt_o","$git_dir/refs/heads/master")
                unless -f "$git_dir/refs/heads/master";
}

system("git-read-tree","-m","-u","$last_branch","$orig_branch");
die "read-tree failed: $?\n" if $?;

unlink("$git_dir/HEAD");
symlink("refs/heads/$orig_branch","$git_dir/HEAD");