#!/usr/bin/perl
# Copyright 2008-2002 Timo Sirainen
# Last updated: 2021-11-10

# NOTE: Requires Dovecot v2.0.13+ for POP3 'O' entries

# Based largely on courier-dovecot-migrate.pl v1.1.8:
# cpanel12 - maildir-migrate                      Copyright(c) 2008 cPanel, Inc.
#                                                           All Rights Reserved.
# copyright@cpanel.net                                         http://cpanel.net

# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#     * Redistributions of source code must retain the above copyright
#       notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above copyright
#       notice, this list of conditions and the following disclaimer in the
#       documentation and/or other materials provided with the distribution.
#     * Neither the name of the cPanel, Inc. nor the
#       names of its contributors may be used to endorse or promote products
#       derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY CPANEL, INC. "AS IS" AND ANY
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL CPANEL, INC BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

use strict;
use warnings;
use Getopt::Long ();

# Key files in maildirs
my $courier_imap_uidfile       = 'courierimapuiddb';
my $courier_pop3_uidfile       = 'courierpop3dsizelist';
my $courier_subscriptions_file = 'courierimapsubscribed';
my $courier_keywords_dir       = 'courierimapkeywords/';
my $courier_keywords_file      = 'courierimapkeywords/:list';
my $dovecot_uidfile            = 'dovecot-uidlist';
my $dovecot_uidvalidity_file   = 'dovecot-uidvalidity';
my $dovecot_subscriptions_file = 'subscriptions';
my $dovecot_keywords_file      = 'dovecot-keywords';

# Globals
my $do_conversion = 0;
my $quiet         = 0;
my $recursive     = 0;
my $overwrite     = 0;

my $depth                     = 1;
my $maildir_subdirs           = -1;
my $global_error_count        = 0;
my $global_mailbox_count      = 0;
my $global_user_count         = 0;
my $uidlist_write_count       = 0;
my $convert_to_dovecot        = 0;
my $convert_to_courier        = 0;
my $help                      = 0;
my $maildir_name              = 'Maildir';

# Argument processing
my %opts = (
    'convert'    => \$do_conversion,
    'quiet'      => \$quiet,
    'overwrite'  => \$overwrite,
    'recursive'  => \$recursive,
    'to-dovecot' => \$convert_to_dovecot,
    'to-courier' => \$convert_to_courier,
    'help'       => \$help,
);

Getopt::Long::GetOptions(%opts);
usage() if $help;

my $mailroot = shift @ARGV || '.';

my $conversion_type;
if ( $convert_to_dovecot && $convert_to_courier ) {
    print "It is not possible to convert to both Dovecot and Courier formats simultaneously!\n";
    exit 1;
}
else {
    print $do_conversion ? 'Converting' : 'Testing conversion' unless $quiet;

    if ($convert_to_courier) {
        print " to Courier format\n" unless $quiet;
        $conversion_type = 'courier';
    }
    elsif ($convert_to_dovecot) {
        print " to Dovecot format\n" unless $quiet;
        $conversion_type = 'dovecot';
    }
    else {
        print " based on newest timestamps\n" unless $quiet;
        $conversion_type = 'auto';
    }
}

# Check/Convert maildirs
print "Finding maildirs under $mailroot\n" if ( !$quiet );
if ( is_maildir($mailroot) ) {
    check_maildir($mailroot);
}
elsif ( -d "$mailroot/$maildir_name" ) {
    if ( !is_maildir("$mailroot/$maildir_name") ) {
        print STDERR "$mailroot/$maildir_name doesn't seem to contain a valid Maildir\n";
    }
    else {
        check_maildir("$mailroot/$maildir_name");
    }
}
elsif ($recursive) {
    if ( $depth > 0 || !userdir_check($mailroot) ) {
        $depth-- if ( $depth > 0 );
        if ( !depth_check( $mailroot, $depth ) ) {
            print STDERR "No maildirs found\n";
            exit;
        }
    }
}

# Totals
if ( !$quiet ) {
    print "\nTotal: $global_mailbox_count mailboxes / $global_user_count users\n";
    print "       $global_error_count errors\n";

    if ( !$do_conversion ) {
        print "No actual conversion done, use --convert parameter\n";
    }
    else {
        print "$uidlist_write_count $dovecot_uidfile files written\n";
    }
    print "\nWARNING: Badly done migration will cause your IMAP and/or POP3 clients to re-download all mails. Read http://wiki.dovecot.org/Migration carefully.\n";
}

sub scan_maildir {
    my ( $dir, $map ) = @_;

    my @scan_maildir_files;
    if ( opendir my $scan_maildir_dh, $dir ) {
        @scan_maildir_files = readdir($scan_maildir_dh);
        closedir $scan_maildir_dh;
    }
    foreach my $real_filename (@scan_maildir_files) {
        next if ( $real_filename eq "." || $real_filename eq ".." );

        my $base_filename;
        if ( $real_filename =~ /^([^:]+):2,/ ) {
            $base_filename = $1;
        }
        else {
            $base_filename = $real_filename;
        }
        $$map{$base_filename} = $real_filename;
    }
}

sub read_courier_pop3 {
    my ( $dir ) = @_;

    my ( $pop3_uidv, $pop3_nextuid ) = ( -1, 0 );
    my $filename_map = {};

    my $f;
    my $pop3_fname = "$dir/$courier_pop3_uidfile";
    open( $f, $pop3_fname ) || die $!;
    my $pop3_hdr = <$f>;
    if ( $pop3_hdr =~ /^\/2 (\d+) (\d+)$/ ) {
        # /2 <next uid> <uidvalidity>
        $_ = <$f>;
    }
    elsif ( $pop3_hdr =~ /^\/3 (\d+) (\d+)$/ ) {
        # /3 <next uid> <uidvalidity>
        $_ = <$f>;
    }
    elsif ( $pop3_hdr =~ /^\/1 (\d+)$/ ) {
        # /1 <next uid>
        $_ = <$f>;
    }
    elsif ( $pop3_hdr !~ /^\// ) {
        # version 0: no UIDs
        $_ = $pop3_hdr;
    }
    else {
        print STDERR "$pop3_fname: Broken header: $pop3_hdr\n";
        close $f;
        return $filename_map;
    }

    my $line = 0;
    do {
        chomp $_;
	$line++;
        
        my ( $full_fname, $fsize, $uid, $uidv );
        
        if ( /^([^ ]+) (\d+) (\d+):(\d+):\d$/ ) {
            # v3
            ( $full_fname, $fsize, $uid, $uidv ) = ( $1, $2, $3, $4 );
        }
        elsif ( /^([^ ]+) (\d+) (\d+):(\d+)$/ ) {
            # v2
            ( $full_fname, $fsize, $uid, $uidv ) = ( $1, $2, $3, $4 );
        }
        elsif ( /^([^ ]+) (\d+) (\d+)$/ ) {
            # v1
            ( $full_fname, $fsize, $uid ) = ( $1, $2, $3 );
            $uidv = 0;
        }
        elsif ( /^([^ ]+) (\d+)$/ ) {
            # v0
            ( $full_fname, $fsize ) = ( $1, $2 );
            $uid = 0;
            $uidv = 0;
        }
        else {
            $global_error_count++;
            print STDERR "$pop3_fname: Broken line: $_\n";
            next;
        }

        # get base filename
        my $fname = $full_fname;
        $fname =~ s/^([^:]+).*$/$1/;

        my $uidl = "";
        if ( $uid == 0 ) {
            # use filename
            foreach (split(//, $fname)) {
                if (ord($_) < 0x21 || ord($_) > 0x7e || $_ eq "'" || $_ eq '"' || $_ eq "+") {
                    $uidl .= sprintf("+%02X", ord($_));
                } else {
                    $uidl .= $_;
                }
            }
        }
        elsif ($uidv != 0) {
            $uidl = "UID$uid-$uidv";
        }
        else {
            $uidl = "UID$uid";
        }
        $filename_map->{$fname} = [ 0, $uidl, $fsize, $full_fname, $line ];
    } while (<$f>);
    close $f;
    return $filename_map;
}

sub read_courier_imap {
    my ( $dir, $filename_map ) = @_;

    # check if we can preserve IMAP UIDs
    my $imap_fname = "$dir/$courier_imap_uidfile";
    if ( !-f $imap_fname ) {
        print "$imap_fname: OK\n" if ( !$quiet );
        return;
    }

    my $f;
    open( $f, $imap_fname ) || die $!;
    my $imap_hdr = <$f>;
    if ( $imap_hdr !~ /^1 (\d+) (\d+)$/ ) {
        $global_error_count++;
        print STDERR "$imap_fname: Broken header: $imap_hdr\n";
        close $f;
        return;
    }
    my ( $uidv, $nextuid ) = ( $1, $2 );

    my %found_files;
    my $found_files_looked_up = 0;
    while (<$f>) {
        chomp $_;

        if (/^(\d+) (.*)$/) {
            my ( $uid, $full_fname ) = ( $1, $2 );

            # get the base filename
            my $fname = $full_fname;
            $fname =~ s/^([^:]+).*$/$1/;

            if ( defined $filename_map->{$fname} ) {
                $filename_map->{$fname}->[0] = $uid;
            }
            else {
                # not in pop3 list
                $filename_map->{$fname} = [ $uid, "", 0, $full_fname, 0 ];
            }
            $nextuid = $uid + 1 if ($uid >= $nextuid);
        }
        else {
            $global_error_count++;
            print STDERR "$imap_fname: Broken header\n";
        }
    }
    close $f;

    return ( $uidv, $nextuid, $filename_map );
}

sub write_dovecot_uidlist {
    my ( $dir, $uidv, $nextuid, $owner_uid, $owner_gid, $filename_map ) = @_;
    
    my $uidlist_fname = "$dir/$dovecot_uidfile";
    if ( !$overwrite && -f $uidlist_fname ) {
        print "$uidlist_fname already exists, not overwritten\n" if ( !$quiet );
        return;
    }
    return if (scalar keys %{$filename_map} == 0);
    
    return if ( !$do_conversion );

    if ($uidv <= 0) {
        # only pop3 UIDLs, generate a new uidvalidity
        $uidv = time();
    }
    
    # POP3 clients may want to get POP3 UIDLs in the same order always.
    # Preserve the order with O flag supported in dovecot 2.0.13+ and dont change order of IMAP UIDs.
    my %order_map;
    foreach my $fname ( keys %{$filename_map} ) {
        my $order = $filename_map->{$fname}->[4];
	$filename_map->{$fname}->[5]=$order;
    }

    my $prev_uid = 0;
    foreach my $order ( sort { $a <=> $b } keys %order_map ) {
        my $file_ar = $filename_map->{ $order_map{$order} };
        if ($file_ar->[0] == 0) {
            $file_ar->[0] = $nextuid;
            $nextuid++;
        }

        if ($file_ar->[0] <= $prev_uid) {
            $file_ar->[0] = 0;
        } else {
            $prev_uid = $file_ar->[0];
        }
    }
    
    # sort all messages by their imap UID
    my @all =  sort {
       ($filename_map->{$a}[0] || 'inf') <=> ($filename_map->{$b}[0] || 'inf')
    } keys %$filename_map;

    $prev_uid = 0;
    my %uidlist_map;
    foreach my $fname ( @all ) {
        my $file_ar = $filename_map->{ $fname };
        my $uid = $file_ar->[0];
        if ($uid == 0 # only in pop3 list or marked for new UID
            # OR: other ill-ordered UID message
            || $uid <= $prev_uid)
        {
            # Assign a new IMAP UID:
            $uid = $nextuid;
            $nextuid++;
        }
        $prev_uid = $uid;
        $uidlist_map{$uid} = $fname;
    }

    open( my $dovecot_uidlist_fh, '>', $uidlist_fname ) || die $!;
    print $dovecot_uidlist_fh "3 V$uidv N$nextuid\n";
    foreach my $uid ( sort { $a <=> $b } keys %uidlist_map ) {
        my $file_ar = $filename_map->{ $uidlist_map{$uid} };
        print $dovecot_uidlist_fh "$uid ";
	if ($file_ar->[5]) {
		print $dovecot_uidlist_fh "O".$file_ar->[5]." ";
	}
        print $dovecot_uidlist_fh 'P' . $file_ar->[1] . ' ' if ( $file_ar->[1] ne "" );
        print $dovecot_uidlist_fh 'W' . $file_ar->[2] . ' ' if ( $file_ar->[2] > 0 );
        print $dovecot_uidlist_fh ':' . $file_ar->[3] . "\n";
    }
    close $dovecot_uidlist_fh;
    chown $owner_uid, $owner_gid, $uidlist_fname;
    $uidlist_write_count++;
}

sub convert_keywords {
    my ( $dir, $owner_uid, $owner_gid ) = @_;

    my $courier_mtime = ( stat("$dir/$courier_keywords_file") )[9] || 0;
    my $dovecot_mtime = ( stat("$dir/$dovecot_keywords_file") )[9] || 0;

    # No need to convert if there are no keywords files
    return unless ( $courier_mtime || $dovecot_mtime );

    # If we're doing auto-conversion, find the newest keywords file
    my $convert_to = $conversion_type;
    if ( $convert_to eq 'auto' ) {
        $convert_to = $dovecot_mtime > $courier_mtime ? 'courier' : 'dovecot';
    }

    if ( $convert_to eq 'dovecot' ) {
        # Courier to Dovecot keyword conversion
        my $keyword_dir      = "$dir/courierimapkeywords";
        my $dovecot_keyfname = "$dir/dovecot-keywords";

        if ( !-f "$keyword_dir/:list" ) {

            # no keywords
            return;
        }

        if ( !$overwrite && -f $dovecot_keyfname ) {
            print "$dovecot_keyfname already exists, not overwritten\n" if ( !$quiet );
            return;
        }

        my ( %keywords, %files );
        my $f;
        open( $f, "$keyword_dir/:list" ) || die $!;

        # read keyword names
        while (<$f>) {
            chomp $_;

            last if (/^$/);
            $keywords{$_} = scalar keys %keywords;
        }

        # read filenames -> keywords mapping
        while (<$f>) {
            if (/([^:]+):([\d ]+)$/) {
                my $fname = $1;
                foreach ( sort { $a <=> $b } split( " ", $2 ) ) {
                    $files{$fname} .= chr( 97 + $_ );
                }
            }
            else {
                print STDERR "$keyword_dir/:list: Broken entry: $_\n";
            }
        }
        close $f;

        # read updates from the directory
        my %updates;
        my @update_files;
        if ( opendir my $kw_dh, $keyword_dir ) {
            @update_files = readdir($kw_dh);
            closedir $kw_dh;
        }
        foreach (@update_files) {
            next if ( $_ eq ":list" || $_ eq "." || $_ eq ".." );

            my $fname = $_;
            if (/^\.(\d+)\.(.*)$/) {
                my ( $num, $base_fname ) = ( $1, $2 );
                if ( !defined $updates{$fname} ) {
                    $updates{$fname} = $num;
                }
                else {
                    my $old = $updates{$fname};
                    if ( $old >= 0 && $num > $old ) {
                        $updates{$fname} = $num;
                    }
                }
            }
            else {

                # "fname" overrides .n.fnames
                $updates{$fname} = -1;
            }
        }

        # apply the updates
        foreach ( keys %updates ) {
            my $base_fname = $_;
            my $num        = $updates{$_};

            my $fname;
            if ( $num < 0 ) {
                $fname = $base_fname;
            }
            else {
                $fname = ".$num.$base_fname";
            }

            my @kw_list;
            open( $f, "$keyword_dir/$fname" ) || next;
            while (<$f>) {
                chomp $_;
                my $kw = $_;
                my $idx;

                if ( defined $keywords{$kw} ) {
                    $idx = $keywords{$kw};
                }
                else {
                    $idx = scalar keys %keywords;
                    $keywords{$kw} = $idx;
                }
                $kw_list[ scalar @kw_list ] = $idx;
            }
            close $f;

            $files{$fname} = "";
            foreach ( sort { $a <=> $b } @kw_list ) {
                $files{$fname} .= chr( 97 + $_ );
            }
        }

        return if ( !$do_conversion );

        # write dovecot-keywords file
        open( $f, ">$dovecot_keyfname" ) || die $!;
        foreach ( sort { $keywords{$a} <=> $keywords{$b} } keys %keywords ) {
            my $idx = $keywords{$_};
            print $f "$idx $_\n";
        }
        close $f;
        chown $owner_uid, $owner_gid, $dovecot_keyfname;

        # update the maildir files
        my $cur_dir = "$dir/cur";
        my @cur_files;
        if ( opendir my $cur_dir_dh, $cur_dir ) {
            @cur_files = readdir($cur_dir_dh);
            closedir $cur_dir_dh;
        }
        foreach (@cur_files) {
            my $fname = $cur_dir . '/' . $_;

            my ( $base_fname, $flags, $extra_flags );
            if (/^([^:]+):2,([^,]*)(,.*)?$/) {
                ( $base_fname, $flags, $extra_flags ) = ( $1, $2, $3 );
                $extra_flags = "" if ( !defined $extra_flags );
            }
            else {
                $base_fname  = $fname;
                $flags       = "";
                $extra_flags = "";
            }

            if ( defined $files{$base_fname} ) {

                # merge old and new flags
                my %newflags;
                foreach ( sort split( "", $files{$base_fname} ) ) {
                    $newflags{$_} = 1;
                }
                foreach ( sort split( "", $flags ) ) {
                    $newflags{$_} = 1;
                }
                $flags = "";
                foreach ( sort keys %newflags ) {
                    $flags .= $_;
                }
                my $new_fname = "$cur_dir/$base_fname:2,$flags$extra_flags";
                if ( $fname ne $new_fname ) {
                    rename( $fname, $new_fname )
                      || print STDERR "rename($fname, $new_fname) failed: $!\n";
                }
            }
        }
    }
    else {

        # Dovecot to Courier keywords conversion
        return unless $dovecot_mtime;

        if ( !$overwrite && -f "$dir/$courier_keywords_file" ) {
            print "$courier_keywords_file already exists, not overwritten\n" if ( !$quiet );
            return;
        }

        # Read Dovecot keywords list into memory
        open my $dovecot_kw_fh, '<', "$dir/$dovecot_keywords_file" || die $!;
        my %keywords;
        while ( my $line = readline($dovecot_kw_fh) ) {
            chomp $line;
            if ( $line =~ /(\d+)\s+(.+)/ ) {

                # Number then Keyword
                $keywords{$1} = $2;
            }
        }
        close $dovecot_kw_fh;

        # Scan files in cur for keywords
        my $cur_dir = "$dir/cur";
        my %file_keyword_map;

        my @cur_files;
        if ( opendir my $cur_dir_dh, $cur_dir ) {
            @cur_files = readdir($cur_dir_dh);
            closedir $cur_dir_dh;
        }
        foreach my $basename (@cur_files) {
            my $flags;
            my $extra_flags;
            my $keywords = '';

            # Split out and process flags
            if ( $basename =~ /^([^:]+):2,([^,]*)(,.*)?$/ ) {
                ( $basename, $flags, $extra_flags ) = ( $1, $2, $3 );
                $extra_flags = "" unless ( defined $extra_flags );
            }
            else {
                $basename    = "";
                $flags       = "";
                $extra_flags = "";
            }
            foreach my $key ( sort split( //, $flags ) ) {
                my $val = ord($key) - 97;
                next unless ( $val >= 0 && $val < 26 );
                next unless ( defined $keywords{$val} );
                $keywords .= ' ' . $val;
            }
            if ($keywords) {
                $keywords =~ s/^\s+//;
                $file_keyword_map{$basename} = $keywords;
            }
        }

        return unless ($do_conversion);

        # Make courier keywords directory if necessary
        my $key_dir = "$dir/$courier_keywords_dir";
        unless ( -d $key_dir ) {
            unlink $key_dir;
            mkdir $key_dir;
            chown $owner_uid, $owner_gid, $key_dir;
        }

        # Remove any old courier keywords files
        my @courier_keywords_files;
        if ( opendir my $courier_keywords_dh, $key_dir ) {
            @courier_keywords_files = readdir($courier_keywords_dh);
            closedir $courier_keywords_dh;
        }
        foreach my $file (@courier_keywords_files) {
            $file = $key_dir . $file;
            next unless -f $file;
            unlink $file;
        }

        # Write courier keywords list
        return unless ( scalar %keywords );
        open my $courier_kw_fh, '>', "$dir/$courier_keywords_file" || die $!;
        foreach my $num ( sort keys %keywords ) {
            print $courier_kw_fh $keywords{$num} . "\n";
        }
        print $courier_kw_fh "\n";
        foreach my $file ( sort keys %file_keyword_map ) {
            print $courier_kw_fh $file . ':' . $file_keyword_map{$file} . "\n";
        }
        close $courier_kw_fh;
        chown $owner_uid, $owner_gid, "$dir/$courier_keywords_file";
    }
}

sub convert_subscriptions {
    my ( $dir, $owner_uid, $owner_gid ) = @_;

    my $courier_mtime = ( stat("$dir/$courier_subscriptions_file") )[9] || 0;
    my $dovecot_mtime = ( stat("$dir/$dovecot_subscriptions_file") )[9] || 0;

    # No need to convert if there is no subscriptions files
    return unless ( $courier_mtime || $dovecot_mtime );

    # If we're doing auto-conversion, find the newest subscription file
    my $convert_to = $conversion_type;
    if ( $convert_to eq 'auto' ) {
        $convert_to = $dovecot_mtime > $courier_mtime ? 'courier' : 'dovecot';
    }

    my $src_file  = "$dir/$dovecot_subscriptions_file";
    my $dst_file  = "$dir/$courier_subscriptions_file";
    my $src_mtime = $dovecot_mtime;
    my $dst_mtime = $courier_mtime;
    if ( $convert_to eq 'dovecot' ) {
        $src_file  = "$dir/$courier_subscriptions_file";
        $dst_file  = "$dir/$dovecot_subscriptions_file";
        $src_mtime = $courier_mtime;
        $dst_mtime = $dovecot_mtime;
    }

    # Sanity checks..
    if ( $dst_mtime && !$overwrite ) {
        print "$dst_file already exists, not overwritten\n" if ( !$quiet );
        return;
    }
    if ( $dst_mtime && !-f $dst_file ) {
        print "$dst_file already exists as something other than a file\n" if ( !$quiet );
        return;
    }
    unless ($src_mtime) {
        return;
    }
    unless ( -f $src_file ) {
        print "$src_file isn't a regular file\n" if ( !$quiet );
        return;
    }

    return unless ($do_conversion);

    open( my $src_fh, '<', $src_file ) || die $!;
    open( my $dst_fh, '>', $dst_file ) || die $!;
    while ( my $line = readline($src_fh) ) {
        chomp $line;
        if ( $line =~ /^INBOX$/i ) {
            print $dst_fh "INBOX\n";
        }
        elsif ( $convert_to eq 'dovecot' ) {
            if ( $line =~ /^INBOX\.(.*)$/i ) {
                print $dst_fh "$1\n";
            }
            else {

                # Unknown. The dovecot migrate script leaves these as-is...
                print $dst_fh "$line\n";
            }
        }
        else {

            # converting to Courier INBOX namespace
            if ( $line =~ /\S/ ) {
                print $dst_fh "INBOX.$line\n";
            }
        }
    }
    close $src_fh;
    close $dst_fh;
    chown $owner_uid, $owner_gid, $dst_file;
}

sub check_maildir_single {
    my ( $dir, $childbox ) = @_;

    $dir =~ s{^\./}{}g;

    my $owner_uid;
    my $owner_gid;

    # Store the relevant stats()
    my @courier_pop_stat = ();
    @courier_pop_stat = stat("$dir/$courier_pop3_uidfile") unless $childbox;
    my @courier_imap_stat = stat("$dir/$courier_imap_uidfile");
    my @dovecot_stat      = stat("$dir/$dovecot_uidfile");

    # Gather mtimes
    my $courier_pop_mtime  = ( scalar @courier_pop_stat > 0 )  ? $courier_pop_stat[9]  : 0;
    my $courier_imap_mtime = ( scalar @courier_imap_stat > 0 ) ? $courier_imap_stat[9] : 0;
    my $dovecot_mtime      = ( scalar @dovecot_stat > 0 )      ? $dovecot_stat[9]      : 0;

    # Determine conversion type
    my $convert_uidl_to = $conversion_type;

    if ( $convert_uidl_to eq 'auto' ) {
        $convert_uidl_to = $dovecot_mtime > $courier_pop_mtime && $dovecot_mtime > $courier_imap_mtime ? 'courier' : 'dovecot';
    }

    # Convert UIDLs

    if ( $convert_uidl_to eq 'dovecot' ) {

        # To Dovecot
        unless ( $courier_pop_mtime || $courier_imap_mtime ) {
            print "$dir: No imap/pop3 uidlist files\n" if ( !$quiet && !$childbox );
            return;
        }

        $owner_uid = $courier_pop_mtime ? $courier_pop_stat[4] : $courier_imap_stat[4];
        $owner_gid = $courier_pop_mtime ? $courier_pop_stat[5] : $courier_imap_stat[5];

        my $uidv    = -1;
        my $nextuid = 1;
        my $filename_map;

        if ( $courier_pop_mtime) {
            $filename_map = read_courier_pop3( $dir );
        }

        if ($courier_imap_mtime) {
            ( $uidv, $nextuid, $filename_map ) = read_courier_imap( $dir, $filename_map );
        }
	$global_mailbox_count++;
	write_dovecot_uidlist( $dir, $uidv, $nextuid, $owner_uid, $owner_gid, $filename_map );
        remove_dovecot_caches($dir) if ($overwrite);
    }
    else {

        # To Courier
        unless ($dovecot_mtime) {
            print "$dir: No imap/pop3 uidlist files\n" if ( !$quiet && !$childbox );
            return;
        }

        $owner_uid = $dovecot_stat[4];
        $owner_gid = $dovecot_stat[5];
        my ( $uidv, $nextuid, $msguids ) = read_dovecot_uidfile($dir);
        if ($uidv) {
            write_courier_pop3( $dir, $uidv, $nextuid, $owner_uid, $owner_gid, $msguids );
            write_courier_imap( $dir, $uidv, $nextuid, $owner_uid, $owner_gid, $msguids );
        }
    }

    # If we get here we did a UIDL conversion.  Now convert subscriptions and keywords

    convert_subscriptions( $dir, $owner_uid, $owner_gid );
    convert_keywords( $dir, $owner_uid, $owner_gid );
}

sub remove_dovecot_caches {
    my $dir = shift;
    foreach my $file ( qw(dovecot.index dovecot.index.cache dovecot.index.log dovecot.index.log2), $dovecot_uidvalidity_file ) {
        unlink $dir . '/' . $file;
    }
    unlink glob( $dir . '/' . $dovecot_uidvalidity_file . '.*' );
}

sub read_dovecot_uidfile {
    my $dir             = shift;
    my $dovecot_uidfile = "$dir/$dovecot_uidfile";

    my $uidv;
    my $nextuid = 1;
    my $dovecot_uid_version;
    my @msguids;

    if ( !-f $dovecot_uidfile ) {
        print "$dovecot_uidfile: OK\n" if ( !$quiet );
        return;
    }

    my $dovecot_uid_fh;
    open( $dovecot_uid_fh, '<', $dovecot_uidfile ) || die $!;
    my $dovecot_hdr = readline($dovecot_uid_fh);
    if ( $dovecot_hdr =~ /^3\s+(.+)$/ ) {
        my $options = $1;
        $dovecot_uid_version = 3;
        foreach my $part ( split( /\s+/, $options ) ) {
            if ( $part =~ /(\w)(.+)/ ) {
                my $type = $1;
                my $val  = $2;
                if ( $type eq 'V' ) {
                    $uidv = $val;
                }
                elsif ( $type eq 'N' ) {
                    $nextuid = $val;
                }
            }
        }

        unless ($uidv) {
            $global_error_count++;
            print STDERR "$dovecot_uidfile: Broken header: $dovecot_hdr\n";
            close $dovecot_uid_fh;
            return;
        }
    }
    elsif ( $dovecot_hdr =~ /^1\s+(\S+)\s+(\S+)$/ ) {
        $dovecot_uid_version = 1;
        $uidv                = $1;
        $nextuid             = $2;
    }
    else {
        $global_error_count++;
        print STDERR "$dovecot_uidfile: Broken header: $dovecot_hdr\n";
        close $dovecot_uid_fh;
        return;
    }

    while ( my $line = readline($dovecot_uid_fh) ) {

        chomp $line;
        my @prts = split( /\s+/, $line );

        if ( $dovecot_uid_version eq '3' ) {
            next unless ( scalar @prts >= 2 );
            my $msgnum   = shift @prts;
            my $filename = pop @prts;
            $filename =~ s/^\://;
            my $msgsize;

            # Dovecot may or may not store the sizes for each message in the uidl file
            # S# is the size with UNIX newlines, W# is the size with windows newlines
          SIZE_LOOP:
            foreach my $subprt (@prts) {
                if ( $subprt =~ s/^W// ) {
                    $msgsize = $subprt;
                    last SIZE_LOOP;
                }
            }
            push @msguids, [ $msgnum, $filename, $msgsize ];
            $nextuid = $msgnum + 1 if ( $msgnum >= $nextuid );
        }
        else {

            # process V1 data
            next unless ( scalar @prts == 2 );
            push @msguids, [ $prts[0], $prts[1], undef ];
            $nextuid = $prts[0] + 1 if ( $prts[0] >= $nextuid );
        }
    }

    return ( $uidv, $nextuid, \@msguids );
}

sub write_courier_pop3 {
    my $dir       = shift;
    my $uidv      = shift;
    my $nextuid   = shift;
    my $owner_uid = shift;
    my $owner_gid = shift;
    my $msguids   = shift;

    # Check file/overwrite/conversion
    my $uidlist_fname = "$dir/$courier_pop3_uidfile";
    if ( !$overwrite && -f $uidlist_fname ) {
        print "$uidlist_fname already exists, not overwritten\n" if ( !$quiet );
        return;
    }

    return if ( !$do_conversion );

    # Check that all entries have sizes..  We don't write the pop3 file if we can't do so correctly
    foreach my $msg_ar ( @{$msguids} ) {
        unless ( defined $msg_ar->[2] ) {
            print "Missing some sizes for $uidlist_fname, skipping\n" if ( !$quiet );
            return;
        }
    }

    # Write file
    open( my $courier_pop_fh, '>', $uidlist_fname ) || die $!;
    print $courier_pop_fh "/2 $nextuid $uidv\n";
    foreach my $msg_ar ( @{$msguids} ) {
        print $courier_pop_fh $msg_ar->[1] . ' ' . $msg_ar->[2] . ' ' . $msg_ar->[0] . ':' . $uidv . "\n";
    }
    close $courier_pop_fh;
    chown $owner_uid, $owner_gid, $uidlist_fname;
    $uidlist_write_count++;

}

sub write_courier_imap {
    my $dir       = shift;
    my $uidv      = shift;
    my $nextuid   = shift;
    my $owner_uid = shift;
    my $owner_gid = shift;
    my $msguids   = shift;

    # Check file/overwrite/conversion
    my $uidlist_fname = "$dir/$courier_imap_uidfile";
    if ( !$overwrite && -f $uidlist_fname ) {
        print "$uidlist_fname already exists, not overwritten\n" if ( !$quiet );
        return;
    }

    return if ( !$do_conversion );

    # Write file
    open( my $courier_imap_fh, '>', $uidlist_fname ) || die $!;
    print $courier_imap_fh "1 $uidv $nextuid\n";
    foreach my $msg_ar ( @{$msguids} ) {
        my $filename = $msg_ar->[1];
        $filename =~ s/\:2.*$//;
        print $courier_imap_fh $msg_ar->[0] . ' ' . $filename . "\n";
    }
    close $courier_imap_fh;
    chown $owner_uid, $owner_gid, $uidlist_fname;
    $uidlist_write_count++;

}

sub check_maildir {
    my ($dir) = @_;

    my $orig_mailboxes = $global_mailbox_count;

    check_maildir_single( $dir, 0 );
    my @check_maildir_files;
    if ( opendir my $check_maildir_dh, $dir ) {
        @check_maildir_files = readdir($check_maildir_dh);
        closedir $check_maildir_dh;
    }
    foreach my $file (@check_maildir_files) {
        next unless ( $file =~ /^\./ );
        next if ( $file =~ /^\.?\.$/ );
        $file = $dir . '/' . $file;
        next if ( -l $file );
        check_maildir_single( $file, 1 );
    }

    $global_user_count++ if ( $orig_mailboxes != $global_mailbox_count );
}

sub is_maildir {
    my ($dir) = @_;

    # Do we need to check for the courier specific files here or is it enough to assume every maildir will have a cur directory?
    return ( -f "$dir/$courier_pop3_uidfile" || -f "$dir/$courier_imap_uidfile" || -d "$dir/cur" );
}

sub userdir_check {
    my ($dir) = @_;
    my $found = 0;

    my @userdir_check_files;
    if ( opendir my $userdir_dh, $dir ) {
        @userdir_check_files = readdir($userdir_dh);
        closedir $userdir_dh;
    }
    foreach my $userdir (@userdir_check_files) {
        $userdir = $dir . '/' . $userdir;
        next if ( -l $userdir );
        next if ( !-d $userdir );

        if ( $maildir_subdirs == -1 ) {

            # unknown if we want $maildir_name/ or not
            if ( -d "$userdir/$maildir_name" && is_maildir("$userdir/$maildir_name") ) {
                $maildir_subdirs = 1;
            }
            elsif ( is_maildir($userdir) ) {
                $maildir_subdirs = 0;
            }
            else {
                next;
            }
        }

        if ( $maildir_subdirs == 1 ) {
            if ( is_maildir("$userdir/$maildir_name") ) {
                check_maildir("$userdir/$maildir_name");
                $found = 1;
            }
        }
        elsif ( $maildir_subdirs == 0 ) {
            if ( is_maildir($userdir) ) {
                check_maildir($userdir);
                $found = 1;
            }
        }
    }
    return $found;
}

sub depth_check {
    my ( $dir, $depth ) = @_;
    my $found = 0;

    my @depth_check_files;
    if ( opendir my $depth_check_dh, $dir ) {
        @depth_check_files = readdir($depth_check_dh);
        closedir $depth_check_dh;
    }
    foreach my $subdir (@depth_check_files) {
        next if ($subdir eq '.' || $subdir eq '..');
        $subdir = $dir . '/' . $subdir;
        next if ( !-d $subdir );

        if ( $depth > 0 ) {
            $found = 1 if ( depth_check( $subdir, $depth - 1 ) );
        }
        else {
            $found = 1 if ( userdir_check($subdir) );
        }
    }
    return $found;
}

sub usage {
    print "Usage: maildir-migrate [options] <maildir>\n\n";
    print "Options:\n";
    print "    --convert       Perform conversion\n";
    print "    --quiet         Silence output\n";
    print "    --overwrite     Overwrite existing files\n";
    print "    --recursive     Recursively look through maildir for subaccounts\n";
    print "    --to-dovecot    Conversion is from Courier to Dovecot\n";
    print "    --to-courier    Conversion is from Dovecot to Courier\n";
    exit 0;
}