##
##  mkshadow -- Make a shadow tree through symbolic links
##  Copyright (c) 1998-2008 Ralf S. Engelschall <rse@engelschall.com>
##
##  This file is part of shtool and free software; you can redistribute
##  it and/or modify it under the terms of the GNU General Public
##  License as published by the Free Software Foundation; either version
##  2 of the License, or (at your option) any later version.
##
##  This file is distributed in the hope that it will be useful,
##  but WITHOUT ANY WARRANTY; without even the implied warranty of
##  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
##  General Public License for more details.
##
##  You should have received a copy of the GNU General Public License
##  along with this program; if not, write to the Free Software
##  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
##  USA, or contact Ralf S. Engelschall <rse@engelschall.com>.
##

str_tool="mkshadow"
str_usage="[-v|--verbose] [-t|--trace] [-a|--all] <src-dir> <dst-dir>"
arg_spec="2="
opt_spec="v.t.a."
opt_alias="v:verbose,t:trace,a:all"
opt_v=no
opt_t=no
opt_a=no

. ./sh.common

#   source and destination directory
src=`echo "$1" | sed -e 's:/$::' -e 's:^\./\(.\):\1:'`
dst=`echo "$2" | sed -e 's:/$::' -e 's:^\./\(.\):\1:'`

#   check whether source exists
if [ ! -d $src ]; then
    echo "$msgprefix:Error: source directory not found: \`$src'" 1>&2
    shtool_exit 1
fi

#   determine if one of the paths is an absolute path,
#   because then we have to use an absolute symlink
oneisabs=0
case $src in
    /* ) oneisabs=1 ;;
esac
case $dst in
    /* ) oneisabs=1 ;;
esac

#   determine reverse directory for destination directory
dstrevdir=''
if [ $oneisabs = 0 ]; then
    #   derive reverse path from forward path
    pwd=`pwd`
    OIFS="$IFS"; IFS='/'
    for pe in $dst; do
        if [ "x$pe" = "x.." ]; then
            OIFS2="$IFS"; IFS="$DIFS"
            eval `echo "$pwd" |\
                  sed -e 's:\([^/]*\)$:; dir="\1":' \
                      -e 's:^\(.*\)/[^/]*;:pwd="\1";:'\
                      -e 's:^;:pwd="";:'`
            dstrevdir="$dir/$dstrevdir"
            IFS="$OIFS2"
        else
            dstrevdir="../$dstrevdir"
        fi
    done
    IFS="$OIFS"
else
    src="`cd $src; pwd`";
fi

#   create directory tree at destination
if [ ! -d $dst ]; then
    if [ ".$opt_t" = .yes ]; then
        echo "mkdir $dst" 1>&2
    fi
    mkdir $dst
fi
if [ ".$opt_a" = .yes ]; then
    DIRS=`cd $src; find . -type d -print |\
          sed -e '/^\.$/d' -e 's:^\./::'`
else
    DIRS=`cd $src; find . -type d -print |\
          sed -e '/\/CVS/d' -e '/^\.$/d' -e 's:^\./::'`
fi
for dir in $DIRS; do
    if [ ".$opt_t" = .yes ]; then
        echo "mkdir $dst/$dir" 1>&2
    fi
    mkdir $dst/$dir
done

#   fill directory tree with symlinks to files
if [ ".$opt_a" = .yes ]; then
    FILES="`cd $src; find . -depth -print |\
            sed -e 's/^\.\///'`"
else
    FILES="`cd $src; find . -depth -print |\
            sed -e '/\.o$/d' -e '/\.a$/d' -e '/\.so$/d' \
                -e '/\.cvsignore$/d' -e '/\/CVS/d' \
                -e '/\/\.#/d' -e '/\.orig$/d' \
                -e 's/^\.\///'`"
fi
for file in $FILES; do
     #  don't use `-type f' above for find because of symlinks
     if [ -d "$src/$file" ]; then
         continue
     fi
     basename=`echo $file | sed -e 's:^.*/::'`
     dir=`echo $file | sed -e 's:[^/]*$::' -e 's:/$::' -e 's:$:/:' -e 's:^/$::'`
     from=`echo "$src/$file" | sed -e 's/^\.\///'`
     to="$dst/$dir$basename"
     if [ $oneisabs = 0 ]; then
         if [ ".$dir" != . ]; then
             subdir=`echo $dir | sed -e 's:/$::'`
             #   derive reverse path from forward path
             revdir=''
             OIFS="$IFS"; IFS='/'
             for pe in $subdir; do
                 revdir="../$revdir"
             done
             IFS="$OIFS"
             #   finalize from
             from="$revdir$from"
         fi
         from="$dstrevdir$from"
     fi
     if [ ".$opt_v" = .yes ]; then
         echo "    $to" 1>&2
     fi
     if [ ".$opt_t" = .yes ]; then
         echo "ln -s $from $to" 1>&2
     fi
     ln -s $from $to
done

shtool_exit 0

##
##  manual page
##

=pod

=head1 NAME

B<shtool mkshadow> - B<GNU shtool> create shadow tree using symlinks

=head1 SYNOPSIS

B<shtool mkshadow>
[B<-v>|B<--verbose>]
[B<-t>|B<--trace>]
[B<-a>|B<--all>]
I<src-dir>
I<dst-dir>

=head1 DESCRIPTION

This command creates a shadow tree of I<src-dir> under I<dst-dir> by
recreating the directory hierarchy of I<src-dir> under I<dst-dir> and by
creating the files of I<src-dir> by linking them into the corresponding
directories under I<dst-dir> via symbolic links. When I<src-dir> can
be reached via relative paths from I<dst-dir>, relative symbolic links
are used, too. This high-level functionality is originally designed for
developers to create copies of source trees.

=head1 OPTIONS

The following command line options are available.

=over 4

=item B<-v>, B<--verbose>

Display some processing information.

=item B<-t>, B<--trace>

Enable the output of the essential shell commands which are executed.

=item B<-a>, B<--all>

Really shadow all files and directories in I<src-dir>. Default is to
skip CVS related files and directories, backup files, object files, etc.

=head1 EXAMPLE

 #   shell script
 shtool mkshadow -v -a . /tmp/shadow

=head1 HISTORY

The B<GNU shtool> B<mkshadow> command was originally written by Ralf S.
Engelschall E<lt>rse@engelschall.comE<gt> in 1998 for B<Apache>. It was
later revised and taken over into B<GNU shtool>.

=head1 SEE ALSO

shtool(1), ln(1).

=cut