#! /usr/bin/env python

# linktree

#

# Make a copy of a directory tree with symbolic links to all files in the

# original tree.

# All symbolic links go to a special symbolic link at the top, so you

# can easily fix things if the original source tree moves.

# See also "mkreal".

#

# usage: mklinks oldtree newtree

import sys, os

LINK = '.LINK' # Name of special symlink at the top.

debug = 0

def main():

    if not 3 <= len(sys.argv) <= 4:

        print 'usage:', sys.argv[0], 'oldtree newtree [linkto]'

        return 2

    oldtree, newtree = sys.argv[1], sys.argv[2]

    if len(sys.argv) > 3:

        link = sys.argv[3]

        link_may_fail = 1

    else:

        link = LINK

        link_may_fail = 0

    if not os.path.isdir(oldtree):

        print oldtree + ': not a directory'

        return 1

    try:

        os.mkdir(newtree, 0777)

    except os.error, msg:

        print newtree + ': cannot mkdir:', msg

        return 1

    linkname = os.path.join(newtree, link)

    try:

        os.symlink(os.path.join(os.pardir, oldtree), linkname)

    except os.error, msg:

        if not link_may_fail:

            print linkname + ': cannot symlink:', msg

            return 1

        else:

            print linkname + ': warning: cannot symlink:', msg

    linknames(oldtree, newtree, link)

    return 0

def linknames(old, new, link):

    if debug: print 'linknames', (old, new, link)

    try:

        names = os.listdir(old)

    except os.error, msg:

        print old + ': warning: cannot listdir:', msg

        return

    for name in names:

        if name not in (os.curdir, os.pardir):

            oldname = os.path.join(old, name)

            linkname = os.path.join(link, name)

            newname = os.path.join(new, name)

            if debug > 1: print oldname, newname, linkname

            if os.path.isdir(oldname) and \

               not os.path.islink(oldname):

                try:

                    os.mkdir(newname, 0777)

                    ok = 1

                except:

                    print newname + \

                          ': warning: cannot mkdir:', msg

                    ok = 0

                if ok:

                    linkname = os.path.join(os.pardir,

                                            linkname)

                    linknames(oldname, newname, linkname)

            else:

                os.symlink(linkname, newname)

if __name__ == '__main__':

    sys.exit(main())