#!/usr/bin/env python
# -*- mode: python -*-

import sys
from optparse import OptionParser, IndentedHelpFormatter
from fat import FAT, FatError

class HelpFormatter(IndentedHelpFormatter):
    def format_description(self, description):
        return description

class Script:

    def __init__(self):
        self.parser = OptionParser(usage='usage: %prog [options] command args',
                                   formatter = HelpFormatter())
        self.parser.add_option('-d', '--device', dest='device', default='/dev/sdb1',
                               help='the device where your filesystem is located')
        self.parser.set_description("""Commands:
  ln SRC DEST       make a hard link from SRC to DEST. DEST must be an
                    already present empty file.

  unlink FILE       remove the directory entry associated to FILE, without
                    marking its clusters as free.""")


    def main(self):
        self.options, args = self.parser.parse_args()
        if not args:
            self.parser.error('Invalid number of arguments')
        cmd, args = args[0], args[1:]
        f = file(self.options.device, 'r+b')
        self.fat = FAT(f)
        meth = getattr(self, cmd)
        meth(args)

    def check_argnum(self, args, n):
        if len(args) != n:
            self.parser.error('Invalid number of arguments')

    def print_fat(self, args):
        self.check_argnum(args, 0)
        for i in range(16):
            print '%2x --> %2x' % (i, self.fat.read_fat(i))
        return 0

    def ln(self, args):
        self.check_argnum(args, 2)
        self.fat.hard_link(*args)

    def unlink(self, args):
        self.check_argnum(args, 1)
        self.fat.unlink(*args)

if __name__ == '__main__':
    script = Script()
    try:
        sys.exit(script.main())
    except (IOError, FatError), e:
        print >> sys.stderr, e