#!/usr/bin/env python2.3
# $Id: sidb.py,v 1.2 2006-03-09 10:12:10-06 annis Exp $
# $Source: /u/annis/talks_articles/pythontut/RCS/sidb.py,v $

import pwd
import os
import cPickle
import re


# Local exceptions:
class SIDBTypeError(TypeError):
    pass


class InventoryItem:
  def __init__(self, hostname, opsys, user, location):
      self.hostname = hostname
      self.os = opsys
      self.user = user
      self.location = location

  def __str__(self):
      try:
          fullname = pwd.getpwnam(self.user)[4]
      except KeyError:
          fullname = "unknown user '%s'" % self.user

      return "%s (%s), used by %s in %s." % (self.hostname, self.os,
                                             fullname, self.location)


class InventoryDB:
    def __init__(self, dbfile):
        self.dbfile = dbfile
        # DB itself is list of InventoryItem instances.
        self.db = []
        # Don't save if not necessary.
        self.need_to_save = False

        if os.path.exists(dbfile):
            self.loaddb()

    def loaddb(self):
        f = open(self.dbfile, "r")
        self.db = cPickle.load(f)
        f.close()

    def savedb(self):
        if self.need_to_save:
            f = open(self.dbfile, "w")
            cPickle.dump(self.db, f)
            f.close()
            self.need_to_save = False
        
    def add(self, item):
        if not isinstance(item, InventoryItem):
            raise SIDBTypeError, "'%s' not InventoryItem" % item
        else:
            self.db.append(item)
            self.need_to_save = True

    def select_exact(self, attr, val):
        return [m for m in self.db if getattr(m, attr) == val]

    def select_match(self, attr, pattern):
        answ = []
        for item in self.db:
            match = re.search(pattern, getattr(item, attr), re.IGNORECASE)
            if match is not None:
                answ.append(item)
        return answ

    def __getitem__(self, hostname):
        return self.select_exact('hostname', hostname)

# EOF