#!/usr/bin/python
import sys, shelve
def store_person(db):
  """
  Query user for data and store it in the shelf object
  """
  pid = raw_input('Enter unique ID number:')
  person = {}
  person['name'] = raw_input('Enter name:')
  person['age'] = raw_input('Enter age:')
  person['phone'] = raw_input('Enter phone number:')
  db[pid] = person
def lookup_person(db):
  """
  Query user for ID and desired field, 
  and fetch the corresponding data 
  from the shelf object
  """
  pid = raw_input('Enter unique ID number:')
  temp = db[pid]
  field = raw_input('Please enter name, age or phone:')
  field.strip().lower()
  print field.capitalize() + ': ', temp[field]
def print_help():
  print 'The avaliable commands are:'
  print 'store  :Stores infomation about a person'
  print 'lookup  :Looks up a person form ID number'
  print 'quit   :Save changes and exit'
  print '?    :Prints this message'
def enter_command():
  cmd = raw_input('Enter command(? for help):')
  cmd = cmd.strip().lower()
  return cmd
def main():
  database = shelve.open('database')
  # database stores in current directory
  try:
    while True:
      cmd = enter_command()
      if cmd == 'store':
        store_person(database)
      elif cmd == 'lookup':
        lookup_person(database)
      elif cmd == '?':
        print_help()
      elif cmd == 'quit':
        return
  finally:
    database.close()
    # Close database in any condition
if __name__ == '__main__':
  main()