#!/usr/bin/python2.5

#

# Copyright 2008 the Melange authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#   http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""Functions for composing Model entity key names.

"""

__authors__ = [

  '"Todd Larsen" <tlarsen@google.com>',

  '"Pawel Solyga" <pawel.solyga@gmail.com>',

  ]

# start with ASCII digit or lowercase

#   (additional ASCII digit or lowercase

#     -OR-

#   underscore and ASCII digit or lowercase)

#     zero or more of OR group

LINKNAME_PATTERN_CORE = r'[0-9a-z](?:[0-9a-z]|_[0-9a-z])*'

LINKNAME_PATTERN = r'^%s$' % LINKNAME_PATTERN_CORE

LINKNAME_ARG_PATTERN = r'(?P<linkname>%s)' % LINKNAME_PATTERN_CORE

# partial path is multiple linkname chunks,

#   each separated by a trailing /

#     (at least 1)

# followed by a single linkname with no trailing /

WORK_PATH_LINKNAME_ARGS_PATTERN = (

    r'(?P<partial_path>%(linkname)s(?:/%(linkname)s)*)/'

     '(?P<linkname>%(linkname)s)' % {

        'linkname': LINKNAME_PATTERN_CORE})

WORK_PATH_LINKNAME_PATTERN = r'^%s$' % WORK_PATH_LINKNAME_ARGS_PATTERN

class Error(Exception):

  """Base class for all exceptions raised by this module."""

  pass

def getFullClassName(cls):

  """Returns fully-qualified module.class name string.""" 

  return '%s.%s' % (cls.__module__, cls.__name__) 

def combinePath(path_parts):

  """Returns path components combined into a single string.

  Args:

    path_parts: a single path string, or a list of path part strings,

      or a nested list of path part strings (where the zeroeth element in

      the list is itself a list); for example:

        'a/complete/path/in/one/string'

        ['some', 'path', 'parts']

        [['path', 'parts', 'and', 'a'], 'link name']

  Returns:

    None if path_parts is False (None, empty string, etc.) or if

    any list elements are False (an empty list, empty string, etc.);

    otherwise, the combined string with the necessary separators.

  """

  if not path_parts:

    # completely empty input, so return early

    return None

  if not isinstance(path_parts, (list, tuple)):

    # a single path string, so just return it as-is (nothing to do)

    return path_parts

  flattened_parts = []

  for part in path_parts:

    if not part:

      # encountered a "False" element, which invalidates everything else

      return None    

    if isinstance(part, (list, tuple)):

      flattened_parts.extend(part)

    else:

      flattened_parts.append(part)

  return '/'.join(flattened_parts)

def nameDocument(partial_path, link_name=None):

  """Returns a Document key name constructed from a path and link name.

  Args:

    partial_path: the first portion of the path to the Document that uniquely

      identifies it

    link_name: optional link name to append to path (when omitted,

      partial_path is actually the entire path, with the link_name already

      appended)

  Raises:

    Error if partial_path and link_Name produce a "False" path (None,

    empty string, etc.)

  """

  path = [partial_path]

  if link_name:

    path.append(link_name)

  path = combinePath(path)

  if not path:

    raise Error('"path" must be non-False: "%s"' % path)

  return 'Document:%s' % path

def nameSiteSettings(path):

  """Returns a SiteSettings key name constructed from a supplied path.

  Raises:

    Error if path is "False" (None, empty string, etc.)

  """

  if not path:

    raise Error('"path" must be non-False: "%s"' % path)

  return 'SiteSettings:%s' % path

def nameUser(email):

  """Returns a User key name constructed from a supplied email address.

  Raises:

    Error if email is "False" (None, empty string, etc.)

  """

  if not email:

    raise Error('"email" must be non-False: "%s"' % email)

  return 'User:%s' % email

def nameSponsor(link_name):

  """Returns a Sponsor key name constructed from a supplied link name.

  Raises:

    Error if link_name is "False" (None, empty string, etc.)

  """

  if not link_name:

    raise Error('"link_name" must be non-False: "%s"' % link_name)

  return 'Group/Sponsor:%s' % link_name

def nameSchool(sponsor_ln, program_ln, link_name):

  """Returns a School key name constructed from link names.

  Args:

    sponsor_ln: Sponsor link name

    program_ln: Program link name

    link_name: School link name

  Raises:

    Error if sponsor_ln, program_ln, and link_Name combine to produce

    a "False" path (None, empty string, etc.)

  """

  path = combinePath([[sponsor_ln, program_ln], link_name])

  if not path:

    raise Error('"path" must be non-False: "%s"' % path)

  return 'Group/School:%s' % path

def nameOrganization(sponsor_ln, program_ln, link_name):

  """Returns a Organization key name constructed from link names.

  Args:

    sponsor_ln: Sponsor link name

    program_ln: Program link name

    link_name: Organization link name

  Raises:

    Error if sponsor_ln, program_ln, and link_Name combine to produce

    a "False" path (None, empty string, etc.)

  """

  path = combinePath([[sponsor_ln, program_ln], link_name])

  if not path:

    raise Error('"path" must be non-False: "%s"' % path)

  return 'Group/Organization:%s' % path 

def nameClub(link_name):

  """Returns a Club key name constructed from a supplied link name.

  Raises:

    Error if link_name is "False" (None, empty string, etc.)

  """

  if not link_name:

    raise Error('"link_name" must be non-False: "%s"' % link_name)

  return 'Group/Club:%s' % link_name