# -*- coding: utf-8 -*-
#
# Copyright (C) 2007-2011 Edgewall Software
# All rights reserved.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at http://babel.edgewall.org/wiki/License.
#
# This software consists of voluntary contributions made by many
# individuals. For the exact contribution history, see the revision
# history and logs, available at http://babel.edgewall.org/log/.

"""Basic infrastructure for extracting localizable messages from source files.

This module defines an extensible system for collecting localizable message
strings from a variety of sources. A native extractor for Python source files
is builtin, extractors for other sources can be added using very simple plugins.

The main entry points into the extraction functionality are the functions
`extract_from_dir` and `extract_from_file`.
"""

import os
import sys
from tokenize import generate_tokens, COMMENT, NAME, OP, STRING

from babel.util import parse_encoding, pathmatch, relpath
from textwrap import dedent

__all__ = ['extract', 'extract_from_dir', 'extract_from_file']
__docformat__ = 'restructuredtext en'

GROUP_NAME = 'babel.extractors'

DEFAULT_KEYWORDS = {
    '_': None,
    'gettext': None,
    'ngettext': (1, 2),
    'ugettext': 
None,
    'ungettext': (1, 2),
    'dgettext': (2,),
    'dngettext': (2, 3),
    'N_': None
}

DEFAULT_MAPPING = [('**.py', 'python')]

empty_msgid_warning = (
'%s: warning: Empty msgid.  It is reserved by GNU gettext: gettext("") '
'returns the header entry with meta information, not the empty string.')


def _strip_comment_tag
s(comments, tags):
    """Helper function for `extract` that strips comment tags from strings
    in a list of comment lines.  This functions operates in-place.
    """
    def _strip(line):
        for tag in tags:
            if line.startswith(tag):
                return line[len(tag):].strip()
        return line
    comments[:] = map(_strip, comments)


def extract_from_dir(dirname=os.getcwd(), method_map=DEFAULT_MAPPING,
                     options_map=None, keywords=DEFAULT_KEYWORDS,
                     comment_tags=(), callback=None, strip_comment_tags=False):
    """Extract messages from any source files found in the given directory.

    This function generates tuples of the form:

        ``(filename, lineno, message, comments)``

    Which extraction method is used per file is determined by the `method_map`
    parameter, which maps extended glob patterns to extraction method names.
    For example, the following is the default mapping:

    >>> method_map = [
    ...     ('**.py', 'python')
    ... ]

    This basically says that files with the filename extension ".py" at any
    level inside the directory should be processed by the "python" extraction
    method. Files that don't match any of the mapping patterns are ignored. See
    the documentation of the `pathmatch` function for details on the pattern
    syntax.

    The following extended mapping would also use the "genshi" extraction
    method on any file in "templates" subdirectory:

    >>> method_map = [
    ...     ('**/templates/**.*', 'genshi'),
    ...     ('**.py', 'python')
    ... ]

    The dictionary provided by the optional `options_map` parameter augments
    these mappings. It uses extended glob patterns as keys, and the values are
    dictionaries mapping options names to option values (both strings).

    The glob patterns of the `options_map` do not necessarily need to be the
    same as those used in the method mapping. For example, while all files in
    the ``templates`` folders in an application may be Genshi applications, the
    options for those files may differ based on extension:

    >>> options_map = {
    ...     '**/templates/**.txt': {
    ...         'template_class': 'genshi.template:TextTemplate',
    ...         'encoding': 'latin-1'
    ...     },
    ...     '**/templates/**.html': {
    ...         'include_attrs': ''
    ...     }
    ... }

    :param dirname: the path to the directory to extract messages from
    :param method_map: a list of ``(pattern, method)`` tuples that maps of
                       extraction method names to extended glob patterns
    :param options_map: a dictionary of additional options (optional)
    :param keywords: a dictionary mapping keywords (i.e. names of functions
                     that should be recognized as translation functions) to
                     tuples that specify which of their arguments contain
                     localizable strings
    :param comment_tags: a list of tags of translator comments to search for
                         and include in the results
    :param callback: a function that is called for every file that message are
                     extracted from, just before the extraction itself is
                     performed; the function is passed the filename, the name
                     of the extraction method and and the options dictionary as
                     positional arguments, in that order
    :param strip_comment_tags: a flag that if set to `True` causes all comment
                               tags to be removed from the collected comments.
    :return: an iterator over ``(filename, lineno, funcname, message)`` tuples
    :rtype: ``iterator``
    :see: `pathmatch`
    """
    if options_map is None:
        options_map = {}

    absname = os.path.abspath(dirname)
    for root, dirnames, filenames in os.walk(absname):
        for subdir in dirnames:
            if subdir.startswith('.') or subdir.startswith('_'):
                dirnames.remove(subdir)
        dirnames.sort()
        filenames.sort()
        for filename in filenames:
            filename = relpath(
                os.path.join(root, filename).replace(os.sep, '/'),
                dirname
            )
            for pattern, method in method_map:
                if pathmatch(pattern, filename):
                    filepath = os.path.join(absname, filename)
                    options = {}
                    for opattern, odict in options_map.items():
                        if pathmatch(opattern, filename):
                            options = odict
                    if callback:
                        callback(filename, method, options)
                    for lineno, message, comments in \
                          extract_from_file(method, filepath,
                                            keywords=keywords,
                                            comment_tags=comment_tags,
                                            options=options,
                                            strip_comment_tags=
                                                strip_comment_tags):
                        yield filename, lineno, message, comments
                    break


def extract_from_file(method, filename, keywords=DEFAULT_KEYWORDS,
                      comment_tags=(), options=None, strip_comment_tags=False):
    """Extract messages from a specific file.

    This function returns a list of tuples of the form:

        ``(lineno, funcname, message)``

    :param filename: the path to the file to extract messages from
    :param method: a string specifying the extraction method (.e.g. "python")
    :param keywords: a dictionary mapping keywords (i.e. names of functions
                     that should be recognized as translation functions) to
                     tuples that specify which of their arguments contain
                     localizable strings
    :param comment_tags: a list of translator tags to search for and include
                         in the results
    :param strip_comment_tags: a flag that if set to `True` causes all comment
                               tags to be removed from the collected comments.
    :param options: a dictionary of additional options (optional)
    :return: the list of extracted messages
    :rtype: `list`
    """
    fileobj = open(filename, 'U')
    try:
        return list(extract(method, fileobj, keywords, comment_tags, options,
                            strip_