# -*- coding: utf-8 -*-
"""
##########
formatting
##########

A library functions for formatting strings/text.

:Copyright: Copyright (c) 2015 Nick Zarczynski <nick@frez.me>
:License: MIT
:Version: 0.0.1

"""

import re

from docutils.core import publish_parts


camelcase_to_space_separated_regex = r"""
    (  # start the group

    # Case 1
    # ======
    #
    # Match an uppercase character, but only if it is preceded by a lowercase
    # character.
    #
    # Example
    # -------
    #
    # .. correct::
    #     'abYZ' -> 'ab YZ'
    #
    # .. incorrect::
    #     'abYZ' -> 'ab Y Z'

    (?<=[a-z])  # current position is preceded by a lowercase char
                # (positive lookbehind: does not consume any char)
    [A-Z]       # match an uppercase char

    |  # or

    # Case 2
    # ======
    #
    # Match an uppercase character, but only if it is preceded by a lowercase
    # character AND NOT at the start of the string.
    #
    # Example
    # -------
    #
    # .. correct::
    #     'ABCyz' -> 'AB Cyz'
    #
    # .. incorrect::
    #     'ABCyz' -> 'A B Cyz'

    (?<!\A)     # current position is not at the beginning of the string
                # (negative lookbehind: does not consume any char)
    [A-Z]       # match an uppercase char
    (?=[a-z])   # matches if next char is a lowercase char
                # lookahead assertion: does not consume any char

    )  # end the group
"""
"""
Regex to split a camelcased string.

Adapted from: http://stackoverflow.com/a/9283563/645663

"""


def camelcase_to_space_separated(target_string):
    """Convert a camelcase string to a space-separated string.

    If a match is found it is replaced with ' \1', which is a string consisting
    of a leading blank and the match itself.

    """
    return re.sub(camelcase_to_space_separated_regex, r' \1', target_string,
                  flags=re.VERBOSE)


def dedent_docstring(docstring):
    """Remove leading indent from a docstring.

    .. NOTE:: Python's ``textwrap.dedent`` isn't used because it doesn't dedent
              multiline docstrings that begin with unindented text (e.g., on
              the initial line).

    Adapted from: rest_framework.utils.formatting.dedent

    """
    whitespace_counts = [len(line) - len(line.lstrip(' '))
                         for line in docstring.splitlines()[1:]
                         if line.lstrip()]

    # unindent the docstring if needed
    if whitespace_counts:
        whitespace_pattern = '^' + (' ' * min(whitespace_counts))
        docstring = re.sub(re.compile(whitespace_pattern, re.MULTILINE), '',
                           docstring)

    return docstring.strip()


def restructured_text_to_html(restructured_text):
    """Render restructured_text as HTML.

    Parameters
    ----------
    restructured_text : str
        A string formatted using ReStructured Text.

    Returns
    -------
    str
        ReStructured Text converted to HTML.

    """
    parts = publish_parts(restructured_text, writer_name='html5')
    return parts
    # return parts.get('body')