# -*- coding: utf-8 -*-
# Copyright (C) 2016 Adrien Vergé
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
Use this rule to control the position and formatting of comments.

.. rubric:: Options

* Use ``require-starting-space`` to require a space character right after the
  ``#``. Set to ``true`` to enable, ``false`` to disable.
* Use ``ignore-shebangs`` to ignore a
  `shebang <https://en.wikipedia.org/wiki/Shebang_(Unix)>`_ at the beginning of
  the file when ``require-starting-space`` is set.
* ``min-spaces-from-content`` is used to visually separate inline comments from
  content. It defines the minimal required number of spaces between a comment
  and its preceding content.

.. rubric:: Examples

#. With ``comments: {require-starting-space: true}``

   the following code snippet would **PASS**:
   ::

    # This sentence
    # is a block comment

   the following code snippet would **PASS**:
   ::

    ##############################
    ## This is some documentation

   the following code snippet would **FAIL**:
   ::

    #This sentence
    #is a block comment

#. With ``comments: {min-spaces-from-content: 2}``

   the following code snippet would **PASS**:
   ::

    x = 2 ^ 127 - 1  # Mersenne prime number

   the following code snippet would **FAIL**:
   ::

    x = 2 ^ 127 - 1 # Mersenne prime number
"""


import re

from yamllint.linter import LintProblem


ID = 'comments'
TYPE = 'comment'
CONF = {'require-starting-space': bool,
        'ignore-shebangs': bool,
        'min-spaces-from-content': int}
DEFAULT = {'require-starting-space': True,
           'ignore-shebangs': True,
           'min-spaces-from-content': 2}


def check(conf, comment):
    if (conf['min-spaces-from-content'] != -1 and comment.is_inline() and
            comment.pointer - comment.token_before.end_mark.pointer <
            conf['min-spaces-from-content']):
        yield LintProblem(comment.line_no, comment.column_no,
                          'too few spaces before comment')

    if conf['require-starting-space']:
        text_start = comment.pointer + 1
        while (comment.buffer[text_start] == '#' and
               text_start < len(comment.buffer)):
            text_start += 1
        if text_start < len(comment.buffer):
            if (conf['ignore-shebangs'] and
                    comment.line_no == 1 and
                    comment.column_no == 1 and
                    re.match(r'^!\S', comment.buffer[text_start:])):
                return
            # We can test for both \r and \r\n just by checking first char
            # \r itself is a valid newline on some older OS.
            elif comment.buffer[text_start] not in {' ', '\n', '\r', '\x00'}:
                column = comment.column_no + text_start - comment.pointer
                yield LintProblem(comment.line_no,
                                  column,
                                  'missing starting space in comment')
