# Copyright (C) 2016 Barry A. Warsaw
#
# 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.

"""setup.py helper functions."""

import os
import re
import sys


DEFAULT_VERSION_RE = re.compile(
    r'(?P<version>\d+\.\d+(?:\.\d+)?(?:(?:a|b|rc)\d+)?)')
EMPTYSTRING = ''

__version__ = '2.3'


def require_python(minimum):
    """Require at least a minimum Python version.

    The version number is expressed in terms of `sys.hexversion`.  E.g. to
    require a minimum of Python 2.6, use::

    >>> require_python(0x206000f0)

    :param minimum: Minimum Python version supported.
    :type minimum: integer
    """
    if sys.hexversion < minimum:
        hversion = hex(minimum)[2:]
        if len(hversion) % 2 != 0:
            hversion = '0' + hversion
        split = list(hversion)
        parts = []
        while split:
            parts.append(int(''.join((split.pop(0), split.pop(0))), 16))
        major, minor, micro, release = parts
        if release == 0xf0:
            print('Python {0}.{1}.{2} or better is required'.format(
                major, minor, micro))
        else:
            print('Python {0}.{1}.{2} ({3}) or better is required'.format(
                major, minor, micro, hex(release)[2:]))
        sys.exit(1)


def get_version(filename, pattern=None):
    """Extract the __version__ from a file without importing it.

    While you could get the __version__ by importing the module, the very act
    of importing can cause unintended consequences.  For example, Distribute's
    automatic 2to3 support will break.  Instead, this searches the file for a
    line that starts with __version__, and extract the version number by
    regular expression matching.

    By default, two or three dot-separated digits are recognized, but by
    passing a pattern parameter, you can recognize just about anything.  Use
    the `version` group name to specify the match group.

    :param filename: The name of the file to search.
    :type filename: string
    :param pattern: Optional alternative regular expression pattern to use.
    :type pattern: string
    :return: The version that was extracted.
    :rtype: string
    """
    if pattern is None:
        cre = DEFAULT_VERSION_RE
    else:
        cre = re.compile(pattern)
    with open(filename) as fp:
        for line in fp:
            if line.startswith('__version__'):
                mo = cre.search(line)
                assert mo, 'No valid __version__ string found'
                return mo.group('version')
    raise AssertionError('No __version__ assignment found')


def find_doctests(start='.', extension='.rst'):
    """Find separate-file doctests in the package.

    This is useful for Distribute's automatic 2to3 conversion support.  The
    `setup()` keyword argument `convert_2to3_doctests` requires file names,
    which may be difficult to track automatically as you add new doctests.

    :param start: Directory to start searching in (default is cwd)
    :type start: string
    :param extension: Doctest file extension (default is .txt)
    :type extension: string
    :return: The doctest files found.
    :rtype: list
    """
    doctests = []
    for dirpath, dirnames, filenames in os.walk(start):
        doctests.extend(os.path.join(dirpath, filename)
                        for filename in filenames
                        if filename.endswith(extension))
    return doctests


def long_description(*filenames):
    """Provide a long description."""
    res = ['']
    for filename in filenames:
        with open(filename) as fp:
            for line in fp:
                res.append('   ' + line)
            res.append('')
        res.append('\n')
    return EMPTYSTRING.join(res)


def description(filename):
    """Provide a short description."""
    # This ends up in the Summary header for PKG-INFO and it should be a
    # one-liner.  It will get rendered on the package page just below the
    # package version header but above the long_description, which ironically
    # gets stuff into the Description header.  It should not include reST, so
    # pick out the first single line after the double header.
    with open(filename) as fp:
        for lineno, line in enumerate(fp):
            if lineno < 3:
                continue
            line = line.strip()
            if len(line) > 0:
                return line