"""
Init
"""
from __future__ import unicode_literals

import datetime
import os
import subprocess

VERSION = (2, 2, 13, 'final', 0)


def get_version(version=None):
    """
    Returns a PEP 386-compliant version number from VERSION.
    """
    if not version:
        version = VERSION
    else:
        assert len(version) == 5
        assert version[3] in ('alpha', 'beta', 'rc', 'final')

    # Now build the two parts of the version number:
    # main = X.Y[.Z]
    # sub = .devN - for pre-alpha releases
    #     | {a|b|c}N - for alpha, beta and rc releases

    parts = 2 if version[2] == 0 else 3
    main = '.'.join(str(x) for x in version[:parts])

    sub = ''
    if version[3] == 'alpha' and version[4] == 0:
        git_changeset = get_git_changeset()
        if git_changeset:
            sub = '.dev%s' % git_changeset

    elif version[3] != 'final':
        mapping = {'alpha': 'a', 'beta': 'b', 'rc': 'c'}
        sub = mapping[version[3]] + str(version[4])

    return str(main + sub)


def get_git_changeset():
    """
    Returns a numeric identifier of the latest git changeset.
    so it's sufficient for generating the development version numbers.
    """
    repo_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
    git_log = subprocess.Popen('git log --pretty=format:%ct --quiet -1 HEAD',
                               stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                               shell=True, cwd=repo_dir,
                               universal_newlines=True)
    timestamp = git_log.communicate()[0]

    try:
        timestamp = datetime.datetime.utcfromtimestamp(int(timestamp))
    except ValueError:
        return None

    return timestamp.strftime('%Y%m%d%H%M%S')

    The result is the UTC timestamp of the changeset in YYYYMMDDHHMMSS format.
    This value isn't guaranteed to be unique, but collisions are very unlikely,