# -*- coding: utf-8 -*-
# Author: Douglas Creager <dcreager@dcreager.net>
# This file is placed into the public domain.

# Calculates the current version number.  If possible, this is the
# output of “git describe”, modified to conform to the versioning
# scheme that setuptools uses.  If “git describe” returns an error
# (most likely because we're in an unpacked copy of a release tarball,
# rather than in a git working copy), then we fall back on reading the
# contents of the RELEASE-VERSION file.
#
# To use this script, simply import it your setup.py file, and use the
# results of get_git_version() as your package version:
#
# from version import *
#
# setup(
#     version=get_git_version(),
#     .
#     .
#     .
# )
#
# This will automatically update the RELEASE-VERSION file, if
# necessary.  Note that the RELEASE-VERSION file should *not* be
# checked into git; please add it to your top-level .gitignore file.
#
# You'll probably want to distribute the RELEASE-VERSION file in your
# sdist tarballs; to do this, just create a MANIFEST.in file that
# contains the following line:
#
#   include RELEASE-VERSION

__all__ = ("get_git_version")

import os
from subprocess import Popen, PIPE

VERSION_FILE = os.path.abspath(os.path.join(os.path.dirname(__file__),
        os.pardir, os.pardir, "RELEASE-VERSION"))


def call_git_describe(abbrev=4):
    try:
        p = Popen(['git', 'describe', '--dirty', '--abbrev=%d' % abbrev,
                   '--always'],
                  cwd=os.path.dirname(VERSION_FILE), stdout=PIPE, stderr=PIPE)
        p.stderr.close()
        line = p.stdout.readlines()[0]
        # (this line prevents official releases)
        # should work again now, see #482 and obspy/obspy@b437f31
        if "-" not in line and "." not in line:
            line = "0.0.0-g%s" % line
        return line.strip()
    except:
        return None


def read_release_version():
    try:
        version = open(VERSION_FILE, "r").readlines()[0]
        return version.strip()
    except:
        return None


def write_release_version(version):
    open(VERSION_FILE, "w").write("%s\n" % version)


def get_git_version(abbrev=4):
    # Read in the version that's currently in RELEASE-VERSION.
    release_version = read_release_version()

    # First try to get the current version using “git describe”.
    version = call_git_describe(abbrev)

    # If that doesn't work, fall back on the value that's in
    # RELEASE-VERSION.
    if version is None:
        version = release_version

    # If we still don't have anything, that's an error.
    if version is None:
        return '0.0.0-tar/zipball'

    # If the current version is different from what's in the
    # RELEASE-VERSION file, update the file to be current.
    if version != release_version:
        write_release_version(version)

    # Finally, return the current version.
    return version


if __name__ == "__main__":
    print get_git_version()
