"""
If the current installed Python version is not supported, prints an error
message to stderr and returns 1
"""
from __future__ import print_function

import os
import sys

version_string = '.'.join(str(_) for _ in sys.version_info[:3])

msg = """ERROR: Your Python version is: %s
Galaxy is currently supported on Python 2.7 only. To run Galaxy, please
install a supported Python version. If a supported version is already
installed but is not your default, https://galaxyproject.org/admin/python/
contains instructions on how to force Galaxy to use a different version.""" % version_string

msg_beta = """WARNING: Your Python version is: %s
Galaxy is currently supported on Python 2.7 only, support for Python >= 3.4
is still in beta stage. Since you are using a virtual environment, we assume
you are developing or testing Galaxy under Python 3. If not,
install a supported Python version. If a supported version is already
installed but is not your default, https://galaxyproject.org/admin/python/
contains instructions on how to force Galaxy to use a different version.""" % version_string


def check_python():
    venv = os.getenv('VIRTUAL_ENV')
    if sys.version_info[:2] == (2, 7):
        # supported
        return
    elif sys.version_info[:2] >= (3, 4) and venv:
        print(msg_beta, file=sys.stderr)
    else:
        print(msg, file=sys.stderr)
        raise Exception(msg)


if __name__ == '__main__':
    try:
        check_python()
    except Exception:
        sys.exit(1)