base.py

"""
Usable base class for all hosting commands.
"""

import datetime
import dateutil.parser
import dateutil.tz
import humanize
import shellish

VERSION = "0.8.4"  # Increment this value when backwards compat is broken.
DEFAULT_STACK_ENV = 'ODYSSEY_DEFAULT_STACK'

localtz = dateutil.tz.tzlocal()


def parse_ts(ts, **kwargs):
    dt = dateutil.parser.parse(ts)
    return localize_dt(dt, **kwargs)


def localize_dt(dt, tz=localtz):
    return dt.astimezone(tz)


def localnow(tz=localtz):
    return datetime.datetime.now(tz=tz)


def formatdate(dt, format='%b %d, %Y'):
    return dt.strftime(format)


def formattime(dt, format='%I:%M %p %Z'):
    return dt.strftime(format)


def formatdatetime(dt, timeformat=None, dateformat=None):
    d = formatdate(dt, format=dateformat) if dateformat else formatdate(dt)
    t = formattime(dt, format=timeformat) if timeformat else formattime(dt)
    return '%s, %s' % (d, t)


def naturaldelta(td):
    return humanize.naturaldelta(td)


class HostingCommand(shellish.Command):

    # Subclasses should override with a set of stack states that their command
    # works with.  Ie. {'init', 'ready', 'normal', 'partial_deploy'}
    allowed_states = set()
    min_version = "0"
    max_version = VERSION

    def add_stack_argument(self, *args, env=DEFAULT_STACK_ENV,
                           help=None, metavar='STACK_NAME', **kwargs):
        if help is None:
            help = "Stack name to apply command to."
        if not args:
            args = ('stack',)
        return self.add_argument(*args, env=env, help=help, metavar=metavar,
                                 **kwargs)

    def check_requirements(self, stack):
        """ Used to assert a stack is compatible and in a viable state. """
        ver = stack.stack_version
        if not (self.min_version <= ver <= self.max_version):
            raise SystemExit("Incompatible version: %s" % ver)
        if stack.state not in self.allowed_states:
            raise SystemExit("Improper stack state: %s" % stack.state)