"""
A hello world module

See doc/mgr/hello.rst for more info.
"""

from mgr_module import MgrModule, HandleCommandResult
from threading import Event
import errno

class Hello(MgrModule):
    # these are CLI commands we implement
    COMMANDS = [
        {
            "cmd": "hello "
                   "name=person_name,type=CephString,req=false",
            "desc": "Say hello",
            "perm": "r"
        },
        {
            "cmd": "count "
                   "name=num,type=CephInt",
            "desc": "Do some counting",
            "perm": "r"
        },
    ]

    # These are module options we understand.  These can be set with
    #
    #   ceph config set global mgr/hello/<name> <value>
    #
    # e.g.,
    #
    #   ceph config set global mgr/hello/place Earth
    #
    MODULE_OPTIONS = [
        {
            'name': 'place',
            'default': 'world',
            'desc': 'a place in the world',
            'runtime': True,   # can be updated at runtime (no mgr restart)
        },
        {
            'name': 'emphatic',
            'type': 'bool',
            'desc': 'whether to say it loudly',
            'default': True,
            'runtime': True,
        },
        {
            'name': 'foo',
            'type': 'enum',
            'enum_allowed': [ 'a', 'b', 'c' ],
            'default': 'a',
            'runtime': True,
        },
    ]

    # These are "native" Ceph options that this module cares about.
    NATIVE_OPTIONS = [
        'mgr_tick_period',
    ]

    def __init__(self, *args, **kwargs):
        super(Hello, self).__init__(*args, **kwargs)

        # set up some members to enable the serve() method and shutdown()
        self.run = True
        self.event = Event()

        # ensure config options members are initialized; see config_notify()
        self.config_notify()


    def config_notify(self):
        """
        This method is called whenever one of our config options is changed.
        """
        # This is some boilerplate that stores MODULE_OPTIONS in a class
        # member, so that, for instance, the 'emphatic' option is always
        # available as 'self.emphatic'.
        for opt in self.MODULE_OPTIONS:
            setattr(self,
                    opt['name'],
                    self.get_module_option(opt['name']))
            self.log.debug(' mgr option %s = %s',
                           opt['name'], getattr(self, opt['name']))
        # Do the same for the native options.
        for opt in self.NATIVE_OPTIONS:
            setattr(self,
                    opt,
                    self.get_ceph_option(opt))
            self.log.debug(' native option %s = %s', opt, getattr(self, opt))

    def handle_command(self, inbuf, cmd):
        ret = 0
        out = ''
        err = ''
        if cmd['prefix'] == 'hello':
            if 'person_name' in cmd:
                out = "Hello, " + cmd['person_name']
            else:
                out = "Hello " + self.get_module_option('place')
            if self.get_module_option('emphatic'):
                out += '!'
        elif cmd['prefix'] == 'count':
            num = cmd.get('num', 0)
            if num < 1:
                err = 'That\'s too small a number'
                ret = -errno.EINVAL
            elif num > 10:
                err = 'That\'s too big a number'
                ret = -errno.EINVAL
            else:
                out = 'Hello, I am the count!\n'
                out += ', '.join([str(x) for x in range(1, num + 1)]) + '!'
        return HandleCommandResult(
            retval=ret,   # exit code
            stdout=out,   # stdout
            stderr=err)

    def serve(self):
        """
        This method is called by the mgr when the module starts and can be
        used for any background activity.
        """
        self.log.info("Starting")
        while self.run:
            # Do some useful background work here.

            # Use mgr_tick_period (default: 2) here just to illustrate
            # consuming native ceph options.  Any real background work
            # would presumably have some more appropriate frequency.
            sleep_interval = self.mgr_tick_period
            self.log.debug('Sleeping for %d seconds', sleep_interval)
            ret = self.event.wait(sleep_interval)
            self.event.clear()

    def shutdown(self):
        """
        This method is called by the mgr when the module needs to shut
        down (i.e., when the serve() function needs to exit).
        """
        self.log.info('Stopping')
        self.run = False
        self.event.set()