#!/usr/bin/env python
# -*- coding: utf-8 -*-
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"""Business logic for reconciliation

Reconcile the contents of the DB with the actual state of the
Ganeti backend.

Let D be the set of VMs in the DB, G the set of VMs in Ganeti.
RULES:
    R1. Stale servers in DB:
            For any v in D but not in G:
            Set deleted=True.
    R2. Orphan instances in Ganet:
            For any v in G with deleted=True in D:
            Issue OP_INSTANCE_DESTROY.
    R3. Unsynced operstate:
            For any v whose operating state differs between G and V:
            Set the operating state in D based on the state in G.
In the code, D, G are Python dicts mapping instance ids to operating state.
For D, the operating state is chosen from VirtualMachine.OPER_STATES.
For G, the operating state is True if the machine is up, False otherwise.

"""

import logging
import sys

from django.core.management import setup_environ
try:
    from synnefo import settings
except ImportError:
    raise Exception("Cannot import settings, make sure PYTHONPATH contains "
                    "the parent directory of the Synnefo Django project.")
setup_environ(settings)

from synnefo.db.models import VirtualMachine
from synnefo.util.dictconfig import dictConfig
from synnefo.util.rapi import GanetiRapiClient


log = logging.getLogger()


def stale_servers_in_db(D, G):
    idD = set(D.keys())
    idG = set(G.keys())

    return idD - idG


def orphan_instances_in_ganeti(D, G):
    idD = set(D.keys())
    idG = set(G.keys())

    return idG - idD


def unsynced_operstate(D, G):
    unsynced = set()
    idD = set(D.keys())
    idG = set(G.keys())

    for i in idD & idG:
        if (G[i] and D[i] != 'STARTED' or
            not G[i] and D[i] not in ('BUILD', 'ERROR', 'STOPPED')):
            unsynced.add((i, D[i], G[i]))

    return unsynced


def get_servers_from_db():
    vms = VirtualMachine.objects.filter(deleted=False)
    return dict(map(lambda x: (x.id, x.operstate), vms))


def get_instances_from_ganeti():
    rapi = GanetiRapiClient(*settings.GANETI_CLUSTER_INFO)
    ganeti_instances = rapi.GetInstances(bulk=True)
    snf_instances = {}

    prefix = settings.BACKEND_PREFIX_ID
    for i in ganeti_instances:
        if i['name'].startswith(prefix):
            try:
                id = int(i['name'].split(prefix)[1])
            except Exception:
                log.error("Ignoring instance with malformed name %s",
                              i['name'])
                continue

            if id in snf_instances:
                log.error("Ignoring instance with duplicate Synnefo id %s",
                    i['name'])
                continue

            snf_instances[id] = i['oper_state']

    return snf_instances


# Only for testing this module individually
def main():
    print get_instances_from_ganeti()


if __name__ == "__main__":
    sys.exit(main())