import datetime
import logging
from typing import Tuple, List

from app import db
from app.models.bridges import BridgeConf, Bridge
from app.models.cloud import CloudProvider, CloudAccount
from app.terraform import BaseAutomation

BRIDGE_PROVIDERS = [
    # In order of cost
    CloudProvider.HCLOUD,
    CloudProvider.GANDI,
    CloudProvider.OVH,
    CloudProvider.AWS,
]


def active_bridges_in_account(account: CloudAccount) -> List[Bridge]:
    bridges: List[Bridge] = Bridge.query.filter(
        Bridge.cloud_account_id == account.id,
        Bridge.destroyed.is_(None),
    ).all()
    return bridges


def create_bridges_in_account(bridgeconf: BridgeConf, account: CloudAccount, count: int) -> int:
    created = 0
    while created < count and len(active_bridges_in_account(account)) < account.max_instances:
        logging.debug("Creating bridge for configuration %s in account %s", bridgeconf.id, account)
        bridge = Bridge()
        bridge.pool_id = bridgeconf.pool.id
        bridge.conf_id = bridgeconf.id
        bridge.cloud_account = account
        bridge.added = datetime.datetime.utcnow()
        bridge.updated = datetime.datetime.utcnow()
        logging.debug("Creating bridge %s", bridge)
        db.session.add(bridge)
        created += 1
    return created


def create_bridges(bridgeconf: BridgeConf, count: int) -> int:
    """
    Creates a bridge resource for the given bridge configuration.
    """
    logging.debug("Creating %s bridges for configuration %s", count, bridgeconf.id)
    created = 0
    for provider in BRIDGE_PROVIDERS:
        if created >= count:
            break
        logging.info("Creating bridges in %s accounts", provider.description)
        for account in CloudAccount.query.filter(
                CloudAccount.destroyed.is_(None),
                CloudAccount.enabled.is_(True),
                CloudAccount.provider == provider,
        ):
            logging.info("Creating bridges in %s", account)
            created += create_bridges_in_account(bridgeconf, account, count - created)
    logging.debug("Created %s bridges", created)
    return created


def deprecate_bridges(bridgeconf: BridgeConf, count: int, reason: str = "redundant") -> int:
    logging.debug("Deprecating %s bridges (%s) for configuration %s", count, reason, bridgeconf.id)
    deprecated = 0
    active_conf_bridges = iter(Bridge.query.filter(
        Bridge.conf_id == bridgeconf.id,
        Bridge.deprecated.is_(None),
        Bridge.destroyed.is_(None),
    ).all())
    while deprecated < count:
        logging.debug("Deprecating bridge %s for configuration %s", deprecated + 1, bridgeconf.id)
        bridge = next(active_conf_bridges)
        logging.debug("Bridge %r", bridge)
        bridge.deprecate(reason=reason)
        deprecated += 1
    return deprecated


class BridgeMetaAutomation(BaseAutomation):
    short_name = "bridge_meta"
    description = "Housekeeping for bridges"
    frequency = 1

    def automate(self, full: bool = False) -> Tuple[bool, str]:
        # Destroy expired bridges
        deprecated_bridges: List[Bridge] = Bridge.query.filter(
            Bridge.destroyed.is_(None),
            Bridge.deprecated.is_not(None),
        ).all()
        logging.debug("Found %s deprecated bridges", len(deprecated_bridges))
        for bridge in deprecated_bridges:
            cutoff = datetime.datetime.utcnow() - datetime.timedelta(hours=bridge.conf.expiry_hours)
            if bridge.deprecated < cutoff:
                logging.debug("Destroying expired bridge")
                bridge.destroy()
        # Deprecate orphaned bridges
        active_bridges = Bridge.query.filter(
            Bridge.deprecated.is_(None),
            Bridge.destroyed.is_(None),
        ).all()
        logging.debug("Found %s active bridges", len(active_bridges))
        for bridge in active_bridges:
            if bridge.conf.destroyed is not None:
                bridge.deprecate(reason="conf_destroyed")
        # Create new bridges
        activate_bridgeconfs = BridgeConf.query.filter(
            BridgeConf.destroyed.is_(None),
        ).all()
        logging.debug("Found %s active bridge configurations", len(activate_bridgeconfs))
        for bridgeconf in activate_bridgeconfs:
            active_conf_bridges = Bridge.query.filter(
                Bridge.conf_id == bridgeconf.id,
                Bridge.deprecated.is_(None),
                Bridge.destroyed.is_(None),
            ).all()
            total_conf_bridges = Bridge.query.filter(
                Bridge.conf_id == bridgeconf.id,
                Bridge.destroyed.is_(None),
            ).all()
            logging.debug("Generating new bridges for %s (active: %s, total: %s, target: %s, max: %s)",
                          bridgeconf.id,
                          len(active_conf_bridges),
                          len(total_conf_bridges),
                          bridgeconf.target_number,
                          bridgeconf.max_number
                          )
            missing = min(
                bridgeconf.target_number - len(active_conf_bridges),
                bridgeconf.max_number - len(total_conf_bridges))
            if missing > 0:
                create_bridges(bridgeconf, missing)
            elif missing < 0:
                deprecate_bridges(bridgeconf, 0 - missing)
        db.session.commit()
        return True, ""