# Copyright 2016 Capital One Services, LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Cloud-Custodian Lambda Entry Point

Mostly this serves to load up the policy and dispatch
an event.
"""

import logging
import os
import uuid
import json

from c7n.policy import PolicyCollection
from c7n.resources import load_resources
from c7n.utils import format_event, get_account_id_from_sts


logging.root.setLevel(logging.DEBUG)
logging.getLogger('botocore').setLevel(logging.WARNING)
log = logging.getLogger('custodian.lambda')


# TODO move me / we should load config options directly from policy config
class Config(dict):

    def __getattr__(self, k):
        try:
            return self[k]
        except KeyError:
            raise AttributeError(k)

    @classmethod
    def empty(cls, **kw):
        try:
            import boto3
            session = boto3.Session()
            account_id = get_account_id_from_sts(session)
        except:
            account_id = None

        d = {}
        d.update({
            'region': os.environ.get('AWS_DEFAULT_REGION'),
            'cache': '',
            'profile': None,
            'account_id': account_id,
            'assume_role': None,
            'log_group': None,
            'metrics_enabled': True,
            'output_dir': os.environ.get(
                'C7N_OUTPUT_DIR',
                '/tmp/' + str(uuid.uuid4())),
            'cache_period': 0,
            'dryrun': False})
        d.update(kw)
        if not os.path.exists(d['output_dir']):
            os.mkdir(d['output_dir'])
        return cls(d)


def dispatch_event(event, context):

    error = event.get('detail', {}).get('errorCode')
    if error:
        log.debug("Skipping failed operation: %s" % error)
        return

    event['debug'] = True
    if event['debug']:
        log.info("Processing event\n %s", format_event(event))

    # policies file should always be valid in lambda so do loading naively
    with open('config.json') as f:
        policy_config = json.load(f)

    if not policy_config or not policy_config.get('policies'):
        return False

    # TODO. This enshrines an assumption of a single policy per lambda.
    options_overrides = policy_config[
        'policies'][0].get('mode', {}).get('execution-options', {})
    options = Config.empty(**options_overrides)

    load_resources()
    policies = PolicyCollection.from_data(policy_config, options)
    if policies:
        for p in policies:
            p.push(event, context)
    return True
