# -*- coding: utf-8 -*-
#
# 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.
import sys
import logging

from airflow.exceptions import AirflowException
from airflow.models import BaseOperator
from airflow.utils import apply_defaults

from airflow.contrib.hooks.aws_hook import AwsHook


class ECSOperator(BaseOperator):

    """
    Execute a task on AWS EC2 Container Service

    :param task_definition: the task definition name on EC2 Container Service
    :type task_definition: str
    :param cluster: the cluster name on EC2 Container Service
    :type cluster: str
    :param: overrides: the same parameter that boto3 will receive: http://boto3.readthedocs.org/en/latest/reference/services/ecs.html#ECS.Client.run_task
    :type: overrides: dict
    :param aws_conn_id: connection id of AWS credentials / region name. If None, credential boto3 strategy will be used (http://boto3.readthedocs.io/en/latest/guide/configuration.html).
    :type aws_conn_id: str
    :param region_name: region name to use in AWS Hook. Override the region_name in connection (if provided)
    """

    ui_color = '#f0ede4'
    client = None
    arn = None
    template_fields = ('overrides',)

    @apply_defaults
    def __init__(self, task_definition, cluster, overrides,
                 aws_conn_id=None, region_name=None, **kwargs):
        super(ECSOperator, self).__init__(**kwargs)

        self.aws_conn_id = aws_conn_id
        self.region_name = region_name
        self.task_definition = task_definition
        self.cluster = cluster
        self.overrides = overrides

        self.hook = self.get_hook()

    def execute(self, context):

        logging.info('Running ECS Task - Task definition: {} - on cluster {}'.format(
            self.task_definition,
            self.cluster
        ))
        logging.info('ECSOperator overrides: {}'.format(self.overrides))

        self.client = self.hook.get_client_type(
            'ecs',
            region_name=self.region_name
        )

        response = self.client.run_task(
            cluster=self.cluster,
            taskDefinition=self.task_definition,
            overrides=self.overrides,
            startedBy=self.owner
        )

        failures = response['failures']
        if (len(failures) > 0):
            raise AirflowException(response)
        logging.info('ECS Task started: {}'.format(response))

        self.arn = response['tasks'][0]['taskArn']
        self._wait_for_task_ended()

        self._check_success_task()
        logging.info('ECS Task has been successfully executed: {}'.format(response))

    def _wait_for_task_ended(self):
        waiter = self.client.get_waiter('tasks_stopped')
        waiter.config.max_attempts = sys.maxint  # timeout is managed by airflow
        waiter.wait(
            cluster=self.cluster,
            tasks=[self.arn]
        )

    def _check_success_task(self):
        response = self.client.describe_tasks(
            cluster=self.cluster,
            tasks=[self.arn]
        )
        logging.info('ECS Task stopped, check status: {}'.format(response))

        if (len(response.get('failures', [])) > 0):
            raise AirflowException(response)

        for task in response['tasks']:
            containers = task['containers']
            for container in containers:
                if container.get('lastStatus') == 'STOPPED' and container['exitCode'] != 0:
                    raise AirflowException('This task is not in success state {}'.format(task))
                elif container.get('lastStatus') == 'PENDING':
                    raise AirflowException('This task is still pending {}'.format(task))
                elif 'error' in container.get('reason', '').lower():
                    raise AirflowException('This containers encounter an error during launching : {}'.format(container.get('reason', '').lower()))

    def get_hook(self):
        return AwsHook(
            aws_conn_id=self.aws_conn_id
        )

    def on_kill(self):
        response = self.client.stop_task(
            cluster=self.cluster,
            task=self.arn,
            reason='Task killed by the user')
        logging.info(response)
