#!/usr/bin/env python
# -*- coding: utf-8 -*-
import boto3

ecs_cli = boto3.client('ecs')
ec2_cli = boto3.client('ec2')

class Terminate():
    MIN_TASKS_RUNNING = 2

    def __init__(self, cluster_name):
        self.cluster_name = cluster_name

    def put_in_draining(self, container_instance_id):
        result = ecs_cli.describe_container_instances(
            cluster=self.cluster_name, containerInstances=[container_instance_id]
        )
        for container_instance in result['containerInstances']:
            ec2_instance_id = container_instance['ec2InstanceId']
            check = self.check_and_get_tag_terminate(ec2_instance_id, tag_key='Terminate')
            if 'yes' in check:
                return ('The instance id is already schedule to terminate, just pass')
            else:
                result = ecs_cli.update_container_instances_state(
                    cluster=self.cluster_name, containerInstances=[container_instance_id], status='DRAINING'
                )
                if result['failures']:
                    return ('Error: ' + str(result['failures'][0]))
                else:
                    # increase_spot_fleet
                    return (
                        'The ContainerInstanceId %s or EC2 - %s * is moving to Draining' %
                        (container_instance_id, ec2_instance_id)
                    )

    def put_tag_terminate(self, ec2_instance_id):
        # tag name terminate with true value
        result = ec2_cli.create_tags(Resources=[ec2_instance_id], Tags=[{'Key': 'Terminate', 'Value': 'yes'}])
        if result['ResponseMetadata']['HTTPStatusCode'] == 200:
            return ('Tagged with Sucess - instanceId ' + ec2_instance_id)
        else:
            return ('Failure to tag - instanceId ' + ec2_instance_id)

    def check_and_get_tag_terminate(self, ec2_instance_id, tag_key):
        result = ec2_cli.describe_instances(InstanceIds=[ec2_instance_id])
        for reservation in result['Reservations']:
            for inst in reservation['Instances']:
                for tag in inst['Tags']:
                    if tag_key in tag['Key']:
                        value = tag['Value']
                        return (value)
        return ('There is no Tag: ' + tag_key)

    def terminate(self, ec2_instance_id, tag_key='Terminate'):
        # check the tag terminate_time exists and your value if the value is equal o less than the time now, terminate.
        check = self.check_and_get_tag_terminate(ec2_instance_id, tag_key='Terminate')
        if 'yes' in check:
            result = ec2_cli.terminate_instances(InstanceIds=[ec2_instance_id])
            return ('Terminating ' + ec2_instance_id)
        else:
            return ('no tag Name: %s founded, just pass' % (tag_key))

    def check_and_terminate(self):
        instances_in_draining = self.check_instance_in_draining()
        if instances_in_draining:
            result = ecs_cli.describe_container_instances(
                cluster=self.cluster_name, containerInstances=instances_in_draining
            )
            for container_instance in result['containerInstances']:
                # if the number os task is less than 2 so terminate then, if not pass
                running_count = container_instance['runningTasksCount']
                if running_count < Terminate.MIN_TASKS_RUNNING or running_count == Terminate.MIN_TASKS_RUNNING:
                    ec2_instance_Id = container_instance['ec2InstanceId']
                    self.terminate(ec2_instance_Id)
                    return ('Killing ' + ec2_instance_Id)
                else:
                    return (
                        'Waiting to reduce the number of Tasks Running, now the instance has ' +
                        str(container_instance['runningTasksCount'])
                    )
        else:
            return 'Nothing to do, just pass'

    def check_instance_in_draining(self):
        instances = []
        result = ecs_cli.list_container_instances(cluster=self.cluster_name, status='DRAINING')
        for instance_arns in result['containerInstanceArns']:
            instances.append(instance_arns)
        return instances

# using the method put_in_draining.

t = Terminate(cluster_name='homolog')
t.put_in_draining(container_instance_id='0b42e17e-7764-4b05-9159-b26cf8cf9fb3')