#!/usr/bin/python3
# finds orphaned items from stacks

import os
import sys
sys.path.insert(0,os.environ["LAMBDA_TASK_ROOT"]+"/packages")
import boto3
from botocore.exceptions import ClientError
import datetime
from dateutil.tz import tzutc
from botocore.config import Config

config = Config(
    retries = dict(
        max_attempts = 10
    )
)

types = {
  'AWS::EC2::SecurityGroup': {
    'type': "boto3.client('ec2')",
    'call': "client.describe_security_groups(GroupIds=[resource['PhysicalResourceId']])"
    },
  'AWS::ECR::Repository': {
    'type': "boto3.client('ecr')",
    'call': "client.describe_repositories(repositoryNames=[resource['PhysicalResourceId']])"
    },
  'AWS::DMS::Endpoint': {
    'type': "boto3.client('dms')",
    'call': "client.describe_endpoints(Filters=[{'Name': 'endpoint-arn', 'Values': [resource['PhysicalResourceId']]}])"
    },
  'AWS::RDS::DBCluster': {
    'type': "boto3.client('rds')",
    'call': "client.describe_db_clusters(DBClusterIdentifier=resource['PhysicalResourceId'])"
    },
  'AWS::RDS::DBInstance': {
    'type': "boto3.client('rds')",
    'call': "client.describe_db_instances(DBInstanceIdentifier=resource['PhysicalResourceId'])"
    },
  'AWS::RDS::DBClusterParameterGroup': {
    'type': "boto3.client('rds')",
    'call': "client.describe_db_cluster_parameter_groups(DBClusterParameterGroupName=resource['PhysicalResourceId'])"
    },
  'AWS::RDS::DBSubnetGroup': {
    'type': "boto3.client('rds')",
    'call': "client.describe_db_subnet_groups(DBSubnetGroupName=resource['PhysicalResourceId'])"
    },
  'AWS::Glue::DevEndpoint': {
    'type': "boto3.client('glue')",
    'call': "client.get_dev_endpoint(EndpointName=resource['PhysicalResourceId'])"
    },
  'AWS::IAM::Role': {
    'type': "boto3.client('iam')",
    'call': "client.get_role(RoleName=resource['PhysicalResourceId'])"
    },
  'Custom::EventStreamSubscription': {
    'type': "boto3.client('sns')",
    'call': "client.get_subscription_attributes(SubscriptionArn=resource['PhysicalResourceId'])"
  }
}

def main(event,context):
  # find all DELETE_COMPLETE stacks, these are from the last 30 days
  # page through the stacks and look for any resources which had the DELETE_SKIPPED status
  # create a list of these resources
  resources = []
  cfClient = boto3.client('cloudformation', config=config)
  cf_paginator = cfClient.get_paginator('list_stacks')
  cf_pages = cf_paginator.paginate(StackStatusFilter=['DELETE_COMPLETE'])
  for page in cf_pages:
    for stack in page['StackSummaries']:
      try:
        sr_paginator = cfClient.get_paginator('list_stack_resources')
        sr_pages = sr_paginator.paginate(StackName=stack['StackId'])
      except Exception as e:
        print("Exception in list_stack_resources:", e)
      for sr_page in sr_pages:
        for resource in sr_page['StackResourceSummaries']:
          # ignore remnant lambda versions
          if resource['ResourceStatus'] == 'DELETE_SKIPPED' and resource['ResourceType'] != 'AWS::Lambda::Version':
            resources.append(resource)

  # for each DELETE_SKIPPED resource, check what kind it is and if it still exists
  # if it still exists, then add it to the found list
  found = []
  missing = []
  for resource in resources:
    # print(resource)
    if resource['ResourceType'] in types:
      # print(types[resource['ResourceType']])
      client = eval(types[resource['ResourceType']]['type'])
      try:
        print("Trying:", resource['ResourceType'], resource['PhysicalResourceId'])
        response = eval(types[resource['ResourceType']]['call'])
        found.append(resource)
      except ClientError as e:
        print("ClientError:", e.response['Error']['Message'])
      except KeyError as e:
        print("KeyError for resource:", resource['PhysicalResourceId'], e)
    elif resource['ResourceType'] == 'AWS::S3::Bucket':
      try:
        client = boto3.client('s3')
        print("Trying:", resource['ResourceType'], resource['PhysicalResourceId'])
        response = client.list_buckets()
        for bucket in response['Buckets']:
          if bucket['Name'] == resource['PhysicalResourceId']:
            found.append(resource)
      except ClientError as e:
        print("ClientError:", e.response['Error']['Message'])
      except KeyError as e:
        print("KeyError for resource:", resource, e)
    else:
      try:
        print(resource)
      except Exception as e:
        print("Exception for resource:", resource['PhysicalResourceId'], e)
      missing.append(resource)

  # if there are items in the found list, send a message with what these are to Slack
  if len(found) > 0:
    message = "CloudFormation DELETE_SKIPPED items found in account " + os.environ['ACCOUNT'] + "!\n"
    for item in found:
      message = message + "\nResource Type: " + item['ResourceType'] + ", with name: " + item['PhysicalResourceId'] + ", exists but referencing stack is gone."
    try:
      print(message)
      snsclient = boto3.client('sns', region_name='us-east-2')
      response = snsclient.publish(TopicArn=os.environ['TOPIC_ARN'], Message=message, Subject='CloudFormation DELETE_SKIPPED items found!')
      print(response)
    except ClientError as e:
      print("ClientError:", e.response['Error']['Message'])
  elif len(found) == 0:
    print("Nothing found with DELETE_SKIPPED.")

  if len(missing) > 0:
    message = "CloudFormation DELETE_SKIPPED items found in account " + os.environ['ACCOUNT'] + "!\n"
    for item in missing:
      message = message + "\nResource Type: " + item['ResourceType'] + ", with name: " + item['PhysicalResourceId'] + ", exists but referencing stack is gone. Unlisted ResourceType."
  try:
    print(message)
    snsclient = boto3.client('sns', region_name='us-east-2')
    response = snsclient.publish(TopicArn=os.environ['TOPIC_ARN'], Message=message, Subject='CloudFormation DELETE_SKIPPED items found!')
    print(response)
  except ClientError as e:
    print("ClientError:", e.response['Error']['Message'])