# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT-0
#
# Copies S3 objects to local S3 bucket. This is usefule if you have lambda functions from a different region 
#

AWSTemplateFormatVersion: 2010-09-09
Description: Copy S3 object to local S3 bucket

Parameters:

  S3BucketSources:
    Type: String
    Description: S3 bucket with sources 
    MaxLength: 63
    MinLength: 3
    Default: my-test-bucket

  S3SourcesPrefix:
    Type: String
    Description: S3 prefix with sources WITH ending slash  
    MaxLength: 128
    MinLength: 3
    Default: prefix

  S3Objects:
    Type: CommaDelimitedList
    Description: S3 Object to be copied
    Default: test1.json, test2.json

Resources:

  S3BucketRegionSources:
    Type: AWS::S3::Bucket
    Properties:
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              SSEAlgorithm: AES256
    DeletionPolicy: Delete

  CopyZips:
    Type: AWS::CloudFormation::CustomResource
    Properties:
      ServiceToken: !GetAtt 'CopyZipsFunction.Arn'
      DestBucket:  !Ref 'S3BucketRegionSources'
      SourceBucket: !Ref 'S3BucketSources'
      SourcePrefix: !Ref 'S3SourcesPrefix'
      Counter: "1"
      Objects: !Ref S3Objects

  CopyZipsRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
      Path: /
      Policies:
        - PolicyName: lambda-copier
          PolicyDocument:
            Version: '2012-10-17'
            Statement:
              - Effect: Allow
                Action:
                  - s3:GetObject
                  - s3:GetObjectTagging
                Resource: 
                  - !Sub 'arn:aws:s3:::${S3BucketSources}/*'
              - Effect: Allow
                Action:
                  - s3:ListBucket
                Resource: 
                  - !Sub 'arn:aws:s3:::${S3BucketSources}'
              - Effect: Allow
                Action:
                  - s3:ListBucket
                Resource: 
                  - !Sub 'arn:aws:s3:::${S3BucketRegionSources}'
              - Effect: Allow
                Action:
                  - s3:PutObject
                  - s3:DeleteObject
                  - s3:PutObjectTagging
                  - s3:GetObject
                Resource: 
                  - !Sub 'arn:aws:s3:::${S3BucketRegionSources}/*'

  CopyZipsFunction:
    Type: AWS::Lambda::Function
    Properties:
      FunctionName:  "CopyZipsFunction"
      Description: Copies objects from a source S3 bucket to a destination
      Handler: index.handler
      Runtime: python3.6
      Role: !GetAtt 'CopyZipsRole.Arn'
      Timeout: 240
      Code:
        ZipFile: |
          import json
          import logging
          import threading
          import boto3
          import cfnresponse
          import botocore
          import uuid

          logger = logging.getLogger()

          def copy_objects(s3, source_bucket, dest_bucket, objects, prefix):
              for o in objects:
                  key =  prefix  + o 
                  copy_source = {
                      'Bucket': source_bucket,
                      'Key': key
                  }
                  logger.info('copy source_bucket:' + source_bucket + ' destination_bucket: '+ dest_bucket + '  key: ' + key) 
                  try: 
                    s3.head_object(Bucket=dest_bucket, Key=key)
                  except botocore.exceptions.ClientError as error:
                    if error.response['Error']['Message']=="Not Found":
                      s3.copy_object(CopySource=copy_source, Bucket=dest_bucket, Key=key)
                  else:
                    raise Exception("ObjectAlreadyExists")

          def delete_objects(s3, bucket, objects, prefix):
              objects = {'Objects': [{'Key':  prefix  + o} for o in objects]}
              s3.delete_objects(Bucket=bucket, Delete=objects)

          def timeout(event, context):
              logger.error('Execution is about to time out, sending failure response to CloudFormation')
              cfnresponse.send(event, context, cfnresponse.FAILED, {}, None)

          def handler(event, context):
              s3 = boto3.client('s3')
              # make sure we send a failure to CloudFormation if the function is going to timeout
              timer = threading.Timer((context.get_remaining_time_in_millis() / 1000.00) - 0.5, timeout, args=[event, context])
              timer.start()
              status = cfnresponse.SUCCESS
              try:
                  source_bucket = event['ResourceProperties']['SourceBucket']
                  source_prefix = event['ResourceProperties']['SourcePrefix']
                  dest_bucket = event['ResourceProperties']['DestBucket']
                  if source_bucket != dest_bucket:
                      objects = event['ResourceProperties']['Objects']
                      if event['RequestType'] == 'Delete':
                          delete_objects(s3, dest_bucket,  objects, source_prefix)
                      else:
                          copy_objects(s3, source_bucket, dest_bucket,  objects, source_prefix)
              except Exception as e:
                  logger.error('Exception: %s' % e, exc_info=True)
                  status = cfnresponse.FAILED
              finally:
                  timer.cancel()
                  # return the same physical ID to prevent delete on stack clenup
                  try:
                      physicalID=event["PhysicalResourceId"]
                      logger.info(f"Found physical ID {physicalID}") # "f
                  except Exception as e:
                      physicalID=str(uuid.uuid1())
                      logger.info(f"Set physical ID {physicalID}") # "f
                  
                  cfnresponse.send(event, context, status, {}, physicalID)

Outputs: 
 
  RegionalS3Bucket:
    Description:  Regional S3 bucket 
    Value: !Ref S3BucketRegionSources