# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT-0
#
# State Machine to wait for Snapshot copy operations to complete.
#
AWSTemplateFormatVersion: "2010-09-09"
Description: "A CloudFormation Template for a State Machine that waits for copies to complete"

Parameters:
  CodeBucket:
    Description: The S3 bucket containing the code
    Default: draco
    Type: String
  CodeKey:
    Description: The path to the Wait4Copy Lambda zipfile
    Default: draco/wait4copy.zip
    Type: String
  CodeVersion:
    Description: The S3 object version of the Wait4Copy Lambda zipfile
    Default: none
    Type: String
  NotifyTopicArn:
    Description: The arn of the topic to notify
    Default: lambdabackup
    Type: String
  PollInterval:
    Description: The interval in seconds between checks
    Default: 300
    Type: Number
  MaxPolls:
    Description: The maximum number of polls
    Default: 60
    Type: Number

Resources:

  Wait4CopyExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action:
              - sts:AssumeRole
      Policies:
        - PolicyName: CloudwatchLogs
          PolicyDocument:
            Statement:
            - Effect: Allow
              Action:
                - logs:CreateLogGroup
                - logs:CreateLogStream
                - logs:PutLogEvents
                - logs:GetLogEvents
              Resource:
                - !Sub arn:aws:logs:${AWS::Region}:${AWS::AccountId}:*
        - PolicyName: InspectSnapshots
          PolicyDocument:
            Statement:
            - Effect: Allow
              Action:
                - rds:DescribeDBSnapshots
                - rds:DescribeDBClusterSnapshots
                - ec2:DescribeSnapshots
              Resource: '*'
  
  Wait4CopyLambda:
    Type: AWS::Lambda::Function
    Properties:
      Description: Wait for a DB snapshot to finish copying
      Handler: wait4copy.handler
      Runtime: nodejs12.x
      Role: !GetAtt Wait4CopyExecutionRole.Arn
      Code:
        S3Bucket: !Ref CodeBucket
        S3Key: !Ref CodeKey
        S3ObjectVersion: !Ref CodeVersion

  Wait4CopySMRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service: states.amazonaws.com
            Action:
              - sts:AssumeRole
      Policies:
        - PolicyName: CloudwatchLogs
          PolicyDocument:
            Statement:
            - Effect: Allow
              Action:
                - logs:CreateLogGroup
                - logs:CreateLogStream
                - logs:PutLogEvents
                - logs:GetLogEvents
              Resource:
                - !Sub arn:aws:logs:${AWS::Region}:${AWS::AccountId}:*
        - PolicyName: Lambda
          PolicyDocument:
            Statement:
            - Effect: Allow
              Action:
                - lambda:InvokeFunction
              Resource: !GetAtt Wait4CopyLambda.Arn
        - PolicyName: SNS
          PolicyDocument:
            Statement:
            - Effect: Allow
              Action:
                - sns:Publish
              Resource: !Ref NotifyTopicArn

  Wait4CopyStateMachine:
    Type: AWS::StepFunctions::StateMachine
    Properties:
      StateMachineName: !Sub "wait4copy-${AWS::AccountId}" # Generate the name to avoid circular deps
      RoleArn: !GetAtt Wait4CopySMRole.Arn
      DefinitionString: !Sub |
        {
          "Comment": "Wait for a Snapshot to become available and fire an SNS snapshot-copy-completed event",
          "StartAt": "Configure",
          "States": {
            "Configure": {
              "Type": "Pass",
              "Result": {
                "count": 0,
                "maxcount": ${MaxPolls},
                "exhausted": false
              },
              "ResultPath": "$.output.body.iterator",
              "Next": "Wait"
            },
            "Wait": {
              "Type": "Wait",
              "Seconds": ${PollInterval},
              "Next": "CheckStatus"
            },
            "CheckStatus": {
              "Type": "Task",
              "Resource": "${Wait4CopyLambda.Arn}",
              "Parameters": {
                "iterator.$": "$.output.body.iterator",
                "ArnToCheck.$": "$.event.ArnToCheck",
                "SnapshotType.$": "$.event.SnapshotType"
              },
              "ResultPath": "$.output",
              "Next": "AreWeThereYet"
            },
            "AreWeThereYet": {
              "Type": "Choice",
              "Choices": [
                {
                  "Variable": "$.output.body.status",
                  "StringEquals": "available",
                  "Next": "NotifyAvailable"
                },
                {
                  "Variable": "$.output.body.iterator.exhausted",
                  "BooleanEquals": true,
                  "Next": "NotifyFailure"
                }
              ],
              "Default": "Wait"
            },
            "NotifyFailure": {
              "Type": "Fail",
              "Error": "MaxPolls",
              "Cause": "Maximum number of polls exceeded"
            },
            "NotifyAvailable": {
              "Type": "Task",
              "Resource": "arn:aws:states:::sns:publish",
              "Parameters": {
                "TopicArn": "${NotifyTopicArn}",
                "Subject": "DRACO Event",
                "Message.$": "$.event"
              },
              "End": true
            }
          }
        }

Outputs:
  StateMachineArn:
    Value: !Ref Wait4CopyStateMachine

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