AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Step Functions Workflow Pattern - Human in the loop

Parameters:
  # During deployment, this paramter will prompt for the email address of a reviewer.
  ModeratorEmailAddress:
    Type: String
    Default: moderator@example.com
    Description: Enter the email address that will receive review notifications.

# Comment each resource section to explain usage.
Resources:
  StateMachine:
    Type: AWS::Serverless::StateMachine # More info about State Machine Resource: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-resource-statemachine.html
    Properties:
      Name: human-in-the-loop
      DefinitionUri: statemachine/statemachine.asl.json
      DefinitionSubstitutions:
        ProcessingLambda: !Ref ProcessingLambda
        TopicName: !Ref NotificationTopic
      Policies: # Find out more about SAM policy templates: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-policy-templates.html
        - SNSPublishMessagePolicy:
            TopicName: !GetAtt NotificationTopic.TopicName
        - LambdaInvokePolicy:
            FunctionName: !Ref ProcessingLambda

  # Amazon SNS topic and subscription, triggers notification email when content needs to be reviewed.
  NotificationTopic:
    Type: AWS::SNS::Topic
    Properties:
      Subscription:
        - Endpoint: !Ref ModeratorEmailAddress
          Protocol: "email"

  # AWS Lambda function processes the review result.
  # Consider using different functions when your logic gets more complex.
  ProcessingLambda:
    Type: AWS::Serverless::Function 
    Properties:
      FunctionName: ProcessingLambda
      CodeUri: lambda/
      Handler: app.handler
      Runtime: nodejs14.x
      Timeout: 3
      Policies:
        - AWSLambdaBasicExecutionRole

Outputs:
  StepFunctionConsoleUrl:
    Description: AWS Console URL of the created StepFunction
    Value: !Sub
      - "https://${AWS::Region}.console.aws.amazon.com/states/home?region=${AWS::Region}#/statemachines/view/${statemachine}"
      - statemachine: !Ref StateMachine