AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: AWS Step Functions sample project for using distributed map for montecarlo simulation.

Globals:
  Function:
    Tracing: Active
    Timeout: 300

Parameters:
  resourcePrefix:
    Type: String 
    Default: "sfn-montecarlo"


Resources:
  SamplingFunction:
    Type: AWS::Serverless::Function 
    Properties:
      CodeUri: functions/sampling_function/
      Handler: sampling.lambda_handler
      Runtime: python3.7
      Description: "Function generating input samples for montecarlo simulation."
      FunctionName: !Sub "${resourcePrefix}-sampling"
      MemorySize: 2048
      Environment:
        Variables:
          DATA_BUCKET: !Ref MonteCarloBucket
    Connectors:
      SamplingBucketConnect:
        Properties:
          Destination:
            Id: MonteCarloBucket
          Permissions:
            - Read
            - Write

  CalculatorFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: functions/calculator_function/
      Handler: calculator.lambda_handler
      Runtime: python3.7
      Description: "Function calculating revenue for each sample in montecarlo simulation."
      FunctionName: !Sub "${resourcePrefix}-calculator"
      Environment:
        Variables:
          DATA_BUCKET: !Ref MonteCarloBucket
    Connectors:
      CalculatorBucketConnect:
        Properties:
          Destination:
            Id: MonteCarloBucket
          Permissions:
            - Read
            - Write

  AggregatorFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: functions/aggregator_function/
      Handler: aggregator.lambda_handler
      Runtime: python3.7
      Description: "Function aggregating montecarlo results."
      FunctionName: !Sub "${resourcePrefix}-aggregator"
      MemorySize: 2048
      Environment:
        Variables:
          DATA_BUCKET: !Ref MonteCarloBucket
    Connectors:
      AggregatorBucketConnect:
        Properties:
          Destination:
            Id: MonteCarloBucket
          Permissions:
            - Read
            - Write

  MonteCarloBucket:
    Type: 'AWS::S3::Bucket'
    DeletionPolicy: Delete
  
  # Create the montecarlo state machine
  MontecarloStateMachine:
    Type: AWS::Serverless::StateMachine
    Properties:
      Name: !Sub "${resourcePrefix}-statemachine"
      DefinitionUri: ./statemachine/statemachine.asl.json
      DefinitionSubstitutions:
        SamplingFunctionArn: !GetAtt SamplingFunction.Arn
        CalculatorFunctionArn: !GetAtt CalculatorFunction.Arn
        AggregatorFunctionArn: !GetAtt AggregatorFunction.Arn
      Policies:
        - S3CrudPolicy: # Add IAM policy to the stepfunction execution role access the S3 bucket
            BucketName: !Ref MonteCarloBucket
        - StepFunctionsExecutionPolicy: # Add IAM policy to the stepfunction execution role start child executions
            StateMachineName: !Sub "${resourcePrefix}-statemachine"

  # Add IAM policy to the stepfunction execution role to invoke SamplingFunction
  SfnToSamplingFunctionConnector:
    Type: AWS::Serverless::Connector 
    Properties:
      Source:
        Id: MontecarloStateMachine
      Destination:
        Id: SamplingFunction
      Permissions:
        - Write

  # Add IAM policy to the stepfunction execution role to invoke CalculatorFunction
  SfnToCalculatorFunctionConnector:
    Type: AWS::Serverless::Connector
    Properties:
      Source:
        Id: MontecarloStateMachine
      Destination:
        Id: CalculatorFunction
      Permissions:
        - Write

  # Add IAM policy to the stepfunction execution role to invoke AggregatorFunction
  SfnToAggregatorFunctionConnector:
    Type: AWS::Serverless::Connector
    Properties:
      Source:
        Id: MontecarloStateMachine
      Destination:
        Id: AggregatorFunction
      Permissions:
        - Write

Outputs:
  StateMachineArn:
    Value: !Ref MontecarloStateMachine