AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31
Description: >
  aws-stepfunction-waitable-pattern

  Sample SAM Template for aws-stepfunction-waitable-pattern

Resources:
  WaitableStateMachine:
    Type: AWS::Serverless::StateMachine 
    Properties:
      DefinitionUri: statemachine/waitable-stepfunction.asl.json
      DefinitionSubstitutions:
        DDBTable: !Ref StatusTable
      Policies: 
        - DynamoDBWritePolicy:
            TableName: !Ref StatusTable

  StatusTable:
    Type: AWS::DynamoDB::Table 
    Properties:
      AttributeDefinitions:
        - AttributeName: "Id"
          AttributeType: "S"
      KeySchema:
        - AttributeName: "Id"
          KeyType: "HASH"
      ProvisionedThroughput:
        ReadCapacityUnits: 1
        WriteCapacityUnits: 1

  ApiGatewayStepFunctionsRole:
    Type: AWS::IAM::Role
    Properties:
      Path: !Join ["", ["/", !Ref "AWS::StackName", "/"]]
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Sid: AllowApiGatewayServiceToAssumeRole
            Effect: Allow
            Action:
              - 'sts:AssumeRole'
            Principal:
              Service:
                - apigateway.amazonaws.com
      Policies:
        - PolicyName: CallStepFunctionsAndScanDynamo
          PolicyDocument:
            Version: 2012-10-17
            Statement:
              - Effect: Allow
                Action:
                  - 'states:StartExecution'
                  - 'dynamodb:Scan'
                Resource:
                  - !Ref WaitableStateMachine
                  - !GetAtt StatusTable.Arn
  
  ApiGateway:
    Type: AWS::ApiGateway::RestApi
    Properties:
      Name: !Sub ${AWS::StackName}-api

  
  ApiGatewayRootMethod:
    Type: AWS::ApiGateway::Method
    Properties:
      AuthorizationType: NONE
      HttpMethod: POST
      OperationName: "StartWorkflow"
      MethodResponses:
        - StatusCode: 200
          ResponseModels:
            application/json: Empty
      Integration:
        IntegrationHttpMethod: POST
        Type: AWS
        Credentials: !GetAtt ApiGatewayStepFunctionsRole.Arn 
        Uri: !Sub arn:aws:apigateway:${AWS::Region}:states:action/StartExecution
        PassthroughBehavior: WHEN_NO_TEMPLATES
        RequestTemplates: 
          application/json: !Sub 
            - |-               
              { 
                "input": "{\"Id\" : \"$context.requestId\", \"StartTimestamp\": \"$input.path('$.StartTimestamp')\"}", 
                "stateMachineArn": "${StateMachineArn}"
              }
            - { StateMachineArn: !Ref WaitableStateMachine }
        IntegrationResponses:
          - StatusCode: 200
            ResponseTemplates:
              application/json: ''
      ResourceId: !GetAtt ApiGateway.RootResourceId
      RestApiId: !Ref ApiGateway

  StatusResource:
    Type: AWS::ApiGateway::Resource
    DependsOn:
      - ApiGateway
    Properties: 
      RestApiId: !Ref ApiGateway
      ParentId: !GetAtt ApiGateway.RootResourceId
      PathPart: "status"
      
  
  StatusMethod:  
    Type: AWS::ApiGateway::Method
    Properties:
      AuthorizationType: NONE
      HttpMethod: GET
      OperationName: "GetStatus"
      MethodResponses:
        - StatusCode: 200
          ResponseModels:
            application/json: Empty
      Integration:
        IntegrationHttpMethod: POST
        Type: AWS
        Credentials: !GetAtt ApiGatewayStepFunctionsRole.Arn 
        Uri: !Sub arn:aws:apigateway:${AWS::Region}:dynamodb:action/Scan
        PassthroughBehavior: WHEN_NO_TEMPLATES
        RequestTemplates: 
          application/json: !Sub 
            - |- 
              {
                "TableName": "${TableName}"          
              }
            - { TableName: !Select [1, !Split ['/', !GetAtt StatusTable.Arn]] }
        IntegrationResponses:
          - StatusCode: 200
            ResponseTemplates:
              application/json: | 
                #set($inputRoot = $input.path('$'))
                {
                    "items": [
                        #foreach($elem in $inputRoot.Items) {
                            "Id": "$elem.Id.S",
                            "StartActionAt": "$elem.StartActionAt.S"
                            "LastUpdated": "$elem.LastUpdated.S",
                            "ProcessStatus": "$elem.ProcessStatus.S"
                        }#if($foreach.hasNext),#end
                  #end
                    ]
                }
      ResourceId: !Ref StatusResource
      RestApiId: !Ref ApiGateway

  apiGatewayDeployment:
    Type: AWS::ApiGateway::Deployment
    DependsOn:
      - ApiGatewayRootMethod
      - StatusMethod
    Properties:
      RestApiId: !Ref ApiGateway
      StageName: 'dev'
      
Outputs:
  WaitableStateMachineArn:
    Description: "Waitable state machine ARN"
    Value: !Ref WaitableStateMachine
  WaitableStateMachineRole:
    Description: "IAM Role created for waitable state machine based on the specified SAM Policy Templates"
    Value: !GetAtt WaitableStateMachineRole.Arn