AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Serverless patterns - Multiple EventBridge Buses filter/pipe to multiple SNS Topics.

Resources:
  # Define 3 EventBridge Buses for 3 example organisations "banks" namely Bluebank, RedBank and GreenBank
  BlueBankBus:
    Type: AWS::Events::EventBus
    Properties:
      Name: bluebank-bus
  RedBankBus:
    Type: AWS::Events::EventBus
    Properties:
      Name: redbank-bus
  GreenBankBus:
    Type: AWS::Events::EventBus
    Properties:
      Name: greenbank-bus

# Define all DLQs
  ReserveBankDLQueue:
    Type: AWS::SQS::Queue
  BlueBankDLQueue:
    Type: AWS::SQS::Queue
  RedBankDLQueue:
    Type: AWS::SQS::Queue
  GreenBankDLQueue:
    Type: AWS::SQS::Queue

# Define the SNS Topics for Bluebank, Redbank, Greenbank - Transactions Warehouses
  BlueBankTopic:
    Type: AWS::SNS::Topic
  RedBankTopic:
    Type: AWS::SNS::Topic
  GreenBankTopic:
    Type: AWS::SNS::Topic

# Define the SNS Topic for Central/Reserve Bank - All reportable cross-border transactions aka Balance of payment "BOP" transactions from all banks.
  ReserveBankTopic:
    Type: AWS::SNS::Topic

# Define the Event Rule to filter reportable Bluebank events to Reserve Bank SNS Topic
  EventRuleBlueBank:
    Type: AWS::Events::Rule
    Properties:
      Description: "EventRule BlueBank transactions to Reserve Bank"
      EventBusName: !Ref BlueBankBus
      EventPattern:
        account:
          - !Sub '${AWS::AccountId}'
        source:
          - "atm.events"
          - "bankbranch.events"
        detail-type:
          - "Bank transaction"
        detail:
          bop_reportable:
            - "Yes"
      Targets:
        - Arn: !Ref ReserveBankTopic
          Id: "ReserveBankTopic"
          DeadLetterConfig:
            Arn:  !GetAtt ReserveBankDLQueue.Arn

# Define the Event Rule to pipe all Bluebank events to Bluebank Warehouse SNS Topic
  EventRuleBlueBankCatchAll:
    Type: AWS::Events::Rule
    Properties:
      Description: "EventRule Bluebank to Bluebank transactions warehouse"
      EventBusName: !Ref BlueBankBus
      EventPattern:
        account:
          - !Sub '${AWS::AccountId}'
        source:
          - "atm.events"
          - "bankbranch.events"
        detail-type:
          - "Bank transaction"
        detail:
          bop_reportable:
            - "Yes"
            - "No"
      Targets:
        - Arn: !Ref BlueBankTopic
          Id: "BlueBankTopic"
          DeadLetterConfig:
            Arn:  !GetAtt BlueBankDLQueue.Arn

# Define the Event Rule to filter reportable Redbank events to Reserve Bank SNS Topic
  EventRuleRedBank:
    Type: AWS::Events::Rule
    Properties:
      Description: "EventRule Redbank transactions to Reserve Bank"
      EventBusName: !Ref RedBankBus
      EventPattern:
        account:
          - !Sub '${AWS::AccountId}'
        source:
          - "atm.events"
          - "bankbranch.events"
        detail-type:
          - "Bank transaction"
        detail:
          bop_reportable:
            - "Yes"
      Targets:
        - Arn: !Ref ReserveBankTopic
          Id: "ReserveBankTopic"
          DeadLetterConfig:
            Arn:  !GetAtt ReserveBankDLQueue.Arn

# Define the Event Rule to pipe all Redbank events to Redbank Warehouse SNS Topic
  EventRuleRedBankCatchAll:
    Type: AWS::Events::Rule
    Properties:
      Description: "EventRule RedBank to RedBank transactions warehouse"
      EventBusName: !Ref RedBankBus
      EventPattern:
        account:
          - !Sub '${AWS::AccountId}'
        source:
          - "atm.events"
          - "bankbranch.events"
        detail-type:
          - "Bank transaction"
        detail:
          bop_reportable:
            - "Yes"
            - "No"
      Targets:
        - Arn: !Ref RedBankTopic
          Id: "RedBankTopic"
          DeadLetterConfig:
            Arn:  !GetAtt RedBankDLQueue.Arn

# Define the Event Rule to filter reportable Greenbank events to Reserve Bank SNS Topic
  EventRuleGreenBank:
    Type: AWS::Events::Rule
    Properties:
      Description: "EventRule Greenbank transactions to Reserve Bank"
      EventBusName: !Ref GreenBankBus
      EventPattern:
        account:
          - !Sub '${AWS::AccountId}'
        source:
          - "atm.events"
          - "bankbranch.events"
        detail-type:
          - "Bank transaction"
        detail:
          bop_reportable:
            - "Yes"
      Targets:
        - Arn: !Ref ReserveBankTopic
          Id: "ReserveBankTopic"
          DeadLetterConfig:
            Arn:  !GetAtt ReserveBankDLQueue.Arn

# Define the Event Rule to pipe all Greenbank events to Greenbank Warehouse SNS Topic
  EventRuleGreenBankCatchAll:
    Type: AWS::Events::Rule
    Properties:
      Description: "EventRule GreenBank to Greenbank transactions warehouse"
      EventBusName: !Ref GreenBankBus
      EventPattern:
        account:
          - !Sub '${AWS::AccountId}'
        source:
          - "atm.events"
          - "bankbranch.events"
        detail-type:
          - "Bank transaction"
        detail:
          bop_reportable:
            - "Yes"
            - "No"
      Targets:
        - Arn: !Ref GreenBankTopic
          Id: "GreenBankTopic"
          DeadLetterConfig:
            Arn: !GetAtt GreenBankDLQueue.Arn

# Allow EventBridge to invoke Bluebank SNS Topic
  SNSPolicyEventBridgeBlueBankTopicAllow:
    Type: AWS::SNS::TopicPolicy
    Properties:
      PolicyDocument:
        Statement:
        - Effect: Allow
          Principal:
            Service: events.amazonaws.com
          Action: "SNS:Publish"
          Resource:
            - !Ref BlueBankTopic
      Topics:
        - !Ref BlueBankTopic

  # Allow EventBridge to invoke Redbank SNS Topic
  SNSPolicyEventBridgeRedBankTopicAllow:
    Type: AWS::SNS::TopicPolicy
    Properties:
      PolicyDocument:
        Statement:
        - Effect: Allow
          Principal:
            Service: events.amazonaws.com
          Action: "SNS:Publish"
          Resource:
            - !Ref RedBankTopic
      Topics:
        - !Ref RedBankTopic

  # Allow EventBridge to invoke Greenbank SNS Topic
  SNSPolicyEventBridgeGreenBankTopicAllow:
    Type: AWS::SNS::TopicPolicy
    Properties:
      PolicyDocument:
        Statement:
        - Effect: Allow
          Principal:
            Service: events.amazonaws.com
          Action: "SNS:Publish"
          Resource:
            - !Ref GreenBankTopic
      Topics:
        - !Ref GreenBankTopic

  # Allow EventBridge to invoke Reserve Bank SNS Topic
  SNSPolicyEventBridgeReserveBankTopicAllow:
    Type: AWS::SNS::TopicPolicy
    Properties:
      PolicyDocument:
        Statement:
        - Effect: Allow
          Principal:
            Service: events.amazonaws.com
          Action: "SNS:Publish"
          Resource:
            - !Ref ReserveBankTopic
      Topics:
        - !Ref ReserveBankTopic

# Define lambda function with permission to send events to 3 bank Buses
  EventsGeneratorFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: src/
      Handler: app.lambda_handler
      Runtime: python3.9
      MemorySize: 128
      Policies:
      - Statement:
        - Sid: SendEvents
          Effect: Allow
          Action:
          - events:DeleteRule
          - events:DescribeRule
          - events:DisableRule
          - events:EnableRule
          - events:ListRuleNamesByTarget
          - events:ListRules
          - events:ListTargetsByRule
          - events:PutEvents
          Resource:
            - !GetAtt BlueBankBus.Arn
            - !GetAtt RedBankBus.Arn
            - !GetAtt GreenBankBus.Arn

# Outputs and links to created resources
Outputs:
  BlueBankTopicName:
    Description: SNS Topic name for Bluebank
    Value: !GetAtt BlueBankTopic.TopicName
  BlueBankBusARN:
    Description: Blue Bank Bus ARN
    Value: !GetAtt BlueBankBus.Arn
  RedBankTopicName:
    Description: SNS Topic name for Redbank
    Value: !GetAtt RedBankTopic.TopicName
  RedBankBusARN:
    Description: Red Bank Bus ARN
    Value: !GetAtt RedBankBus.Arn
  GreenBankTopicName:
    Description: SNS Topic name for Greenbank
    Value: !GetAtt GreenBankTopic.TopicName
  GreenBankBusARN:
    Description: Green Bank Bus ARN
    Value: !GetAtt GreenBankBus.Arn
  ReserveBankTopicName:
    Description: SNS Topic name for Reservebank
    Value: !GetAtt ReserveBankTopic.TopicName
  Lambdafunction:
    Description: Main Lambda function for generating events
    Value: !Ref EventsGeneratorFunction