AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: EventBridge source bus - API Gateway webhook to custom event bus 

Parameters:
  EventSource:
    Type: String
    Description: Webhook source 
    Default: 'CrossRegionTest'

Resources:
  MyEventBus:
    Type: AWS::Events::EventBus
    Properties:
      Name: "CrossRegionSource"

  EventRuleRegion1: 
    Type: AWS::Events::Rule
    Properties: 
      Description: "EventRule - us-east-1 routing"
      EventBusName: !Ref MyEventBus
      State: "ENABLED"
      EventPattern: 
        source:
          - !Ref EventSource
        detail:
          apiEvent:
            region:
              - "us-east-1"
      Targets: 
        - Arn: !Sub "arn:aws:events:us-east-1:${AWS::AccountId}:event-bus/CrossRegionDestination"
          Id: "CrossRegionEventBus1"
          RoleArn: !GetAtt EventBridgeIAMrole.Arn

  EventRuleRegion2: 
    Type: AWS::Events::Rule
    Properties: 
      Description: "EventRule - us-west-2 routing"
      EventBusName: !Ref MyEventBus
      State: "ENABLED"
      EventPattern: 
        source:
          - !Ref EventSource
        detail:
          apiEvent:
            region:
              - "us-west-2"
      Targets: 
        - Arn: !Sub "arn:aws:events:us-west-2:${AWS::AccountId}:event-bus/CrossRegionDestination"
          Id: "CrossRegionEventBus2"
          RoleArn: !GetAtt EventBridgeIAMrole.Arn

  EventRuleRegion3: 
    Type: AWS::Events::Rule
    Properties: 
      Description: "EventRule - eu-west-1 routing"
      EventBusName: !Ref MyEventBus
      State: "ENABLED"
      EventPattern: 
        source:
          - !Ref EventSource
        detail:
          apiEvent:
            region:
              - "eu-west-1"
      Targets: 
        - Arn: !Sub "arn:aws:events:eu-west-1:${AWS::AccountId}:event-bus/CrossRegionDestination"
          Id: "CrossRegionEventBus3"
          RoleArn: !GetAtt EventBridgeIAMrole.Arn

  EventBridgeIAMrole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
        - Effect: Allow
          Principal:
            Service:
              !Sub events.amazonaws.com
          Action: sts:AssumeRole
      Path: /
      Policies:
      - PolicyName: PutEventsDestinationBus
        PolicyDocument:
          Version: 2012-10-17
          Statement:
          - Effect: Allow
            Action:
            - events:PutEvents
            Resource:
            - !Sub "arn:aws:events:us-east-1:${AWS::AccountId}:event-bus/CrossRegionDestination"
            - !Sub "arn:aws:events:us-west-2:${AWS::AccountId}:event-bus/CrossRegionDestination"
            - !Sub "arn:aws:events:eu-west-1:${AWS::AccountId}:event-bus/CrossRegionDestination"

  # Optional section of the template that create an API Gateway webhook to put events
  # onto the bus via a Lambda function. You can route the event to one of the three regions
  # by using /?region=REGION_CODE as a query parameter.

  # DELETE everything after this comment if you don't need the webhook for testing.

  WebhookFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: src/
      Handler: app.handler
      MemorySize: 128
      Timeout: 3
      Runtime: nodejs14.x
      Environment:
        Variables:
          EVENTSOURCE: !Ref EventSource
          EVENT_BUS_NAME: !Ref MyEventBus
      Policies:
        - EventBridgePutEventsPolicy:
            EventBusName: !Ref MyEventBus
      Events:
        HttpApiEvent:
          Type: HttpApi
          Properties:
            Path: /
            Method: GET

Outputs:
  WebhookApiUrl:
    Description: "API Gateway HTTP API endpoint for webhook"
    Value: !Sub "https://${ServerlessHttpApi}.execute-api.${AWS::Region}.amazonaws.com?region=<<region code>>"