AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Create an API destination in EventBridge - use Slack as a target.

Parameters:
  MySlackToken:
    Type: String
    Default: "xoxb-ENTER YOUR BOT'S ACCESS TOKEN HERE"
  MySlackChannel:
    Type: String
    Default: "ENTER YOUR SLACK CHANNEL ID"
  MyEventBusName:
    Type: String
    Default: "MyEventBus"

Resources:
  MyConnection:
    Type: AWS::Events::Connection
    Properties:
      AuthorizationType: API_KEY
      Description: "My connection with an API key"
      AuthParameters:
        ApiKeyAuthParameters:
          ApiKeyName: "Authorization"
          ApiKeyValue: !Sub 'Bearer ${MySlackToken}'

  MyApiDestination:
    Type: AWS::Events::ApiDestination
    Properties:
      Name: "MySlackNotifier"
      ConnectionArn: !GetAtt MyConnection.Arn
      InvocationEndpoint: "https://slack.com/api/chat.postMessage"
      HttpMethod: POST
      InvocationRateLimitPerSecond: 10

  EventBridgeTargetRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - events.amazonaws.com
            Action:
              - sts:AssumeRole      
      Policies:
        - PolicyName: AllowAPIdestinationAccess
          PolicyDocument:
            Version: '2012-10-17'
            Statement:
              - Effect: Allow
                Action: 'events:InvokeApiDestination'
                Resource: !GetAtt MyApiDestination.Arn

  EventRule: 
    Type: AWS::Events::Rule
    Properties: 
      Description: "EventRule"
      State: "ENABLED"
      EventBusName: !Ref MyEventBusName
      EventPattern: 
        source:
          - "MyTestApp"
        detail-type:
          - "MyTestMessage"       
      Targets: 
        - Arn: !GetAtt MyApiDestination.Arn
          RoleArn: !GetAtt EventBridgeTargetRole.Arn
          Id: "MyAPIdestination"
          InputTransformer:
            InputPathsMap:
              text: $.detail.event
            InputTemplate: !Sub >
              {
                "channel": "${MySlackChannel}",
                "text": <text>
              }

Outputs:
  MyConnectionName:
    Value: !Ref MyConnection
  MyConnectionArn:
    Value: !GetAtt MyConnection.Arn        

  MyApiDestinationName:
    Value: !Ref MyApiDestination
  MyApiDestinationArn:
    Value: !GetAtt MyApiDestination.Arn

  EventBridgeTargetRoleArn:
    Value: !GetAtt EventBridgeTargetRole.Arn