---
AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::Serverless-2016-10-31
Description: >
  Example template deploying a VPC and subnet, which is a dependency for a EC2 instance in another template.

  WARNING: You will be billed for the AWS resources created using this template. Make sure to delete the stack
  and clean up resources if you do not intend to keep it running

Parameters:
  pVpcCidr:
    Type: String
    Description: Defines CIDR block to be used by this example VPC
    Default: 10.0.0.0/16
  pSubnetCidr:
    Type: String
    Description: Defines CIDR block to be used by this example subnet
    Default: 10.0.1.0/24

Resources:

  # Dependency

  rVpc:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: !Ref pVpcCidr
      EnableDnsSupport: true
      EnableDnsHostnames: true

  rSubnet:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref rVpc
      AvailabilityZone: !Select [ 0, !GetAZs '' ]
      CidrBlock: !Ref pSubnetCidr

  # Dependency Coordination

  rLogGroup:
    Type: AWS::Logs::LogGroup
    Properties:
      LogGroupName: !Sub /aws/lambda/${rSignalFunction}
      RetentionInDays: 7

  rSignalFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: ./dependency-resolver
      Handler: app.handler
      Runtime: python3.9
      Timeout: 60
      Policies:
        - AWSLambdaBasicExecutionRole
        - Version: 2012-10-17
          Statement:
          - Sid: ParameterStore
            Effect: Allow
            Action:
              - ssm:GetParametersByPath
              - ssm:PutParameter
            Resource:
              - !Sub arn:${AWS::Partition}:ssm:${AWS::Region}:${AWS::AccountId}:parameter/cf-deps/mySubnetDep/*
              - !Sub arn:${AWS::Partition}:ssm:${AWS::Region}:${AWS::AccountId}:parameter/cf-deps/mySubnetDep
      Environment:
        Variables:
          DEPENDENCY_ID: mySubnetDep
          SUBNET_ID: !Ref rSubnet
      Events:
        ParameterRule:
          Type: EventBridgeRule
          Properties:
            Pattern:
              source: [ aws.ssm ]
              detail-type: [ Parameter Store Change ]
              detail:
                name: [ { prefix: /cf-deps/mySubnetDep } ]
                operation: [ Create ]

  rResolvePending:
    Type: AWS::CloudFormation::CustomResource
    DependsOn: rLogGroup # Do not execute Lambda before LogGroup is created
    Properties:
      ServiceToken: !GetAtt rSignalFunction.Arn