AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Custom Domain

Parameters:
  DomainName:
    Type: String
    Description: Domian name for api
  ZoneId:
    Type: String
    Description: Zone ID if exists. If not leave as none.
    Default: none
  CertArn:
    Type: String
    Description: Certificate ARN if exists. If not leave as none.
    Default: none

Conditions:
  CreateZone:
    !Equals [!Ref ZoneId, 'none']
  CreateCert:
    !Equals [!Ref CertArn, 'none']

Resources:
  GeneratedZone: # If a Zone ID is not passed in the parameteres, then a new zone is created for the domain
    Type: AWS::Route53::HostedZone
    Condition: CreateZone
    Properties: 
      Name: !Ref DomainName

  GeneratedCert: # If a Certificate ARN is not passed in the parameters, then a new cert is created and will required validation during the deploy
    Type: AWS::CertificateManager::Certificate
    Condition: CreateCert
    Properties: 
      DomainName: !Ref DomainName
      ValidationMethod: DNS

  RestApiGateway: # Creates a REST API endpoint under the custom domain
    Type: AWS::Serverless::Api
    Properties:
      StageName: Prod
      Domain:
        DomainName: !Ref DomainName
        CertificateArn: !If [CreateCert, !Ref GeneratedCert, !Ref CertArn]
        Route53:
          HostedZoneId: !If [CreateZone, !Ref GeneratedZone, !Ref ZoneId]

  RestApiFunction:  # Integration Lambda function for the Rest API
    Type: AWS::Serverless::Function
    Properties:
      InlineCode: |
        exports.handler = async (event) => {
          const response = {
            statusCode: 200,
            body: JSON.stringify('Hello from Lambda!'),
          };
          return response;
        };
      Handler: index.handler
      Runtime: nodejs12.x
      Events:
        FetchRest:
          Type: Api
          Properties:
            RestApiId: !Ref RestApiGateway
            Method: GET
            Path: /