AWSTemplateFormatVersion: 2010-09-09
Transform: 'AWS::Serverless-2016-10-31'
Description: An Amazon REST API gateway with request validator to validate querystring, header, and body, and integrated with a AWS Lambda function.

# Global values that are applied to all applicable resources in this template
Globals:
  Function:
    CodeUri: ./src
    Runtime: nodejs14.x
    MemorySize: 128
    Timeout: 15

# Parameter values that should be given as input while stack creation
Parameters:
  AppName:
    Description: Name of the API Gateway
    Type: String
    Default: apigw-validator-lambda

Resources:
  # Lambda Function - uses Globals to define additional configuration values
  LambdaFunction:
    Type: 'AWS::Serverless::Function'
    Properties:
      FunctionName: !Sub '${AppName}-function'
      Handler: app.handler

  # API Gateway REST API
  RestApi:
    Type: AWS::ApiGateway::RestApi
    Properties:
      Name: !Ref AppName
      Description: An Amazon API Gateway HTTP API with mutual TLS and an AWS Lambda function.
      EndpointConfiguration:
        Types:
          - REGIONAL

  # Request Validator for the REST API
  RestApiRequestValidator:
      Type: AWS::ApiGateway::RequestValidator
      Properties:
        Name: MyAPIRequestValidator
        RestApiId: !Ref RestApi
        ValidateRequestBody: true
        ValidateRequestParameters: true

  # Request model for the REST API
  RestApiModel:
    Type: AWS::ApiGateway::Model
    Properties:
      Name: MyRequestModel
      ContentType: 'application/json'
      RestApiId: !Ref RestApi
      Schema: {
          "$schema": "https://json-schema.org/draft/2020-12/schema",
          "title": "Person",
          "type": "object",
          "required": [ "firstName", "lastName" ],
          "properties": {
            "firstName": {
              "type": "string",
              "description": "The person's first name."
              },
              "lastName": {
                "type": "string",
                "description": "The person's last name."
              }
            }
        }

  # POST method for the REST API
  RestApiMethod:
    Type: AWS::ApiGateway::Method
    Properties:
      AuthorizationType: NONE
      HttpMethod: POST
      RequestModels:
        $default: !Ref RestApiModel
      # QueryString and Header for the REST Api
      RequestParameters:
        method.request.querystring.myQueryString: true
        method.request.header.myHeader: true
      RequestValidatorId: !GetAtt RestApiRequestValidator.RequestValidatorId
      MethodResponses:
        - ResponseModels:
            application/json : 'Empty'
          StatusCode: 200
      Integration:
        IntegrationHttpMethod: POST
        Type: AWS_PROXY
        Uri: !Sub
          - 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${lambdaArn}/invocations'
          - lambdaArn: !GetAtt LambdaFunction.Arn
      ResourceId: !GetAtt RestApi.RootResourceId
      RestApiId: !Ref RestApi

  # REST API Deployment
  RestApiDeployment:
    Type: AWS::ApiGateway::Deployment
    DependsOn: RestApiMethod
    Properties:
      Description: Lambda Rest API Deployment
      RestApiId: !Ref RestApi

  # Stage for REST API Deployment
  RestApiStage:
    Type: AWS::ApiGateway::Stage
    Properties:
      DeploymentId: !Ref RestApiDeployment
      Description: Lambda API Stage
      RestApiId: !Ref RestApi
      StageName: prod

  # Function permissions grant an AWS service
  FunctionResourcePermission:
    Type: 'AWS::Lambda::Permission'
    Properties:
      Action: 'lambda:InvokeFunction'
      Principal: apigateway.amazonaws.com
      FunctionName: !Ref LambdaFunction
      SourceArn: !Sub 'arn:aws:execute-api:${AWS::Region}:${AWS::AccountId}:${RestApi}/*'

Outputs:
  RestApiEndpoint:
    Description: The endpoint for the REST API Gateway.
    Value: !Sub "https://${RestApi}.execute-api.${AWS::Region}.amazonaws.com/prod/"