Resources:
  AppSyncApiLambdaInvocationRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
        - Effect: Allow
          Principal:
            Service: appsync.amazonaws.com
          Action:
          - sts:AssumeRole

  HelloLambda:
    Type: AWS::Serverless::Function
    Properties:
      InlineCode: |
        exports.handler = async (_) => {
          return "Hello World"
        }
      Handler: index.handler
      Runtime: nodejs14.x

  AppSyncApi:
    Type: AWS::AppSync::GraphQLApi
    Properties:
      AuthenticationType: API_KEY
      Name: AppSyncApi

  ApiSchema:
    Type: AWS::AppSync::GraphQLSchema
    Properties:
      ApiId: !GetAtt AppSyncApi.ApiId
      Definition: |
        type Query {
          sayHello: String!
        }
        schema {
          query: Query
        }

  AppSyncLambdaDataSource:
    Type: AWS::AppSync::DataSource
    Properties:
      ApiId: !GetAtt AppSyncApi.ApiId
      Name: AppSyncLambdaDataSource
      Type: AWS_LAMBDA
      ServiceRoleArn: !GetAtt AppSyncApiLambdaInvocationRole.Arn
      LambdaConfig:
        LambdaFunctionArn: !GetAtt HelloLambda.Arn

  AppSyncSayHelloResolver:
    DependsOn: ApiSchema
    Type: AWS::AppSync::Resolver
    Properties:
      ApiId: !GetAtt AppSyncApi.ApiId
      TypeName: Query
      FieldName: sayHello
      DataSourceName: !GetAtt AppSyncLambdaDataSource.Name
      RequestMappingTemplate: |
        {
          "version" : "2017-02-28",
          "operation": "Invoke",
          "payload": $util.toJson($context.args)
        }
      ResponseMappingTemplate: |
        $util.toJson($context.result)

  DataSourceToLambdaConnector:
    Type: AWS::Serverless::Connector
    Properties:
      Source:
        Id: AppSyncLambdaDataSource
      Destination:
        Id: HelloLambda
      Permissions:
      - Write

  ApiKey:
    Type: AWS::AppSync::ApiKey
    Properties:
      ApiId: !GetAtt AppSyncApi.ApiId

  TriggerFunction:
    Type: AWS::Serverless::Function
    Properties:
      Environment:
        Variables:
          API_KEY: !GetAtt ApiKey.ApiKey
          GRAPHQL_URL: !GetAtt AppSyncApi.GraphQLUrl
      Runtime: nodejs14.x
      Handler: index.handler
      InlineCode: |
        const https = require("https");

        exports.handler = async (_) => {
          const queries = {
            sayHello: /* GraphQL */ `
              query {
                sayHello
              }
            `,
          };


          const fetch = async (url, options) =>
            new Promise((resolve, reject) => {
              const req = https.request(url, options, (res) => {
                const body = [];
                res.on("data", (chunk) => body.push(chunk));
                res.on("end", () => {
                  const resString = Buffer.concat(body).toString();
                  resolve(resString);
                });
              });

              req.on("error", (err) => {
                reject(err);
              });

              req.on("timeout", () => {
                req.destroy();
                reject(new Error("Request time out"));
              });

              req.write(options.body);
              req.end();
            });


          const makeRequest = async (queryName) => {
            const options = {
              method: "POST",
              headers: {
                "x-api-key": process.env.API_KEY,
              },
              body: JSON.stringify({ query: queries[queryName] }),
              timeout: 10000, // ms
            };

            const response = await fetch(process.env.GRAPHQL_URL, options);
            const body = JSON.parse(response);
            const data = body.data?.[queryName];

            if (body.errors !== undefined) {
              throw JSON.stringify(body.errors);
            }
            
            if (data !== "Hello World") {
              throw new Error(`${queryName} error: '${data}' must be 'Hello World'`);
            }

            return body.data;
          };


          return await makeRequest("sayHello");
        };


Metadata:
  SamTransformTest: true