import { Construct } from 'constructs';
import * as ec2 from 'aws-cdk-lib/aws-ec2'
import * as rds from "aws-cdk-lib/aws-rds";

interface RdsProps {
  vpc: ec2.Vpc
  dbSG:ec2.SecurityGroup
}

export class Rds extends Construct{
  readonly rdsCluster: rds.DatabaseCluster

  constructor(scope: Construct, id:string, props: RdsProps){
    super(scope, id);

    const {vpc, dbSG} = props
    const instanceType = ec2.InstanceType.of(ec2.InstanceClass.BURSTABLE4_GRAVITON, ec2.InstanceSize.MEDIUM)

    // RDSのパスワードを自動生成してSecrets Managerに格納
    const rdsCredentials = rds.Credentials.fromGeneratedSecret('db_user',{
      secretName: 'langflow-DbSecret',
    })

    // DB クラスターのパラメータグループ作成
    const clusterParameterGroup = new rds.ParameterGroup(scope, 'ClusterParameterGroup',{
      engine: rds.DatabaseClusterEngine.auroraMysql({
        version: rds.AuroraMysqlEngineVersion.VER_3_02_0
      }),
      description: 'for-langflow',
    })
    clusterParameterGroup.bindToCluster({})

    // DB インスタンスのパラメタグループ作成
    const instanceParameterGroup = new rds.ParameterGroup(scope, 'InstanceParameterGroup',{
      engine: rds.DatabaseClusterEngine.auroraMysql({
        version: rds.AuroraMysqlEngineVersion.VER_3_02_0,
      }),
      description: 'for-langflow',
    })
    instanceParameterGroup.bindToInstance({})

    this.rdsCluster = new rds.DatabaseCluster(scope, 'LangflowDbCluster', {
      engine: rds.DatabaseClusterEngine.auroraMysql({
        version: rds.AuroraMysqlEngineVersion.VER_3_02_0,
      }),
      storageEncrypted: true,
      credentials: rdsCredentials,
      instanceIdentifierBase: 'langflow-instance',
      vpc:vpc,
      vpcSubnets:vpc.selectSubnets({
        subnetGroupName: 'langflow-Isolated',
      }),
      securityGroups:[dbSG],
      writer: rds.ClusterInstance.provisioned("WriterInstance", {
        instanceType: instanceType,
        enablePerformanceInsights: true,
        parameterGroup:instanceParameterGroup,
      }),
      // 2台目以降はreaders:で設定 
      parameterGroup: clusterParameterGroup,
      defaultDatabaseName: 'langflow',
    })
  }
}