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

interface RdsStackProps extends cdk.StackProps {
  /**
   * Environment name (dev, staging, prod)
   */
  environment: string;

  /**
   * VPC to deploy the database in
   */
  vpc: ec2.IVpc;

  /**
   * Database credentials secret from SecretsStack
   */
  databaseSecret: secretsmanager.ISecret;

  /**
   * Database name (default: rentall)
   */
  databaseName?: string;

  /**
   * Instance type (default: t3.micro for Free Tier)
   */
  instanceType?: ec2.InstanceType;

  /**
   * Allocated storage in GB (default: 20)
   */
  allocatedStorage?: number;

  /**
   * Enable Multi-AZ deployment (default: false for dev/staging)
   */
  multiAz?: boolean;

  /**
   * Backup retention days (default: 7)
   */
  backupRetentionDays?: number;
}

export class RdsStack extends cdk.Stack {
  /**
   * The RDS database instance
   */
  public readonly database: rds.DatabaseInstance;

  /**
   * Security group for the database
   */
  public readonly databaseSecurityGroup: ec2.SecurityGroup;

  /**
   * Database endpoint address
   */
  public readonly dbEndpoint: string;

  /**
   * Database port
   */
  public readonly dbPort: number;

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

    const {
      environment,
      vpc,
      databaseSecret,
      databaseName = "rentall",
      instanceType = ec2.InstanceType.of(
        ec2.InstanceClass.T3,
        ec2.InstanceSize.MICRO
      ),
      allocatedStorage = 20,
      multiAz = false,
      backupRetentionDays = 7,
    } = props;

    // Security group for the database
    this.databaseSecurityGroup = new ec2.SecurityGroup(
      this,
      "DatabaseSecurityGroup",
      {
        vpc,
        securityGroupName: `rentall-db-sg-${environment}`,
        description: `Security group for RDS database (${environment})`,
        allowAllOutbound: false,
      }
    );

    // Create the RDS instance
    this.database = new rds.DatabaseInstance(this, "Database", {
      instanceIdentifier: `rentall-db-${environment}`,
      engine: rds.DatabaseInstanceEngine.postgres({
        version: rds.PostgresEngineVersion.VER_15,
      }),
      instanceType,
      vpc,
      vpcSubnets: {
        subnetType: ec2.SubnetType.PRIVATE_ISOLATED,
      },
      securityGroups: [this.databaseSecurityGroup],
      credentials: rds.Credentials.fromSecret(databaseSecret),
      databaseName,
      allocatedStorage,
      maxAllocatedStorage: allocatedStorage * 2, // Allow storage autoscaling up to 2x
      storageType: rds.StorageType.GP2,
      multiAz,
      autoMinorVersionUpgrade: true,
      deletionProtection: environment === "prod",
      removalPolicy:
        environment === "prod"
          ? cdk.RemovalPolicy.RETAIN
          : cdk.RemovalPolicy.DESTROY,
      backupRetention: cdk.Duration.days(backupRetentionDays),
      preferredBackupWindow: "03:00-04:00", // UTC
      preferredMaintenanceWindow: "Sun:04:00-Sun:05:00", // UTC
      storageEncrypted: true,
      monitoringInterval: cdk.Duration.seconds(60),
      enablePerformanceInsights: true,
      performanceInsightRetention: rds.PerformanceInsightRetention.DEFAULT, // 7 days (free)
      parameterGroup: new rds.ParameterGroup(this, "ParameterGroup", {
        engine: rds.DatabaseInstanceEngine.postgres({
          version: rds.PostgresEngineVersion.VER_15,
        }),
        parameters: {
          // Enforce SSL connections
          "rds.force_ssl": "1",
          // Log slow queries (> 1 second)
          log_min_duration_statement: "1000",
        },
      }),
      publiclyAccessible: false,
    });

    this.dbEndpoint = this.database.dbInstanceEndpointAddress;
    this.dbPort = this.database.dbInstanceEndpointPort
      ? parseInt(this.database.dbInstanceEndpointPort)
      : 5432;

    // Outputs
    new cdk.CfnOutput(this, "DatabaseEndpoint", {
      value: this.database.dbInstanceEndpointAddress,
      description: "Database endpoint address",
      exportName: `DatabaseEndpoint-${environment}`,
    });

    new cdk.CfnOutput(this, "DatabasePort", {
      value: this.database.dbInstanceEndpointPort,
      description: "Database port",
      exportName: `DatabasePort-${environment}`,
    });

    new cdk.CfnOutput(this, "DatabaseSecurityGroupId", {
      value: this.databaseSecurityGroup.securityGroupId,
      description: "Database security group ID",
      exportName: `DatabaseSecurityGroupId-${environment}`,
    });

    new cdk.CfnOutput(this, "DatabaseInstanceIdentifier", {
      value: this.database.instanceIdentifier,
      description: "Database instance identifier",
      exportName: `DatabaseInstanceIdentifier-${environment}`,
    });
  }
}