Parameters:
  Environment:
    Type: String
    Description: Environment name
    Default: wsi

  PolicyName:
    Type: String
    Description: IAM Policy Name for S3 Access
    Default: AmazonS3ReadOnlyAccess

  AutoScalingGroupName:
    Type: String
    Description: "The Name of Auto Scaling Group"
    Default: wsi-app

  TargetGroupArn:
    Type: String
    Description: Target Group ARN

  BastionSecurityGroupId:
    Type: AWS::EC2::SecurityGroup::Id
    Description: Bastion Host Security Group ID

  LatestAmazonLinux2023AMI:
    Type: AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>
    Default: /aws/service/ami-amazon-linux-latest/al2023-ami-minimal-kernel-default-x86_64

Resources:
  ASGInstanceRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Sub "${Environment}-role-bastion"
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Action: sts:AssumeRole
            Effect: Allow
            Principal:
              Service: ec2.amazonaws.com

  S3AccessPolicy:
    Type: AWS::IAM::RolePolicyAttachment
    Properties:
      Role: !Ref ASGInstanceRole
      PolicyArn: !Sub "arn:aws:iam::aws:policy/${PolicyName}"

  ASGInstanceProfile:
    Type: AWS::IAM::InstanceProfile
    Properties:
      InstanceProfileName: !Sub "${Environment}-profile-asg"
      Roles:
        - !Ref ASGInstanceRole

  ASGSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupName: !Sub "${Environment}-asg-sg"
      VpcId: !Ref VPC
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: !Ref <Port>
          ToPort: !Ref <Port>
          SourceSecurityGroupId: !Ref BastionSecurityGroupId
      SecurityGroupEgress:
        - IpProtocol: tcp
          FromPort: !Ref <Port>
          ToPort: !Ref <Port>
          CidrIp: 0.0.0.0/0
      Tags:
        - Key: Name
          Value: !Sub "${Environment}-asg-sg"

  ASGLaunchTemplate:
    Type: AWS::EC2::LaunchTemplate
    Properties:
      LaunchTemplateName: web_test_lt
      LaunchTemplateData:
        ImageId: !Ref LatestAmazonLinux2023AMI
        InstanceType: <InstanceType>
        KeyName: <KeyPairName>
        SecurityGroupIds:
          - !Ref ASGSecurityGroup
        IamInstanceProfile:
          Arn: !GetAtt ASGInstanceProfile.Arn
        UserData:
          Fn::Base64: |
            #!/bin/bash
            yum update -y
        TagSpecifications:
          - ResourceType: instance
            Tags:
              - Key: Name
                Value: !Sub ${AutoScalingGroupName}

  AutoScalingGroup:
    Type: AWS::AutoScaling::AutoScalingGroup
    Properties:
      AutoScalingGroupName: !Ref AutoScalingGroupName
      DesiredCapacity: 2
      MinSize: 2
      MaxSize: 10
      VPCZoneIdentifier:
        - !Ref PrivateSubnet1
        - !Ref PrivateSubnet2
        - !Ref PrivateSubnet3
      TargetGroupARNs:
        - !Ref TargetGroupArn
      LaunchTemplate:
        LaunchTemplateId: !Ref ASGLaunchTemplate
        Version: !GetAtt ASGLaunchTemplate.LatestVersionNumber

  AutoScalingPolicy:
    Type: AWS::AutoScaling::ScalingPolicy
    Properties:
      AutoScalingGroupName: !Ref AutoScalingGroup
      PolicyType: TargetTrackingScaling
      TargetTrackingConfiguration:
        PredefinedMetricSpecification:
          PredefinedMetricType: ASGAverageCPUUtilization
        TargetValue: 10.0

Outputs:
  AutoScalingGroupName:
    Description: Auto Scaling Group Name
    Value: !Ref AutoScalingGroup

  AutoScalingPolicyArn:
    Description: Auto Scaling Policy ARN
    Value: !Ref AutoScalingPolicy