# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT-0

AWSTemplateFormatVersion: 2010-09-09
Description: Create a S3 storage bucket to store soruce code.

Parameters:
  OrganizationId:
    Type: 'String'
    Description: ID of the AWS Organization of the Landing Zone
    Default: 'o-'
  SSEAlgorithm:
    Type: 'String'
    Default: 'AES256'
    Description: S3 bucket SSE Algorithm.
    AllowedValues:
    - 'AES256'
    - 'aws:kms'
  KMSMasterKeyID:
    Type: 'String'
    Description: 'Optional: KMS key ID required if SSE algorithm is aws:kms.'
    Default: ""

Conditions:
  UseKMS: !Equals
    - !Ref SSEAlgorithm
    - 'aws:kms'
  UseAES256: !Equals
    - !Ref SSEAlgorithm
    - 'AES256'

Resources:
  # Create buckets using KMS keys for default encryption
  S3KmsUploadBucket:
    Condition: UseKMS
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub control-tower-storage-${AWS::AccountId}-${AWS::Region}
      LoggingConfiguration:
        DestinationBucketName: !Ref UploadBucketS3AccessLogsBucket
      VersioningConfiguration:
        Status: Enabled
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              KMSMasterKeyID: !Ref KMSMasterKeyID
              SSEAlgorithm: !Ref SSEAlgorithm

  S3KmsUploadBucketPolicy:
    Metadata:
      cfn_nag:
        rules_to_suppress:
          - id: F16
            reason: "We can allow * for the Principal as we are limiting access to the Org."
    Type: AWS::S3::BucketPolicy
    Condition: UseKMS
    Properties:
      Bucket: !Ref S3KmsUploadBucket
      PolicyDocument:
        Version: 2012-10-17
        Statement:
          - Sid: AllowOrganizationRead
            Effect: Allow
            Principal: "*"
            Action: 
              - s3:GetObject
            Resource:
              - !Sub "arn:aws:s3:::${S3KmsUploadBucket}/*"
            Condition: 
              StringEquals:
                aws:PrincipalOrgID: !Ref OrganizationId

  # Create buckets using S3-SSE keys for default encryption
  S3UploadBucket:
    Condition: UseAES256
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub control-tower-storage-${AWS::AccountId}-${AWS::Region}
      LoggingConfiguration:
        DestinationBucketName: !Ref UploadBucketS3AccessLogsBucket
      VersioningConfiguration:
        Status: Enabled
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              SSEAlgorithm: !Ref SSEAlgorithm

  S3UploadBucketPolicy:
    Metadata:
      cfn_nag:
        rules_to_suppress:
          - id: F16
            reason: "We can allow * for the Principal as we are limiting access to the Org."
    #It goes at the same level as Type: and Properties:, so directly under your resource.
    Type: AWS::S3::BucketPolicy
    Condition: UseAES256
    Properties:
      Bucket: !Ref S3UploadBucket
      PolicyDocument:
        Version: 2012-10-17
        Statement:
          - Sid: AllowOrganizationRead
            Effect: Allow
            Principal: "*"
            Action: 
              - s3:GetObject
            Resource:
              - !Sub "arn:aws:s3:::${S3UploadBucket}/*"
            Condition: 
              StringEquals:
                aws:PrincipalOrgID: !Ref OrganizationId

  # Create buckets using S3-SSE keys for default encryption
  UploadBucketS3AccessLogsBucket:
    DeletionPolicy: Retain
    UpdateReplacePolicy: Retain
    Type: AWS::S3::Bucket
    Metadata:
      cfn_nag:
        rules_to_suppress:
          - id: W35
            reason: "This S3 bucket is used as the destination for 'S3UploadBucket'"
    Properties:
      BucketName: !Sub control-tower-uploadbuckets3accesslogs-${AWS::AccountId}-${AWS::Region}
      AccessControl: LogDeliveryWrite
      VersioningConfiguration:
        Status: Enabled
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              SSEAlgorithm: AES256
      PublicAccessBlockConfiguration:
        BlockPublicAcls: True
        BlockPublicPolicy: True
        IgnorePublicAcls: True
        RestrictPublicBuckets: True

  UploadBucketS3AccessLogsBucketPolicy:
    Type: AWS::S3::BucketPolicy
    Properties:
      Bucket: !Ref UploadBucketS3AccessLogsBucket
      PolicyDocument:
        Statement:
          - Sid: DenyDeleteBucket
            Effect: Deny
            Principal: "*"
            Action: s3:DeleteBucket
            Resource: !Sub arn:${AWS::Partition}:s3:::${UploadBucketS3AccessLogsBucket}

Outputs:
  BucketName:
    Description: AWS Control Tower Upload bucket name
    Value: !If [UseAES256, !Ref S3UploadBucket, !Ref S3KmsUploadBucket]