---
AWSTemplateFormatVersion: 2010-09-09

Description: Reference Architecture to host Moodle on AWS - Creates ElastiCache cache cluster

Metadata:
  AWS::CloudFormation::Interface:
    ParameterGroups:
    - Label:
        default: Cache Parameters
      Parameters:
        - CacheUsageType
        - CacheEngineType
        - ElastiCacheNodeType
        - ElastiCacheClusterName
        - ElastiCacheSecurityGroup
        - NumberOfSubnets
        - Subnet
    ParameterLabels:
      CacheEngineType:
        default: Cache Engine Type
      CacheUsageType:
        default: Cache Usage Type
      ElastiCacheClusterName:
        default: Cache Cluster Name
      ElastiCacheNodeType:
        default: Cache Cluster Node Type
      ElastiCacheSecurityGroup:
        default: ElastiCache Security Group
      NumberOfSubnets:
        default: Number of subnets
      Subnet:
        default: Subnets

Parameters:
  CacheEngineType:
    AllowedValues:
      - Redis
      - Memcached
    Default: Memcached
    Description: Indicates whether to use ElastiCache Memcached or Redis. 
    Type: String
  CacheUsageType:
    AllowedValues:
      - application
      - session
    Default: session
    Description: Indicates whether to use ElastiCache for session or application caching. 
    Type: String
  ElastiCacheClusterName:
    AllowedPattern: ^([a-zA-Z0-9]*)$
    Description: ElastiCache cluster name.
    Type: String
  ElastiCacheNodeType:
    AllowedValues:
      - cache.t3.micro
      - cache.t3.small
      - cache.t3.medium
      - cache.m5.large
      - cache.m5.xlarge
      - cache.m5.2xlarge
      - cache.m5.4xlarge
      - cache.m5.12xlarge
      - cache.m5.24xlarge
      - cache.m6g.large
      - cache.m6g.xlarge
      - cache.m6g.2xlarge
      - cache.m6g.4xlarge
      - cache.m6g.8xlarge
      - cache.m6g.12xlarge
      - cache.m6g.16xlarge
    ConstraintDescription: Must be a valid Amazon ElastiCache node type.
    Default: cache.m6g.large
    Description: ElastiCache cluster node type.
    Type: String
  ElastiCacheSecurityGroup:
    Description: Select the ElastiCache security group.
    Type: AWS::EC2::SecurityGroup::Id
  NumberOfSubnets:
    AllowedValues:
    - 1
    - 2
    - 3
    Default: 2
    Description: Number of subnets. This must match your selections in the list of subnets below.
    Type: String 
  Subnet:
    Description: Select existing subnets. The number selected must match the number of subnets above. Subnets selected must be in separate AZs.
    Type: List<AWS::EC2::Subnet::Id>
  ProjectName:
    AllowedPattern: ^([a-zA-Z0-9]*)$
    Default: App
    Description: Moodle Project Name
    Type: String

Conditions:
  UseRedis:
    !Equals [!Ref CacheEngineType, Redis]
  UseMemcached:
    !Equals [!Ref CacheEngineType, Memcached]
  NumberOfSubnets1:
      !Equals [ 1, !Ref NumberOfSubnets ]
  NumberOfSubnets2:
      !Equals [ 2, !Ref NumberOfSubnets ]
  NumberOfSubnets3:
      !Equals [ 3, !Ref NumberOfSubnets ]
  Subnet0: !Or
    - !Condition NumberOfSubnets1
    - !Condition NumberOfSubnets2
    - !Condition NumberOfSubnets3
  Subnet1: !Or
    - !Condition NumberOfSubnets2
    - !Condition NumberOfSubnets3
  Subnet2: !Condition NumberOfSubnets3

Resources:
  ElastiCacheClusterRedis:
    Condition: UseRedis
    Type: AWS::ElastiCache::ReplicationGroup
    Properties:
      ReplicationGroupId: !Ref ElastiCacheClusterName
      ReplicationGroupDescription: !Ref ElastiCacheClusterName
      AtRestEncryptionEnabled: true
      TransitEncryptionEnabled: false
      AutoMinorVersionUpgrade: true
      MultiAZEnabled: true
      CacheNodeType: !Ref ElastiCacheNodeType
      CacheSubnetGroupName: !Ref ElastiCacheSubnetGroup
      SecurityGroupIds:
        - !Ref ElastiCacheSecurityGroup
      Engine: redis
      NumCacheClusters:
        !Ref NumberOfSubnets

  ElastiCacheClusterMemcached:
    Condition: UseMemcached
    Type: AWS::ElastiCache::CacheCluster
    Properties:
      AZMode: cross-az
      CacheNodeType: !Ref ElastiCacheNodeType
      CacheSubnetGroupName: !Ref ElastiCacheSubnetGroup
      ClusterName: !Ref ElastiCacheClusterName
      Engine: memcached
      NumCacheNodes:
        !Ref NumberOfSubnets
      Tags:
        - Key: Name
          Value: !Join [ '', [ 'Moodle / ', !Ref 'AWS::StackName' ] ]
      VpcSecurityGroupIds:
      - !Ref ElastiCacheSecurityGroup      
 
  ElastiCacheSubnetGroup: 
    Type: AWS::ElastiCache::SubnetGroup
    Properties: 
      CacheSubnetGroupName: !Join [ '', [ !Ref ElastiCacheClusterName, SubnetGroup ] ]
      Description: ElastiCache Subnet Group for Moodle
      SubnetIds: 
        !If
          [ NumberOfSubnets1,
          [ !Select [ 0, !Ref Subnet ] ],
          !If
            [ NumberOfSubnets2,
            [ !Select [ 0, !Ref Subnet ], !Select [ 1, !Ref Subnet ] ],
            [ !Select [ 0, !Ref Subnet ], !Select [ 1, !Ref Subnet ], !Select [ 2, !Ref Subnet ] ]
            ]
          ]

  ElastiCacheClusterEndpoint:
    Type: AWS::SSM::Parameter
    Properties:
      Name: !Join [ '', [ '/Moodle/',!Ref ProjectName, '/Cache/', !Ref CacheUsageType, '/ElastiCacheClusterEndpoint' ] ]
      Type: String
      Value: !If [UseRedis, 
                  !Join [ ':', [!GetAtt ElastiCacheClusterRedis.PrimaryEndPoint.Address, !GetAtt ElastiCacheClusterRedis.PrimaryEndPoint.Port]],
                  !Join [ ':', [!GetAtt ElastiCacheClusterMemcached.ConfigurationEndpoint.Address, !GetAtt ElastiCacheClusterMemcached.ConfigurationEndpoint.Port]] 
                 ]
      Description: SSM Parameter for ElastiCache Cluster Endpoint

  ElastiCacheEngine:
    Type: AWS::SSM::Parameter
    Properties:
      Name: !Join [ '', [ '/Moodle/',!Ref ProjectName, '/Cache/', !Ref CacheUsageType, '/Engine' ] ]
      Type: String
      Value: !Ref CacheEngineType
      Description: SSM Parameter for ElastiCache Engine Type

Outputs:
  ElastiCacheClusterEndpointAddress:
    Value: !If [UseRedis, 
                  !Join [ ':', [!GetAtt ElastiCacheClusterRedis.PrimaryEndPoint.Address, !GetAtt ElastiCacheClusterRedis.PrimaryEndPoint.Port]],
                  !Join [ ':', [!GetAtt ElastiCacheClusterMemcached.ConfigurationEndpoint.Address, !GetAtt ElastiCacheClusterMemcached.ConfigurationEndpoint.Port]] 
                 ]