Parameters:
    BucketName:
        Description: "The S3 bucket where you want to store email template."
        Type: "String"
    DashboardName:
        Description: "The CloudWatch dashboard name."
        Type: "String"
    FunctionName:
        Description: "The Lambda function name."
        Type: "String"
    MailingListEmail:
        Description: "The email address of the mailing list where all the team members are subscribed and use to recieve automatic notifications."
        Type: "String"
    RootTemplateFilename:
        Description: "The handlebars template hosted in the S3 bucket used for the email body."
        Type: "String"
    ScheduleExpression:
        Description: "The cron expression that will set the frequency of notifications."
        Type: "String"
    TeamMemberNames:
        Description: "A list of team members names."
        Type: "String"
Resources:
    CodeBuddyLambdaExecutionRole:
        Type: AWS::IAM::Role
        Properties:
            AssumeRolePolicyDocument:
                Version: '2012-10-17'
                Statement:
                - Effect: Allow
                  Principal:
                    Service:
                    - lambda.amazonaws.com
                  Action:
                    - sts:AssumeRole
            Path: "/"
            Policies:
            - PolicyName: codebuddy
              PolicyDocument:
                Version: '2012-10-17'
                Statement:
                - Effect: Allow
                  Action:
                  - logs:*
                  Resource: "arn:aws:logs:*"
                - Effect: Allow
                  Action:
                  - s3:getObject
                  - s3:listObjects
                  Resource: !Join ["", ["arn:aws:s3:::", !Ref BucketName, "/*"]]
                - Effect: Allow
                  Action:
                  - sns:*
                  Resource: !Ref NotificationSystem
            RoleName: "CodeBuddyLambdaExecutionRole"
    DataStorage:
        Type: "AWS::S3::Bucket"
        Properties:
            BucketName: !Ref BucketName
    LambdaFunction:
        Type: "AWS::Lambda::Function"
        Properties:
            Code:
                ZipFile: !Sub |
                    exports.handler = function(event, context, callback) {
                        callback(null,'Please run `make update-function` from your CodeBuddy project root directory');
                    };
            Description: "The function that perform the scheduled notification for CodeBuddy utility"
            Environment:
                Variables:
                    MAILING_LIST: !Ref MailingListEmail
                    ROOT_TEMPLATE: !Ref RootTemplateFilename
                    SNS_TOPIC_ARN: !Ref NotificationSystem
                    TEAM_NAMES: !Ref TeamMemberNames
            FunctionName: !Ref FunctionName
            Handler: "index.handler"
            MemorySize: 512
            Role:
                Fn::GetAtt:
                    - "CodeBuddyLambdaExecutionRole"
                    - "Arn"
            Runtime: "nodejs6.10"
            Timeout: 60
    LogGroup:
        Type: "AWS::Logs::LogGroup"
        Properties:
            LogGroupName: !Join ["", ["/aws/lambda/", !Ref FunctionName]]
    MetricFilterMaxMemoryUsed:
        Type: "AWS::Logs::MetricFilter"
        DependsOn: LogGroup
        Properties:
            LogGroupName: !Join ["", ["/aws/lambda/", !Ref FunctionName]]
            FilterPattern: "[..., maxMemoryLabel=\"Used:\", maxMemory, maxMemoryUnit=MB]"
            MetricTransformations:
                -
                    MetricValue: "$maxMemory"
                    MetricNamespace: !Ref FunctionName
                    MetricName: "MaxMemoryUsedMB"
    MetricFilterMemorySize:
        Type: "AWS::Logs::MetricFilter"
        DependsOn: LogGroup
        Properties:
            LogGroupName: !Join ["", ["/aws/lambda/", !Ref FunctionName]]
            FilterPattern: "[..., sizeLabel=\"Size:\", sizeMemory, sizeMemoryUnit=MB, maxLabel, memoryLabel, maxMemoryLabel=\"Used:\", maxMemory, maxMemoryUnit=MB]"
            MetricTransformations:
                -
                    MetricValue: "$sizeMemory"
                    MetricNamespace: !Ref FunctionName
                    MetricName: "MemorySizeMB"
    NotificationSystem:
        Type: "AWS::SNS::Topic"
        Properties:
            DisplayName: "CodeBuddy"
            Subscription:
                -
                    Endpoint:
                        Ref: MailingListEmail
                    Protocol: "email"
            TopicName: "CodeBuddy"
    SchedulerEventRule:
        Type: "AWS::Events::Rule"
        Properties:
            Description: "CodeBuddy notification scheduling event"
            Name: "CodeBuddySchedulerRule"
            ScheduleExpression: !Ref ScheduleExpression
            State: "ENABLED"
            Targets:
            - Arn: !GetAtt LambdaFunction.Arn
              Id: "CodeBuddyFunction"
    DurationAlarm:
      Type: "AWS::CloudWatch::Alarm"
      DependsOn: LambdaFunction
      Properties:
          AlarmName: "CodeBuddyDurationAlarm"
          AlarmDescription: "Trigger an alarm if the duration is over 500ms"
          MetricName: "Duration"
          Namespace: "AWS/Lambda"
          Dimensions:
              -
                  Name: "FunctionName"
                  Value: !Ref FunctionName
          Statistic: "Average"
          Period: 60
          EvaluationPeriods: 1
          Threshold: 500
          ComparisonOperator: "GreaterThanThreshold"
    ErrorsAlarm:
      Type: "AWS::CloudWatch::Alarm"
      DependsOn: LambdaFunction
      Properties:
          AlarmName: "CodeBuddyErrorsAlarm"
          AlarmDescription: "Trigger an alarm if an error is recorded"
          MetricName: "Errors"
          Namespace: "AWS/Lambda"
          Dimensions:
              -
                  Name: "FunctionName"
                  Value: !Ref FunctionName
          Statistic: "Sum"
          Period: 60
          EvaluationPeriods: 1
          Threshold: 0
          ComparisonOperator: "GreaterThanThreshold"
    InvocationsAlarm:
        Type: "AWS::CloudWatch::Alarm"
        DependsOn: LambdaFunction
        Properties:
            AlarmName: "CodeBuddyInvocationsAlarm"
            AlarmDescription: "Trigger an alarm if the function is not invoked at least one per day"
            MetricName: "Invocations"
            Namespace: "AWS/Lambda"
            Dimensions:
              -
                  Name: "FunctionName"
                  Value: !Ref FunctionName
            Statistic: "Sum"
            Period: 86400
            EvaluationPeriods: 1
            Threshold: 1
            ComparisonOperator: "LessThanThreshold"
    ThrottlesAlarm:
        Type: "AWS::CloudWatch::Alarm"
        DependsOn: LambdaFunction
        Properties:
            AlarmName: "CodeBuddyThrottlesAlarm"
            AlarmDescription: "Trigger an alarm if a throttle is recorded"
            MetricName: "Throttles"
            Namespace: "AWS/Lambda"
            Dimensions:
              -
                  Name: "FunctionName"
                  Value: !Ref FunctionName
            Statistic: "Sum"
            Period: 60
            EvaluationPeriods: 1
            Threshold: 0
            ComparisonOperator: "GreaterThanThreshold"
    Dashboard:
        Type: "AWS::CloudWatch::Dashboard"
        Properties:
            DashboardName: !Ref DashboardName
            DashboardBody: !Sub |
                DASHBOARD_BODY
Outputs:
    Dashboard:
        Description: "Dashboard created to monitor Lambda function"
        Value: !Sub |
            "https://${AWS::Region}.console.aws.amazon.com/cloudwatch/home#dashboards:name=${DashboardName}"