AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: Serverless Fanout using Amazon SNS and Amazon Lambda
Parameters:
  S3BucketName:
    Type: String
  SnsTopicName:
    Type: String

Resources:
  MediaInfoFunction:
    Type: 'AWS::Serverless::Function'
    Properties:
      Handler: media_info.lambda_handler
      Runtime: python2.7
      FunctionName: media_info

  MediaInfoFunctionInvokePermission:
    Type: 'AWS::Lambda::Permission'
    Properties:
      Action: 'lambda:InvokeFunction'
      FunctionName: !Ref MediaInfoFunction
      Principal: sns.amazonaws.com

  TranscodeAudioFunction:
    Type: 'AWS::Serverless::Function'
    Properties:
      Handler: transcode_audio.lambda_handler
      Runtime: python2.7
      FunctionName: transcode_audio

  TranscodeAudioFunctionInvokePermission:
    Type: 'AWS::Lambda::Permission'
    Properties:
      Action: 'lambda:InvokeFunction'
      FunctionName: !Ref TranscodeAudioFunction
      Principal: sns.amazonaws.com

  FanoutFunction:
    Type: 'AWS::Serverless::Function'
    Properties:
      Handler: fanout.lambda_handler
      Runtime: python2.7
      FunctionName: fanout
      Policies:
        - Version: '2012-10-17'
          Statement:
            - Effect: Allow
              Resource: '*'
              Action:
                - 'lambda:InvokeFunction'

  FanoutFunctionsInvokePermission:
    Type: 'AWS::Lambda::Permission'
    Properties:
      Action: 'lambda:InvokeFunction'
      FunctionName: !Ref FanoutFunction
      Principal: s3.amazonaws.com

  SnsTopic:
    Type: 'AWS::SNS::Topic'
    Properties:
      TopicName: !Ref SnsTopicName
      Subscription:
        - Protocol: lambda
          Endpoint: !GetAtt MediaInfoFunction.Arn
        - Protocol: lambda
          Endpoint: !GetAtt TranscodeAudioFunction.Arn

  SNSTopicPolicy:
    Type: 'AWS::SNS::TopicPolicy'
    Properties:
      Topics:
        - !Ref SnsTopic
      PolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Action: 'sns:Publish'
            Resource: !Ref SnsTopic
            Condition:
              ArnLike:
                aws:SourceArn: !Sub "arn:aws:s3:::${S3BucketName}"
            Principal:
              AWS: '*'

  S3Bucket:
    Type: 'AWS::S3::Bucket'
    DependsOn: SnsTopic
    Properties:
      BucketName: !Ref S3BucketName
      NotificationConfiguration:
        LambdaConfigurations:
          - Function: !GetAtt FanoutFunction.Arn
            Event: 's3:ObjectCreated:*'
            Filter:
              S3Key:
                Rules:
                  - Name: prefix
                    Value: 'uploads/lambda/'
        TopicConfigurations:
          - Topic: !Ref SnsTopic
            Event: 's3:ObjectCreated:*'
            Filter:
              S3Key:
                Rules:
                  - Name: prefix
                    Value: 'uploads/sns/'

Outputs:
  S3Bucket:
    Value: !Ref S3Bucket
  SnsTopic:
    Value: !Ref SnsTopic