Parameters:
  PollingFrequencyInMinutes:
    Default: 1
    Type: Number
    Description: Frequency in minutes to poll for more tweets.
    MinValue: 1
  SearchText:
    Type: String
    Description: Non-URL-encoded search text poller should use when querying Twitter Search API.
  StreamModeEnabled:
    Default: false
    Type: String
    Description: If true, the app will remember the last tweet found and only invoke the tweet processor function for newer tweets. If false, the app will be stateless and invoke the tweet processor function with all tweets found in each polling cycle.
    AllowedValues:
    - true
    - false
  BatchSize:
    Default: 15
    Type: Number
    Description: Max number of tweets to send to the TweetProcessor lambda function on each invocation.
    MinValue: 1
  SSMParameterPrefix:
    Default: twitter-event-source
    Type: String
    Description: |
      This app assumes API keys needed to use the Twitter API are stored as SecureStrings in SSM Parameter Store under the prefix defined by this parameter. See the app README for details.
  TweetProcessorFunctionName:
    Type: String
    Description: Name of lambda function that should be invoked to process tweets. Note, this must be a function name and not a function ARN.
AWSTemplateFormatVersion: '2010-09-09'
Outputs:
  TwitterSearchPollerFunctionArn:
    Value:
      Fn::GetAtt:
      - TwitterSearchPoller
      - Arn
  SearchCheckpointTableArn:
    Value:
      Fn::GetAtt:
      - SearchCheckpoint
      - Arn
  TwitterSearchPollerFunctionName:
    Value:
      Ref: TwitterSearchPoller
  SearchCheckpointTableName:
    Value:
      Ref: SearchCheckpoint
Conditions:
  IsPollingFrequencyInMinutesSingular:
    Fn::Equals:
    - Ref: PollingFrequencyInMinutes
    - 1
Transform: AWS::Serverless-2016-10-31
Resources:
  TwitterSearchPoller:
    Type: AWS::Serverless::Function
    Properties:
      Policies:
      - Statement:
        - Action:
          - lambda:InvokeFunction
          Resource:
            Fn::Sub:
            - arn:${AWS::Partition}:lambda:${AWS::Region}:${AWS::AccountId}:function:${functionName}*
            - functionName:
                Ref: TweetProcessorFunctionName
          Effect: Allow
      - Statement:
        - Action:
          - dynamodb:GetItem
          - dynamodb:DeleteItem
          - dynamodb:PutItem
          - dynamodb:Scan
          - dynamodb:Query
          - dynamodb:UpdateItem
          - dynamodb:BatchWriteItem
          - dynamodb:BatchGetItem
          - dynamodb:DescribeTable
          Resource:
            Fn::Sub:
            - arn:${AWS::Partition}:dynamodb:${AWS::Region}:${AWS::AccountId}:table/${tableName}
            - tableName:
                Ref: SearchCheckpoint
          Effect: Allow
      - Statement:
          Action:
          - ssm:GetParameters
          Resource:
            Fn::Sub: arn:${AWS::Partition}:ssm:${AWS::Region}:${AWS::AccountId}:parameter/${SSMParameterPrefix}/*
          Effect: Allow
      Tracing: Active
      MemorySize: 128
      Environment:
        Variables:
          SSM_PARAMETER_PREFIX:
            Ref: SSMParameterPrefix
          SEARCH_CHECKPOINT_TABLE_NAME:
            Ref: SearchCheckpoint
          SEARCH_TEXT:
            Ref: SearchText
          TWEET_PROCESSOR_FUNCTION_NAME:
            Ref: TweetProcessorFunctionName
          BATCH_SIZE:
            Ref: BatchSize
          STREAM_MODE_ENABLED:
            Ref: StreamModeEnabled
      Handler: poller.handler
      Timeout: 60
      CodeUri:
        Bucket: <%REPO_BUCKET%>
        Key: 3fa2a8d3-bad5-4cd4-b1e2-f9d09cf96414
      Runtime: python3.6
      Events:
        Timer:
          Type: Schedule
          Properties:
            Schedule:
              Fn::If:
              - IsPollingFrequencyInMinutesSingular
              - Fn::Sub: rate(${PollingFrequencyInMinutes} minute)
              - Fn::Sub: rate(${PollingFrequencyInMinutes} minutes)
  SearchCheckpoint:
    Type: AWS::Serverless::SimpleTable
    Properties: {}