---
AWSTemplateFormatVersion: "2010-09-09"
Parameters:
  AppName:
    Description: SHD Health Event Application
    Type: String
    Default: Health-Event
  ChatClient:
    Description: Which notification client to use
    Type: String
    Default: chime
    AllowedValues:
      - chime
      - slack
      - sns
  MessagePrefix:
    Description: Prefix for chat messages
    Type: String
    Default: "[SHD AUTO]"
  EndpointArray:
    Description: Array of Webhook/endpoints for the selected notification client
    Type: String
  Bail:
    Description: Skip delivery of messages with no updates
    Type: Number
    Default: 1
    AllowedValues:
      - 0
      - 1
  DEBUG:
    Description: Enable Debugging
    Type: Number
    Default: 0
    AllowedValues:
        - 0
        - 1
  LambdaRate:
    Description: >
      The rate (frequency) that determines when CloudWatch Events runs the rule that
      triggers the Lambda function.
    Default: rate(1 minute)
    AllowedValues:
      - rate(1 minute)
      - rate(5 minutes)
      - rate(10 minutes)
    Type: String
  RegionFilter:
    Description: Array of regions of interest used to filter events
    Type: String
    Default: "[]"
  WaitSeconds:
    Description: >
      The rate (frequency) in seconds that determines State Machine waits before checking Event status again.
      Longer wait allows State Machine to run for long duration
    Type: Number
    Default: 60
    AllowedValues:
      - 60
      - 300
      - 600
Conditions:
  CreateSNSResources: !Equals [ !Ref ChatClient, sns ]
Resources:
  LambdaSchedule:
    Type: AWS::Events::Rule
    Properties:
      Description: Schedule to poll for SHD Events
      ScheduleExpression: !Ref LambdaRate
      State: ENABLED
      Targets:
        - Arn: !GetAtt EventPoller.Arn
          Id: LambdaSchedule
  LambdaSchedulePermission:
    Type: "AWS::Lambda::Permission"
    Properties:
      Action: 'lambda:InvokeFunction'
      FunctionName: !Sub ${EventPoller.Arn}
      Principal: 'events.amazonaws.com'
      SourceArn: !Sub ${LambdaSchedule.Arn}
  StatesExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      Path: "/"
      Policies:
        - PolicyName: StatesExecutionPolicy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Action:
                  - "lambda:InvokeFunction"
                Resource: "*"
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Principal:
              Service:
                - !Sub states.${AWS::Region}.amazonaws.com
            Action: "sts:AssumeRole"
  LambdaRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service: lambda.amazonaws.com
            Action: "sts:AssumeRole"
      Policies:
        - PolicyName: LambdaHealthPolicy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Action:
                  - "health:Describe*"
                Resource: "*"
        - PolicyName: LambdaSNSPolicy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Action:
                  - "SNS:Publish"
                Resource: "*"
        - PolicyName: LambdaStatesPolicy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Action:
                  - "states:StartExecution"
                Resource: "*"
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
  PostFunction:
    Type: AWS::Lambda::Function
    Properties:
      Description: Posts messages to chime, slack or sns topics
      FunctionName: !Sub ${AppName}-Chat-Post
      Handler: index.lambda_handler
      MemorySize: 128
      Role: !GetAtt "LambdaRole.Arn"
      Runtime: python3.7
      Timeout: 30
      Environment:
        Variables:
          DEBUG: !Ref DEBUG
          MESSAGEPREFIX: !Ref MessagePrefix
          CHATCLIENT: !Ref ChatClient
          ENDPOINTARRAY: !Ref EndpointArray
          BAIL_NOCHANGE: !Ref Bail
      Code:
        ZipFile: |
          import os
          def lambda_handler(event):
              print("coming soon")

  EventPoller:
    Type: AWS::Lambda::Function
    Properties:
      Description: Polls SHD for new events
      FunctionName: !Sub ${AppName}-Poller
      Handler: index.lambda_handler
      MemorySize: 128
      Role: !GetAtt LambdaRole.Arn
      Runtime: python3.7
      Timeout: 30
      Environment:
        Variables:
          SFN_ARN: !Ref SHDChecker
          DEBUG: !Ref DEBUG
          REGION_FILTER: !Ref RegionFilter
      Code:
        ZipFile: |
          import os
          def lambda_handler(event):
              print("coming soon")
  EventStatusFunction:
    Type: AWS::Lambda::Function
    Properties:
      Description: Gets the current status of a SHD event
      FunctionName: !Sub ${AppName}-Status
      Handler: index.lambda_handler
      MemorySize: 128
      Role: !GetAtt LambdaRole.Arn
      Runtime: python3.7
      Timeout: 30
      Code:
        ZipFile: |
          import os
          def lambda_handler(event):
              print("coming soon")
  IteratorFunction:
    Type: AWS::Lambda::Function
    Properties:
      Description: Counter to decide when the health check sfn should finish
      FunctionName: !Sub ${AppName}-Iterator
      Handler: index.lambda_handler
      MemorySize: 128
      Role: !GetAtt LambdaRole.Arn
      Runtime: python3.7
      Timeout: 30
      Code:
        ZipFile: |
          import os
          def lambda_handler(event):
              print("coming soon")
  SHDChecker:
    Type: "AWS::StepFunctions::StateMachine"
    Properties:
      DefinitionString: !Sub
        - |-
          {
            "Comment": "A state machine that monitors open AWS health issues and posts them regularly until they are closed. When closed it sends one last final closed post.",
            "StartAt": "Post Event Status",
            "States": {
              "Post Event Status": {
                "Type": "Task",
                "Resource": "${postFunction}",
                "ResultPath": "$.lastUpdatedTime",
                "Next": "Wait ${waitSeconds} Seconds",
                "Retry": [
                  {
                    "ErrorEquals": ["States.ALL"],
                    "IntervalSeconds": 1,
                    "MaxAttempts": 3,
                    "BackoffRate": 2
                  }
                ]
              },
              "Wait ${waitSeconds} Seconds": {
                "Type": "Wait",
                  "Seconds": ${waitSeconds},
                  "Next": "Get Event Status"
              },
              "Get Event Status": {
                "Type": "Task",
                "Resource": "${eventStatusFunction}",
                "Next": "Event Complete?",
                "ResultPath": "$.status",
                "Retry": [
                  {
                    "ErrorEquals": ["States.ALL"],
                    "IntervalSeconds": 1,
                    "MaxAttempts": 3,
                    "BackoffRate": 2
                  }
                ]
              },
              "Event Complete?": {
                "Type": "Choice",
                "Choices": [
                  {
                    "Variable": "$.status",
                    "StringEquals": "closed",
                    "Next": "Post Final Event Status"
                  }
                ],
                "Default": "Iterator"
              },
              "Iterator": {
                "Type": "Task",
                "Resource": "${iteratorFunction}",
                "Next": "Time to post again?",
                "ResultPath": "$.count",
                "Retry": [
                  {
                    "ErrorEquals": ["States.ALL"],
                    "IntervalSeconds": 1,
                    "MaxAttempts": 3,
                    "BackoffRate": 2
                  }
                ]
              },
              "Time to post again?": {
                "Type": "Choice",
                "Choices": [
                  {
                    "Variable": "$.count",
                    "NumericEquals": 0,
                    "Next": "Post Event Status"
                  }
                ],
                "Default": "Wait ${waitSeconds} Seconds"
              },
              "Post Final Event Status": {
                "Type": "Task",
                "Resource": "${postFunction}",
                "End": true,
                "Retry": [
                  {
                    "ErrorEquals": ["States.ALL"],
                    "IntervalSeconds": 1,
                    "MaxAttempts": 3,
                    "BackoffRate": 2
                  }
                ]
              }
            }
          }
        - postFunction: !GetAtt PostFunction.Arn
          waitSeconds: !Ref WaitSeconds
          eventStatusFunction: !GetAtt EventStatusFunction.Arn
          iteratorFunction: !GetAtt IteratorFunction.Arn
      RoleArn: !GetAtt StatesExecutionRole.Arn