AWSTemplateFormatVersion: '2010-09-09'
Description: Creates an IAM role that a self-hosted Temporal Service can assume to invoke Lambda functions for Serverless Workers.

Parameters:
  TemporalIamRoleArn:
    Type: String
    Description: The ARN of the IAM role or user that the Temporal Service runs as.

  AssumeRoleExternalId:
    Type: String
    Description: A unique identifier to prevent confused deputy attacks.
    AllowedPattern: '[a-zA-Z0-9_+=,.@-]*'
    MinLength: 5
    MaxLength: 45

  LambdaFunctionARNs:
    Type: CommaDelimitedList
    Description: >-
      Comma-separated list of Lambda function ARNs to invoke
      (e.g., arn:aws:lambda:us-west-2:123456789012:function:worker-1,arn:aws:lambda:us-west-2:123456789012:function:worker-2)

  RoleName:
    Type: String
    Default: 'Temporal-Serverless-Worker'

Resources:
  TemporalServerlessWorker:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Sub '${RoleName}-${AWS::StackName}'
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              AWS:
                [!Ref TemporalIamRoleArn]
            Action: sts:AssumeRole
            Condition:
              StringEquals:
                'sts:ExternalId': [!Ref AssumeRoleExternalId]
      Description: "The role the Temporal Service uses to invoke Lambda functions for Serverless Workers"
      MaxSessionDuration: 3600

  TemporalLambdaInvokePermissions:
    Type: AWS::IAM::Policy
    DependsOn: TemporalServerlessWorker
    Properties:
      PolicyName: 'Temporal-Lambda-Invoke-Permissions'
      PolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Action:
              - lambda:InvokeFunction
              - lambda:GetFunction
            Resource: !Ref LambdaFunctionARNs
      Roles:
        - !Sub '${RoleName}-${AWS::StackName}'

Outputs:
  RoleARN:
    Description: The ARN of the IAM role created for the Temporal Service
    Value: !GetAtt TemporalServerlessWorker.Arn
    Export:
      Name: !Sub "${AWS::StackName}-RoleARN"

  RoleName:
    Description: The name of the IAM role
    Value: !Ref RoleName

  LambdaFunctionARNs:
    Description: The Lambda function ARNs that can be invoked
    Value: !Join [", ", !Ref LambdaFunctionARNs]