module Lono::AwsServices
  module Helper
    def stack_exists?(stack_name)
      exist = nil
      begin
        # When the stack does not exist an exception is raised. Example:
        # Aws::CloudFormation::Errors::ValidationError: Stack with id blah does not exist
        cfn.describe_stacks(stack_name: stack_name)
        exist = true
      rescue Aws::CloudFormation::Errors::ValidationError => e
        if e.message =~ /does not exist/
          exist = false
        elsif e.message.include?("'stackName' failed to satisfy constraint")
          # Example of e.message when describe_stack with invalid stack name
          # "1 validation error detected: Value 'instance_and_route53' at 'stackName' failed to satisfy constraint: Member must satisfy regular expression pattern: [a-zA-Z][-a-zA-Z0-9]*|arn:[-a-zA-Z0-9:/._+]*"
          logger.info "Invalid stack name: #{stack_name}"
          logger.info "Full error message: #{e.message}"
          exit 1
        else
          raise # re-raise exception  because unsure what other errors can happen
        end
      end
      exist
    end

    def find_stack(stack_name)
      resp = cfn.describe_stacks(stack_name: stack_name)
      resp.stacks.first
    rescue Aws::CloudFormation::Errors::ValidationError => e
      # example: Stack with id demo-web does not exist
      if e.message =~ /Stack with/ && e.message =~ /does not exist/
        nil
      else
        raise
      end
    end

    def find_stack_resources(stack_name)
      resp = cfn.describe_stack_resources(stack_name: stack_name)
      resp.stack_resources
    rescue Aws::CloudFormation::Errors::ValidationError => e
      if e.message.include?("does not exist")
        nil
      else
        raise
      end
    end
  end
end
