module BBC
  module Cosmos
    module Config
      class AWS
        def initialize(ec2, s3)
          @ec2 = ec2
          @s3  = s3
        end

        def tags
          @tags ||= instance.tags
        end

        def region
          @region ||= ::AWS.config.region
        end

        def instance_id
          @instance_id ||= BBC::Cosmos.production? ? aws_instance_id : "instance_id"
        end

        private

        def s3_config_location
          tags['AppName']
        end

        def s3_config(config)
          path = [
            config[:configuration][:config_path], 
            config[:environment],
            'config',
            config[:configuration][:commit],
            "#{s3_config_location}.json"
          ].join('/')

          JSON.parse(@s3.buckets[config[:component_resources_bucket]].objects[path].read, :symbolize_names => true)
        end

        def instance
          BBC::Cosmos.production? ? aws_instance : dummy_instance
        end

        def dummy_instance
          Struct.new(:tags).new({
            "aws:cloudformation:stack-name" => "stack_name",
            "Component" => "component_name",
            "AppName"   => "app_name"
          })
        end

        def aws_instance
          @ec2.regions[region].instances[instance_id]
        end

        def aws_instance_id
          `curl http://169.254.169.254/latest/meta-data/instance-id`
        end
      end
    end
  end
end