require 'elixir/aws/handler/version'

module Elixir
  module Aws
    module Handler
      # noinspection RubyResolve
      # Rack
      class Rack
        LAMBDA_EVENT ||= 'lambda.event'.freeze
        LAMBDA_CONTEXT ||= 'lambda.context'.freeze
        HTTP_X_REQUESTID ||= 'HTTP_X_REQUEST_ID'.freeze

        attr_reader :event, :context

        def initialize(event, context, use_stage)
          @event = event
          @context = context
          @use_stage = use_stage
        end

        def env
          @env ||= env_base.merge!(env_headers)
        end

        private

        def env_base # rubocop:disable all
          path_info = unless @use_stage
                        stage = ENV['STAGE']
                        (event['path'] || '').sub(%r{/#{stage}/}, '/')
                      else
                        (event['path'] || '')
                      end
          { ::Rack::REQUEST_METHOD => event['httpMethod'],
            ::Rack::SCRIPT_NAME => '',
            ::Rack::PATH_INFO => path_info || '',
            ::Rack::QUERY_STRING => query_string,
            ::Rack::SERVER_NAME => headers['Host'],
            ::Rack::SERVER_PORT => headers['X-Forwarded-Port'],
            ::Rack::SERVER_PROTOCOL => server_protocol,
            ::Rack::RACK_VERSION => ::Rack::VERSION,
            ::Rack::RACK_URL_SCHEME => 'https',
            ::Rack::RACK_INPUT => StringIO.new(body || ''),
            ::Rack::RACK_ERRORS => $stderr,
            ::Rack::RACK_MULTITHREAD => false,
            ::Rack::RACK_MULTIPROCESS => false,
            ::Rack::RACK_RUNONCE => false,
            'rack.env' => ENV['RACK_ENV'],
            LAMBDA_EVENT => event,
            LAMBDA_CONTEXT => context
          }.tap do |env|
            ct = content_type
            cl = content_length
            env['CONTENT_TYPE'] = ct if ct
            env['CONTENT_LENGTH'] = cl if cl
          end
        end

        def env_headers
          headers.transform_keys do |key|
            "HTTP_#{key.to_s.upcase.tr '-', '_'}"
          end.tap do |hdrs|
            hdrs[HTTP_X_REQUESTID] = request_id
          end
        end

        def content_type
          headers.delete('Content-Type') || headers.delete('content-type') || headers.delete('CONTENT_TYPE')
        end

        def content_length
          bytesize = body.bytesize.to_s if body
          headers.delete('Content-Length') || headers.delete('content-length') || headers.delete('CONTENT_LENGTH') || bytesize
        end

        def body
          @body ||= if event['body'] && base64_encoded?
                      Base64.decode64 event['body']
                    else
                      event['body']
                    end
        end

        def headers
          event['headers'] || {}
        end

        def query_string
          @query_string ||= event['queryStringParameters'].try(:to_query)
        end

        def base64_encoded?
          event['isBase64Encoded']
        end

        def server_protocol
          event.dig('requestContext', 'protocol') || 'HTTP/1.1'
        end

        def request_id
          context.aws_request_id
        end
      end
    end
  end
end