class ZuoraConnect::MetricsMiddleware

def call(env)
  @bad_headers = ["HTTP_X_FORWARDED_FOR", "HTTP_X_FORWARDED_HOST", "HTTP_X_FORWARDED_PORT", "HTTP_X_FORWARDED_PROTO", "HTTP_X_FORWARDED_SCHEME", "HTTP_X_FORWARDED_SSL"] 
  if !ActionDispatch::Request::HTTP_METHODS.include?(env["REQUEST_METHOD"].upcase)
    [405, {"Content-Type" => "text/plain"}, ["Method Not Allowed"]]
  else
    if (env['HTTP_ZUORA_LAYOUT_FETCH_TEMPLATE_ID'].present?)
      Thread.current[:isHallway] = "/#{env['HTTP_ZUORA_LAYOUT_FETCH_TEMPLATE_ID']}"
      env['PATH_INFO'] = env['PATH_INFO'].gsub(Thread.current[:isHallway], '')
      env['REQUEST_URI'] = env['REQUEST_URI'].gsub(Thread.current[:isHallway], '')
      env['REQUEST_PATH'] = env['REQUEST_PATH'].gsub(Thread.current[:isHallway], '')
      #We need the forwarded host header to identify location of tenant
      whitelist = Regexp.new(".*[\.]zuora[\.]com$|^zuora[\.]com$")
      if whitelist.match(env['HTTP_X_FORWARDED_HOST']).present?
        @bad_headers.delete('HTTP_X_FORWARDED_HOST')
      end
    else
      Thread.current[:isHallway] = nil
    end
    #Remove bad headers
    @bad_headers.each { |header| env.delete(header) }
    if defined?(Prometheus) && env['PATH_INFO'] == '/connect/internal/metrics'
      # Prometheus Stuff
      metrics = ZuoraConnect::AppInstance.get_metrics('stats')
      redis_up = metrics.present? && metrics.dig(:Resque, :Workers_Total).present? ? 1 : 0
      Prometheus::REDIS_CONNECTION.set(redis_up)
      process_prometheus_metric(metrics: metrics)
      if defined?(Unicorn) && Unicorn.respond_to?(:listener_names)
        ZuoraConnect::AppInstanceBase.unicorn_listener_stats.each do |key, value|
          gauge = Prometheus.const_get("unicorn_#{key}".gsub(/[^a-zA-Z0-9_]/, '_').upcase)
          gauge.set(value) if gauge.present?
        end
      end
    end
    #Thread.current[:appinstance] = nil
    start_time = Time.now
    begin
      @status, @headers, @response = @app.call(env)
    ensure 
      
      # If the url contains any CSS or JavaScript files then do not collect metrics for them
      if ["css", "assets", "jpg", "png", "jpeg", "ico"].any? { |word| env['PATH_INFO'].include?(word) } || /.*\.js$/.match(env['PATH_INFO'])
        tags = {status: @status, controller: 'ActionController', action: 'Assets', app_instance: 0}
        values = {response_time: ((Time.now - start_time)*1000).round(2) }
        ZuoraConnect::AppInstanceBase.write_to_telegraf(direction: 'request-inbound-assets', tags: tags, values: values)
      end
      # Uncomment following block of code for handling engine requests/requests without controller
      # else
      #   # Handling requests which do not have controllers (engines)
      if env["SCRIPT_NAME"].present?
        controller_path = "#{env['SCRIPT_NAME'][1..-1]}"
        controller_path = controller_path.sub("/", "::")
        request_path = "#{controller_path}#UnknownAction"
      else
        # Writing to telegraf: Handle 404
        if [404, 500].include?(@status)
          content_type = @headers['Content-Type'].split(';')[0] if @headers['Content-Type']
          content_type = content_type.gsub('text/javascript', 'application/javascript')
          tags = {status: @status, content_type: content_type}
          tags = tags.merge({controller: 'ActionController'})
          tags = tags.merge({action: 'RoutingError' }) if @status == 404
          values = {response_time: ((Time.now - start_time)*1000).round(2) }
          ZuoraConnect::AppInstanceBase.write_to_telegraf(direction: :inbound, tags: tags, values: values)
        end
      end
      Thread.current[:inbound_metric] = nil
    end
    [@status, @headers, @response]
  end
end

def initialize(app)
  @app = app
end

def process_prometheus_metric(type: 'none', metrics: {})
  return if metrics.blank?
  prometheus = Prometheus::Client.registry
  most_recent_aggregation = {}
  if Prometheus::Client.config.data_store.is_a?(Prometheus::Client::DataStores::DirectFileStore)
    most_recent_aggregation[:aggregation] = :most_recent
  end
  metrics.each do |key, value|
    next if %w[app_name url].include?(key.to_s)
    if value.is_a?(Hash)
      process_prometheus_metric(type: key.to_s, metrics: value)
    else
      gauge_name = key.to_s.downcase.gsub(/[^a-z0-9_]/, '_')
      gauge = prometheus.get(gauge_name.to_sym) || prometheus.gauge(
        gauge_name.to_sym,
        docstring: "#{key} metric",
        labels: %i(type name),
        preset_labels: { type: type, name: ZuoraConnect::Telegraf.app_name },
        store_settings: most_recent_aggregation
      )
      gauge.set(value)
    end
  end
end