# frozen_string_literal: true

require "active_support/core_ext/hash/keys"

module DjiMqttConnect
  module Utils
    # Sanitizes MQTT messages to remove any personally-identifiable information
    class MessageSanitizer
      DEFAULT_LATITUDE = "-33.865143"
      DEFAULT_LONGITUDE = "151.209900"

      SECRET_KEYS = %w[app_id app_key app_license callsign device_secret nonce]

      SERIAL_NUMBER_KEYS = %w[device_sn gateway sn]

      TOPIC_REGEX = /\A.+\/.+\/(.+)\/.+/

      def initialize(latitude: DEFAULT_LATITUDE, longitude: DEFAULT_LONGITUDE, secret_keys: SECRET_KEYS, serial_number_keys: SERIAL_NUMBER_KEYS, serial_number_aliases: {})
        @latitude = latitude
        @longitude = longitude

        @secret_keys = secret_keys
        @serial_number_keys = serial_number_keys

        serial_aliases = serial_number_aliases.stringify_keys
        @serial_number_generator = Hash.new do |h, k|
          return "" if k.length == 0
          h[k] = serial_aliases.fetch(k) { sprintf("%s%02d", "SERIAL", h.length + 1) }
        end
        serial_aliases.keys.each { |k| serial_number_generator[k] }
      end

      def sanitize_topic(topic)
        topic.sub(TOPIC_REGEX) { |topic_match| topic_match.sub($1, serial_number_generator[$1]) }
      end

      def sanitize_message(message)
        sanitized_message = sanitize_object(message)
        strip_serial_numbers(sanitized_message)
      end

      private

      attr_reader :latitude, :longitude
      attr_reader :secret_keys, :serial_number_keys, :serial_number_generator

      def sanitize_object(object)
        case object
        when Hash
          serial_number_keys.each do |key|
            if object.key?(key) && object[key].length > 0
              object[key] = serial_number_generator[object[key]]
            end
          end
          secret_keys.each do |key|
            object[key] = key.upcase if object.key?(key)
          end
          if object.key?("latitude")
            obj_latitude = object["latitude"]
            object["latitude"] = (obj_latitude.is_a?(Integer) && obj_latitude.zero?) ? 0 : latitude
          end
          if object.key?("longitude")
            obj_longitude = object["longitude"]
            object["longitude"] = (obj_longitude.is_a?(Integer) && obj_longitude.zero?) ? 0 : longitude
          end

          object.transform_values { |v| sanitize_object(v) }
        when Array
          object.map { |v| sanitize_object(v) }
        else
          object
        end
      end

      # Strips known serial numbers from an object
      def strip_serial_numbers(object)
        case object
        when Hash
          object.transform_values { |v| strip_serial_numbers(v) }
        when Array
          object.map { |v| strip_serial_numbers(v) }
        when String
          object.split("-").map { |s| serial_number_generator.fetch(s, s) }.join("-")
        else
          object
        end
      end
    end
  end
end