# frozen_string_literal: true

module Sonezaki
  # @api public
  # @author darthjee
  #
  # Accessor that readis and write values into Redis
  #
  # @example Simple usage
  #   accessor = Sonezaki::RedisAccessor.new('my_key', type: :integer)
  #
  #   accessor.set('10.1')
  #
  #   accessor.get # returns 10
  class RedisAccessor
    MONTH = 30 * 24 * 3600

    # @param key [Symbol,String] Key used to save the data on redis
    # @param type [Symbol] Type of convertion when retrieving the data
    # @param ttl [Integer] Seconds the data will exist before expiration
    def initialize(key, type: :string, ttl: MONTH)
      @key = key
      @type = type
      @ttl = ttl
    end

    # Save the value into redis
    #
    # @param value [Object] Object to be saved
    #
    # Saving will convert the value as string
    #
    # @return [Object] the value itself as it is read from Redis
    #
    # @example (see RedisAccessor)
    def set(value)
      options = { ex: ttl }.compact
      connection.set(key, value, **options)
      get
    end

    # Fetch the value from redis
    #
    # The value is converted using {#type}
    #
    # @return [Object]
    #
    # @example (see RedisAccessor)
    def get
      value = connection.get(key)
      return unless value
      return value unless type

      convert(value)
    end

    private

    attr_reader :key, :type, :ttl

    # @method key
    # @private
    # @api private
    #
    # Retrieve saving / reading key
    #
    # @return [Symbol, String]

    # @method type
    # @private
    # @api private
    #
    # Type conversion when reading data
    #
    # @return [Symbol]

    # @method ttl
    # @private
    # @api private
    #
    # Time until the value expires in Redis
    #
    # @return [Integer]

    # @private
    # @api private
    #
    # Convert the string read from Redis
    #
    # The value will be converted using {#type}
    #
    # @param value [String] The value read from redis
    #
    # @return [Object]
    def convert(value)
      case type
      when :integer
        return value.to_i
      when :float
        return value.to_f
      end
      value
    end

    # @private
    # @api private
    #
    # Connection to redis
    #
    # @return [Redis]
    def connection
      @connection ||= build_connection
    end

    # @private
    # @api private
    #
    # builds the connection to redis
    #
    # When this method is called is when redis is required.
    #
    # This is done so that projects can choose which accessor
    # they want insted of use always Reds
    #
    # @return [Redis]
    def build_connection
      require 'redis'

      Redis.new
    end
  end
end