This algorithm seems really ignorant... any suggestions?

find.rb

class JTask

  # JTask.find()
  # Retrieves records from the database file.
  # --------------------------------------------------------------------------------
  # Eg: JTask.find("test.json", 1) || JTask.find("test.json", first: 10)
  # #=> <JTask id=x, ...>
  # --------------------------------------------------------------------------------
  # See wiki guide for more usage examples...
  # https://github.com/adammcarthur/jtask/wiki/find

  def self.find(file, id=nil, dir=nil)
    # Start off by setting some variables and performing validations...
    JTask::Helpers.validate_id(id)
    @file_directory = JTask::Helpers.set_directory(dir)
    @database = File.join(@file_directory, file)
    JTask::Helpers.validate_file(@database)
    @records = JSON.parse(File.read(@database))

    # Return nil if there are no records in the database
    return nil if @records.empty?

    # [Integer] Look for the unique id in the database
    if id.is_a?(Integer)
      # we should return nil if the record doesn't exist...
      return nil unless @records["#{id}"]
      # ...load the single record to the results
      results = JTask.new({ "id" => id.to_i }.merge(@records["#{id}"]))
    end

    # [Array] We need to find a number of records with their unique id
    if id.is_a?(Array)
      results = Array.new
      id.each do |unique_id|
        if @records["#{unique_id}"] # used so that only records that exist are added to the results
          results << JTask.new({ "id" => unique_id.to_i }.merge(@records["#{unique_id}"]))
        end
        # Once again, return nil if it turns out that no id's
        # in the array exist as a record in the database.
        return nil if results.empty?
      end
    end

    # [Hash] The first or last n records need to be found
    if id.is_a?(Hash)
      # Think of this more as `{first/last: number} do |key, value|`
      id.each do |method, num|
        if method.to_sym == :first
          # get first `num` records
          results = Hash[@records.to_a.first(num)]
        elsif method.to_sym == :last
          # get last `num` records (in reverse order)
          results = Hash[@records.to_a.last(num).reverse]
        end
      end

      # Finally, map each record to the results
      results = results.map { |unique_id, record| JTask.new({ "id" => unique_id.to_i }.merge(record)) }
    end

    # [Symbol or nil] :all of the records need to be retrieved
    if id.is_a?(Symbol) or id == nil
      results = Array.new
      @records.each do |unique_id, record|
        results << JTask.new({ "id" => unique_id.to_i }.merge(record))
      end
    end

    return results
  end

end