The initial implementation of a Whereable query filter for KameSame.

whereable.rb

class Whereable
  def initialize(where:, model: Item, ranking_conditions: [], valid: true, data_source: nil)
    @model = model
    @where = where
    @data_source = data_source
    @ranking_conditions = ranking_conditions
    @valid = valid
  end

  def valid?
    @valid
  end

  def where
    return unless @valid

    @valid = if !@data_source.present? ||
        data_source_results.present?
      normalize_where(@where, args: [data_source_results])
    end
  end

  def ranking_conditions
    return unless @valid

    if @ranking_conditions.respond_to?(:call)
      normalize_rankings(@ranking_conditions.call(data_source_results))
    else
      normalize_rankings(@ranking_conditions)
    end
  end

  private

  def data_source_results
    @data_source_results ||= @data_source&.call
  end

  def sanitize(sql, *values)
    ActiveRecord::Base.sanitize_sql_for_conditions([sql, *values])
  end

  def normalize_where(where, args: [])
    if where.respond_to?(:to_sql)
      where
    elsif where.respond_to?(:call)
      normalize_where(where.call(*args.compact))
    else
      @model.where(*sanitize(*@where))
    end
  end

  def normalize_rankings(rankings)
    Array.wrap(rankings).map { |ranking|
      if ranking.is_a?(Array)
        sanitize(*ranking)
      else
        ranking
      end
    }
  end
end