# This module is extended by ProductScope
module Scopes::Dynamic
  module_function

  # Sample dynamic scope generating from set of products
  # generates 0 or (2..scope_limit) scopes for prices, based
  # on number of products (uses Math.log, to guess number of scopes)
  def price_scopes_for(products, scope_limit=5)
    scopes = []

    # Price based scopes
    all_prices = products.map(&:price).sort

    ranges = [Math.log(products.length).floor, scope_limit].max

    if ranges >= 2
      l = all_prices.length / ranges
      scopes << ProductScope.new({:name => "master_price_lte", :arguments => [all_prices[l]] })

      (ranges - 2).times do |x|
        scopes << ProductScope.new({:name => "price_between",
                                    :arguments => [ all_prices[l*(x+1)+1], all_prices[l*(x+2)] ] })
      end

      scopes << ProductScope.new({:name => "master_price_gte", :arguments => [all_prices[l*(ranges-1)+1]] })
    end

    scopes
  end

end