defmodule Frenzy.FilterEngine do
  def matches?(item, filter) do
    score =
      filter.rules
      |> Enum.map(fn rule -> score(item, rule) end)
      |> Enum.sum()

    score >= filter.score
  end

  def score(item, rule) do
    prop_value = get_property(item, rule.property)

    if matches(prop_value, rule.mode, rule.param) do
      rule.weight
    else
      0
    end
  end

  def matches(value, "contains_string", param) do
    String.contains?(value, param)
  end

  def matches(value, "matches_regex", param) do
    regex = Regex.compile(param)
    String.match?(value, regex)
  end

  def get_property(item, "url"), do: item.url
  def get_property(item, "title"), do: item.title
  def get_property(item, "author"), do: item.author
end