dictionary_filter.ex

defmodule Project.DictionaryFilter do
  import Ecto.Query, warn: false

  def create_val(val) do
    if is_bitstring(val) && String.starts_with?(val, "self.") do
      val = String.replace(val, "self.", "")
      dynamic([q], field(q, ^String.to_atom(val)))
    else
      val
    end
  end

  def create_query(name, op, val) do
    field_value = create_val(val)

    case op do
      "gte" -> dynamic([q], field(q, ^String.to_atom(name)) >= ^field_value)
      "gt" -> dynamic([q], field(q, ^String.to_atom(name)) > ^field_value)
      "lt" -> dynamic([q], field(q, ^String.to_atom(name)) < ^field_value)
      "lte" -> dynamic([q], field(q, ^String.to_atom(name)) <= ^field_value)
      "eq" -> dynamic([q], field(q, ^String.to_atom(name)) == ^field_value)
      "neq" -> dynamic([q], field(q, ^String.to_atom(name)) != ^field_value)
      "startswith" -> dynamic([q], like(field(q, ^String.to_atom(name)), ^"#{val}%"))
      "istartswith" -> dynamic([q], ilike(field(q, ^String.to_atom(name)), ^"#{val}%"))
      "endswith" -> dynamic([q], like(field(q, ^String.to_atom(name)), ^"%#{val}"))
      "iendswith" -> dynamic([q], ilike(field(q, ^String.to_atom(name)), ^"%#{val}"))
      "contains" -> dynamic([q], like(field(q, ^String.to_atom(name)), ^"%#{val}%"))
      "icontains" -> dynamic([q], ilike(field(q, ^String.to_atom(name)), ^"%#{val}%"))
    end
  end

  def parse_filter(filter) do
    case filter do
      %{"or" => filters} ->
        mapped = Enum.map(filters, fn x -> parse_filter(x) end)
        Enum.reduce(mapped, false, fn x, y -> dynamic(^x or ^y) end)

      %{"and" => filters} ->
        mapped = Enum.map(filters, fn x -> parse_filter(x) end)
        Enum.reduce(mapped, false, fn x, y -> dynamic(^x and ^y) end)

      %{"name" => name, "op" => op, "val" => val} ->
        create_query(name, op, val)
    end
  end

  def get_order_by(query, orderby) do
    if String.starts_with?(orderby, "-") do
      orderby = String.replace(orderby, "-", "")
      order_by(query, [q], desc: field(q, ^String.to_atom(orderby)))
    else
      order_by(query, [q], field(q, ^String.to_atom(orderby)))
    end
  end
end