class RearORM
  include RearUtils

  attr_reader :model, :pkey

  def initialize model, pkey = :id
    @model, @pkey, @orm = model, pkey, orm(model)
  end

  def [] id
    sequel? ?
      model[id] :
      model.first(conditions: {pkey => id})
  end

  def count conditions = {}
    if sequel?
      sequel_dataset(model, conditions).count
    else
      model.count(conditions)
    end
  end

  def filter conditions = {}
    if sequel?
      sequel_dataset(model, conditions).all
    else
      model.all(conditions)
    end
  end

  def assoc_filter assoc, item, conditions
    if sequel?
      sequel_dataset(item.send('%s_dataset' % assoc), conditions).all
    else
      result = item.send(assoc, conditions)
      result.respond_to?(:size) ? result : [result].compact
    end
  end

  def assoc_count assoc, item, conditions
    if sequel?
      sequel_dataset(item.send('%s_dataset' % assoc), conditions).count
    else
      if result = item.send(assoc)
        result.respond_to?(:count) ? result.count(conditions) : 1
      else
        0
      end
    end
  end

  def delete_multiple *ids
    ids.flatten!
    model.destroy(ids) if @orm == :ar
    model.all(pkey => ids).destroy! if @orm == :dm
    model.filter(pkey => ids).destroy if @orm == :sq
  end

  def sequel?; @orm == :sq end

  def sequel_dataset dataset, conditions = {}
    filters, limit, offset, order =
      conditions.values_at(:conditions, :limit, :offset, :order)
    ds = limit ? dataset.limit(*[limit, offset].compact) : dataset
    ds.filter(filters || {}).order(*[order].compact)
  end

  def singularize smth
    model.send(:singularize, smth) if sequel?
  end

end