module CollectiveIdea::Acts::NestedSet::Model::Validatable

def all_roots_valid?
  if acts_as_nested_set_options[:scope]
    all_roots_valid_by_scope?(roots)
  else
    each_root_valid?(roots)
  end
end

def all_roots_valid_by_scope?(roots_to_validate)
  roots_grouped_by_scope(roots_to_validate).all? do |scope, grouped_roots|
    each_root_valid?(grouped_roots)
  end
end

def each_root_valid?(roots_to_validate)
  left_column = acts_as_nested_set_options[:left_column]
  reordered_roots = roots_reordered_by_column(roots_to_validate, left_column)
  left = right = 0
  reordered_roots.all? do |root|
    (root.left > left && root.right > right).tap do
      left = root.left
      right = root.right
    end
  end
end

def left_and_rights_valid?
  SetValidator.new(self).valid?
end

def no_duplicates_for_columns?
  [quoted_left_column_full_name, quoted_right_column_full_name].all? do |column|
    # No duplicates
    select("#{scope_string}#{column}, COUNT(#{column}) as _count").
      group("#{scope_string}#{column}", quoted_primary_key_column_full_name).
      having("COUNT(#{column}) > 1").
      order(primary_column_name => :asc).
      first.nil?
  end
end

def roots_grouped_by_scope(roots_to_group)
  roots_to_group.group_by {|record|
    scope_column_names.collect {|col| record.send(col) }
  }
end

def roots_reordered_by_column(roots_to_reorder, column)
  if roots_to_reorder.respond_to?(:reorder) # ActiveRecord's relation
    roots_to_reorder.reorder(column)
  elsif roots_to_reorder.respond_to?(:sort) # Array
    roots_to_reorder.sort { |a, b| a.send(column) <=> b.send(column) }
  else
    roots_to_reorder
  end
end

def scope_string
  Array(acts_as_nested_set_options[:scope]).map do |c|
    connection.quote_column_name(c)
  end.push(nil).join(", ")
end

def valid?
  left_and_rights_valid? && no_duplicates_for_columns? && all_roots_valid?
end