module Mongoid::Criteria::Modifiable

def build(attrs = {}, &block)
  create_document(:new, attrs, &block)
end

def create(attrs = {}, &block)
  create_document(:create, attrs, &block)
end

def create!(attrs = {}, &block)
  create_document(:create!, attrs, &block)
end

def create_document(method, attrs = nil, &block)
  attributes = selector.reduce(attrs ? attrs.dup : {}) do |hash, (key, value)|
    unless key.to_s =~ /\$/ || value.is_a?(Hash)
      hash[key] = value
    end
    hash
  end
  if embedded?
    attributes[:_parent] = parent_document
    attributes[:__metadata] = metadata
  end
  klass.__send__(method, attributes, &block)
end

def create_with(attrs = {})
  where(selector.merge(attrs))
end

def find_or(method, attrs = {}, &block)
  where(attrs).first || send(method, attrs, &block)
end

def find_or_create_by(attrs = {}, &block)
  find_or(:create, attrs, &block)
end

def find_or_create_by!(attrs = {}, &block)
  find_or(:create!, attrs, &block)
end

def find_or_initialize_by(attrs = {}, &block)
  find_or(:new, attrs, &block)
end

def first_or(method, attrs = {}, &block)
  first || create_document(method, attrs, &block)
end

def first_or_create(attrs = nil, &block)
  first_or(:create, attrs, &block)
end

def first_or_create!(attrs = nil, &block)
  first_or(:create!, attrs, &block)
end

def first_or_initialize(attrs = nil, &block)
  first_or(:new, attrs, &block)
end