gem 'slim_form_object'

class User < ActiveRecord::Base
  has_many :review_books
  has_many :ratings
  has_and_belongs_to_many :addresses
end

class ReviewBook < ActiveRecord::Base
  belongs_to :user
  has_one    :rating
end

class Rating < ActiveRecord::Base
  belongs_to :user
  belongs_to :review_book
end

class Address < ActiveRecord::Base
  has_and_belongs_to_many :users
end

class ReviewForm < SlimFormObject::Base

  set_model_name('ReviewBook')          # name of model for params.require(:model_name).permit(...) e.g. 'ReviewBook'
  # you must define structure of data input params, also it will be data for the permit method 
  input_data_structure(
    [
      rating: [:value], 
      review_book: [:theme, :text], 
      user: [
        address_ids: [],
        address: [:city, :street, :created_at]
      ]
    ]
  )
  
  validate :validation_models           # optional - if you want to save and check validations of your models
  base_module = EngineName              # optional - default nil, e.g. you using engine and your models are named EngineName::User  
  not_save_empty_object_for Rating      # optional - if you do not want to validate and save object Rating with params like empty string
  not_save_nil_object_for Rating        # optional - if you do not want to validate and save object Rating with empty params like {} or all attributes is nil
   
  after_save_form            { |form|  } # code inside current activerecord transaction after save this form 
  before_validation_form     { |form|  } 
  allow_to_save_object       { |object, form|  true or false } 
  allow_to_validate_object   { |data_object|  true or false } 
  allow_object_processing { |data_object|  true or false } # ignore object if false
  
  allow_object_processing do |data_object|
  
    case data_object.model.to_s
    when 'Rating'
      # e.g. do not save object if input rating value <= 0 
      data_object.attributes[:value]&.to_i <= 0
    else
      # html form can send empty attributes and method .blank_or_empty?(except fields: []) will check it. Also we can ignore :id check or any input attributes with argument :except_fields  
      !data_object.blank_or_empty?(except_fileds: [:id]) 
    end
  end
  
  def initialize(params: {}, current_user: nil)
    # hash of http parameters must be for automatic save input attributes
    super(params: permit_params(params))
    
    # create the objects of models which will be saved
    if current_user
      self.user             = current_user
    end

    # new objects will generate automatically if you not created their
    # self.review_book      = ReviewBook.new
    # self.rating           = Rating.new
  end
end

class ReviewController < ApplicationController
 def new
   @reviewForm = ReviewForm.new(current_user: current_user)
 end
   
 def create
   reviewForm = ReviewForm.new(params: params, current_user: current_user)
   reviewForm.apply_parameters       # assign attributes of *params*. Will return the instance of ReviewForm with assigned attributes
   if reviewForm.save
     render json: {status: 200}
   else
     render json: reviewForm.errors, status: 422
   end
 end
end

# data_for_assign format
# 
# [
#   { :model      => Product(id: integer, category_id: integer, brand_id: integer), 
#     :attributes => {:id=>"3871", :category_id=>"1", :brand_id=>"1"}, 
#     :nested     => [ 
#                      { :model      => FiltersProduct(id: integer, product_id: integer, filter_id: integer, value_id: integer), 
#                        :attributes => {:id=>"", :product_id=>"111", filter_id: "222", value_id: "333"}, 
#                        :nested     => []
#                      }
#                    ]
#   }
# ]