Enum machine

# aasm
event :complete do # complete/collected - dichotomy between states and events
  before { puts "event complete" }
  transitions from: :collecting, to: :collected
end

# pay/archived difficult to remember the relationship between statuses and events
# try to explain this to the logic of business stakeholders
event :pay do
  transitions from: [:created, :collected], to: :archived
end

order = Order.create(state: "collecting")
order.update(state: "archived") # not check transitions, invalid logic
order.update(state: "collected") # not run callbacks 
order.complete # need use event for transition, but your object in UI and DB have only states

# enum_machine
transitions( # simple readable transitions map
  "collecting" => "collected",
  "collected"  => "archived",
)
before_transition("collecting" => "collected") { puts "event complete" }

order = Order.create(state: "collecting")
order.update(state: "archived") # checked transitions, raise exception
order.update(state: "collected") # run callbacks

gem "enum_machine"

# With ActiveRecord
class Product < ActiveRecord::Base
  enum_machine :color, %w[red green]
end

# Or with plain class
class Product
  # attributes must be defined before including the EnumMachine module
  attr_accessor :color
  
  include EnumMachine[color: { enum: %w[red green] }]
  # or reuse from model
  Product::COLOR.decorator_module
end

Product::COLOR.values # => ["red", "green"]
Product::COLOR::RED # => "red"
Product::COLOR::RED__GREEN # => ["red", "green"]

product = Product.new
product.color # => nil
product.color = "red"
product.color.red? # => true
product.color.human_name # => "Красный"

class Product < ActiveRecord::Base
  enum_machine :state, %w[created approved published] do
    aliases(
      "forming" => %w[created approved],
    )
  end
end

Product::STATE.forming # => %w[created approved]

product = Product.new(state: "created")
product.state.forming? # => true

class Product < ActiveRecord::Base
  enum_machine :color, %w[red green blue]
  enum_machine :state, %w[created approved cancelled activated] do
    # transitions(any => any) - allow all transitions
    transitions(
      nil                    => "created",
      "created"              => [nil, "approved"],
      %w[cancelled approved] => "activated",
      "activated"            => %w[created cancelled],
    )

    # Will be executed in `before_save` callback
    before_transition "created" => "approved" do |product|
      product.color = "green" if product.color.red?
    end

    # Will be executed in `after_save` callback
    after_transition %w[created] => %w[approved] do |product|
      product.color = "red"
    end

    after_transition any => "cancelled" do |product|
      product.cancelled_at = Time.zone.now
    end
  end
end

product = Product.create(state: "created")
product.state.possible_transitions # => [nil, "approved"]
product.state.can_activated? # => false
product.state.to_activated! # => EnumMachine::Error: transition "created" => "activated" not defined in enum_machine
product.state.to_approved! # => true; equal to `product.update!(state: "approve")`

product = Product.new(state: "created")
product.skip_state_transitions { product.save }

FactoryBot.define do
  factory :product do
    name { Faker::Commerce.product_name }
    to_create { |product| product.skip_state_transitions { product.save! } }
  end
end

# ActiveRecord
class Product < ActiveRecord::Base
  enum_machine :color, %w[red green]
end

# Plain class
class Product
  # attributes must be defined before including the EnumMachine module
  attr_accessor :color
  # `i18n_scope` option must be explicitly set to use methods below
  include EnumMachine[color: { enum: %w[red green], i18n_scope: "product" }]
end

Product::COLOR.human_name_for("red") # => "Красный"
Product::COLOR.values_for_form # => [["Красный", "red"], ["Зеленый", "green"]]

product = Product.new(color: "red")
product.color.human_name # => "Красный"

# For AciveRecord
class Product < ActiveRecord::Base
  enum_machine :color, %w[red green], i18n_scope: "users.product"
end

# For plain class
class Product
  include EnumMachine[color: { enum: %w[red green], i18n_scope: "users.product" }]
end