module FactoryBot
  class DefinitionProxy
    UNPROXIED_METHODS = %w[
      __send__
      __id__
      nil?
      send
      object_id
      extend
      instance_eval
      initialize
      block_given?
      raise
      caller
      method
    ].freeze

    (instance_methods + private_instance_methods).each do |method|
      undef_method(method) unless UNPROXIED_METHODS.include?(method.to_s)
    end

    delegate :before, :after, :callback, to: :@definition

    attr_reader :child_factories

    def initialize(definition, ignore = false)
      @definition = definition
      @ignore = ignore
      @child_factories = []
    end

    def singleton_method_added(name)
      message = "Defining methods in blocks (trait or factory) is not supported (#{name})"
      raise FactoryBot::MethodDefinitionError, message
    end

    # Adds an attribute to the factory.
    # The attribute value will be generated "lazily"
    # by calling the block whenever an instance is generated.
    # The block will not be called if the
    # attribute is overridden for a specific instance.
    #
    # Arguments:
    # * name: +Symbol+ or +String+
    #   The name of this attribute. This will be assigned using "name=" for
    #   generated instances.
    def add_attribute(name, &block)
      declaration = Declaration::Dynamic.new(name, @ignore, block)
      @definition.declare_attribute(declaration)
    end

    def transient(&block)
      proxy = DefinitionProxy.new(@definition, true)
      proxy.instance_eval(&block)
    end

    # Calls add_attribute using the missing method name as the name of the
    # attribute, so that:
    #
    #   factory :user do
    #     name { 'Billy Idol' }
    #   end
    #
    # and:
    #
    #   factory :user do
    #     add_attribute(:name) { 'Billy Idol' }
    #   end
    #
    # are equivalent.
    #
    # If no argument or block is given, factory_bot will first look for an
    # association, then for a sequence, and finally for a trait with the same
    # name. This means that given an "admin" trait, an "email" sequence, and an
    # "account" factory:
    #
    #   factory :user, traits: [:admin] do
    #     email { generate(:email) }
    #     association :account
    #   end
    #
    # and:
    #
    #   factory :user do
    #     admin
    #     email
    #     account
    #   end
    #
    # are equivalent.
    def method_missing(name, *args, &block) # rubocop:disable Style/MissingRespondToMissing
      association_options = args.first

      if association_options.nil?
        __declare_attribute__(name, block)
      elsif __valid_association_options?(association_options)
        association(name, association_options)
      else
        raise NoMethodError.new(<<~MSG)
          undefined method '#{name}' in '#{@definition.name}' factory
          Did you mean? '#{name} { #{association_options.inspect} }'
        MSG
      end
    end

    # Adds an attribute that will have unique values generated by a sequence with
    # a specified format.
    #
    # The result of:
    #   factory :user do
    #     sequence(:email) { |n| "person#{n}@example.com" }
    #   end
    #
    # Is equal to:
    #   sequence(:email) { |n| "person#{n}@example.com" }
    #
    #   factory :user do
    #     email { FactoryBot.generate(:email) }
    #   end
    #
    # Except that no globally available sequence will be defined.
    def sequence(name, ...)
      sequence = Sequence.new(name, ...)
      FactoryBot::Internal.register_inline_sequence(sequence)
      add_attribute(name) { increment_sequence(sequence) }
    end

    # Adds an attribute that builds an association. The associated instance will
    # be built using the same build strategy as the parent instance.
    #
    # Example:
    #   factory :user do
    #     name 'Joey'
    #   end
    #
    #   factory :post do
    #     association :author, factory: :user
    #   end
    #
    # Arguments:
    # * name: +Symbol+
    #   The name of this attribute.
    # * options: +Hash+
    #
    # Options:
    # * factory: +Symbol+ or +String+
    #    The name of the factory to use when building the associated instance.
    #    If no name is given, the name of the attribute is assumed to be the
    #    name of the factory. For example, a "user" association will by
    #    default use the "user" factory.
    def association(name, *options)
      if block_given?
        raise AssociationDefinitionError.new(
          "Unexpected block passed to '#{name}' association " \
          "in '#{@definition.name}' factory"
        )
      else
        declaration = Declaration::Association.new(name, *options)
        @definition.declare_attribute(declaration)
      end
    end

    def to_create(&block)
      @definition.to_create(&block)
    end

    def skip_create
      @definition.skip_create
    end

    def factory(name, options = {}, &block)
      @child_factories << [name, options, block]
    end

    def trait(name, &block)
      @definition.define_trait(Trait.new(name, &block))
    end

    # Creates traits for enumerable values.
    #
    # Example:
    #   factory :task do
    #     traits_for_enum :status, [:started, :finished]
    #   end
    #
    # Equivalent to:
    #   factory :task do
    #     trait :started do
    #       status { :started }
    #     end
    #
    #     trait :finished do
    #       status { :finished }
    #     end
    #   end
    #
    # Example:
    #   factory :task do
    #     traits_for_enum :status, {started: 1, finished: 2}
    #   end
    #
    # Example:
    #   class Task
    #     def statuses
    #       {started: 1, finished: 2}
    #     end
    #   end
    #
    #   factory :task do
    #     traits_for_enum :status
    #   end
    #
    # Both equivalent to:
    #   factory :task do
    #     trait :started do
    #       status { 1 }
    #     end
    #
    #     trait :finished do
    #       status { 2 }
    #     end
    #   end
    #
    #
    # Arguments:
    #   attribute_name: +Symbol+ or +String+
    #     the name of the attribute these traits will set the value of
    #   values: +Array+, +Hash+, or other +Enumerable+
    #     An array of trait names, or a mapping of trait names to values for
    #     those traits. When this argument is not provided, factory_bot will
    #     attempt to get the values by calling the pluralized `attribute_name`
    #     class method.
    def traits_for_enum(attribute_name, values = nil)
      @definition.register_enum(Enum.new(attribute_name, values))
    end

    def initialize_with(&block)
      @definition.define_constructor(&block)
    end

    private

    def __declare_attribute__(name, block)
      if block.nil?
        declaration = Declaration::Implicit.new(name, @definition, @ignore)
        @definition.declare_attribute(declaration)
      else
        add_attribute(name, &block)
      end
    end

    def __valid_association_options?(options)
      options.respond_to?(:has_key?) && options.has_key?(:factory)
    end
  end
end