module Eco
  module API
    module Common
      module ClassHelpers

        def class_resolver(name, klass)
          define_singleton_method(name) { resolve_class(klass) }
          define_method(name) { self.class.resolve_class(klass) }
        end

        def resolve_class(klass, exception: true)
          @resolved ||= {}
          @resolved[klass] ||=
            case klass
              when Class
                klass
              when String
                begin
                  Kernel.const_get(klass)
                rescue NameError => e
                  raise if exception
                end
              when Symbol
                resolve_class(self.send(klass))
              else
                raise "Unknown class: #{klass}" if exception
            end
        end

        # Helper to normalize `key` into a correct `ruby` **constant name**
        # @param key [String, Symbol] to be normalized
        # @return [String] a correct constant name
        def to_constant(key)
          str_name = key.to_s.strip.split(/[\-\_ ]/i).compact.map do |str|
            str.slice(0).upcase + str.slice(1..-1).downcase
          end.join("")
        end

        # If the class for `name` exists, it returns it. Otherwise it generates it.
        # @param name [String, Symbol] the name of the new class
        # @param inherits [Class] the parent class to _inherit_ from
        # @param parent_space [String] parent namespace of the generated class, if not given: `self`
        # @yield [child_class] configure the new class
        # @yieldparam child_class [Class] the new class
        # @return [Class] the new generated class
        def new_class(name, inherits:, parent_space: nil)
          name            = name.to_sym.freeze
          class_name      = to_constant(name)
          parent_space    = parent_space ? resolve_class(parent_space) : self
          full_class_name = "#{parent_space}::#{class_name}"

          unless target_class = resolve_class(full_class_name, exception: false)
            target_class = Class.new(inherits)
            parent_space.const_set class_name, target_class
          end

          target_class.tap do |klass|
            yield(klass) if block_given?
          end
        end

      end
    end
  end
end