module Hyperstack
  module Internal
    module Store
      class MutatorWrapper < BaseStoreClass # < BasicObject

        class << self
          def add_method(klass, method_name, opts = {})
            define_method(:"#{method_name}") do |*args|
              from = opts[:scope] == :shared ? klass.state.__from__ : __from__
              from.init_store if from.respond_to? :init_store
              current_value = State::Variable.get(from, method_name.to_s)

              if args.count > 0
                State::Variable.set(from, method_name.to_s, args[0])
                current_value
              else
                State::Variable.set(from, method_name.to_s, current_value)
                Observable.new(current_value) do |update|
                  State::Variable.set(from, method_name.to_s, update)
                end
              end
            end

            initialize_values(klass, method_name, opts) if initialize_values?(opts)
          end

          def initialize_values?(opts)
            [:class, :shared].include?(opts[:scope]) && (opts[:initializer] || opts[:block])
          end

          def initialize_values(klass, name, opts)
            initializer = initializer_proc(opts[:initializer], klass, name) if opts[:initializer]

            if initializer && opts[:block]
              klass.receives(Hyperstack::Application::Boot, initializer) do
                klass.mutate.__send__(:"#{name}", opts[:block].call)
              end
            elsif initializer
              klass.receives(Hyperstack::Application::Boot, initializer)
            elsif opts[:block]
              klass.receives(Hyperstack::Application::Boot) do
                klass.mutate.__send__(:"#{name}", opts[:block].call)
              end
            end
          end

          private

          def initializer_proc(initializer, klass, name)
            # We gotta check the arity because a Proc passed in directly from initializer has no args,
            # but if we created one then we might have wanted the class
            if initializer.arity > 0
              -> { klass.mutate.__send__(:"#{name}", initializer.call(klass)) }
            else
              -> { klass.mutate.__send__(:"#{name}", initializer.call) }
            end
          end
        end

        attr_accessor :__from__

        def self.new(from)
          instance = allocate
          instance.__from__ = from
          instance
        end

        def []=(name, value)
          __send__(name, value)
        end

        def [](name)
          __send__(name)
        end

        # Any method_missing call will create a state and accessor with that name
        def method_missing(name, *args, &block) # rubocop:disable Style/MethodMissing
          (class << self; self end).add_method(nil, name)
          __send__(name, *args, &block)
        end
      end
    end
  end
end