# frozen_string_literal: true

require 'set'

module Micro
  class Case
    class Result
      Kind::Types.add(self)

      INVALID_INVOCATION_OF_THE_THE_METHOD =
        Error::InvalidInvocationOfTheThenMethod.new(self.name)

      @@transitions_enabled = true

      def self.transitions_enabled?
        @@transitions_enabled
      end

      attr_reader :type, :data, :use_case

      alias value data

      def initialize
        @__transitions = @@transitions_enabled ? [] : Kind::Empty::ARRAY
        @__accumulated_data = {}
        @__accessible_attributes = {}
      end

      def to_ary
        [data, type]
      end

      def [](key)
        data[key]
      end

      def values_at(*keys)
        data.values_at(*keys)
      end

      def key?(key)
        data.key?(key)
      end

      def value?(value)
        data.value?(value)
      end

      def slice(*keys)
        Utils.slice_hash(data, keys)
      end

      def success?
        @success
      end

      def failure?
        !success?
      end

      def on_success(expected_type = nil)
        return self unless __success_type?(expected_type)

        hook_data = expected_type.nil? ? self : data

        yield(hook_data, @use_case)

        self
      end

      def on_failure(expected_type = nil)
        return self unless __failure_type?(expected_type)

        hook_data = expected_type.nil? ? self : data

        yield(hook_data, @use_case)

        self
      end

      def on_exception(expected_exception = nil)
        return self unless __failure_type?(:exception)

        if !expected_exception || (Kind.is(Exception, expected_exception) && data.fetch(:exception).is_a?(expected_exception))
          yield(data, @use_case)
        end

        self
      end

      def then(use_case = nil, attributes = nil, &block)
        can_yield_self = respond_to?(:yield_self)

        if block
          raise INVALID_INVOCATION_OF_THE_THE_METHOD if use_case
          raise NotImplementedError if !can_yield_self

          yield_self(&block)
        else
          return yield_self if !use_case && can_yield_self
          return failure? ? self : __call_proc(use_case, 'then(-> {})'.freeze) if use_case.is_a?(Proc)
          return failure? ? self : __call_method(use_case, attributes) if use_case.is_a?(Method)

          raise INVALID_INVOCATION_OF_THE_THE_METHOD unless ::Micro.case_or_flow?(use_case)

          return self if failure?

          input = attributes.is_a?(Hash) ? self.data.merge(attributes) : self.data

          if use_case.is_a?(::Micro::Cases::Flow)
            use_case.call!(input: input, result: self)
          else
            use_case.__new__(self, input).__call__
          end
        end
      end

      def |(arg)
        return self if failure?

        return __call_proc(arg, '| -> {}'.freeze) if arg.is_a?(Proc)
        return __call_method(arg) if arg.is_a?(Method)

        raise INVALID_INVOCATION_OF_THE_THE_METHOD unless ::Micro.case_or_flow?(arg)

        failure? ? self : arg.__new__(self, data).__call__
      end

      def transitions
        @__transitions.clone
      end

      FetchData = -> (data) do
        return data if data.is_a?(Hash)
        return { data => true } if data.is_a?(Symbol)

        { exception: data } if data.is_a?(Exception)
      end

      def __set__(is_success, data, type, use_case)
        raise Error::InvalidResultType unless type.is_a?(Symbol)
        raise Error::InvalidUseCase unless use_case.is_a?(::Micro::Case)

        @success, @type, @use_case = is_success, type, use_case

        @data = FetchData.call(data)

        raise Micro::Case::Error::InvalidResult.new(is_success, type, use_case) unless @data

        @__accumulated_data.merge!(@data)

        use_case_attributes = Utils.symbolize_hash_keys(@use_case.attributes)

        __update_accessible_attributes(use_case_attributes)

        __set_transition(use_case_attributes) unless @__transitions.frozen?

        self
      end

      def __set_accessible_attributes__(arg)
        return arg unless arg.is_a?(Hash)

        attributes = Utils.symbolize_hash_keys(arg)

        __update_accessible_attributes(attributes)
      end

      private

        def __fetch_accumulated_data(opt = nil)
          __update_accessible_attributes(
            opt ? opt.merge(@__accumulated_data) : @__accumulated_data
          )
        end

        def __call_proc(fn, expected)
          input = __fetch_accumulated_data

          result = fn.arity.zero? ? fn.call : fn.call(input)

          return self if result === self

          raise Error::UnexpectedResult.new("#{Result.name}##{expected}")
        end

        def __call_method(methd, attributes = nil)
          input = __fetch_accumulated_data(attributes)

          result = methd.arity.zero? ? methd.call : methd.call(**input)

          return self if result === self

          raise Error::UnexpectedResult.new("#{use_case.class.name}#method(:#{methd.name})")
        end

        def __success_type?(expected_type)
          success? && (expected_type.nil? || expected_type == type)
        end

        def __failure_type?(expected_type)
          failure? && (expected_type.nil? || expected_type == type)
        end

        def __update_accessible_attributes(attributes)
          @__accessible_attributes.merge!(attributes)
          @__accessible_attributes.dup
        end

        def __set_transition(use_case_attributes)
          use_case_class = @use_case.class

          result = @success ? :success : :failure

          @__transitions << {
            use_case: { class: use_case_class, attributes: use_case_attributes },
            result => { type: @type, result: data },
            accessible_attributes: @__accessible_attributes.keys
          }
        end

        private_constant :FetchData, :INVALID_INVOCATION_OF_THE_THE_METHOD
    end
  end
end