serradura/u-case

# frozen_string_literal: true

module Micro
  module Cases
    class Flow
      IsAUseCaseWithDefaults = -> arg { arg.is_a?(Array) && Micro.case?(arg[0]) && arg[1].is_a?(Hash) }
      IsAValidUseCase = -> use_case { Micro.case?(use_case) || IsAUseCaseWithDefaults[use_case] }

      attr_reader :use_cases

      def self.build(args)
        use_cases = Utils.map_use_cases(args)

        raise Error::InvalidUseCases if use_cases.none?(&IsAValidUseCase)

        new(use_cases)
      end

      def initialize(use_cases)
        @use_cases = use_cases.dup.freeze
        @next_ones = use_cases.dup
        @first = @next_ones.shift
      end

      def inspect
        '#<(%s) use_cases=%s>' % [self.class, @use_cases]
      end

      def call!(input:, result:)
        first_result = __call_use_case(@first, result, input)

        return first_result if @next_ones.empty?

        __call_next_use_cases(first_result)
      end

      def call(input = Kind::Empty::HASH)
        result = call!(input: input, result: Case::Result.new)

        return result unless block_given?

        result_wrapper = ::Micro::Case::Result::Wrapper.new(result)

        yield(result_wrapper)

        result_wrapper.output
      end

      alias __call__ call

      def to_proc
        Proc.new { |arg| call(arg) }
      end

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

        if block
          raise_invalid_invocation_of_the_then_method if use_case
          raise NotImplementedError if !can_yield_self

          yield_self(&block)
        else
          return yield_self if !use_case && can_yield_self

          raise_invalid_invocation_of_the_then_method unless ::Micro.case_or_flow?(use_case)

          self.call.then(use_case)
        end
      end

      private

        def raise_invalid_invocation_of_the_then_method
          raise Case::Error::InvalidInvocationOfTheThenMethod.new("#{self.class.name}#")
        end

        def __call_use_case(use_case, result, input)
          __build_use_case(use_case, result, input).__call__
        end

        def __call_next_use_cases(first_result)
          @next_ones.reduce(first_result) do |result, use_case|
            break result if result.failure?

            __call_use_case(use_case, result, result.data)
          end
        end

        def __build_use_case(use_case, result, input)
          return use_case.__new__(result, input) unless use_case.is_a?(Array)

          use_case[0].__new__(result, input.merge(use_case[1]))
        end
    end
  end
end