module RSpec
  module Matchers
    module BuiltIn
      # @api private
      # Provides the implementation for `include`.
      # Not intended to be instantiated directly.
      class Include < BaseMatcher
        def initialize(*expected)
          @expected = expected
        end

        # @api private
        # @return [Boolean]
        def matches?(actual)
          @actual = actual
          perform_match(:all?, :all?)
        end

        # @api private
        # @return [Boolean]
        def does_not_match?(actual)
          @actual = actual
          perform_match(:none?, :any?)
        end

        # @api private
        # @return [String]
        def description
          described_items = surface_descriptions_in(expected)
          improve_hash_formatting "include#{to_sentence(described_items)}"
        end

        # @api private
        # @return [String]
        def failure_message
          improve_hash_formatting(super) + invalid_object_message
        end

        # @api private
        # @return [String]
        def failure_message_when_negated
          improve_hash_formatting(super) + invalid_object_message
        end

        # @api private
        # @return [Boolean]
        def diffable?
          true
        end

      private

        def invalid_object_message
          return '' if actual.respond_to?(:include?)
          ", but it does not respond to `include?`"
        end

        def perform_match(predicate, hash_subset_predicate)
          return false unless actual.respond_to?(:include?)

          expected.__send__(predicate) do |expected_item|
            if comparing_hash_to_a_subset?(expected_item)
              expected_item.__send__(hash_subset_predicate) do |(key, value)|
                actual_hash_includes?(key, value)
              end
            elsif comparing_hash_keys?(expected_item)
              actual_hash_has_key?(expected_item)
            else
              actual_collection_includes?(expected_item)
            end
          end
        end

        def comparing_hash_to_a_subset?(expected_item)
          actual.is_a?(Hash) && expected_item.is_a?(Hash)
        end

        def actual_hash_includes?(expected_key, expected_value)
          actual_value = actual.fetch(expected_key) { return false }
          values_match?(expected_value, actual_value)
        end

        def comparing_hash_keys?(expected_item)
          actual.is_a?(Hash) && !expected_item.is_a?(Hash)
        end

        def actual_hash_has_key?(expected_key)
          # We check `key?` first for perf:
          # `key?` is O(1), but `any?` is O(N).
          actual.key?(expected_key) ||
          actual.keys.any? { |key| values_match?(expected_key, key) }
        end

        def actual_collection_includes?(expected_item)
          return true if actual.include?(expected_item)

          # String lacks an `any?` method...
          return false unless actual.respond_to?(:any?)

          actual.any? { |value| values_match?(expected_item, value) }
        end
      end
    end
  end
end