# frozen_string_literal: true

RSpec.describe DeclarativePolicy do
  describe '.class_for' do
    context 'when the value is nil' do
      it 'uses the default fallback policy' do
        expect(described_class.class_for(nil)).to eq(DeclarativePolicy::NilPolicy)
      end

      context 'when nil_policy has been configured' do
        let(:custom_nil_policy) { Class.new(DeclarativePolicy::Base) }

        before do
          policy = custom_nil_policy

          described_class.configure do
            nil_policy policy
          end
        end

        it 'uses the custom class' do
          expect(described_class.class_for(nil)).to eq(custom_nil_policy)
        end
      end
    end

    context 'when the value is a symbol' do
      it 'uses the configured class' do
        expect(described_class.class_for(:global)).to eq(GlobalPolicy)
      end

      it 'raises an error if no policy was configured' do
        expect { described_class.class_for(:custom) }.to raise_error('No custom policy configured')
      end

      context 'when a policy has been configured' do
        let(:custom_policy) { Class.new(DeclarativePolicy::Base) }
        let(:my_global_policy) { Class.new(DeclarativePolicy::Base) }

        before do
          custom = custom_policy
          global = my_global_policy

          described_class.configure do
            named_policy :custom, custom
            named_policy :global, global
          end
        end

        it 'returns the configured policy' do
          expect(described_class.class_for(:global)).to eq(my_global_policy)
          expect(described_class.class_for(:custom)).to eq(custom_policy)
        end
      end
    end

    context 'when the policy class is present' do
      before do
        stub_const('Foo', Class.new)
        stub_const('FooPolicy', Class.new(DeclarativePolicy::Base))
      end

      it 'uses declarative_policy_class' do
        instance = Foo.new

        expect(described_class.class_for(instance)).to eq(FooPolicy)
      end
    end

    context 'when there is no policy for the class, but there is one for a superclass' do
      before do
        foo = Class.new
        stub_const('Foo', foo)
        stub_const('Bar', Class.new(foo))
        stub_const('FooPolicy', Class.new(DeclarativePolicy::Base))
      end

      it 'uses declarative_policy_class' do
        instance = Bar.new

        expect(described_class.class_for(instance)).to eq(FooPolicy)
      end
    end

    context 'when name transformation has been configured' do
      before do
        stub_const('Bar', Class.new)
        stub_const('Policies::Bar', Class.new(DeclarativePolicy::Base))

        described_class.configure do
          name_transformation { |name| "Policies::#{name}" }
        end
      end

      it 'uses the configured transformation' do
        expect(described_class.class_for(Bar.new)).to eq(Policies::Bar)
      end
    end

    it 'raises error if not found' do
      instance = Object.new

      expect { described_class.class_for(instance) }.to raise_error('no policy for Object')
    end

    context 'when found policy class does not inherit base' do
      before do
        stub_const('Foo', Class.new)
        stub_const('FooPolicy', Class.new)
      end

      it 'raises error if inferred class does not inherit Base' do
        instance = Foo.new

        expect { described_class.class_for(instance) }.to raise_error('no policy for Foo')
      end
    end
  end

  describe '.policy_for' do
    before do
      stub_const('Human', Class.new { attr_accessor :id })
      stub_const('Bot', Class.new { attr_accessor :id })
      stub_const('Foo', Class.new)
      stub_const('FooPolicy', Class.new(DeclarativePolicy::Base))
    end

    context 'when the policy has been instantiated before' do
      it 'returns the same instance' do
        cache = {}
        user = Human.new
        user.id = 100
        object = Foo.new

        expect(described_class.policy_for(user, object, cache: cache))
          .to equal(described_class.policy_for(user, object, cache: cache))
      end
    end

    context 'when actors have different types, but the same ID' do
      it 'returns different instances' do
        cache = {}
        user = Human.new
        user.id = 100
        bot = Bot.new
        bot.id = 100
        object = Foo.new

        expect(described_class.policy_for(user, object, cache: cache))
          .not_to be(described_class.policy_for(bot, object, cache: cache))
      end
    end
  end

  describe '.invalidate' do
    let(:user) { User.new(name: 'Filbert', driving_license: License[:valid], trusted: ['Finnigan']) }
    let(:other_user) { User.new(name: 'Finnigan') }

    let(:car) do
      country = Country.moderate
      reg = Registration.new(country: country)
      Vehicle.new(owner: user, registration: reg)
    end

    let(:cache) { {} }

    let(:keys) do
      [
        '/dp/condition/ReadmePolicy/has_driving_license/User:Filbert',
        '/dp/condition/ReadmePolicy/has_driving_license/User:Finnigan'
      ]
    end

    def filbert_can_drive
      ReadmePolicy.new(user, car, cache: cache).allowed?(:drive_vehicle)
    end

    def finn_can_drive
      ReadmePolicy.new(other_user, car, cache: cache).allowed?(:drive_vehicle)
    end

    def swap_licenses!
      other_user.driving_license = user.driving_license # invalidates policy
      user.driving_license = nil # invalidates policy
    end

    it 'is possible to invalidate a runner, and clear dirty state' do
      # verifies that we benefit from caching for other conditions
      expect(user).to receive(:trusts?).with(other_user).once.and_call_original

      expect(filbert_can_drive).to be true
      expect(finn_can_drive).to be false

      swap_licenses!

      # state is still stale
      expect(filbert_can_drive).to be true
      expect(finn_can_drive).to be false

      expect { described_class.invalidate(cache, keys.take(1)) }
        .to change { cache.size }.by(-1)

      expect(filbert_can_drive).to be false # state is now good!
      expect(finn_can_drive).to be false # but this is still stale

      expect { described_class.invalidate(cache, keys.drop(1)) }
        .to change { finn_can_drive }.from(false).to(true)
    end

    it 'can invalidate several keys at once' do
      expect do
        swap_licenses!
        described_class.invalidate(cache, keys)
      end
        .to change { filbert_can_drive }.from(true).to(false)
        .and change { finn_can_drive }.from(false).to(true)
    end
  end
end