th: add invite limits behind TH_USE_INVITE_QUOTA

TH_USE_INVITE_QUOTA: feature flag
TH_INVITE_MAX_USES: max uses per invite for non-moderators
TH_ACTIVE_INVITE_SLOT_QUOTA: max slots in active invites, including consumed slots

.env.development

@@ -5,3 +5,5 @@ DB_HOST=$(pwd)/data/postgres
 DB_USER=mastodon
 DB_NAME=mastodon_dev
 REDIS_URL=unix://./data/redis/redis-dev.sock
+
+TH_USE_INVITE_QUOTA=1

app/controllers/invites_controller.rb

@@ -15,6 +15,8 @@ class InvitesController < ApplicationController
 
     @invites = invites
     @invite  = Invite.new
+    @invite.max_uses ||= 1
+    @invite.expires_in ||= 1.day.in_seconds
   end
 
   def create

app/models/invite.rb

@@ -19,6 +19,11 @@
 class Invite < ApplicationRecord
   include Expireable
 
+  # FIXME: make this a rails cfg key or whatev?
+  TH_USE_INVITE_QUOTA = !!ENV['TH_USE_INVITE_QUOTA']
+  TH_INVITE_MAX_USES = ENV.fetch('TH_INVITE_MAX_USES', 25)
+  TH_ACTIVE_INVITE_SLOT_QUOTA = ENV.fetch('TH_ACTIVE_INVITE_SLOT_QUOTA', 40)
+
   belongs_to :user, inverse_of: :invites
   has_many :users, inverse_of: :invite
 
@@ -26,6 +31,15 @@ class Invite < ApplicationRecord
 
   validates :comment, length: { maximum: 420 }
 
+  with_options if: :th_use_invite_quota?, unless: :created_by_moderator? do |invite|
+    invite.validates :expires_at, presence: true
+    invite.validate :expires_in_at_most_one_week?
+    invite.validates :max_uses, presence: true
+    # In Rails 6.1, numericality doesn't support :in
+    invite.validates :max_uses, numericality: { only_integer: true, greater_than: 0, less_than_or_equal_to: TH_INVITE_MAX_USES }
+    invite.validate :reasonable_outstanding_invite_count?
+  end
+
   before_validation :set_code
 
   def valid_for_use?
@@ -40,4 +54,31 @@ class Invite < ApplicationRecord
       break if Invite.find_by(code: code).nil?
     end
   end
+
+  def created_by_moderator?
+    self.user.moderator
+  end
+
+  def th_use_invite_quota?
+    TH_USE_INVITE_QUOTA
+  end
+
+  def expires_in_at_most_one_week?
+    return if self.expires_in.to_i.seconds <= 1.week
+    # FIXME: Localize this
+    errors.add(:expires_in, 'must expire within one week')
+  end
+
+  def reasonable_outstanding_invite_count?
+    valid_invites = self.user.invites.filter { |i| i.valid_for_use? }
+    count = valid_invites.sum do |i|
+      next i.max_uses unless i.max_uses.nil?
+
+      errors.add(:max_uses, 'must not have any active unlimited-use invites')
+      return
+    end
+
+    return if count + max_uses <= TH_ACTIVE_INVITE_SLOT_QUOTA
+    errors.add(:max_uses, "must not exceed active invite slot quota of #{TH_ACTIVE_INVITE_SLOT_QUOTA}")
+  end
 end

app/views/invites/_form.html.haml

@@ -3,9 +3,9 @@
 
   .fields-row
     .fields-row__column.fields-row__column-6.fields-group
-      = f.input :max_uses, wrapper: :with_label, collection: [1, 5, 10, 25, 50, 100], label_method: lambda { |num| I18n.t('invites.max_uses', count: num) }, prompt: I18n.t('invites.max_uses_prompt')
+      = f.input :max_uses, wrapper: :with_label, collection: [1, 5, 10, 25], label_method: lambda { |num| I18n.t('invites.max_uses', count: num) }, prompt: I18n.t('invites.max_uses_prompt'), include_blank: false, include_hidden: false # required: true
     .fields-row__column.fields-row__column-6.fields-group
-      = f.input :expires_in, wrapper: :with_label, collection: [30.minutes, 1.hour, 6.hours, 12.hours, 1.day, 1.week].map(&:to_i), label_method: lambda { |i| I18n.t("invites.expires_in.#{i}") }, prompt: I18n.t('invites.expires_in_prompt')
+      = f.input :expires_in, wrapper: :with_label, collection: [30.minutes, 1.hour, 6.hours, 12.hours, 1.day, 1.week, 1.month].map(&:to_i), label_method: lambda { |i| I18n.t("invites.expires_in.#{i}") }, prompt: I18n.t('invites.expires_in_prompt'), include_blank: false, include_hidden: false, selected: 1 # required: true
 
   .fields-group
     = f.input :autofollow, wrapper: :with_label

spec/controllers/invites_controller_spec.rb

@@ -56,6 +56,50 @@ describe InvitesController do
         expect(subject).to redirect_to invites_path
         expect(Invite.last).to have_attributes(user_id: user.id, max_uses: 10)
       end
+
+      # context 'when th_invite_limits_active?' do
+      #   let(:max_uses) { 25 }
+      #   let(:expires_in) { 86400 }
+
+      #   subject { post :create, params: { invite: { max_uses: "#{max_uses}", expires_in: expires_in } } }
+
+      #   before do
+      #     # expect_any_instance_of(Invite).to receive(:th_invite_limits_active?).and_return true
+      #     allow_any_instance_of(Invite).to receive(:th_invite_limits_active?).and_return true
+      #     # expect_any_instance_of(Invite).to receive(:created_by_moderator?).and_return false
+      #     allow_any_instance_of(Invite).to receive(:created_by_moderator?).and_return false
+      #   end
+
+      #   it do
+      #     expect(user.moderator).to be_falsy
+      #   end
+
+      #   shared_examples 'fails to create an invite' do
+      #     it 'fails to create an invite' do
+      #       expect { subject }.not_to change { Invite.count }
+      #     end
+      #   end
+
+      #   it 'succeeds to create a invite' do
+      #     expect { subject }.to change { Invite.count }.by(1)
+      #     expect(subject).to redirect_to invites_path
+      #     expect(Invite.last).to have_attributes(user_id: user.id, max_uses: max_uses)
+      #   end
+
+      #   context 'when the request is over the limits' do
+      #     context do
+      #       let(:max_uses) { 26 }
+
+      #       include_examples 'fails to create an invite'
+      #     end
+
+      #     context do
+      #       let(:expires_in) { 86401 }
+
+      #       include_examples 'fails to create an invite'
+      #     end
+      #   end
+      # end
     end
 
     context 'when not everyone can invite' do

spec/models/invite_spec.rb

@@ -35,4 +35,67 @@ RSpec.describe Invite do
       expect(invite.valid_for_use?).to be false
     end
   end
+
+  context 'when th_use_invite_quota?' do
+    let(:max_uses) { 25 }
+    let(:expires_in) { 1.week.in_seconds }
+    let(:regular_user) { Fabricate(:user) }
+    let(:moderator_user) { Fabricate(:user, moderator: true) }
+    let(:user) { regular_user }
+    let(:created_at) { Time.at(0) }
+    let(:expires_at) { Time.at(0) + expires_in }
+
+    subject { Fabricate.build(:invite, user: user, max_uses: max_uses, created_at: created_at, expires_at: expires_at ) }
+
+    before do
+      stub_const('Invite::TH_USE_INVITE_QUOTA', true)
+      stub_const('Invite::TH_INVITE_MAX_USES', 25)
+      stub_const('Invite::TH_ACTIVE_INVITE_SLOT_QUOTA', 30)
+    end
+
+    it { is_expected.to be_valid }
+
+    context 'and' do
+      context 'max_uses exceeds quota' do
+        let(:max_uses) { 26 }
+
+        it { is_expected.not_to be_valid }
+      end
+
+      context 'expires_in exceeds quota' do
+        let(:expires_in) { 1.week.in_seconds + 1 }
+
+        it { is_expected.not_to be_valid }
+      end
+
+      context 'multiple values exceed quota' do
+        let(:max_uses) { 26 }
+        let(:expires_in) { 86401 }
+
+        it { is_expected.not_to be_valid }
+      end
+
+      context 'an unlimited use invite' do
+        before do
+          Fabricate.build(:invite, user: user).save(validate: false)
+        end
+
+        it { is_expected.not_to be_valid }
+      end
+
+      context 'too many outstanding invites' do
+        before do
+          Fabricate.build(:invite, user: user, max_uses: 6).save(validate: false)
+        end
+
+        it { is_expected.not_to be_valid }
+      end
+
+      context 'a moderator created the invite' do
+        let(:user) { moderator_user }
+
+        it { is_expected.to be_valid }
+      end
+    end
+  end
 end