Add more generic implementation of inbox filtering

app/controllers/inbox_controller.rb

@@ -4,16 +4,8 @@ class InboxController < ApplicationController
   before_action :authenticate_user!
 
   def show
-    find_author
     find_inbox_entries
 
-    if @author_user && @inbox_count.zero?
-      # rubocop disabled because of a false positive
-      flash[:info] = t(".author.info", author: @author) # rubocop:disable Rails/ActionControllerFlashBeforeRender
-      redirect_to inbox_path(last_id: params[:last_id])
-      return
-    end
-
     @delete_id = find_delete_id
     @disabled = true if @inbox.empty?
 
@@ -47,36 +39,24 @@ class InboxController < ApplicationController
 
   private
 
-  def find_author
-    return if params[:author].blank?
-
-    @author = params[:author]
-
-    @author_user = User.where("LOWER(screen_name) = ?", @author.downcase).first
-    flash.now[:error] = t(".author.error", author: @author) unless @author_user
+  def filter_params
+    params.slice(*InboxFilter::KEYS).permit(*InboxFilter::KEYS)
   end
 
   def find_inbox_entries
-    @inbox = current_user.cursored_inbox(last_id: params[:last_id]).then(&method(:filter_author_chain))
+    filter = InboxFilter.new(current_user, filter_params)
+    @inbox = filter.cursored_results(last_id: params[:last_id])
     @inbox_last_id = @inbox.map(&:id).min
-    @more_data_available = current_user.cursored_inbox(last_id: @inbox_last_id, size: 1).then(&method(:filter_author_chain)).count.positive?
-    @inbox_count = current_user.inboxes.then(&method(:filter_author_chain)).count
+    @more_data_available = filter.cursored_results(last_id: @inbox_last_id, size: 1).count.positive?
+    @inbox_count = filter.results.count
   end
 
   def find_delete_id
-    return "ib-delete-all-author" if @author_user && @inbox_count.positive?
+    return "ib-delete-all-author" if params[:author].present? && @inbox_count.positive?
 
     "ib-delete-all"
   end
 
-  def filter_author_chain(query)
-    return query unless @author_user
-
-    query
-      .joins(:question)
-      .where(questions: { user: @author_user, author_is_anonymous: false })
-  end
-
   # rubocop:disable Rails/SkipsModelValidations
   def mark_inbox_entries_as_read
     # using .dup to not modify @inbox -- useful in tests

app/models/inbox_filter.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+class InboxFilter
+  include CursorPaginatable
+
+  define_cursor_paginator :cursored_results, :results
+
+  KEYS = %i(
+    author
+    anonymous
+  ).freeze
+
+  attr_reader :params, :user
+
+  def initialize(user, params)
+    @user = user
+    @params = params
+  end
+
+  def results
+    scope = @user.inboxes
+                 .includes(:question, user: :profile)
+                 .order(:created_at)
+                 .reverse_order
+
+    params.each do |key, value|
+      scope.merge!(scope_for(key, value)) if value.present?
+    end
+
+    scope
+  end
+
+  private
+
+  def scope_for(key, value)
+    case key.to_s
+    when "author"
+      @user.inboxes.joins(question: [:user])
+                   .where(questions: { users: { screen_name: value }, author_is_anonymous: false })
+    when "anonymous"
+      @user.inboxes.joins(:question)
+                   .where(questions: { author_is_anonymous: true })
+    end
+  end
+end

spec/controllers/inbox_controller_spec.rb

@@ -144,39 +144,10 @@ describe InboxController, type: :controller do
 
         subject { get :show, params: { author: author_param } }
 
-        context "with a nonexisting screen name" do
-          let(:author_param) { "xXx420MegaGamer2003xXx" }
-
-          it "sets the error flash" do
-            subject
-            expect(flash[:error]).to eq "No user with the name @xXx420MegaGamer2003xXx found, showing entries from all users instead!"
-          end
-
-          include_examples "sets the expected ivars" do
-            let(:expected_assigns) do
-              {
-                inbox:               [generic_inbox_entry2, generic_inbox_entry1],
-                inbox_last_id:       generic_inbox_entry1.id,
-                more_data_available: false,
-                inbox_count:         2,
-                delete_id:           "ib-delete-all",
-                disabled:            nil
-              }
-            end
-          end
-        end
-
         context "with an existing screen name" do
           let(:author_param) { other_user.screen_name }
 
           context "with no questions from the other user in the inbox" do
-            it { is_expected.to redirect_to inbox_path }
-
-            it "sets the info flash" do
-              subject
-              expect(flash[:info]).to eq "No questions from @#{other_user.screen_name} found, showing entries from all users instead!"
-            end
-
             include_examples "sets the expected ivars" do
               # these are the ivars set before the redirect happened
               let(:expected_assigns) do
@@ -202,13 +173,6 @@ describe InboxController, type: :controller do
               )
             end
 
-            it { is_expected.to redirect_to inbox_path }
-
-            it "sets the info flash" do
-              subject
-              expect(flash[:info]).to eq "No questions from @#{other_user.screen_name} found, showing entries from all users instead!"
-            end
-
             include_examples "sets the expected ivars" do
               # these are the ivars set before the redirect happened
               let(:expected_assigns) do
@@ -259,6 +223,37 @@ describe InboxController, type: :controller do
           end
         end
       end
+
+      context "when passed the anonymous param" do
+        let!(:other_user) { FactoryBot.create(:user) }
+        let!(:generic_inbox_entry) do
+          Inbox.create(
+            user:,
+            question: FactoryBot.create(
+              :question,
+              user:                other_user,
+              author_is_anonymous: false
+            )
+          )
+        end
+
+        let!(:inbox_entry_fillers) do
+          # 9 times => 1 entry less than default page size
+          9.times.map { Inbox.create(user:, question: FactoryBot.create(:question, author_is_anonymous: true)) }
+        end
+
+        subject { get :show, params: { anonymous: true } }
+
+        include_examples "sets the expected ivars" do
+          let(:expected_assigns) do
+            {
+              inbox:               [*inbox_entry_fillers.reverse],
+              more_data_available: false,
+              inbox_count:         9
+            }
+          end
+        end
+      end
     end
   end