FIX: Allow to add the same watched word with a different case (#17799)

Currently we can’t add a case-sensitive watched word if another one
exists with a different case. For example, the existing watched word
`Meta` has been created and is case-sensitive. Now an admin tries to add
`metA` while marking it as case-sensitive too, this won’t work and the
word won’t be added.

This patch changes this behavior by allowing to add same words that have
different cases, so the example above will now work as expected.

We still check for uniqueness but case-sensitivy is now taken
into account. It means that if the watched word `meta` already exists
and is not case-sensitive then it will not be possible to add `Meta`
(case-sensitive or not) as `meta` already matches every possible
variations of this word.

app/assets/javascripts/admin/addon/components/watched-word-form.js

@@ -47,9 +47,12 @@ export default Component.extend({
     const filtered = words.filter(
       (content) => content.action === this.actionKey
     );
-    return filtered.every(
-      (content) => content.word.toLowerCase() !== word.toLowerCase()
-    );
+    return filtered.every((content) => {
+      if (content.case_sensitive === true) {
+        return content.word !== word;
+      }
+      return content.word.toLowerCase() !== word.toLowerCase();
+    });
   },
 
   actions: {

app/assets/javascripts/discourse/tests/acceptance/admin-watched-words-test.js

@@ -86,6 +86,14 @@ acceptance("Admin - Watched Words", function (needs) {
     assert
       .dom(".watched-words-list .watched-word")
       .hasText(`Discourse ${I18n.t("admin.watched_words.case_sensitive")}`);
+
+    fillIn(".watched-word-form input", "discourse");
+    click(".case-sensitivity-checkbox");
+    await click(".watched-word-form button");
+
+    assert
+      .dom(".watched-words-list .watched-word")
+      .hasText(`discourse ${I18n.t("admin.watched_words.case_sensitive")}`);
   });
 
   test("remove words", async function (assert) {

app/models/watched_word.rb

@@ -40,6 +40,9 @@ class WatchedWord < ActiveRecord::Base
   after_destroy :clear_cache
 
   scope :by_action, -> { order("action ASC, word ASC") }
+  scope :for, ->(word:) do
+    where("(word ILIKE :word AND case_sensitive = 'f') OR (word LIKE :word AND case_sensitive = 't')", word: word)
+  end
 
   def self.normalize_word(w)
     w.strip.squeeze('*')
@@ -61,7 +64,7 @@ class WatchedWord < ActiveRecord::Base
 
   def self.create_or_update_word(params)
     new_word = normalize_word(params[:word])
-    w = WatchedWord.where("word ILIKE ?", new_word).first || WatchedWord.new(word: new_word)
+    w = self.for(word: new_word).first_or_initialize(word: new_word)
     w.replacement = params[:replacement] if params[:replacement]
     w.action_key = params[:action_key] if params[:action_key]
     w.action = params[:action] if params[:action]

spec/models/watched_word_spec.rb

@@ -125,5 +125,36 @@ RSpec.describe WatchedWord do
       expect(updated.case_sensitive?).to eq(false)
     end
 
+    context "when a case-sensitive word already exists" do
+      subject(:create_or_update) do
+        described_class.create_or_update_word(word: word, action_key: :block, case_sensitive: true)
+      end
+
+      fab!(:existing_word) { Fabricate(:watched_word, case_sensitive: true, word: "Meta") }
+
+      context "when providing the exact same word" do
+        let(:word) { existing_word.word }
+
+        it "doesn't create a new watched word" do
+          expect { create_or_update }.not_to change { described_class.count }
+        end
+
+        it "returns the existing watched word" do
+          expect(create_or_update).to eq(existing_word)
+        end
+      end
+
+      context "when providing the same word with a different case" do
+        let(:word) { "metA" }
+
+        it "creates a new watched word" do
+          expect(create_or_update).not_to eq(existing_word)
+        end
+
+        it "returns the new watched word" do
+          expect(create_or_update).to have_attributes word: "metA", case_sensitive: true, action: 1
+        end
+      end
+    end
   end
 end