FIX: Automatically generate category channel slugs (#18879)

This commit automatically ensures that category channels
have slugs when they are created or updated based on the
channel name, category name, or existing slug. The behaviour
has been copied from the Category model.

We also include a backfill here with a simplified version
of Slug.for with deduplication to fill the slugs for already
created Category chat channels.

The channel slug is also now used for chat notifications,
and for the UI and navigation for chat. `slugifyChannel`
is still used, but now does the following fallback:

* Uses channel.slug if it is present
* Uses channel.escapedTitle if it is present
* Uses channel.title if it is present

In future we may want to remove this altogether
and always rely on the slug being present, but this
is currently not possible because we are not generating
slugs for DM channels at this point.

plugins/chat/app/controllers/chat_controller.rb

@@ -352,6 +352,7 @@ class Chat::ChatController < Chat::ChatBaseController
           message: "chat.invitation_notification",
           chat_channel_id: @chat_channel.id,
           chat_channel_title: @chat_channel.title(user),
+          chat_channel_slug: @chat_channel.slug,
           invited_by_username: current_user.username,
         }
         data[:chat_message_id] = params[:chat_message_id] if params[:chat_message_id]

plugins/chat/app/jobs/regular/chat_notify_mentioned.rb

@@ -39,9 +39,10 @@ module Jobs
         is_direct_message_channel: @chat_channel.direct_message_channel?,
       }
 
-      data[:chat_channel_title] = @chat_channel.title(
-        membership.user,
-      ) unless @is_direct_message_channel
+      if !@is_direct_message_channel
+        data[:chat_channel_title] = @chat_channel.title(membership.user)
+        data[:chat_channel_slug] = @chat_channel.slug
+      end
 
       return data if identifier_type == :direct_mentions
 
@@ -64,8 +65,7 @@ module Jobs
         username: @creator.username,
         tag: Chat::ChatNotifier.push_notification_tag(:mention, @chat_channel.id),
         excerpt: @chat_message.push_notification_excerpt,
-        post_url:
-          "/chat/channel/#{@chat_channel.id}/#{@chat_channel.title(membership.user)}?messageId=#{@chat_message.id}",
+        post_url: "#{@chat_channel.relative_url}?messageId=#{@chat_message.id}",
       }
 
       translation_prefix =

plugins/chat/app/jobs/regular/chat_notify_watching.rb

@@ -62,7 +62,7 @@ module Jobs
       payload = {
         username: @creator.username,
         notification_type: Notification.types[:chat_message],
-        post_url: "/chat/channel/#{@chat_channel.id}/#{@chat_channel.title(user)}",
+        post_url: @chat_channel.relative_url,
         translated_title: I18n.t(translation_key, translation_args),
         tag: Chat::ChatNotifier.push_notification_tag(:message, @chat_channel.id),
         excerpt: @chat_message.push_notification_excerpt,

plugins/chat/app/models/category_channel.rb

@@ -21,7 +21,23 @@ class CategoryChannel < ChatChannel
     name.presence || category.name
   end
 
-  def slug
-    title.truncate(100).parameterize
+  def generate_auto_slug
+    return if self.slug.present?
+    self.slug = Slug.for(self.title.strip, "")
+    self.slug = "" if duplicate_slug?
+  end
+
+  def ensure_slug_ok
+    # if we don't unescape it first we strip the % from the encoded version
+    slug = SiteSetting.slug_generation_method == "encoded" ? CGI.unescape(self.slug) : self.slug
+    self.slug = Slug.for(slug, "", method: :encoded)
+
+    if self.slug.blank?
+      errors.add(:slug, :invalid)
+    elsif SiteSetting.slug_generation_method == "ascii" && !CGI.unescape(self.slug).ascii_only?
+      errors.add(:slug, I18n.t("chat.category_channel.errors.slug_contains_non_ascii_chars"))
+    elsif duplicate_slug?
+      errors.add(:slug, I18n.t("chat.category_channel.errors.is_already_in_use"))
+    end
   end
 end

plugins/chat/app/models/chat_channel.rb

@@ -21,6 +21,8 @@ class ChatChannel < ActiveRecord::Base
             },
             presence: true,
             allow_nil: true
+  validate :ensure_slug_ok
+  before_validation :generate_auto_slug
 
   scope :public_channels,
         -> {
@@ -74,7 +76,11 @@ class ChatChannel < ActiveRecord::Base
   end
 
   def url
-    "#{Discourse.base_url}/chat/channel/#{self.id}/-"
+    "#{Discourse.base_url}#{relative_url}"
+  end
+
+  def relative_url
+    "/chat/channel/#{self.id}/#{self.slug || "-"}"
   end
 
   def public_channel_title
@@ -109,6 +115,10 @@ class ChatChannel < ActiveRecord::Base
 
     ChatPublisher.publish_channel_status(self)
   end
+
+  def duplicate_slug?
+    ChatChannel.where(slug: self.slug).where.not(id: self.id).any?
+  end
 end
 
 # == Schema Information
@@ -132,6 +142,7 @@ end
 #  auto_join_users         :boolean          default(FALSE), not null
 #  user_count_stale        :boolean          default(FALSE), not null
 #  slug                    :string
+#  type                    :string
 #
 # Indexes
 #

plugins/chat/app/models/direct_message_channel.rb

@@ -18,4 +18,12 @@ class DirectMessageChannel < ChatChannel
   def title(user)
     direct_message.chat_channel_title_for_user(self, user)
   end
+
+  def ensure_slug_ok
+    true
+  end
+
+  def generate_auto_slug
+    self.slug = nil
+  end
 end

plugins/chat/app/serializers/chat_channel_serializer.rb

@@ -9,6 +9,7 @@ class ChatChannelSerializer < ApplicationSerializer
              :chatable_url,
              :description,
              :title,
+             :slug,
              :last_message_sent_at,
              :status,
              :archive_failed,