Use Neopets username as base name for new NeoPass accounts, if possible

Yay, we got the API endpoint for this! The `linkage` scope is the key.

Rather than pulling back the specific fallback behavior we had wrote
for usernames before, which was slightly different and involved
appending `neopass` in there too (e.g. `matchu-neopass-1234`), I
figured let's just use a lot of the same logic, and just use the
preferred name as the base name. (I figure the `neopass` suffix isn't
that useful anyway, `matchu-1234` kinda looks better tbh! And it's all
fallback stuff that I expect serious users to replace, anyway.)

app/controllers/neopass_connections_controller.rb

@@ -1,4 +1,4 @@
-class NeopassConnectionsController < ApplicationController
+class NeoPassConnectionsController < ApplicationController
 	def destroy
 		@user = load_user
 

app/models/auth_user.rb

@@ -156,9 +156,26 @@ class AuthUser < AuthRecord
       find_or_create_by!(provider: auth.provider, uid: auth.uid) do |user|
         # This account is new! Let's do the initial setup.
 
-        # TODO: Can we somehow get the Neopets username if one exists, instead
-        # of just using total randomness?
-        user.name = build_unique_username
+        # First, get the user's Neopets username if possible, as a base for the
+        # name we create for them. (This is an async task under the hood, which
+        # means we can wrap it in a `with_timeout` block!)
+        neopets_username = Sync do |task|
+          task.with_timeout(5) do
+            NeoPass.load_main_neopets_username(auth.credentials.token)
+          end
+        rescue Async::TimeoutError
+          nil # If the request times out, just move on!
+        rescue => error
+          # If the request fails, log it and move on. (Could be a service
+          # outage, or a change on NeoPass's end that we're not in sync with.)
+          Rails.logger.error error
+          Sentry.capture_exception error
+          nil
+        end
+
+        # Generate a unique username for this user, based on their Neopets
+        # username, if they have one.
+        user.name = build_unique_username(neopets_username)
 
         # Copy the email address from their Neopets account to their DTI
         # account, unless they already have a DTI account with this email, in
@@ -183,17 +200,28 @@ class AuthUser < AuthRecord
     end
   end
 
-  def self.build_unique_username
-    # Start with a base name like "neopass-kougra-".
-    random_species_name = Species.all.pluck(:name).sample
-    base_name = "neopass-#{random_species_name}"
+  def self.build_unique_username(preferred_name = nil)
+    # If there's no preferred name provided (ideally the user's Neopets
+    # username), start with a base name like `neopass-kougra`.
+    if preferred_name.present?
+      base_name = preferred_name
+    else
+      random_species_name = Species.all.pluck(:name).sample
+      base_name = "neopass-#{random_species_name}"
+    end
 
     # Fetch the list of names that already start with that.
     name_query = sanitize_sql_like(base_name) + "%"
     similar_names = where("name LIKE ?", name_query).pluck(:name).to_set
 
-    # Shuffle the list of four-digit numbers to create 10000 possible names,
-    # then use the first one that's not already claimed.
+    # If this was the user's preferred name (rather than a random one), try
+    # using the preferred name itself, if not already taken.
+    if preferred_name.present? && !similar_names.include?(preferred_name)
+      return preferred_name
+    end
+
+    # Otherwise, shuffle the list of four-digit numbers to create 10000
+    # possible names, then use the first one that's not already claimed.
     potential_names = (0..9999).map { |n| "#{base_name}-#{n}" }.shuffle
     name = potential_names.find { |name| !similar_names.include?(name) }
     return name unless name.nil?

app/services/neopass.rb

@@ -0,0 +1,73 @@
+require "async/http/internet/instance"
+
+# While most of our NeoPass logic is built into Devise -> OmniAuth -> OIDC
+# OmniAuth plugin, NeoPass also offers some supplemental APIs that we use here.
+module NeoPass
+	# Share a pool of persistent connections, rather than reconnecting on
+	# each request. (This library does that automatically!)
+	INTERNET = Async::HTTP::Internet.instance
+
+	def self.load_main_neopets_username(access_token)
+		linkages = load_linkages(access_token)
+
+		begin
+			# Get the Neopets.com linkages, sorted with your "main" account to the
+			# front. (In theory, if there are any Neopets.com linkages, then one
+			# should be main—but let's be resilient and be prepared for none of them
+			# to be marked as such!)
+			neopets_linkages = linkages.
+				select { |l| l.fetch("client_name") == "Neopets.com" }.
+				sort_by { |l| l.fetch("extra", {}).fetch("main") == true ? 0 : 1 }
+
+			# Read the username from that linkage, if any.
+			neopets_linkages.first.try { |l| l.fetch("user_identifier") }
+		rescue KeyError => error
+			raise UnexpectedResponseFormat,
+				"missing field #{error.key} in NeoPass linkage response"
+		end
+	end
+
+	private
+
+	LINKAGE_URL = "https://oidc.neopets.com/linkage/all"
+	def self.load_linkages(access_token)
+		response = Sync do
+			response = INTERNET.get(LINKAGE_URL, [
+				["User-Agent", Rails.configuration.user_agent_for_neopets],
+				["Authorization", "Bearer #{access_token}"],
+			])
+		end
+
+		if response.status != 200
+			raise ResponseNotOK.new(response.status),
+				"expected status 200 but got #{response.status} (#{LINKAGE_URL})"
+		end
+
+		linkages_str = response.body.read
+
+		begin
+			linkages = JSON.parse(linkages_str)
+		rescue JSON::ParserError
+			Rails.logger.debug "Unexpected NeoPass linkage response:\n#{linkages_str}"
+			raise UnexpectedResponseFormat,
+				"failed to parse NeoPass linkage response as JSON"
+		end
+
+		if !linkages.is_a? Array
+			Rails.logger.debug "Unexpected NeoPass linkage response:\n#{linkages_str}"
+			raise UnexpectedResponseFormat,
+				"NeoPass linkage response was not an array of linkages"
+		end
+
+		linkages
+	end
+
+	class ResponseNotOK < StandardError
+		attr_reader :status
+		def initialize(status)
+			super
+			@status = status
+		end
+	end
+	class UnexpectedResponseFormat < StandardError;end
+end

config/initializers/devise.rb

@@ -278,7 +278,7 @@ Devise.setup do |config|
 
     # We'll request only basic info, and we'll "discover" most of the server's
     # configuration by reading its `/.well-known/openid_configuation` endpoint.
-    scope: [:openid, :email],
+    scope: [:openid, :email, :linkage],
     response_type: :code,
     issuer: Rails.configuration.neopass_origin,
     discovery: true,

config/initializers/inflections.rb

@@ -18,4 +18,7 @@
 ActiveSupport::Inflector.inflections(:en) do |inflect|
   # Teach Zeitwerk that `RocketAMF` is what to expect in `lib/rocketamf`.
   inflect.acronym "RocketAMF"
+
+  # Teach Zeitwerk that `NeoPass` is what to expect in `app/services/neopass.rb`.
+  inflect.acronym "NeoPass"
 end