Determine device names with device_detector

Replace the hand-rolled user-agent regexes with the device_detector gem.
Its UA database recognises many more clients (and, e.g., GNOME Web when
its UA carries the Epiphany token). WebKit "Safari" user agents on Linux
(WebKitGTK, which GNOME Web sends) are labelled "WebKit on Linux", since
Safari never runs on Linux.

Part of #254

Gemfile

@@ -43,6 +43,7 @@ gem 'flipper-ui'
 gem 'gpgme', '~> 2.0.24'
 gem 'zbase32', '~> 0.1.1'
 gem 'kramdown'
+gem 'device_detector'
 
 # HTTP requests
 gem 'faraday'

Gemfile.lock

@@ -136,6 +136,7 @@ GEM
       database_cleaner-core (~> 2.0.0)
     database_cleaner-core (2.0.1)
     date (3.5.1)
+    device_detector (1.1.3)
     devise (5.0.4)
       bcrypt (~> 3.0)
       orm_adapter (~> 0.1)
@@ -543,6 +544,7 @@ DEPENDENCIES
   capybara
   cssbundling-rails
   database_cleaner
+  device_detector
   devise (~> 5.0)
   devise_ldap_authenticatable
   discourse_api

app/models/remote_storage_authorization.rb

@@ -47,25 +47,17 @@ class RemoteStorageAuthorization < ApplicationRecord
   def device_name
     return nil if user_agent.blank?
 
-    browser =
-      case user_agent
-      when /Firefox/ then "Firefox"
-      when /Edg\// then "Edge"
-      when /Chrome/ then "Chrome"
-      when /Safari/ then "Safari"
-      else "Unknown browser"
-      end
+    client = DeviceDetector.new(user_agent)
+    name = client.name.presence
+    os = client.os_name.presence
+    os = "Linux" if os == "GNU/Linux"
+    os = "macOS" if os == "Mac"
 
-    os =
-      case user_agent
-      when /Android/ then "Android"
-      when /iPhone|iPad|iPod/ then "iOS"
-      when /Mac OS X/ then "macOS"
-      when /Windows/ then "Windows"
-      when /Linux/ then "Linux"
-      end
+    # Safari never runs on Linux. A WebKit "Safari" user agent on Linux is a
+    # WebKitGTK browser (e.g. GNOME Web), which sends a Safari-compatible UA.
+    name = "WebKit" if name == "Safari" && os == "Linux"
 
-    os ? "#{browser} on #{os}" : browser
+    [name, os].compact.join(" on ").presence
   end
 
   def delete_token_from_redis

spec/models/remote_storage_authorization_spec.rb

@@ -344,10 +344,28 @@ RSpec.describe RemoteStorageAuthorization, type: :model do
       expect(auth_with_user_agent(ua).device_name).to eq("Chrome on macOS")
     end
 
-    it "recognizes Safari on iOS" do
+    it "recognizes Mobile Safari on iOS" do
       ua = "Mozilla/5.0 (iPhone; CPU iPhone OS 17_1 like Mac OS X) " \
            "AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.1 Mobile/15E148 Safari/604.1"
-      expect(auth_with_user_agent(ua).device_name).to eq("Safari on iOS")
+      expect(auth_with_user_agent(ua).device_name).to eq("Mobile Safari on iOS")
+    end
+
+    it "recognizes GNOME Web on Linux (Epiphany's Safari-like user agent)" do
+      ua = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/605.1.15 (KHTML, like Gecko) " \
+           "Version/16.0 Safari/605.1.15 Epiphany/45.0"
+      expect(auth_with_user_agent(ua).device_name).to eq("GNOME Web on Linux")
+    end
+
+    it "treats a WebKit Safari user agent on Linux as WebKit (WebKitGTK)" do
+      ua = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/605.1.15 (KHTML, like Gecko) " \
+           "Version/60.5 Safari/605.1.15"
+      expect(auth_with_user_agent(ua).device_name).to eq("WebKit on Linux")
+    end
+
+    it "keeps Safari on macOS as Safari" do
+      ua = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 " \
+           "(KHTML, like Gecko) Version/17.1 Safari/605.1.15"
+      expect(auth_with_user_agent(ua).device_name).to eq("Safari on macOS")
     end
 
     it "falls back to the browser when the OS is unknown" do