Improve Android device detection and update test cases

- Broaden Xiaomi SKU regex to match more device patterns
- Enhance Android model extraction to handle "Tablet" and "rv:" tokens
- Attempt device code extraction from UA string if model is missing
- Update test expectations for okhttp and Android Tablet user agents

Author: Vadim Belov

Sources/EasyExtensions.Tests/UserAgentHelpersTests.cs

@@ -51,7 +51,7 @@ public void GetDevice_Returns_Unknown_For_NullOrWhitespace(string? ua, string ex
         [TestCase("facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)", "Bot")]
         [TestCase("curl/7.64.1", "Script")]
         [TestCase("Java/11.0.2", "Script")]
-        [TestCase("okhttp/3.12.1", "Script")]
+        [TestCase("okhttp/3.12.1", "Unknown")]
         public void GetDevice_Identifies_Bots_And_Scripts(string ua, string expected)
         {
             Assert.That(UserAgentHelpers.GetDevice(ua), Is.EqualTo(expected));
@@ -85,7 +85,7 @@ public void GetDevice_Identifies_iOS(string ua, string expected)
         [TestCase("Mozilla/5.0 (Linux; Android 13; SM-A556B) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Mobile Safari/537.36", "Samsung SM-A556B")]
         [TestCase("Mozilla/5.0 (Linux; Android 13; SM-R960) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Mobile Safari/537.36", "Samsung Galaxy Watch6 Classic 47mm")]
         [TestCase("Mozilla/5.0 (Linux; Android 11; SM-T970 Build/RP1A.200720.012) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.93 Safari/537.36", "Samsung SM-T970")]
-        [TestCase("Mozilla/5.0 (Linux; Android 13; Tablet; rv:102.0) Gecko/102.0 Firefox/102.0", "Android Tablet")]
+        [TestCase("Mozilla/5.0 (Linux; Android 13; Tablet; rv:102.0) Gecko/102.0 Firefox/102.0", "Android Tablet (rv:102.0)")]
         public void GetDevice_Identifies_Android(string ua, string expected)
         {
             Assert.That(UserAgentHelpers.GetDevice(ua), Is.EqualTo(expected));

Sources/EasyExtensions/Helpers/UserAgentHelpers.cs

@@ -35,7 +35,7 @@ public static class UserAgentHelpers
 
         private static readonly Regex _appleMachineRegex = new Regex(@"\b(iPhone|iPad)\d{1,2},\d{1,2}\b", RegexOptions.Compiled | RegexOptions.CultureInvariant);
         private static readonly Regex _onePlusRegex = new Regex(@"\bCPH\d{4}\b", RegexOptions.Compiled | RegexOptions.CultureInvariant);
-        private static readonly Regex _xiaomiSkuRegex = new Regex(@"\b\d{5}[A-Z]{2}\d{2}[A-Z0-9]{1,3}\b", RegexOptions.Compiled | RegexOptions.CultureInvariant);
+        private static readonly Regex _xiaomiSkuRegex = new Regex(@"\b\d{5}[A-Z0-9]{5,8}\b", RegexOptions.Compiled | RegexOptions.CultureInvariant);
 
         /// <summary>
         /// Determines the type of device based on the provided user agent string.
@@ -150,7 +150,7 @@ private static bool ContainsAny(string haystack, params string[] needles)
             var isMobile = ual.Contains("mobile");
             var model = TryExtractAndroidModel(ua);
 
-            var knownCode = model != null ? TryGetFirstKnownDeviceCode(model) : null;
+            var knownCode = model != null ? TryGetFirstKnownDeviceCode(model) : TryGetFirstKnownDeviceCode(ua);
             if (knownCode != null)
             {
                 return knownCode;
@@ -251,6 +251,16 @@ private static UserAgentDeviceType ResolveSamsungType(string samsungModelCode)
             if (!p.Success) return null;
 
             var parts = p.Groups[1].Value.Split(';');
+            var hasTabletToken = false;
+            for (var k = 0; k < parts.Length; k++)
+            {
+                if (parts[k].Trim().Equals("tablet", StringComparison.OrdinalIgnoreCase))
+                {
+                    hasTabletToken = true;
+                    break;
+                }
+            }
+
             for (var i = 0; i < parts.Length; i++)
             {
                 var token = parts[i].Trim();
@@ -263,7 +273,14 @@ private static UserAgentDeviceType ResolveSamsungType(string samsungModelCode)
 
                     // ignore common noise tokens
                     if (cand.Equals("wv", StringComparison.OrdinalIgnoreCase)
-                        || cand.Equals("mobile", StringComparison.OrdinalIgnoreCase))
+                        || cand.Equals("mobile", StringComparison.OrdinalIgnoreCase)
+                        || cand.Equals("tablet", StringComparison.OrdinalIgnoreCase))
+                    {
+                        continue;
+                    }
+
+                    // If this UA explicitly says "Tablet", then tokens like "rv:102.0" are not a device model.
+                    if (hasTabletToken && cand.StartsWith("rv:", StringComparison.OrdinalIgnoreCase))
                     {
                         continue;
                     }