Start generating UserAgent instead of relying on Webkit (#341)

* Added user-agent sim and tests

* Updated vendor files to pull from UserAgent.

* Removed webkit dependency

Sources/Segment/Plugins/Platforms/Vendors/AppleUtils.swift

@@ -13,13 +13,9 @@ import Foundation
 
 import SystemConfiguration
 import UIKit
-#if !os(tvOS)
-import WebKit
-#endif
 
 internal class iOSVendorSystem: VendorSystem {
     private let device = UIDevice.current
-    @Atomic private static var asyncUserAgent: String? = nil
 
     override var manufacturer: String {
         return "Apple"
@@ -72,23 +68,7 @@ internal class iOSVendorSystem: VendorSystem {
     }
 
     override var userAgent: String? {
-        #if !os(tvOS)
-        // BKS: It was discovered that on some platforms there can be a delay in retrieval.
-        // It has to be fetched on the main thread, so we've spun it off
-        // async and cache it when it comes back.
-        // Note that due to how the `@Atomic` wrapper works, this boolean check may pass twice or more
-        // times before the value is updated, fetching the user agent multiple times as the result.
-        // This is not a big deal as the `userAgent` value is not expected to change often.
-        if Self.asyncUserAgent == nil {
-            DispatchQueue.main.async {
-                Self.asyncUserAgent = WKWebView().value(forKey: "userAgent") as? String
-            }
-        }
-        return Self.asyncUserAgent
-        #else
-        // webkit isn't on tvos
-        return "unknown"
-        #endif
+        return UserAgent.value
     }
 
     override var connection: ConnectionStatus {
@@ -156,7 +136,7 @@ internal class watchOSVendorSystem: VendorSystem {
     }
 
     override var userAgent: String? {
-        return nil
+        return UserAgent.value
     }
 
     override var connection: ConnectionStatus {
@@ -207,7 +187,6 @@ import WebKit
 
 internal class MacOSVendorSystem: VendorSystem {
     private let device = ProcessInfo.processInfo
-    @Atomic private static var asyncUserAgent: String? = nil
 
     override var manufacturer: String {
         return "Apple"
@@ -248,18 +227,7 @@ internal class MacOSVendorSystem: VendorSystem {
     }
 
     override var userAgent: String? {
-        // BKS: It was discovered that on some platforms there can be a delay in retrieval.
-        // It has to be fetched on the main thread, so we've spun it off
-        // async and cache it when it comes back.
-        // Note that due to how the `@Atomic` wrapper works, this boolean check may pass twice or more
-        // times before the value is updated, fetching the user agent multiple times as the result.
-        // This is not a big deal as the `userAgent` value is not expected to change often.
-        if Self.asyncUserAgent == nil {
-            DispatchQueue.main.async {
-                Self.asyncUserAgent = WKWebView().value(forKey: "userAgent") as? String
-            }
-        }
-        return Self.asyncUserAgent
+        return UserAgent.value
     }
 
     override var connection: ConnectionStatus {

Sources/Segment/Plugins/Platforms/Vendors/LinuxUtils.swift

@@ -43,7 +43,7 @@ class LinuxVendorSystem: VendorSystem {
     }
 
     override var userAgent: String? {
-        return "unknown"
+        return UserAgent.value
     }
 
     override var connection: ConnectionStatus {

Sources/Segment/Utilities/UserAgent.swift

@@ -0,0 +1,86 @@
+//
+//  UserAgent.swift
+//
+//
+//  Created by Brandon Sneed on 5/6/24.
+//
+
+import Foundation
+
+#if os(iOS) || os(visionOS)
+import UIKit
+#endif
+
+// macOS:     "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko)"
+// iOS:       "Mozilla/5.0 (iPhone; CPU iPhone OS 17_0_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148"
+// iPad:      "Mozilla/5.0 (iPad; CPU OS 17_4 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148"
+// visionOS:  "Mozilla/5.0 (iPad; CPU OS 16_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148"
+// catalyst:  "Mozilla/5.0 (iPad; CPU OS 14_4_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148"
+// appleTV:   no-webkit
+// watchOS:   no-webkit
+// linux:     no-webkit
+
+internal struct UserAgent {
+    // Duplicate the app names that webkit uses on a given platform.
+    // Broken out in case they change in the future.
+    #if os(macOS)
+    private static let defaultWebKitAppName = ""
+    #elseif targetEnvironment(macCatalyst)
+    private static let defaultWebKitAppName = "Mobile/15E148"
+    #elseif os(iOS)
+    private static let defaultWebKitAppName = "Mobile/15E148"
+    #elseif os(visionOS)
+    private static let defaultWebKitAppName = "Mobile/15E148"
+    #else
+    private static let defaultWebKitAppName = ""
+    #endif
+
+    internal static var _value: String = ""
+
+    public static var value: String {
+        if _value.isEmpty {
+            _value = value(applicationName: defaultWebKitAppName)
+        }
+        return _value
+    }
+
+    private static func version() -> String {
+        let v = ProcessInfo.processInfo.operatingSystemVersion
+        var result: String
+        if v.patchVersion > 0 {
+            result = "\(v.majorVersion)_\(v.minorVersion)_\(v.patchVersion)"
+        } else {
+            // webkit leaves the patch version off if it's zero.
+            result = "\(v.majorVersion)_\(v.minorVersion)"
+        }
+        return result
+    }
+
+    public static func value(applicationName: String) -> String {
+        let separator: String = applicationName.isEmpty ? "" : " "
+        #if os(macOS)
+        // Webkit hard-codes the info if it's on mac desktop
+        return "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko)\(separator)\(applicationName)"
+        #elseif os(iOS) || os(visionOS) || targetEnvironment(macCatalyst)
+        var model = UIDevice.current.model
+
+        // doing this just in case ... i don't have all these devices to test, only sims.
+        if model.contains("iPhone") { model = "iPhone" }
+        else if model.contains("iPad") { model = "iPad" }
+        // it's not one of the two above .. webkit defaults to iPad (ie: visionOS, catalyst), so use that instead of whatever we got.
+        else { model = "iPad" }
+
+        let osVersion = Self.version()
+        #if os(iOS)
+        // ios likes to tell you it's an iphone twice.
+        return "Mozilla/5.0 (\(model); CPU \(model) OS \(osVersion) like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko)\(separator)\(applicationName)"
+        #else
+        return "Mozilla/5.0 (\(model); CPU OS \(osVersion) like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko)\(separator)\(applicationName)"
+        #endif
+
+        #else
+        return "unknown"
+        #endif
+    }
+}
+

Tests/Segment-Tests/UserAgentTests.swift

@@ -0,0 +1,34 @@
+//
+//  UserAgentTests.swift
+//  
+//
+//  Created by Brandon Sneed on 5/6/24.
+//
+
+import XCTest
+#if canImport(WebKit)
+import WebKit
+#endif
+@testable import Segment
+
+final class UserAgentTests: XCTestCase {
+
+    override func setUpWithError() throws {
+        // Put setup code here. This method is called before the invocation of each test method in the class.
+    }
+
+    override func tearDownWithError() throws {
+        // Put teardown code here. This method is called after the invocation of each test method in the class.
+    }
+
+    func testUserAgent() throws {
+        #if canImport(WebKit)
+        let wkUserAgent = WKWebView().value(forKey: "userAgent") as! String
+        #else
+        let wkUserAgent = "unknown"
+        #endif
+        let userAgent = UserAgent.value
+        XCTAssertEqual(wkUserAgent, userAgent, "UserAgent's don't match! system: \(wkUserAgent), generated: \(userAgent)")
+    }
+
+}