fix: improve user-agent with more detail (#74)

* adding user agent

* can import UIKit

* Minor fix

* conditional import statements

* minor fix for deviceInfo.

Need to discuss for the 'default value' in case UIKit is unavailable

* added test case and comments

Sources/Tracking/DeviceInfo.swift

@@ -0,0 +1,15 @@
+import Foundation
+#if canImport(UIKit)
+import UIKit
+
+internal enum DeviceInfo {
+    /// Device's model on which SDK is running eg. iPhone12,3
+    static let deviceInfo: String = UIDevice.deviceModelCode
+    /// Operating system and version of OS of the Device
+    static let osInfo : String = "\(UIDevice().systemName) \(UIDevice().systemVersion)"
+    /// Name of customer's application using the SDK
+    static let customerAppName : String = Bundle.main.infoDictionary?["CFBundleName"] as? String ?? ""
+    /// Version of the customer's application using the SDK
+    static let customerAppVersion : String = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? ""
+}
+#endif

Sources/Tracking/Extensions/DeviceExtension.swift

@@ -0,0 +1,31 @@
+import Foundation
+#if canImport(UIKit)
+import UIKit
+
+
+/**
+ Extend `UIDevice` to get user's device information such as
+ device's model. If running on Simulator `deviceModelCode`
+ will return values like`x86_64` but when running on a device, this function
+ returns exact device model for example, `iPhone12,3`
+
+ Use case :
+ To get model detail, simply use
+
+ let deviceModelInfo = UIDevice.deviceModelCode
+ */
+public extension UIDevice {
+
+    static let deviceModelCode : String = {
+
+        var systemInfo = utsname()
+        uname(&systemInfo)
+        let machineMirror = Mirror(reflecting: systemInfo.machine)
+        let identifier = machineMirror.children.reduce("") { identifier, element in
+            guard let value = element.value as? Int8, value != 0 else { return identifier }
+            return identifier + String(UnicodeScalar(UInt8(value)))
+        }
+        return identifier
+    }()
+}
+#endif

Sources/Tracking/Service/HttpClient.swift

@@ -111,12 +111,13 @@ extension CIOHttpClient {
         let urlSessionConfig = URLSessionConfiguration.ephemeral
         let basicAuthHeaderString = "Basic \(getBasicAuthHeaderString(siteId: siteId, apiKey: apiKey))"
 
+
         urlSessionConfig.allowsCellularAccess = true
         urlSessionConfig.timeoutIntervalForResource = 30
         urlSessionConfig.timeoutIntervalForRequest = 60
         urlSessionConfig.httpAdditionalHeaders = ["Content-Type": "application/json; charset=utf-8",
                                                   "Authorization": basicAuthHeaderString,
-                                                  "User-Agent": "CustomerIO-SDK-iOS/\(SdkVersion.version)"]
+                                                  "User-Agent": getUserAgent()]
 
         return URLSession(configuration: urlSessionConfig, delegate: nil, delegateQueue: nil)
     }
@@ -127,4 +128,25 @@ extension CIOHttpClient {
 
         return encodedRawHeader.base64EncodedString(options: NSData.Base64EncodingOptions(rawValue: 0))
     }
+
+    /**
+     * getUserAgent - To get `user-agent` header value. This value depends on SDK version
+     * and device detail such as OS version, device model, customer's app name etc
+     *
+     * In case, UIKit is available then this function returns value in following format :
+     * `Customer.io iOS Client/1.0.0-alpha.16 (iPhone 11 Pro; iOS 14.5) User App/1.0`
+     *
+     * Otherwise will return
+     * `Customer.io iOS Client/1.0.0-alpha.16`
+     */
+    static func getUserAgent() -> String {
+        var userAgent = "Customer.io iOS Client/"
+        userAgent += SdkVersion.version
+        #if canImport(UIKit)
+        userAgent += " (\(DeviceInfo.deviceInfo); \(DeviceInfo.osInfo))"
+        userAgent += " \(DeviceInfo.customerAppName)/"
+        userAgent += DeviceInfo.customerAppVersion
+        #endif
+        return userAgent
+    }
 }

Tests/Tracking/Service/HttpClientTest.swift

@@ -167,4 +167,20 @@ class HttpClientTest: UnitTest {
 
         XCTAssertEqual(actual, expected)
     }
+
+    func testGetUserAgent() {
+        let userAgentValue = CIOHttpClient.getUserAgent()
+
+        var expectedUserAgent = "Customer.io iOS Client/\(SdkVersion.version)"
+
+        #if canImport(UIKit)
+        let deviceModel = UIDevice.deviceModelCode
+        let appName = Bundle.main.infoDictionary?["CFBundleName"] as? String ?? ""
+        let osInfo = "\(UIDevice().systemName) \(UIDevice().systemVersion)"
+        let appVersion = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? ""
+        expectedUserAgent += " (\(deviceModel); \(osInfo)) \(appName)/\(appVersion)"
+        #endif
+
+        XCTAssertEqual(userAgentValue, expectedUserAgent)
+    }
 }