Autofill Script performance improvements (#740)

Task/Issue URL: https://app.asana.com/0/414709148257752/1206900948756760/f
iOS PR: duckduckgo/iOS#2625
macOS PR: duckduckgo/macos-browser#2481
What kind of version bump will this require?: Patch

Description:
Greatly reduces the amount of data passed into the autofill script to improve performance and resolve occasional out of memory crashes

Sources/BrowserServicesKit/Autofill/AutofillUserScript+SourceProvider.swift

@@ -18,6 +18,7 @@
 
 import Foundation
 import Autofill
+import Common
 
 public protocol AutofillUserScriptSourceProvider {
     var source: String { get }
@@ -101,15 +102,59 @@ public class DefaultAutofillSourceProvider: AutofillUserScriptSourceProvider {
     }
 
     private func buildReplacementsData() -> ProviderData? {
-        guard let userUnprotectedDomains = try? JSONEncoder().encode(privacyConfigurationManager.privacyConfig.userUnprotectedDomains),
+        guard let filteredPrivacyConfigData = filteredDataFrom(configData: privacyConfigurationManager.currentConfig,
+                                                               keepingTopLevelKeys: ["features", "unprotectedTemporary"],
+                                                               andSubKey: "autofill",
+                                                               inTopLevelKey: "features"),
+              let userUnprotectedDomains = try? JSONEncoder().encode(privacyConfigurationManager.privacyConfig.userUnprotectedDomains),
               let jsonProperties = try? JSONEncoder().encode(properties) else {
             return nil
         }
-        return ProviderData(privacyConfig: privacyConfigurationManager.currentConfig,
+
+        return ProviderData(privacyConfig: filteredPrivacyConfigData,
                             userUnprotectedDomains: userUnprotectedDomains,
                             userPreferences: jsonProperties)
     }
 
+    /// `contentScope` only needs these properties from the privacy config, so creating a filtered version to improve performance
+    ///  {
+    ///     features: {
+    ///         autofill: {
+    ///             state: 'enabled',
+    ///             exceptions: []
+    ///         }
+    ///     },
+    ///     unprotectedTemporary: []
+    /// }
+    private func filteredDataFrom(configData: Data, keepingTopLevelKeys topLevelKeys: [String], andSubKey subKey: String, inTopLevelKey topLevelKey: String) -> Data? {
+        do {
+            if let jsonDict = try JSONSerialization.jsonObject(with: configData, options: []) as? [String: Any] {
+                var filteredDict = [String: Any]()
+
+                // Keep the specified top-level keys
+                for key in topLevelKeys {
+                    if let value = jsonDict[key] {
+                        filteredDict[key] = value
+                    }
+                }
+
+                // Handle the nested dictionary for a specific top-level key to keep only the sub-key
+                if let nestedDict = jsonDict[topLevelKey] as? [String: Any],
+                   let valueToKeep = nestedDict[subKey] {
+                    filteredDict[topLevelKey] = [subKey: valueToKeep]
+                }
+
+                // Convert filtered dictionary back to Data
+                let filteredData = try JSONSerialization.data(withJSONObject: filteredDict, options: [])
+                return filteredData
+            }
+        } catch {
+            os_log(.debug, "Error during JSON serialization of privacy config: \(error.localizedDescription)")
+        }
+
+        return nil
+    }
+
     public class Builder {
         private var privacyConfigurationManager: PrivacyConfigurationManaging
         private var properties: ContentScopeProperties

Tests/BrowserServicesKitTests/Autofill/AutofillUserScriptSourceProviderTests.swift

@@ -26,11 +26,65 @@ final class AutofillUserScriptSourceProviderTests: XCTestCase {
     {
         "features": {
             "autofill": {
-                "status": "enabled",
-                "exceptions": []
+              "state": "enabled",
+              "features": {
+                "credentialsSaving": {
+                  "state": "enabled",
+                  "minSupportedVersion": "7.74.0"
+                },
+                "credentialsAutofill": {
+                  "state": "enabled",
+                  "minSupportedVersion": "7.74.0"
+                },
+                "inlineIconCredentials": {
+                  "state": "enabled",
+                  "minSupportedVersion": "7.74.0"
+                },
+                "accessCredentialManagement": {
+                  "state": "enabled",
+                  "minSupportedVersion": "7.74.0"
+                },
+                "autofillPasswordGeneration": {
+                  "state": "enabled",
+                  "minSupportedVersion": "7.75.0"
+                },
+                "onByDefault": {
+                  "state": "enabled",
+                  "minSupportedVersion": "7.93.0",
+                  "rollout": {
+                    "steps": [
+                      {
+                        "percent": 1
+                      },
+                      {
+                        "percent": 10
+                      },
+                      {
+                        "percent": 100
+                      }
+                    ]
+                  }
+                }
+              },
+              "hash": "ffaa2e81fb2bf264cb5ce2dadac549e1"
+            },
+            "contentBlocking": {
+              "state": "enabled",
+              "exceptions": [
+                {
+                  "domain": "test-domain.com"
+                }
+              ],
+              "hash": "910e25ffe4d683b3c708a1578d097a16"
+            },
+            "voiceSearch": {
+              "exceptions": [],
+              "state": "disabled",
+              "hash": "728493ef7a1488e4781656d3f9db84aa"
             }
         },
-        "unprotectedTemporary": []
+        "unprotectedTemporary": [],
+        "unprotectedOtherKey": []
     }
     """.data(using: .utf8)!
     lazy var privacyConfig = AutofillTestHelper.preparePrivacyConfig(embeddedConfig: embeddedConfig)
@@ -53,4 +107,37 @@ final class AutofillUserScriptSourceProviderTests: XCTestCase {
         XCTAssertNotNil(runtimeConfiguration)
         XCTAssertFalse(runtimeConfiguration!.isEmpty)
     }
+
+    func testWhenBuildRuntimeConfigurationThenContentScopeContainsRequiredAutofillKeys() throws {
+        let runtimeConfiguration = DefaultAutofillSourceProvider.Builder(privacyConfigurationManager: privacyConfig,
+                                                                         properties: properties)
+            .build()
+            .buildRuntimeConfigResponse()
+
+        let jsonData = runtimeConfiguration!.data(using: .utf8)!
+        let json = try JSONSerialization.jsonObject(with: jsonData, options: []) as? [String: Any]
+        let success = json?["success"] as? [String: Any]
+        let contentScope = success?["contentScope"] as? [String: Any]
+        let features = contentScope?["features"] as? [String: Any]
+        XCTAssertNotNil(features?["autofill"] as? [String: Any])
+        XCTAssertNotNil(contentScope?["unprotectedTemporary"] as? [Any])
+        XCTAssertNil(features?["contentBlocking"])
+    }
+
+    func testWhenBuildRuntimeConfigurationThenContentScopeDoesNotContainUnnecessaryKeys() throws {
+        let runtimeConfiguration = DefaultAutofillSourceProvider.Builder(privacyConfigurationManager: privacyConfig,
+                                                                         properties: properties)
+                                                                .build()
+                                                                .buildRuntimeConfigResponse()
+
+        let jsonData = runtimeConfiguration!.data(using: .utf8)!
+        let json = try JSONSerialization.jsonObject(with: jsonData, options: []) as? [String: Any]
+        let success = json?["success"] as? [String: Any]
+        let contentScope = success?["contentScope"] as? [String: Any]
+        XCTAssertNil(contentScope?["unprotectedOtherKey"])
+
+        let features = contentScope?["features"] as? [String: Any]
+        XCTAssertNil(features?["contentBlocking"])
+        XCTAssertNil(features?["voiceSearch"])
+    }
 }