Add FXIOS-14757 [Stories Scroll Direction Experiment] Feature flag (#31861)

Author: Foxbolts

firefox-ios/Client/FeatureFlags/LegacyFeatureFlagsManager.swift

@@ -89,13 +89,15 @@ class LegacyFeatureFlagsManager: HasNimbusFeatureFlags, @unchecked Sendable {
         switch featureID {
         case .searchBarPosition: return SearchBarPosition(rawValue: userSetting) as? T
         case .startAtHome: return StartAtHome(rawValue: userSetting) as? T
+        case .homepageStoriesScrollDirection: return ScrollDirection(rawValue: userSetting) as? T
         }
     }
 
     private func convertCustomIDToStandard(_ featureID: NimbusFeatureFlagWithCustomOptionsID) -> NimbusFeatureFlagID {
         switch featureID {
         case .searchBarPosition: return .bottomSearchBar
         case .startAtHome: return .startAtHome
+        case .homepageStoriesScrollDirection: return .homepageStoriesScrollDirection
         }
     }
 
@@ -140,6 +142,8 @@ class LegacyFeatureFlagsManager: HasNimbusFeatureFlags, @unchecked Sendable {
             if let option = desiredState as? StartAtHome {
                 feature.setUserPreference(to: option.rawValue)
             }
+        default:
+            break
         }
     }
 

firefox-ios/Client/FeatureFlags/NimbusFlaggableFeature.swift

@@ -26,6 +26,7 @@ enum NimbusFeatureFlagID: String, CaseIterable {
     case homepageBookmarksSectionDefault
     case homepageJumpBackinSectionDefault
     case homepageSearchBar
+    case homepageStoriesScrollDirection
     case shouldUseBrandRefreshConfiguration
     case shouldUseJapanConfiguration
     case menuDefaultBrowserBanner
@@ -119,6 +120,7 @@ enum NimbusFeatureFlagID: String, CaseIterable {
 /// This enum is a constraint for any feature flag options that have more than
 /// just an ON or OFF setting. These option must also be added to `NimbusFeatureFlagID`
 enum NimbusFeatureFlagWithCustomOptionsID {
+    case homepageStoriesScrollDirection
     case searchBarPosition
     case startAtHome
 }
@@ -158,6 +160,7 @@ struct NimbusFlaggableFeature: HasNimbusSearchBar {
                 .feltPrivacySimplifiedUI,
                 .firefoxJpGuideDefaultSite,
                 .homepageSearchBar,
+                .homepageStoriesScrollDirection,
                 .shouldUseBrandRefreshConfiguration,
                 .shouldUseJapanConfiguration,
                 .menuDefaultBrowserBanner,
@@ -259,6 +262,8 @@ struct NimbusFlaggableFeature: HasNimbusSearchBar {
         switch featureID {
         case .bottomSearchBar:
             return nimbusSearchBar.getDefaultPosition().rawValue
+        case .homepageStoriesScrollDirection:
+            return FxNimbus.shared.features.homepageRedesignFeature.value().storiesScrollDirection.rawValue
         case .splashScreen:
             return nimbusSearchBar.getDefaultPosition().rawValue
         case .startAtHome:

firefox-ios/Client/Nimbus/NimbusFeatureFlagLayer.swift

@@ -58,6 +58,9 @@ final class NimbusFeatureFlagLayer: Sendable {
         case .homepageSearchBar:
             return checkHomepageSearchBarFeature(from: nimbus)
 
+        case .homepageStoriesScrollDirection:
+            return checkHomepageStoriesScrollDirectionFeature(from: nimbus) != .baseline
+
         case .shouldUseBrandRefreshConfiguration:
             return checkShouldUseBrandRefreshConfigurationFeature(from: nimbus)
 
@@ -247,6 +250,10 @@ final class NimbusFeatureFlagLayer: Sendable {
         return nimbus.features.homepageRedesignFeature.value().searchBar
     }
 
+    private func checkHomepageStoriesScrollDirectionFeature(from nimbus: FxNimbus) -> ScrollDirection {
+        return nimbus.features.homepageRedesignFeature.value().storiesScrollDirection
+    }
+
     private func checkSnapKitRemovalRefactor(from nimbus: FxNimbus) -> Bool {
         let config = nimbus.features.snapkitRemovalRefactor.value()
         return config.enabled

firefox-ios/nimbus-features/homepageRedesignFeature.yaml

@@ -9,6 +9,11 @@ features:
           If true, enables the search bar feature on homepage for users.
         type: Boolean
         default: false
+      stories-scroll-direction:
+        description: >
+          Controls the layout direction for stories on the homepage.
+        type: ScrollDirection
+        default: baseline
       bookmarks-section-default:
         description: >
           If true, enables the bookmarks homepage section by default
@@ -24,11 +29,24 @@ features:
       - channel: beta
         value:
           search-bar: false
+          stories-scroll-direction: baseline
           bookmarks-section-default: false
           jbi-section-default: false
 
       - channel: developer
         value:
           search-bar: false
+          stories-scroll-direction: baseline
           bookmarks-section-default: false
           jbi-section-default: false
+
+enums:
+  ScrollDirection:
+    description: The layout direction for stories on the homepage.
+    variants:
+      baseline:
+        description: Uses the current default stories layout.
+      vertical:
+        description: Shows stories in a vertical layout.
+      horizontal:
+        description: Shows stories in a horizontal layout.