[AI-FSSDK] [FSSDK-12337] Add Feature Rollout support

core-api/src/main/java/com/optimizely/ab/config/DatafileProjectConfig.java

@@ -194,6 +194,10 @@ public DatafileProjectConfig(String accountId,
         List<Experiment> allExperiments = new ArrayList<Experiment>();
         allExperiments.addAll(experiments);
         allExperiments.addAll(aggregateGroupExperiments(groups));
+
+        // Inject "everyone else" variation into feature_rollout experiments
+        allExperiments = injectFeatureRolloutVariations(allExperiments, this.featureFlags, this.rollouts);
+
         this.experiments = Collections.unmodifiableList(allExperiments);
 
         if (holdouts == null) {
@@ -357,6 +361,110 @@ public Experiment getExperimentForVariationId(String variationId) {
         return this.variationIdToExperimentMapping.get(variationId);
     }
 
+    /**
+     * Injects the "everyone else" variation from the flag's rollout into any experiment
+     * with type "feature_rollout". This enables Feature Rollout experiments to fall back
+     * to the everyone else variation when users are outside the rollout percentage.
+     */
+    private List<Experiment> injectFeatureRolloutVariations(
+        List<Experiment> allExperiments,
+        List<FeatureFlag> featureFlags,
+        List<Rollout> rollouts
+    ) {
+        if (featureFlags == null || featureFlags.isEmpty()) {
+            return allExperiments;
+        }
+
+        // Build rollout ID to Rollout mapping
+        Map<String, Rollout> rolloutMap = new HashMap<>();
+        if (rollouts != null) {
+            for (Rollout rollout : rollouts) {
+                rolloutMap.put(rollout.getId(), rollout);
+            }
+        }
+
+        // Build experiment ID to index mapping for quick lookup
+        Map<String, Integer> experimentIndexMap = new HashMap<>();
+        for (int i = 0; i < allExperiments.size(); i++) {
+            experimentIndexMap.put(allExperiments.get(i).getId(), i);
+        }
+
+        List<Experiment> result = new ArrayList<>(allExperiments);
+
+        for (FeatureFlag flag : featureFlags) {
+            Variation everyoneElseVariation = getEveryoneElseVariation(flag, rolloutMap);
+            if (everyoneElseVariation == null) {
+                continue;
+            }
+
+            for (String experimentId : flag.getExperimentIds()) {
+                Integer index = experimentIndexMap.get(experimentId);
+                if (index == null) {
+                    continue;
+                }
+                Experiment experiment = result.get(index);
+                if (!"feature_rollout".equals(experiment.getType())) {
+                    continue;
+                }
+
+                // Create new experiment with injected variation and traffic allocation
+                List<Variation> newVariations = new ArrayList<>(experiment.getVariations());
+                newVariations.add(everyoneElseVariation);
+
+                List<TrafficAllocation> newTrafficAllocation = new ArrayList<>(experiment.getTrafficAllocation());
+                newTrafficAllocation.add(new TrafficAllocation(everyoneElseVariation.getId(), 10000));
+
+                Experiment updatedExperiment = new Experiment(
+                    experiment.getId(),
+                    experiment.getKey(),
+                    experiment.getStatus(),
+                    experiment.getLayerId(),
+                    experiment.getAudienceIds(),
+                    experiment.getAudienceConditions(),
+                    newVariations,
+                    experiment.getUserIdToVariationKeyMap(),
+                    newTrafficAllocation,
+                    experiment.getGroupId(),
+                    experiment.getCmab(),
+                    experiment.getType()
+                );
+
+                result.set(index, updatedExperiment);
+            }
+        }
+
+        return result;
+    }
+
+    /**
+     * Gets the "everyone else" variation from the flag's rollout.
+     * The everyone else rule is the last experiment in the rollout,
+     * and the variation is the first variation of that rule.
+     *
+     * @return the everyone else variation, or null if it cannot be resolved
+     */
+    @Nullable
+    private Variation getEveryoneElseVariation(FeatureFlag flag, Map<String, Rollout> rolloutMap) {
+        String rolloutId = flag.getRolloutId();
+        if (rolloutId == null || rolloutId.isEmpty()) {
+            return null;
+        }
+        Rollout rollout = rolloutMap.get(rolloutId);
+        if (rollout == null) {
+            return null;
+        }
+        List<Experiment> rolloutExperiments = rollout.getExperiments();
+        if (rolloutExperiments == null || rolloutExperiments.isEmpty()) {
+            return null;
+        }
+        Experiment everyoneElseRule = rolloutExperiments.get(rolloutExperiments.size() - 1);
+        List<Variation> variations = everyoneElseRule.getVariations();
+        if (variations == null || variations.isEmpty()) {
+            return null;
+        }
+        return variations.get(0);
+    }
+
     private List<Experiment> aggregateGroupExperiments(List<Group> groups) {
         List<Experiment> groupExperiments = new ArrayList<Experiment>();
         for (Group group : groups) {

core-api/src/main/java/com/optimizely/ab/config/Experiment.java

@@ -41,6 +41,7 @@ public class Experiment implements ExperimentCore {
     private final String status;
     private final String layerId;
     private final String groupId;
+    private final String type;
     private final Cmab cmab;
 
     private final List<String> audienceIds;
@@ -72,7 +73,7 @@ public String toString() {
 
     @VisibleForTesting
     public Experiment(String id, String key, String layerId) {
-        this(id, key, null, layerId, Collections.emptyList(), null, Collections.emptyList(), Collections.emptyMap(), Collections.emptyList(), "", null);
+        this(id, key, null, layerId, Collections.emptyList(), null, Collections.emptyList(), Collections.emptyMap(), Collections.emptyList(), "", null, null);
     }
 
     @VisibleForTesting
@@ -81,7 +82,7 @@ public Experiment(String id, String key, String status, String layerId,
                       List<Variation> variations, Map<String, String> userIdToVariationKeyMap,
                       List<TrafficAllocation> trafficAllocation, String groupId) {
         this(id, key, status, layerId, audienceIds, audienceConditions, variations,
-            userIdToVariationKeyMap, trafficAllocation, groupId, null); // Default cmab=null
+            userIdToVariationKeyMap, trafficAllocation, groupId, null, null); // Default cmab=null, type=null
     }
 
     @VisibleForTesting
@@ -90,7 +91,27 @@ public Experiment(String id, String key, String status, String layerId,
                       List<Variation> variations, Map<String, String> userIdToVariationKeyMap,
                       List<TrafficAllocation> trafficAllocation) {
         this(id, key, status, layerId, audienceIds, audienceConditions, variations,
-            userIdToVariationKeyMap, trafficAllocation, "", null); // Default groupId="" and cmab=null
+            userIdToVariationKeyMap, trafficAllocation, "", null, null); // Default groupId="", cmab=null, type=null
+    }
+
+    @VisibleForTesting
+    public Experiment(String id, String key, String status, String layerId,
+                      List<String> audienceIds, Condition audienceConditions,
+                      List<Variation> variations, Map<String, String> userIdToVariationKeyMap,
+                      List<TrafficAllocation> trafficAllocation,
+                      Cmab cmab) {
+        this(id, key, status, layerId, audienceIds, audienceConditions, variations,
+            userIdToVariationKeyMap, trafficAllocation, "", cmab, null); // Default groupId="" and type=null
+    }
+
+    @VisibleForTesting
+    public Experiment(String id, String key, String status, String layerId,
+                      List<String> audienceIds, Condition audienceConditions,
+                      List<Variation> variations, Map<String, String> userIdToVariationKeyMap,
+                      List<TrafficAllocation> trafficAllocation, String groupId,
+                      Cmab cmab) {
+        this(id, key, status, layerId, audienceIds, audienceConditions, variations,
+            userIdToVariationKeyMap, trafficAllocation, groupId, cmab, null); // Default type=null
     }
 
     @JsonCreator
@@ -103,8 +124,9 @@ public Experiment(@JsonProperty("id") String id,
                       @JsonProperty("variations") List<Variation> variations,
                       @JsonProperty("forcedVariations") Map<String, String> userIdToVariationKeyMap,
                       @JsonProperty("trafficAllocation") List<TrafficAllocation> trafficAllocation,
-                      @JsonProperty("cmab") Cmab cmab) {
-        this(id, key, status, layerId, audienceIds, audienceConditions, variations, userIdToVariationKeyMap, trafficAllocation, "", cmab);
+                      @JsonProperty("cmab") Cmab cmab,
+                      @JsonProperty("type") String type) {
+        this(id, key, status, layerId, audienceIds, audienceConditions, variations, userIdToVariationKeyMap, trafficAllocation, "", cmab, type);
     }
 
     public Experiment(@Nonnull String id,
@@ -117,7 +139,8 @@ public Experiment(@Nonnull String id,
                       @Nonnull Map<String, String> userIdToVariationKeyMap,
                       @Nonnull List<TrafficAllocation> trafficAllocation,
                       @Nonnull String groupId,
-                      @Nullable Cmab cmab) {
+                      @Nullable Cmab cmab,
+                      @Nullable String type) {
         this.id = id;
         this.key = key;
         this.status = status == null ? ExperimentStatus.NOT_STARTED.toString() : status;
@@ -131,6 +154,7 @@ public Experiment(@Nonnull String id,
         this.variationKeyToVariationMap = ProjectConfigUtils.generateNameMapping(variations);
         this.variationIdToVariationMap = ProjectConfigUtils.generateIdMapping(variations);
         this.cmab = cmab;
+        this.type = type;
     }
 
     public String getId() {
@@ -181,6 +205,11 @@ public String getGroupId() {
         return groupId;
     }
 
+    @Nullable
+    public String getType() {
+        return type;
+    }
+
     public Cmab getCmab() {
         return cmab;
     }
@@ -211,6 +240,7 @@ public String toString() {
             ", variationKeyToVariationMap=" + variationKeyToVariationMap +
             ", userIdToVariationKeyMap=" + userIdToVariationKeyMap +
             ", trafficAllocation=" + trafficAllocation +
+            ", type='" + type + '\'' +
             ", cmab=" + cmab +
             '}';
     }

core-api/src/main/java/com/optimizely/ab/config/Group.java

@@ -63,7 +63,8 @@ public Group(@JsonProperty("id") String id,
                     experiment.getUserIdToVariationKeyMap(),
                     experiment.getTrafficAllocation(),
                     id,
-                    experiment.getCmab()
+                    experiment.getCmab(),
+                    experiment.getType()
                 );
             }
             this.experiments.add(experiment);

core-api/src/main/java/com/optimizely/ab/config/parser/GsonHelpers.java

@@ -168,8 +168,16 @@ static Experiment parseExperiment(JsonObject experimentJson, String groupId, Jso
             }
         }
 
+        String type = null;
+        if (experimentJson.has("type")) {
+            JsonElement typeElement = experimentJson.get("type");
+            if (!typeElement.isJsonNull()) {
+                type = typeElement.getAsString();
+            }
+        }
+
         return new Experiment(id, key, status, layerId, audienceIds, conditions, variations, userIdToVariationKeyMap,
-            trafficAllocations, groupId, cmab);
+            trafficAllocations, groupId, cmab, type);
     }
 
     static Experiment parseExperiment(JsonObject experimentJson, JsonDeserializationContext context) {

core-api/src/main/java/com/optimizely/ab/config/parser/JsonConfigParser.java

@@ -179,8 +179,10 @@ private List<Experiment> parseExperiments(JSONArray experimentJson, String group
                 cmab = parseCmab(cmabObject);
             }
 
+            String type = experimentObject.optString("type", null);
+
             experiments.add(new Experiment(id, key, status, layerId, audienceIds, conditions, variations, userIdToVariationKeyMap,
-                trafficAllocations, groupId, cmab));
+                trafficAllocations, groupId, cmab, type));
         }
 
         return experiments;

core-api/src/main/java/com/optimizely/ab/config/parser/JsonSimpleConfigParser.java

@@ -189,8 +189,17 @@ private List<Experiment> parseExperiments(JSONArray experimentJson, String group
                 }
             }
 
-            experiments.add(new Experiment(id, key, status, layerId, audienceIds, conditions, variations, 
-                userIdToVariationKeyMap, trafficAllocations, groupId, cmab));
+            // Parse type field
+            String type = null;
+            if (experimentObject.containsKey("type")) {
+                Object typeObj = experimentObject.get("type");
+                if (typeObj != null) {
+                    type = (String) typeObj;
+                }
+            }
+
+            experiments.add(new Experiment(id, key, status, layerId, audienceIds, conditions, variations,
+                userIdToVariationKeyMap, trafficAllocations, groupId, cmab, type));
         }
 
         return experiments;