feat: Added ODPSegmentManager (#484)

## Summary
Added an ODPSegmentManager which provides functionality to fetch segments from ODP server and cache and re-use them. 

## Test plan
- Manually tested thoroughly
- Added new unit tests
- Existing unit tests pass
- All Full stack compatibility suite tests pass

## JIRA
[OASIS-8383](https://optimizely.atlassian.net/browse/OASIS-8383)

core-api/src/main/java/com/optimizely/ab/odp/ODPConfig.java

@@ -0,0 +1,74 @@
+/**
+ *
+ *    Copyright 2022, Optimizely
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+package com.optimizely.ab.odp;
+
+import java.util.Collections;
+import java.util.List;
+
+public class ODPConfig {
+
+    private String apiKey;
+
+    private String apiHost;
+
+    private List<String> allSegments;
+
+    public ODPConfig(String apiKey, String apiHost, List<String> allSegments) {
+        this.apiKey = apiKey;
+        this.apiHost = apiHost;
+        this.allSegments = allSegments;
+    }
+
+    public ODPConfig(String apiKey, String apiHost) {
+        this(apiKey, apiHost, Collections.emptyList());
+    }
+
+    public synchronized Boolean isReady() {
+        return !(
+            this.apiKey == null || this.apiKey.isEmpty()
+            || this.apiHost == null || this.apiHost.isEmpty()
+        );
+    }
+
+    public synchronized Boolean hasSegments() {
+        return allSegments != null && !allSegments.isEmpty();
+    }
+
+    public synchronized void setApiKey(String apiKey) {
+        this.apiKey = apiKey;
+    }
+
+    public synchronized void setApiHost(String apiHost) {
+        this.apiHost = apiHost;
+    }
+
+    public synchronized String getApiKey() {
+        return apiKey;
+    }
+
+    public synchronized String getApiHost() {
+        return apiHost;
+    }
+
+    public synchronized List<String> getAllSegments() {
+        return allSegments;
+    }
+
+    public synchronized void setAllSegments(List<String> allSegments) {
+        this.allSegments = allSegments;
+    }
+}

core-api/src/main/java/com/optimizely/ab/odp/ODPSegmentManager.java

@@ -0,0 +1,108 @@
+/**
+ *
+ *    Copyright 2022, Optimizely
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+package com.optimizely.ab.odp;
+
+import com.optimizely.ab.internal.Cache;
+import com.optimizely.ab.internal.DefaultLRUCache;
+import com.optimizely.ab.odp.parser.ResponseJsonParser;
+import com.optimizely.ab.odp.parser.ResponseJsonParserFactory;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Collections;
+import java.util.List;
+
+public class ODPSegmentManager {
+
+    private static final Logger logger = LoggerFactory.getLogger(ODPSegmentManager.class);
+
+    private static final String SEGMENT_URL_PATH = "/v3/graphql";
+
+    private final ODPApiManager apiManager;
+
+    private final ODPConfig odpConfig;
+
+    private final Cache<List<String>> segmentsCache;
+
+    public ODPSegmentManager(ODPConfig odpConfig, ODPApiManager apiManager) {
+        this(odpConfig, apiManager, Cache.DEFAULT_MAX_SIZE, Cache.DEFAULT_TIMEOUT_SECONDS);
+    }
+
+    public ODPSegmentManager(ODPConfig odpConfig, ODPApiManager apiManager, Cache<List<String>> cache) {
+        this.apiManager = apiManager;
+        this.odpConfig = odpConfig;
+        this.segmentsCache = cache;
+    }
+
+    public ODPSegmentManager(ODPConfig odpConfig, ODPApiManager apiManager, Integer cacheSize, Integer cacheTimeoutSeconds) {
+        this.apiManager = apiManager;
+        this.odpConfig = odpConfig;
+        this.segmentsCache = new DefaultLRUCache<>(cacheSize, cacheTimeoutSeconds);
+    }
+
+    public List<String> getQualifiedSegments(String fsUserId) {
+        return getQualifiedSegments(ODPUserKey.FS_USER_ID, fsUserId, Collections.emptyList());
+    }
+    public List<String> getQualifiedSegments(String fsUserId, List<ODPSegmentOption> options) {
+        return getQualifiedSegments(ODPUserKey.FS_USER_ID, fsUserId, options);
+    }
+
+    public List<String> getQualifiedSegments(ODPUserKey userKey, String userValue) {
+        return getQualifiedSegments(userKey, userValue, Collections.emptyList());
+    }
+
+    public List<String> getQualifiedSegments(ODPUserKey userKey, String userValue, List<ODPSegmentOption> options) {
+        if (!odpConfig.isReady()) {
+            logger.error("Audience segments fetch failed (ODP is not enabled)");
+            return Collections.emptyList();
+        }
+
+        if (!odpConfig.hasSegments()) {
+            logger.debug("No Segments are used in the project, Not Fetching segments. Returning empty list");
+            return Collections.emptyList();
+        }
+
+        List<String> qualifiedSegments;
+        String cacheKey = getCacheKey(userKey.getKeyString(), userValue);
+
+        if (options.contains(ODPSegmentOption.RESET_CACHE)) {
+            segmentsCache.reset();
+        } else if (!options.contains(ODPSegmentOption.IGNORE_CACHE)) {
+            qualifiedSegments = segmentsCache.lookup(cacheKey);
+            if (qualifiedSegments != null) {
+                logger.debug("ODP Cache Hit. Returning segments from Cache.");
+                return qualifiedSegments;
+            }
+        }
+
+        logger.debug("ODP Cache Miss. Making a call to ODP Server.");
+
+        ResponseJsonParser parser = ResponseJsonParserFactory.getParser();
+        String qualifiedSegmentsResponse = apiManager.fetchQualifiedSegments(odpConfig.getApiKey(), odpConfig.getApiHost() + SEGMENT_URL_PATH, userKey.getKeyString(), userValue, odpConfig.getAllSegments());
+        qualifiedSegments = parser.parseQualifiedSegments(qualifiedSegmentsResponse);
+
+        if (qualifiedSegments != null && !options.contains(ODPSegmentOption.IGNORE_CACHE)) {
+            segmentsCache.save(cacheKey, qualifiedSegments);
+        }
+
+        return qualifiedSegments;
+    }
+
+    private String getCacheKey(String userKey, String userValue) {
+        return userKey + "-$-" + userValue;
+    }
+}

core-api/src/main/java/com/optimizely/ab/odp/ODPSegmentOption.java

@@ -0,0 +1,25 @@
+/**
+ *
+ *    Copyright 2022, Optimizely
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+package com.optimizely.ab.odp;
+
+public enum ODPSegmentOption {
+
+    IGNORE_CACHE,
+
+    RESET_CACHE;
+
+}

core-api/src/main/java/com/optimizely/ab/odp/ODPUserKey.java

@@ -0,0 +1,34 @@
+/**
+ *
+ *    Copyright 2022, Optimizely
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+package com.optimizely.ab.odp;
+
+public enum ODPUserKey {
+
+    VUID("vuid"),
+
+    FS_USER_ID("fs_user_id");
+
+    private final String keyString;
+
+    ODPUserKey(String keyString) {
+        this.keyString = keyString;
+    }
+
+    public String getKeyString() {
+        return keyString;
+    }
+}