Improved Snapshot scheduler and watcher APIs interface

src/main/java/com/github/switcherapi/client/SnapshotCallback.java

@@ -2,27 +2,24 @@
 
 import com.github.switcherapi.client.utils.SwitcherUtils;
 import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
 
-public class SnapshotCallback {
-
-    private static final Logger logger = LogManager.getLogger(SnapshotCallback.class);
+public interface SnapshotCallback {
 
     /**
      * Callback method that will be invoked when the snapshot is updated
      *
      * @param version of the new snapshot
      */
-    public void onSnapshotUpdate(long version) {
-        SwitcherUtils.debug(logger, "Snapshot updated: {}", version);
+    default void onSnapshotUpdate(long version) {
+        SwitcherUtils.debug(LogManager.getLogger(SnapshotCallback.class), "Snapshot updated: {}", version);
     }
 
     /**
      * Callback method that will be invoked when the snapshot update fails
      *
      * @param e Exception
      */
-    public void onSnapshotUpdateError(Exception e) {
-        SwitcherUtils.debug(logger, "Failed to update snapshot: {}", e.getMessage());
+    default void onSnapshotUpdateError(Exception e) {
+        SwitcherUtils.debug(LogManager.getLogger(SnapshotCallback.class), "Failed to update snapshot: {}", e.getMessage());
     }
 }

src/main/java/com/github/switcherapi/client/SwitcherContextBase.java

@@ -178,7 +178,7 @@ public static boolean scheduleSnapshotAutoUpdate(String intervalValue, SnapshotC
 		}
 
 		final long interval = SwitcherUtils.getMillis(intervalValue);
-		final SnapshotCallback callbackFinal = Optional.ofNullable(callback).orElse(new SnapshotCallback());
+		final SnapshotCallback callbackFinal = Optional.ofNullable(callback).orElse(new SnapshotCallback() {});
 		final Runnable runnableSnapshotValidate = () -> {
 			try {
 				if (validateSnapshot()) {
@@ -270,19 +270,31 @@ public static boolean validateSnapshot() {
 	/**
 	 * Start watching snapshot files for modifications.<br>
 	 * When the file is modified the in-memory snapshot will reload
+	 *
+	 * <p>
+	 *     (*) Requires client to use local settings
 	 */
 	public static void watchSnapshot() {
-		watchSnapshot(new SnapshotEventHandler());
+		watchSnapshot(new SnapshotEventHandler() {});
 	}
 
 	/**
 	 * Start watching snapshot files for modifications.<br>
 	 * When the file is modified the in-memory snapshot will reload
+	 *
+	 * <p>
+	 *     (*) Requires client to use local settings
 	 * 
 	 * @param handler to notify snapshot change events
+	 * @throws SwitcherException if using remote service
 	 */
 	public static void watchSnapshot(SnapshotEventHandler handler) {
-		SwitcherUtils.watchSnapshot(instance, handler);
+		if (!(instance instanceof SwitcherLocalService)) {
+			throw new SwitcherException("Cannot watch snapshot when using remote", new UnsupportedOperationException());
+		}
+
+		SwitcherLocalService executorInstance = (SwitcherLocalService) instance;
+		SwitcherUtils.watchSnapshot(executorInstance, handler);
 	}
 
 	/**

src/main/java/com/github/switcherapi/client/SwitcherExecutor.java

@@ -8,7 +8,6 @@
 import com.github.switcherapi.client.model.criteria.Snapshot;
 import com.github.switcherapi.client.model.response.CriteriaResponse;
 import com.github.switcherapi.client.service.remote.ClientRemote;
-import com.github.switcherapi.client.utils.SnapshotEventHandler;
 import com.github.switcherapi.client.utils.SnapshotLoader;
 import com.github.switcherapi.client.utils.SwitcherUtils;
 import com.google.gson.Gson;
@@ -59,16 +58,6 @@ public abstract class SwitcherExecutor {
 	 * @param switchers To be validated
 	 */
 	public abstract void checkSwitchers(final Set<String> switchers);
-
-	/**
-	 * Update in-memory snapshot.
-	 * 
-	 * @param snapshotFile Path location
-	 * @param handler to notify snapshot change events
-	 * 
-	 * @return true if valid change
-	 */
-	public abstract boolean notifyChange(final String snapshotFile, SnapshotEventHandler handler);
 
 	/**
 	 * Retrieve local snapshot version

src/main/java/com/github/switcherapi/client/service/local/SwitcherLocalService.java

@@ -62,6 +62,44 @@ public void init() {
 			}
 		}
 	}
+
+	/**
+	 * Update in-memory snapshot.
+	 *
+	 * @param snapshotFile Path location
+	 * @param handler to notify snapshot change events
+	 *
+	 * @return true if valid change
+	 */
+	public boolean notifyChange(final String snapshotFile, SnapshotEventHandler handler) {
+		final String environment = SwitcherContextBase.contextStr(ContextKey.ENVIRONMENT);
+		final String snapshotLocation = SwitcherContextBase.contextStr(ContextKey.SNAPSHOT_LOCATION);
+
+		try {
+			if (snapshotFile.equals(String.format("%s.json", environment))) {
+				SwitcherUtils.debug(logger, "Updating domain");
+
+				this.domain = SnapshotLoader.loadSnapshot(snapshotLocation, environment);
+				handler.onSuccess();
+			}
+		} catch (SwitcherSnapshotLoadException | IOException e) {
+			handler.onError(new SwitcherException(e.getMessage(), e));
+			logger.error(e);
+			return false;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Update in-memory snapshot.
+	 *
+	 * @param snapshotFile Path location
+	 * @return true if valid change
+	 */
+	public boolean notifyChange(final String snapshotFile) {
+		return this.notifyChange(snapshotFile, new SnapshotEventHandler() {});
+	}
 
 	@Override
 	public CriteriaResponse executeCriteria(final Switcher switcher) {
@@ -111,27 +149,6 @@ public void checkSwitchers(final Set<String> switchers) {
 			throw new SwitchersValidationException(response.toString());
 		}
 	}
-
-	@Override
-	public boolean notifyChange(final String snapshotFile, SnapshotEventHandler handler) {
-		final String environment = SwitcherContextBase.contextStr(ContextKey.ENVIRONMENT);
-		final String snapshotLocation = SwitcherContextBase.contextStr(ContextKey.SNAPSHOT_LOCATION);
-
-		try {
-			if (snapshotFile.equals(String.format("%s.json", environment))) {
-				SwitcherUtils.debug(logger, "Updating domain");
-
-				this.domain = SnapshotLoader.loadSnapshot(snapshotLocation, environment);
-				handler.onSuccess();
-			}
-		} catch (SwitcherSnapshotLoadException | IOException e) {
-			handler.onError(new SwitcherException(e.getMessage(), e));
-			logger.error(e);
-			return false;
-		}
-
-		return true;
-	}
 
 	@Override
 	public long getSnapshotVersion() {

src/main/java/com/github/switcherapi/client/service/remote/SwitcherRemoteService.java

@@ -1,13 +1,5 @@
 package com.github.switcherapi.client.service.remote;
 
-import java.util.Arrays;
-import java.util.Set;
-
-import com.github.switcherapi.client.utils.SwitcherUtils;
-import org.apache.commons.lang3.StringUtils;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
-
 import com.github.switcherapi.client.SwitcherContextBase;
 import com.github.switcherapi.client.SwitcherExecutor;
 import com.github.switcherapi.client.exception.SwitcherRemoteException;
@@ -17,7 +9,13 @@
 import com.github.switcherapi.client.model.criteria.SwitchersCheck;
 import com.github.switcherapi.client.model.response.CriteriaResponse;
 import com.github.switcherapi.client.service.local.SwitcherLocalService;
-import com.github.switcherapi.client.utils.SnapshotEventHandler;
+import com.github.switcherapi.client.utils.SwitcherUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import java.util.Arrays;
+import java.util.Set;
 
 /**
  * @author Roger Floriano (petruki)
@@ -95,11 +93,6 @@ public void checkSwitchers(final Set<String> switchers) {
 			throw new SwitchersValidationException(Arrays.toString(response.getNotFound()));
 		}
 	}
-
-	@Override
-	public boolean notifyChange(String snapshotFile, SnapshotEventHandler handler) {
-		return this.switcherLocal.notifyChange(snapshotFile, handler);
-	}
 
 	@Override
 	public long getSnapshotVersion() {

src/main/java/com/github/switcherapi/client/utils/SnapshotEventHandler.java

@@ -1,9 +1,7 @@
 package com.github.switcherapi.client.utils;
 
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
-
 import com.github.switcherapi.client.exception.SwitcherException;
+import org.apache.logging.log4j.LogManager;
 
 /**
  * Access snapshot event handler when a file is modified.<br>
@@ -12,16 +10,22 @@
  * @author Roger Floriano (petruki)
  * @since 2022-06-29
  */
-public class SnapshotEventHandler {
-
-	private static final Logger logger = LogManager.getLogger(SnapshotEventHandler.class);
-
-	public void onSuccess() {
-		SwitcherUtils.debug(logger, "Snapshot has been changed");
+public interface SnapshotEventHandler {
+
+	/**
+	 * Callback method that will be invoked when the snapshot is updated
+	 */
+	default void onSuccess() {
+		SwitcherUtils.debug(LogManager.getLogger(SnapshotEventHandler.class), "Snapshot has been changed");
 	}
-
-	public void onError(SwitcherException exception) {
-		logger.error(exception);
+
+	/**
+	 * Callback method that will be invoked when the snapshot update fails
+	 *
+	 * @param exception Exception
+	 */
+	default void onError(SwitcherException exception) {
+		LogManager.getLogger(SnapshotEventHandler.class).error(exception);
 	}
 
 }

src/main/java/com/github/switcherapi/client/utils/SnapshotWatcher.java

@@ -1,23 +1,17 @@
 package com.github.switcherapi.client.utils;
 
-import java.io.IOException;
-import java.nio.file.ClosedWatchServiceException;
-import java.nio.file.FileSystems;
-import java.nio.file.Path;
-import java.nio.file.Paths;
-import java.nio.file.StandardWatchEventKinds;
-import java.nio.file.WatchEvent;
-import java.nio.file.WatchKey;
-import java.nio.file.WatchService;
-
+import com.github.switcherapi.client.SwitcherContextBase;
+import com.github.switcherapi.client.model.ContextKey;
+import com.github.switcherapi.client.service.local.SwitcherLocalService;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
-import com.github.switcherapi.client.SwitcherContextBase;
-import com.github.switcherapi.client.SwitcherExecutor;
-import com.github.switcherapi.client.model.ContextKey;
+import java.io.IOException;
+import java.nio.file.*;
 
 /**
+ * SnapshotWatcher runs in a separate thread to watch for changes in the snapshot file.
+ *
  * @author Roger Floriano (petruki)
  * @since 2020-05-13
  */
@@ -29,9 +23,9 @@ public class SnapshotWatcher implements Runnable {
 
 	private WatchService watcher;
 
-	private SwitcherExecutor executorInstance;
+	private SwitcherLocalService executorInstance;
 
-	public SnapshotWatcher(final SwitcherExecutor executorInstance, SnapshotEventHandler handler) {
+	public SnapshotWatcher(final SwitcherLocalService executorInstance, SnapshotEventHandler handler) {
 		this.executorInstance = executorInstance;
 		this.handler = handler;
 	}

src/main/java/com/github/switcherapi/client/utils/SwitcherUtils.java

@@ -1,10 +1,10 @@
 package com.github.switcherapi.client.utils;
 
-import com.github.switcherapi.client.SwitcherExecutor;
 import com.github.switcherapi.client.exception.SwitcherContextException;
 import com.github.switcherapi.client.exception.SwitcherInvalidDateTimeArgumentException;
 import com.github.switcherapi.client.model.ContextKey;
 import com.github.switcherapi.client.service.WorkerName;
+import com.github.switcherapi.client.service.local.SwitcherLocalService;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonParser;
@@ -141,7 +141,7 @@ public static Set<String> payloadReader(String jsonStr, String prevKey) {
 	 * @param executorInstance of a Remote or Local Switcher
 	 * @param handler to notify snapshot change events
 	 */
-	public static void watchSnapshot(final SwitcherExecutor executorInstance, SnapshotEventHandler handler) {
+	public static void watchSnapshot(final SwitcherLocalService executorInstance, SnapshotEventHandler handler) {
 		if (watcher == null) {
 			watcher = new SnapshotWatcher(executorInstance, handler);
 		}

src/test/java/com/github/switcherapi/client/service/local/SwitcherLocalServiceTest.java

@@ -37,15 +37,15 @@ void shouldNotifyWithError() {
 		SwitchersBase.configure(ContextBuilder.builder()
 				.environment("defect_default"));
 
-		assertFalse(service.notifyChange("defect_default.json", new SnapshotEventHandler()));
+		assertFalse(service.notifyChange("defect_default.json"));
 	}
 
 	@Test
 	void shouldNotifyWithSuccess() {
 		SwitchersBase.configure(ContextBuilder.builder()
 				.environment("snapshot_watcher"));
 
-		assertTrue(service.notifyChange("snapshot_watcher.json", new SnapshotEventHandler()));
+		assertTrue(service.notifyChange("snapshot_watcher.json"));
 	}
 
 	@Test

src/test/java/com/github/switcherapi/client/utils/SnapshotWatcherErrorTest.java

@@ -0,0 +1,30 @@
+package com.github.switcherapi.client.utils;
+
+import com.github.switcherapi.SwitchersBase;
+import com.github.switcherapi.client.ContextBuilder;
+import com.github.switcherapi.client.exception.SwitcherException;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+class SnapshotWatcherErrorTest {
+
+	@Test
+	void shouldNotWatchSnapshotWhenRemote() {
+		//given
+		SwitchersBase.configure(ContextBuilder.builder()
+			.contextLocation(SwitchersBase.class.getCanonicalName())
+			.url("https://api.switcherapi.com")
+			.apiKey("[API_KEY]")
+			.domain("Test")
+			.component("switcher-test")
+			.local(false));
+
+		SwitchersBase.initializeClient();
+
+		//test
+		SwitcherException exception = assertThrows(SwitcherException.class, SwitchersBase::watchSnapshot);
+		assertEquals("Something went wrong: Cannot watch snapshot when using remote", exception.getMessage());
+	}
+}