feat: added collection change listener

Author: Wojtach

.prettierignore

@@ -1,6 +1,6 @@
 android/
 build/
-expo-example/
+# expo-example/
 node_modules/
 dist/
 lib/

android/src/main/java/com/cblreactnative/cbl-js-kotlin

@@ -5,6 +5,24 @@ @interface RCT_EXTERN_MODULE(CblReactnative, RCTEventEmitter)
 
 // MARK: - Collection Functions
 
+RCT_EXTERN_METHOD(
+  collection_AddChangeListener:(NSString *)changeListenerToken
+  fromCollectionWithName:(NSString *)collectionName
+  fromDatabaseWithName:(NSString *)name
+  fromScopeWithName:(NSString *)scopeName
+  withResolver:(RCTPromiseResolveBlock)resolve
+  withRejecter:(RCTPromiseRejectBlock)reject
+)
+
+RCT_EXTERN_METHOD(
+  collection_RemoveChangeListener:(NSString *)changeListenerToken
+  fromCollectionWithName:(NSString *)collectionName
+  fromDatabaseWithName:(NSString *)name
+  fromScopeWithName:(NSString *)scopeName
+  withResolver:(RCTPromiseResolveBlock)resolve
+  withRejecter:(RCTPromiseRejectBlock)reject
+)
+
 RCT_EXTERN_METHOD(collection_CreateCollection:
   (NSString *) collectionName
   fromDatabaseWithName:(NSString *) name

expo-example/cblite-js-tests

@@ -57,6 +57,84 @@ class CblReactnative: RCTEventEmitter {
    }
 
   // MARK: - Collection Functions
+@objc(collection_AddChangeListener:fromCollectionWithName:fromDatabaseWithName:fromScopeWithName:withResolver:withRejecter:)
+func collection_AddChangeListener(
+  changeListenerToken: NSString,
+  collectionName: NSString,
+  name: NSString, 
+  scopeName: NSString,
+  resolve: @escaping RCTPromiseResolveBlock,
+  reject: @escaping RCTPromiseRejectBlock
+) -> Void {
+  let (isError, args) = DataAdapter.shared.adaptCollectionArgs(name: name, collectionName: collectionName, scopeName: scopeName, reject: reject)
+  let (isTokenError, token) = DataAdapter.shared.adaptNonEmptyString(value: changeListenerToken, propertyName: "changeListenerToken", reject: reject)
+
+  if isError || isTokenError {
+    return
+  }
+
+  backgroundQueue.async {
+    do {
+      guard let collection = try CollectionManager.shared.getCollection(
+        args.collectionName, 
+        scopeName: args.scopeName, 
+        databaseName: args.databaseName
+      ) else {
+        reject("DATABASE_ERROR", "Could not find collection", nil)
+        return
+      }
+    
+      let listener = collection.addChangeListener(queue: self.backgroundQueue) { [weak self] (change) in
+        guard let self = self else {
+          // Log.log(domain: .database, level: .warning, message: "Unable to notify changes as the handler object was released")
+          return
+        }
+        
+        // Format the data to match the CollectionChange interface
+        let resultData = NSMutableDictionary()
+        resultData.setValue(token, forKey: "token")
+        resultData.setValue(change.documentIDs, forKey: "documentIDs")
+        
+        // Use DataAdapter to convert the Collection to a consistent dictionary format
+        let collectionDict = DataAdapter.shared.adaptCollectionToNSDictionary(collection, databaseName: args.databaseName)
+        resultData.setValue(collectionDict, forKey: "collection")
+      
+        self.sendEvent(withName: self.kCollectionChange, body: resultData)
+      }
+    
+      self.collectionChangeListeners[token] = listener
+      resolve(nil)
+    } catch let error as NSError {
+      reject("DATABASE_ERROR", error.localizedDescription, nil)
+    } catch {
+      reject("DATABASE_ERROR", error.localizedDescription, nil)
+    }
+  }
+}
+
+  @objc(collection_RemoveChangeListener:fromCollectionWithName:fromDatabaseWithName:fromScopeWithName:withResolver:withRejecter:)
+  func collection_RemoveChangeListener(
+    changeListenerToken: NSString,
+    collectionName: NSString,
+    name: NSString,
+    scopeName: NSString,
+    resolve: @escaping RCTPromiseResolveBlock,
+    reject: @escaping RCTPromiseRejectBlock
+  ) -> Void {
+    let token = String(changeListenerToken)
+  
+    backgroundQueue.async {
+      if let listener = self.collectionChangeListeners[token] as? ListenerToken {
+        // Remove the listener
+        listener.remove()
+        self.collectionChangeListeners.removeValue(forKey: token)
+        resolve(nil)
+      } else {
+        reject("DATABASE_ERROR", "No listener found for token \(token)", nil)
+      }
+    }
+  }
+
 
   @objc(collection_CreateCollection:fromDatabaseWithName:fromScopeWithName:withResolver:withRejecter:)
   func collection_CreateCollection(

ios/CblReactnative.mm

@@ -78,6 +78,8 @@ export class CblReactNativeEngine implements ICoreEngine {
     new Map();
   private _isReplicatorDocumentChangeEventSetup: boolean = false;
 
+  private _collectionChangeListeners: Map<string, ListenerCallback> = new Map();
+
   private static readonly LINKING_ERROR =
     `The package 'cbl-reactnative' doesn't seem to be linked. Make sure: \n\n` +
     Platform.select({ ios: "- You have run 'pod install'\n", default: '' }) +
@@ -133,12 +135,45 @@ export class CblReactNativeEngine implements ICoreEngine {
   };
 
   collection_AddChangeListener(
-    // eslint-disable-next-line
     args: CollectionChangeListenerArgs,
-    // eslint-disable-next-line
     lcb: ListenerCallback
   ): Promise<void> {
-    return Promise.resolve(undefined);
+    return new Promise((resolve, reject) => {
+      const token = args.changeListenerToken;
+      const subscriptionKey = `${args.name}.${args.scopeName}.${args.collectionName}_${token}`;
+
+      if (this._collectionChangeListeners.has(token)) {
+        reject(new Error('Change listener token already exists'));
+        return;
+      }
+
+      const subscription = this.startListeningEvents(
+        this._eventCollectionChange,
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        (results: any) => {
+          if (results.token === token) {
+            this.debugLog(
+              `::DEBUG:: Received collection change event for token: ${token}`
+            );
+            lcb(results);
+          }
+        }
+      );
+
+      this._emitterSubscriptions.set(subscriptionKey, subscription);
+      this._collectionChangeListeners.set(token, lcb);
+
+      this.CblReactNative.collection_AddChangeListener(
+        token,
+        args.collectionName,
+        args.name,
+        args.scopeName
+      ).then(
+        () => resolve(),
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        (error: any) => reject(error)
+      );
+    });
   }
 
   // eslint-disable-next-line
@@ -442,7 +477,47 @@ export class CblReactNativeEngine implements ICoreEngine {
     // eslint-disable-next-line
     args: CollectionChangeListenerArgs
   ): Promise<void> {
-    return Promise.resolve(undefined);
+    return new Promise((resolve, reject) => {
+      const token = args.changeListenerToken;
+      const collectionId = `${args.name}.${args.scopeName}.${args.collectionName}`;
+      const subscriptionKey = `${collectionId}_${token}`;
+
+      // Remove the subscription
+      if (this._emitterSubscriptions.has(subscriptionKey)) {
+        this._emitterSubscriptions.get(subscriptionKey)?.remove();
+        this._emitterSubscriptions.delete(subscriptionKey);
+      }
+
+      // Remove the listener from the collection listeners map
+      if (this._collectionChangeListeners.has(token)) {
+        this._collectionChangeListeners.delete(token);
+      } else {
+        reject(new Error(`No listener found with token: ${token}`));
+        return;
+      }
+
+      // Remove the listener from the native side
+      this.CblReactNative.collection_RemoveChangeListener(
+        token,
+        args.collectionName,
+        args.name,
+        args.scopeName
+      ).then(
+        () => {
+          this.debugLog(
+            `::DEBUG:: collection_RemoveChangeListener completed for token: ${token}`
+          );
+          resolve();
+        },
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        (error: any) => {
+          this.debugLog(
+            `::DEBUG:: collection_RemoveChangeListener Error: ${error}`
+          );
+          reject(error);
+        }
+      );
+    });
   }
 
   collection_RemoveDocumentChangeListener(