Added support for spelling correction in our bindings.

* Created `spellingdb.cpp`, and `SpellingsDB` files for this.
* Added test cases for spelling corrections.

Author: MohitMaliDeveloper

lib/build.gradle

@@ -365,7 +365,8 @@ String getLibkiwixFiles() {
         "${projectDir}/src/main/java/org/kiwix/libkiwix/JNIKiwixException.java " +
         "${projectDir}/src/main/java/org/kiwix/libkiwix/Library.java " +
         "${projectDir}/src/main/java/org/kiwix/libkiwix/Manager.java " +
-        "${projectDir}/src/main/java/org/kiwix/libkiwix/Server.java"
+        "${projectDir}/src/main/java/org/kiwix/libkiwix/Server.java " +
+        "${projectDir}/src/main/java/org/kiwix/libkiwix/SpellingsDB.java"
 }
 
 String getLibzimFiles() {

lib/src/main/cpp/CMakeLists.txt

@@ -48,6 +48,7 @@ add_library(kiwix_wrapper
         libkiwix/bookmark.cpp
         libkiwix/manager.cpp
         libkiwix/illustration.cpp
+        libkiwix/spellingdb.cpp
         )
 
 # Linux target

lib/src/main/cpp/libkiwix/spellingdb.cpp

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2025 Matthieu Gautier <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU  General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#include <jni.h>
+#include "org_kiwix_libkiwix_SpellingsDB.h"
+#include "spelling_correction.h"
+#include <zim/archive.h>
+#include "utils.h"
+#define NATIVE_TYPE kiwix::SpellingsDB
+#define TYPENAME libkiwix_SpellingsDB
+#include <macros.h>
+
+METHOD(void, setNativeSpellingsDB, jobject archive, jstring cacheDirPath)
+{
+    auto archive1 = getPtr<zim::Archive>(env, archive);
+    std::string cPath = TO_C(cacheDirPath);
+
+    auto spellingsDB = std::make_shared<kiwix::SpellingsDB>(*archive1, cPath);
+    SET_PTR(spellingsDB);
+} CATCH_EXCEPTION()
+
+DISPOSE
+
+METHOD(jobjectArray, getSpellingCorrections, jstring jWord, jint maxCount)
+{
+    auto results = THIS->getSpellingCorrections(TO_C(jWord), TO_C(maxCount));
+    jclass stringClass = env->FindClass("java/lang/String");
+    jobjectArray jArray = env->NewObjectArray(results.size(), stringClass, nullptr);
+
+    for (size_t i = 0; i < results.size(); ++i)
+    {
+        env->SetObjectArrayElement(jArray, i, TO_JNI(results[i]));
+    }
+
+    return jArray;
+} CATCH_EXCEPTION(nullptr)

lib/src/main/java/org/kiwix/libkiwix/SpellingsDB.java

@@ -0,0 +1,21 @@
+package org.kiwix.libkiwix;
+
+import org.kiwix.libzim.Archive;
+
+public class SpellingsDB {
+    public SpellingsDB(Archive archive, String cacheDirPath) {
+        setNativeSpellingsDB(archive, cacheDirPath);
+    }
+
+    private native void setNativeSpellingsDB(Archive archive, String cacheDirPath);
+    public native String[] getSpellingCorrections(String word, int maxCount);
+
+    @Override
+    protected void finalize() { dispose(); }
+
+    ///--------- The wrapper thing
+    // To delete our native wrapper
+    public native void dispose();
+    // A pointer (as a long) to a native Handle
+    private long nativeHandle;
+}

lib/src/test/org/kiwix/test/libkiwix/TestSpellingsDB.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2025 Matthieu Gautier <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU  General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+package org.kiwix.test.libkiwix;
+
+import org.kiwix.libkiwix.SpellingsDB;
+import org.kiwix.libzim.Archive;
+import org.kiwix.test.libzim.TestArchive;
+
+public class TestSpellingsDB {
+    private SpellingsDB inner;
+
+    public TestSpellingsDB(TestArchive archive, String cacheDirPath) {
+        inner = new SpellingsDB(archive.inner(), cacheDirPath);
+    }
+
+    public String[] getSpellingCorrections(String word, int maxCount) {
+        return inner.getSpellingCorrections(word, maxCount);
+    }
+}

lib/src/test/test.java

@@ -783,6 +783,17 @@ public void testSearcher() throws Exception, ZimFileFormatException, JNIKiwixExc
             assertEquals("main.html", suggestionItem.getPath());
             assertTrue(suggestionItem.hasSnippet());
             assertEquals("<b>Test</b> ZIM file", suggestionItem.getSnippet());
+
+            File cacheDir = new File("build/test-cache");
+            if (cacheDir.exists()) {
+                cacheDir.delete();
+            }
+            cacheDir.mkdirs();
+            TestSpellingsDB testSpellingsDB = new TestSpellingsDB(archive, cacheDir.getAbsolutePath());
+            String[] spellingCorrections = testSpellingsDB.getSpellingCorrections("Test ZIM fileeee", 1);
+            assertEquals("Test ZIM file", spellingCorrections[0]);
+            String[] spellingCorrections1 = testSpellingsDB.getSpellingCorrections("Test ZIM f", 1);
+            assertEquals("Test ZIM file", spellingCorrections1[0]);
         }
         System.gc();
         System.runFinalization();