Merge pull request #4445 from kiwix/Fixes#41

Introduced similarly spelled suggestions results.

Author: kelson42

app/src/main/java/org/kiwix/kiwixmobile/nav/destination/library/local/LocalLibraryFragment.kt

@@ -513,7 +513,7 @@ class LocalLibraryFragment : BaseFragment(), SelectedZimFileCallback {
   @Suppress("InjectDispatcher")
   override fun addBookToLibkiwixBookOnDisk(file: File) {
     CoroutineScope(Dispatchers.IO).launch {
-      zimReaderFactory.create(ZimReaderSource(file))
+      zimReaderFactory.create(ZimReaderSource(file), false)
         ?.let { zimFileReader ->
           val book = Book().apply { update(zimFileReader.jniKiwixReader) }
           mainRepositoryActions.saveBook(book)

buildSrc/src/main/kotlin/custom/CustomApp.kt

@@ -38,6 +38,7 @@ data class CustomApp(
   val disableTitle: Boolean = false,
   val disableExternalLinks: Boolean = false,
   val disableHelpMenu: Boolean = false,
+  val showSearchSuggestionsSpellChecked: Boolean = false,
   val aboutAppUrl: String = "",
   val supportUrl: String = ""
 ) {
@@ -53,6 +54,7 @@ data class CustomApp(
     parsedJson.getAndCast("disable_title") ?: false,
     parsedJson.getAndCast("disable_external_links") ?: false,
     parsedJson.getAndCast("disable_help_menu") ?: false,
+    parsedJson.getAndCast("show_search_suggestions_spellchecked") ?: false,
     parsedJson.getAndCast("about_app_url") ?: "",
     parsedJson.getAndCast("support_url") ?: ""
   )

buildSrc/src/main/kotlin/custom/CustomApps.kt

@@ -48,6 +48,10 @@ fun ProductFlavors.create(customApps: List<CustomApp>) {
       buildConfigField("String", "ENFORCED_LANG", "\"${customApp.enforcedLanguage}\"")
       buildConfigField("String", "ABOUT_APP_URL", "\"${customApp.aboutAppUrl}\"")
       buildConfigField("String", "SUPPORT_URL", "\"${customApp.supportUrl}\"")
+      buildConfigField(
+        "Boolean",
+        "SHOW_SEARCH_SUGGESTIONS_SPELLCHECKED", "${customApp.showSearchSuggestionsSpellChecked}"
+      )
       buildConfigField("Boolean", "DISABLE_SIDEBAR", "${customApp.disableSideBar}")
       buildConfigField("Boolean", "DISABLE_TABS", "${customApp.disableTabs}")
       buildConfigField("Boolean", "DISABLE_READ_ALOUD", "${customApp.disableReadAloud}")

core/src/main/java/org/kiwix/kiwixmobile/core/StorageObserver.kt

@@ -63,7 +63,7 @@ class StorageObserver @Inject constructor(
     downloads.none { file.absolutePath.endsWith(it.fileNameFromUrl) }
 
   private suspend fun convertToLibkiwixBook(file: File) =
-    zimReaderFactory.create(ZimReaderSource(file))
+    zimReaderFactory.create(ZimReaderSource(file), false)
       ?.let { zimFileReader ->
         libkiwixBookFactory.create().apply {
           update(zimFileReader.jniKiwixReader)

core/src/main/java/org/kiwix/kiwixmobile/core/main/reader/CoreReaderFragment.kt

@@ -1543,10 +1543,20 @@ abstract class CoreReaderFragment :
     )
   }
 
-  private suspend fun openAndSetInContainer(zimReaderSource: ZimReaderSource) {
+  /**
+   * Creates the ZimFileReader and loads the MainPage.
+   * Subclasses override this method to provide the showSearchSuggestion based on configuration.
+   *
+   * WARNING: If modifying this method, ensure thorough testing with custom apps
+   * to verify proper functionality.
+   */
+  open suspend fun openAndSetInContainer(
+    zimReaderSource: ZimReaderSource,
+    showSearchSuggestionsSpellChecked: Boolean = false
+  ) {
     clearWebViewListIfNotPreviouslyOpenZimFile(zimReaderSource)
     zimReaderContainer?.let { zimReaderContainer ->
-      zimReaderContainer.setZimReaderSource(zimReaderSource)
+      zimReaderContainer.setZimReaderSource(zimReaderSource, showSearchSuggestionsSpellChecked)
 
       zimReaderContainer.zimFileReader?.let { zimFileReader ->
         // uninitialized the service worker to fix https://github.com/kiwix/kiwix-android/issues/2561

core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimFileReader.kt

@@ -24,16 +24,23 @@ import android.util.Base64
 import androidx.core.net.toUri
 import eu.mhutti1.utils.storage.KB
 import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
 import kotlinx.coroutines.withContext
 import org.kiwix.kiwixmobile.core.CoreApp
 import org.kiwix.kiwixmobile.core.entity.LibkiwixBook
 import org.kiwix.kiwixmobile.core.main.UNINITIALISER_ADDRESS
 import org.kiwix.kiwixmobile.core.main.UNINITIALISE_HTML
 import org.kiwix.kiwixmobile.core.reader.ZimFileReader.Companion.CONTENT_PREFIX
+import org.kiwix.kiwixmobile.core.utils.TAG_KIWIX
 import org.kiwix.kiwixmobile.core.utils.files.FileUtils
+import org.kiwix.kiwixmobile.core.utils.files.FileUtils.getSpellingDBDir
 import org.kiwix.kiwixmobile.core.utils.files.Log
 import org.kiwix.libkiwix.JNIKiwixException
+import org.kiwix.libkiwix.SpellingsDB
 import org.kiwix.libzim.Archive
 import org.kiwix.libzim.DirectAccessInfo
 import org.kiwix.libzim.Item
@@ -57,20 +64,33 @@ class ZimFileReader constructor(
   private val searcher: SuggestionSearcher
 ) {
   interface Factory {
-    suspend fun create(zimReaderSource: ZimReaderSource): ZimFileReader?
+    suspend fun create(
+      zimReaderSource: ZimReaderSource,
+      showSearchSuggestionsSpellChecked: Boolean
+    ): ZimFileReader?
 
     class Impl @Inject constructor() : Factory {
       @Suppress("InjectDispatcher")
-      override suspend fun create(zimReaderSource: ZimReaderSource): ZimFileReader? =
+      override suspend fun create(
+        zimReaderSource: ZimReaderSource,
+        showSearchSuggestionsSpellChecked: Boolean
+      ): ZimFileReader? =
         withContext(Dispatchers.IO) { // Bug Fix #3805
           try {
             zimReaderSource.createArchive()?.let {
               ZimFileReader(
                 zimReaderSource,
                 jniKiwixReader = it,
-                searcher = SuggestionSearcher(it)
-              ).also {
+                searcher = SuggestionSearcher(it),
+              ).also { zimFileReader ->
                 Log.e(TAG, "create: ${zimReaderSource.toDatabase()}")
+                if (showSearchSuggestionsSpellChecked) {
+                  // Prepare the SpellingsDB asynchronously(when it configure to create) so that creating the
+                  // ZIM reader doesn’t block the user experience.
+                  CoroutineScope(Dispatchers.IO).launch {
+                    zimFileReader.prepareSpellingsDB(zimFileReader.jniKiwixReader)
+                  }
+                }
               }
             } ?: kotlin.run {
               Log.e(
@@ -101,6 +121,8 @@ class ZimFileReader constructor(
     }
   }
 
+  private var spellingsDB: SpellingsDB? = null
+
   /**
    * Note that the value returned is NOT unique for each zim file. Versions of the same wiki
    * (complete, nopic, novid, etc) may return the same title.
@@ -173,6 +195,52 @@ class ZimFileReader constructor(
       null
     }
 
+  /**
+   * Initializes the `SpellingsDB` instance using the currently opened ZIM archive.
+   *
+   * This prepares the spell correction database used by libkiwix
+   * for suggesting alternative or corrected search terms.
+   */
+  suspend fun prepareSpellingsDB(archive: Archive) {
+    spellingsDBCreationMutex.withLock {
+      if (spellingsDB != null) {
+        Log.d(TAG_KIWIX, "SpellingsDB already initialized, skipping.")
+        return
+      }
+      runCatching {
+        Log.d(TAG_KIWIX, "Initializing SpellingsDB")
+        val cachedDir = getSpellingDBDir(CoreApp.instance)?.absolutePath
+        spellingsDB = SpellingsDB(archive, cachedDir)
+        Log.d(TAG_KIWIX, "SpellingsDB successfully initialized.")
+      }.onFailure {
+        Log.e(
+          TAG_KIWIX,
+          "Failed to initialize SpellingsDB: ${it.message}",
+          it
+        )
+      }
+    }
+  }
+
+  /**
+   * Retrieves a list of suggested or corrected spellings for a given search term.
+   *
+   * @param word The search term for which to retrieve spelling suggestions.
+   * @param maxCount The maximum number of suggestions to return.
+   * @return A list of suggested words ordered by relevance, or an empty list if
+   *         suggestions are unavailable or the SpellingsDB is not initialized.
+   */
+  fun getSuggestedSpelledWords(word: String, maxCount: Int): List<String> =
+    runCatching {
+      spellingsDB?.getSpellingCorrections(word, maxCount)?.toList().orEmpty()
+    }.onFailure {
+      Log.e(
+        TAG,
+        "Error fetching suggested spellings: ${it.message}",
+        it
+      )
+    }.getOrDefault(emptyList())
+
   fun getPageUrlFrom(title: String): String? =
     try {
       jniKiwixReader.getEntryByTitle(title).path
@@ -386,6 +454,7 @@ class ZimFileReader constructor(
   fun dispose() {
     jniKiwixReader.dispose()
     searcher.dispose()
+    spellingsDB?.dispose()
   }
 
   @Suppress("TooGenericExceptionCaught")
@@ -397,6 +466,8 @@ class ZimFileReader constructor(
     }
 
   companion object {
+    private val spellingsDBCreationMutex = Mutex()
+
     /*
      * these uris aren't actually nullable but unit tests fail to compile as
      * Uri.parse returns null without android dependencies loaded

core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimReaderContainer.kt

@@ -35,13 +35,16 @@ class ZimReaderContainer @Inject constructor(private val zimFileReaderFactory: F
     }
 
   @Suppress("InjectDispatcher")
-  suspend fun setZimReaderSource(zimReaderSource: ZimReaderSource?) {
+  suspend fun setZimReaderSource(
+    zimReaderSource: ZimReaderSource?,
+    showSearchSuggestionsSpellChecked: Boolean = false
+  ) {
     if (zimReaderSource == zimFileReader?.zimReaderSource) {
       return
     }
     zimFileReader = withContext(Dispatchers.IO) {
       if (zimReaderSource?.exists() == true && zimReaderSource.canOpenInLibkiwix()) {
-        zimFileReaderFactory.create(zimReaderSource)
+        zimFileReaderFactory.create(zimReaderSource, showSearchSuggestionsSpellChecked)
       } else {
         null
       }

core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimReaderSource.kt

@@ -24,6 +24,7 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.FileProvider
 import androidx.core.net.toUri
 import org.kiwix.kiwixmobile.core.CoreApp
+import org.kiwix.kiwixmobile.core.downloader.downloadManager.ZERO
 import org.kiwix.kiwixmobile.core.extensions.canReadFile
 import org.kiwix.kiwixmobile.core.extensions.isFileExist
 import org.kiwix.kiwixmobile.core.utils.files.FileUtils.getAssetFileDescriptorFromUri
@@ -60,7 +61,7 @@ class ZimReaderSource(
     return when {
       file != null -> file.isFileExist()
       assetFileDescriptorList?.isNotEmpty() == true ->
-        assetFileDescriptorList[0].parcelFileDescriptor.fileDescriptor.valid()
+        assetFileDescriptorList.first().parcelFileDescriptor.fileDescriptor.valid()
 
       else -> false
     }
@@ -69,7 +70,7 @@ class ZimReaderSource(
   suspend fun canOpenInLibkiwix(): Boolean {
     return when {
       file?.canReadFile() == true -> true
-      assetFileDescriptorList?.get(0)?.parcelFileDescriptor?.fd
+      assetFileDescriptorList?.first()?.parcelFileDescriptor?.fd
         ?.let(::isFileDescriptorCanOpenWithLibkiwix) == true -> true
 
       else -> false
@@ -109,12 +110,25 @@ class ZimReaderSource(
 
   fun toDatabase(): String = file?.canonicalPath ?: uri.toString()
 
+  /**
+   * Compares two sources for equality based on the underlying file, URI,
+   * or descriptor list.
+   */
   override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is ZimReaderSource) return false
     return when {
-      file != null && other is ZimReaderSource && other.file != null ->
+      file != null && other.file != null ->
         file.canonicalPath == other.file.canonicalPath
 
-      uri != null && other is ZimReaderSource && other.uri != null -> uri == other.uri
+      uri != null && other.uri != null -> uri == other.uri
+
+      !assetFileDescriptorList.isNullOrEmpty() && !other.assetFileDescriptorList.isNullOrEmpty() ->
+        assetFileDescriptorList.size == other.assetFileDescriptorList.size &&
+          assetFileDescriptorList.zip(other.assetFileDescriptorList).all { (a, b) ->
+            a.startOffset == b.startOffset && a.length == b.length
+          }
+
       else -> false
     }
   }
@@ -133,5 +147,12 @@ class ZimReaderSource(
     }
   }
 
-  override fun hashCode(): Int = file?.hashCode() ?: assetFileDescriptorList.hashCode()
+  override fun hashCode(): Int = when {
+    file != null -> file.canonicalPath.hashCode()
+    uri != null -> uri.hashCode()
+    !assetFileDescriptorList.isNullOrEmpty() ->
+      assetFileDescriptorList.sumOf { it.startOffset.hashCode() + it.length.hashCode() }
+
+    else -> ZERO
+  }
 }

core/src/main/java/org/kiwix/kiwixmobile/core/search/SearchFragment.kt

@@ -51,6 +51,7 @@ import org.kiwix.kiwixmobile.core.search.viewmodel.Action.ClickedSearchInText
 import org.kiwix.kiwixmobile.core.search.viewmodel.Action.OnItemClick
 import org.kiwix.kiwixmobile.core.search.viewmodel.Action.OnItemLongClick
 import org.kiwix.kiwixmobile.core.search.viewmodel.Action.OnOpenInNewTabClick
+import org.kiwix.kiwixmobile.core.search.viewmodel.MAX_SUGGEST_WORD_COUNT
 import org.kiwix.kiwixmobile.core.search.viewmodel.SearchOrigin.FromWebView
 import org.kiwix.kiwixmobile.core.search.viewmodel.SearchState
 import org.kiwix.kiwixmobile.core.search.viewmodel.SearchViewModel
@@ -102,7 +103,9 @@ class SearchFragment : BaseFragment() {
       onLoadMore = { loadMoreSearchResult() },
       onKeyboardSubmitButtonClick = {
         getSearchListItemForQuery(it)?.let(::onItemClick)
-      }
+      },
+      spellingCorrectionSuggestions = emptyList(),
+      onSuggestionClick = { onSuggestionItemClick(it) }
     )
   )
 
@@ -247,6 +250,11 @@ class SearchFragment : BaseFragment() {
     searchViewModel.searchResults(searchText.trim())
   }
 
+  private fun onSuggestionItemClick(suggestionText: String) {
+    searchScreenState.update { copy(spellingCorrectionSuggestions = emptyList()) }
+    onSearchValueChanged(suggestionText)
+  }
+
   private fun actionMenuItems() = listOfNotNull(
     // Check if the `FIND_IN_PAGE` is visible or not.
     // If visible then show it in menu.
@@ -304,11 +312,34 @@ class SearchFragment : BaseFragment() {
             "Error in getting searched result\nOriginal exception ${ignore.message}"
           )
         } finally {
-          searchScreenState.update { copy(isLoading = false) }
+          updateSuggestedWords()
         }
       }
   }
 
+  /**
+   * Updates the suggested word list using the libkiwix spellings database.
+   */
+  private suspend fun updateSuggestedWords() {
+    val onlyRecentSearches =
+      searchScreenState.value.searchList.all { it is SearchListItem.RecentSearchListItem }
+
+    if (onlyRecentSearches && searchScreenState.value.searchText.isNotEmpty()) {
+      val suggestedWords = searchViewModel.getSuggestedSpelledWords(
+        searchScreenState.value.searchText,
+        MAX_SUGGEST_WORD_COUNT
+      )
+
+      searchScreenState.update {
+        copy(spellingCorrectionSuggestions = suggestedWords, isLoading = false)
+      }
+    } else {
+      searchScreenState.update {
+        copy(spellingCorrectionSuggestions = emptyList(), isLoading = false)
+      }
+    }
+  }
+
   private fun setIsPageSearchEnabled(searchText: String) {
     findInPageMenuItem.value = searchText.isNotBlank() to findInPageMenuItem.value.second
   }