Implemented error handling for cases when the selected file is not a ZIM file.

* We retrieve the file name from the incoming Uri using `DocumentFile` (the official way to handle Uris) and check if it contains `.zim` or `.zimma` before proceeding with the copy/move operation. If the file name is null, we copy/move the file first and then validate it as a ZIM file using `libkiwix`. If valid, the file opens in our reader; otherwise, we revert the copy/move operation.
* Added test cases for this new functionality.

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

@@ -28,6 +28,7 @@ import android.view.View
 import android.widget.ProgressBar
 import android.widget.TextView
 import androidx.appcompat.app.AlertDialog
+import androidx.core.net.toUri
 import androidx.documentfile.provider.DocumentFile
 import io.reactivex.android.schedulers.AndroidSchedulers
 import io.reactivex.disposables.Disposable
@@ -40,6 +41,7 @@ import org.kiwix.kiwixmobile.R.layout
 import org.kiwix.kiwixmobile.core.R
 import org.kiwix.kiwixmobile.core.extensions.deleteFile
 import org.kiwix.kiwixmobile.core.extensions.isFileExist
+import org.kiwix.kiwixmobile.core.reader.ZimReaderSource
 import org.kiwix.kiwixmobile.core.settings.StorageCalculator
 import org.kiwix.kiwixmobile.core.utils.SharedPreferenceUtil
 import org.kiwix.kiwixmobile.core.utils.dialog.AlertDialogShower
@@ -69,7 +71,8 @@ class CopyMoveFileHandler @Inject constructor(
   private var lifecycleScope: CoroutineScope? = null
   private var progressBar: ProgressBar? = null
   private var progressBarTextView: TextView? = null
-  private var isMoveOperation = false
+  var isMoveOperation = false
+  private var shouldValidateZimFile: Boolean = false
   private var fileSystemDisposable: Disposable? = null
 
   private val copyMoveTitle: String by lazy {
@@ -87,7 +90,12 @@ class CopyMoveFileHandler @Inject constructor(
     }
   }
 
-  fun showMoveFileToPublicDirectoryDialog(uri: Uri? = null, documentFile: DocumentFile? = null) {
+  fun showMoveFileToPublicDirectoryDialog(
+    uri: Uri? = null,
+    documentFile: DocumentFile? = null,
+    shouldValidateZimFile: Boolean = false
+  ) {
+    this.shouldValidateZimFile = shouldValidateZimFile
     setSelectedFileAndUri(uri, documentFile)
     if (!sharedPreferenceUtil.copyMoveZimFilePermissionDialog) {
       showMoveToPublicDirectoryPermissionDialog()
@@ -210,50 +218,63 @@ class CopyMoveFileHandler @Inject constructor(
         showProgressDialog()
         copyFile(sourceUri, destinationFile)
         withContext(Dispatchers.Main) {
-          notifyFileOperationSuccess(destinationFile)
+          notifyFileOperationSuccess(destinationFile, sourceUri)
         }
       } catch (ignore: Exception) {
         ignore.printStackTrace()
-        handleFileOperationError(ignore.message, destinationFile)
+        handleFileOperationError(
+          activity.getString(R.string.copy_file_error_message, ignore.message),
+          destinationFile
+        )
       }
     }
   }
 
+  @Suppress("UnsafeCallOnNullableType")
   private fun moveZimFileToPublicAppDirectory() {
     lifecycleScope?.launch {
       val destinationFile = getDestinationFile()
       try {
         val sourceUri = selectedFileUri ?: throw FileNotFoundException("Selected file not found")
         showProgressDialog()
-        var moveSuccess = false
-        if (tryMoveWithDocumentContract(sourceUri)) {
-          moveSuccess = true
-        } else {
-          moveSuccess = true
+        val moveSuccess = selectedFile?.parentFile?.uri?.let { parentUri ->
+          tryMoveWithDocumentContract(
+            sourceUri,
+            parentUri,
+            DocumentFile.fromFile(File(sharedPreferenceUtil.prefStorage)).uri
+          )
+        } ?: run {
           copyFile(sourceUri, destinationFile)
-          deleteSourceFile(sourceUri)
+          true
         }
         withContext(Dispatchers.Main) {
           if (moveSuccess) {
-            notifyFileOperationSuccess(destinationFile)
+            notifyFileOperationSuccess(destinationFile, sourceUri)
           } else {
-            handleFileOperationError("File move failed", destinationFile)
+            handleFileOperationError(
+              activity.getString(R.string.move_file_error_message, "File move failed"),
+              destinationFile
+            )
           }
         }
       } catch (ignore: Exception) {
         ignore.printStackTrace()
-        handleFileOperationError(ignore.message, destinationFile)
+        handleFileOperationError(
+          activity.getString(R.string.move_file_error_message, ignore.message),
+          destinationFile
+        )
       }
     }
   }
 
-  @Suppress("UnsafeCallOnNullableType")
-  private fun tryMoveWithDocumentContract(selectedUri: Uri): Boolean {
+  fun tryMoveWithDocumentContract(
+    selectedUri: Uri,
+    sourceParentFolderUri: Uri,
+    destinationFolderUri: Uri
+  ): Boolean {
     return try {
       val contentResolver = activity.contentResolver
       if (documentCanMove(selectedUri, contentResolver)) {
-        val sourceParentFolderUri = selectedFile?.parentFile!!.uri
-        val destinationFolderUri = DocumentFile.fromFile(File(sharedPreferenceUtil.prefStorage)).uri
 
         DocumentsContract.moveDocument(
           contentResolver,
@@ -289,17 +310,12 @@ class CopyMoveFileHandler @Inject constructor(
     return flags and DocumentsContract.Document.FLAG_SUPPORTS_MOVE != 0
   }
 
-  private fun handleFileOperationError(
+  fun handleFileOperationError(
     errorMessage: String?,
     destinationFile: File
   ) {
     dismissProgressDialog()
-    val userFriendlyMessage = if (isMoveOperation) {
-      activity.getString(R.string.move_file_error_message, errorMessage)
-    } else {
-      activity.getString(R.string.copy_file_error_message, errorMessage)
-    }
-    fileCopyMoveCallback?.onError(userFriendlyMessage).also {
+    fileCopyMoveCallback?.onError("$errorMessage").also {
       // Clean up the destination file if an error occurs
       lifecycleScope?.launch {
         destinationFile.deleteFile()
@@ -307,16 +323,55 @@ class CopyMoveFileHandler @Inject constructor(
     }
   }
 
-  private fun notifyFileOperationSuccess(destinationFile: File) {
+  suspend fun notifyFileOperationSuccess(destinationFile: File, sourceUri: Uri) {
+    if (shouldValidateZimFile && !isValidZimFile(destinationFile)) {
+      handleInvalidZimFile(destinationFile, sourceUri)
+      return
+    }
     dismissProgressDialog()
     if (isMoveOperation) {
+      deleteSourceFile(sourceUri)
       fileCopyMoveCallback?.onFileMoved(destinationFile)
     } else {
       fileCopyMoveCallback?.onFileCopied(destinationFile)
     }
   }
 
-  private fun deleteSourceFile(uri: Uri) {
+  fun handleInvalidZimFile(destinationFile: File, sourceUri: Uri) {
+    val errorMessage = activity.getString(R.string.error_file_invalid)
+    if (isMoveOperation) {
+      val moveSuccessful = tryMoveWithDocumentContract(
+        destinationFile.toUri(),
+        destinationFile.parentFile.toUri(),
+        sourceUri
+      )
+
+      if (moveSuccessful) {
+        // If files is moved back using the documentContract then show the error message to user
+        dismissProgressDialog()
+        fileCopyMoveCallback?.onError(errorMessage)
+      } else {
+        // Show error message and delete the moved file if move failed.
+        handleFileOperationError(errorMessage, destinationFile)
+      }
+    } else {
+      // For copy operation, show error message and delete the copied file.
+      handleFileOperationError(errorMessage, destinationFile)
+    }
+  }
+
+  suspend fun isValidZimFile(destinationFile: File): Boolean {
+    return try {
+      // create archive object, and check if it has the mainEntry or not to validate the ZIM file.
+      val archive = ZimReaderSource(destinationFile).createArchive()
+      archive?.hasMainEntry() == true
+    } catch (ignore: Exception) {
+      // if it is a invalid ZIM file
+      false
+    }
+  }
+
+  fun deleteSourceFile(uri: Uri) {
     try {
       DocumentsContract.deleteDocument(activity.applicationContext.contentResolver, uri)
     } catch (ignore: Exception) {
@@ -413,7 +468,7 @@ class CopyMoveFileHandler @Inject constructor(
     progressBarDialog?.show()
   }
 
-  private fun dismissProgressDialog() {
+  fun dismissProgressDialog() {
     if (progressBarDialog?.isShowing == true) {
       progressBarDialog?.dismiss()
     }

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

@@ -415,9 +415,19 @@ class LocalLibraryFragment : BaseFragment(), CopyMoveFileHandler.FileCopyMoveCal
           DocumentFile.fromSingleUri(requireActivity(), uri)
         }
       }
+      // If the file is not valid, it shows an error message and stops further processing.
+      // If the file name is not found, then let them to copy the file
+      // and we will handle this later.
+      val fileName = documentFile?.name
+      if (fileName != null && !FileUtils.isValidZimFile(fileName)) {
+        activity.toast(string.error_file_invalid)
+        return
+      }
       copyMoveFileHandler?.showMoveFileToPublicDirectoryDialog(
         uri,
-        documentFile
+        documentFile,
+        // pass if fileName is null then we will validate it after copying/moving
+        fileName == null
       )
     } else {
       getZimFileFromUri(uri)?.let(::navigateToReaderFragment)

app/src/test/java/org/kiwix/kiwixmobile/localLibrary/CopyMoveFileHandlerTest.kt

@@ -19,17 +19,22 @@
 package org.kiwix.kiwixmobile.localLibrary
 
 import android.app.Activity
+import android.net.Uri
 import androidx.documentfile.provider.DocumentFile
 import io.mockk.Runs
 import io.mockk.clearAllMocks
+import io.mockk.coEvery
+import io.mockk.coVerify
 import io.mockk.every
 import io.mockk.just
 import io.mockk.mockk
+import io.mockk.mockkConstructor
 import io.mockk.slot
 import io.mockk.spyk
 import io.mockk.verify
 import kotlinx.coroutines.test.StandardTestDispatcher
 import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.runTest
 import org.junit.jupiter.api.AfterEach
 import org.junit.jupiter.api.Assertions.assertFalse
 import org.junit.jupiter.api.Assertions.assertTrue
@@ -46,6 +51,9 @@ import org.kiwix.kiwixmobile.zimManager.Fat32Checker.FileSystemState.CanWrite4Gb
 import org.kiwix.kiwixmobile.zimManager.Fat32Checker.FileSystemState.CannotWrite4GbFile
 import org.kiwix.kiwixmobile.zimManager.Fat32Checker.FileSystemState.DetectingFileSystem
 import java.io.File
+import org.kiwix.kiwixmobile.core.R
+import org.kiwix.kiwixmobile.core.reader.ZimReaderSource
+import org.kiwix.libzim.Archive
 
 class CopyMoveFileHandlerTest {
   private lateinit var fileHandler: CopyMoveFileHandler
@@ -61,6 +69,8 @@ class CopyMoveFileHandlerTest {
   private val storageFile: File = mockk(relaxed = true)
   private val selectedFile: DocumentFile = mockk(relaxed = true)
   private val storagePath = "storage/0/emulated/Android/media/org.kiwix.kiwixmobile"
+  private val destinationFile = mockk<File>()
+  private val sourceUri = mockk<Uri>()
 
   @BeforeEach
   fun setup() {
@@ -76,6 +86,7 @@ class CopyMoveFileHandlerTest {
       setLifeCycleScope(testScope)
       setFileCopyMoveCallback(this@CopyMoveFileHandlerTest.fileCopyMoveCallback)
     }
+    every { destinationFile.canRead() } returns true
   }
 
   @Test
@@ -292,6 +303,91 @@ class CopyMoveFileHandlerTest {
     every { fat32Checker.fileSystemStates.value } returns fileSystemState
   }
 
+  @Test
+  fun notifyFileOperationSuccessShouldCallOnFileMovedIfValidZIMFileAndIsMoveOperationIsTrue() =
+    runTest {
+      fileHandler = spyk(fileHandler)
+      coEvery { fileHandler.isValidZimFile(destinationFile) } returns true
+      fileHandler.isMoveOperation = true
+
+      fileHandler.notifyFileOperationSuccess(destinationFile, sourceUri)
+
+      verify { fileCopyMoveCallback.onFileMoved(destinationFile) }
+      verify { fileHandler.dismissProgressDialog() }
+      coVerify { fileHandler.deleteSourceFile(sourceUri) }
+    }
+
+  @Test
+  fun notifyFileOperationSuccessShouldCallOnFileCopiedIfValidZIMFileAndIsMoveOperationIsFalse() =
+    runTest {
+      fileHandler = spyk(fileHandler)
+      coEvery { fileHandler.isValidZimFile(destinationFile) } returns true
+      fileHandler.isMoveOperation = false
+
+      fileHandler.notifyFileOperationSuccess(destinationFile, sourceUri)
+
+      verify { fileCopyMoveCallback.onFileCopied(destinationFile) }
+      verify { fileHandler.dismissProgressDialog() }
+    }
+
+  @Test
+  fun `notifyFileOperationSuccess should handle invalid ZIM file`() = runTest {
+    mockkConstructor(Archive::class)
+    val archiveMock = mockk<Archive>(relaxed = true)
+    every { constructedWith<Archive>(any()) } returns archiveMock
+    coEvery { fileHandler.isValidZimFile(destinationFile) } returns false
+
+    fileHandler.notifyFileOperationSuccess(destinationFile, sourceUri)
+
+    verify { fileHandler.handleInvalidZimFile(destinationFile, sourceUri) }
+  }
+
+  @Test
+  fun `handleInvalidZimFile should call onError if move is successful`() {
+    every { fileHandler.tryMoveWithDocumentContract(any(), any(), any()) } returns true
+    fileHandler.isMoveOperation = true
+
+    fileHandler.handleInvalidZimFile(destinationFile, sourceUri)
+
+    verify { fileHandler.dismissProgressDialog() }
+    verify { fileCopyMoveCallback.onError(activity.getString(R.string.error_file_invalid)) }
+  }
+
+  @Test
+  fun `handleInvalidZimFile should delete file and show error if move fails`() {
+    every { fileHandler.tryMoveWithDocumentContract(any(), any(), any()) } returns false
+    fileHandler.isMoveOperation = true
+
+    fileHandler.handleInvalidZimFile(destinationFile, sourceUri)
+
+    verify {
+      fileHandler.handleFileOperationError(
+        activity.getString(R.string.error_file_invalid),
+        destinationFile
+      )
+    }
+  }
+
+  @Test
+  fun `isValidZimFile should return true if ZIM file has main entry`() = runTest {
+    val archive: Archive = mockk()
+    every { archive.hasMainEntry() } returns true
+    coEvery { ZimReaderSource(destinationFile).createArchive() } returns archive
+
+    val result = fileHandler.isValidZimFile(destinationFile)
+
+    assertTrue(result)
+  }
+
+  @Test
+  fun `isValidZimFile should return false if ZIM file creation fails`() = runTest {
+    coEvery { ZimReaderSource(destinationFile).createArchive() } throws Exception()
+
+    val result = fileHandler.isValidZimFile(destinationFile)
+
+    assertFalse(result)
+  }
+
   @AfterEach
   fun dispose() {
     fileHandler.dispose()