Add drag-and-drop support for TEXT/CSV files

Author: sanjaysargam

AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt

@@ -660,7 +660,7 @@ open class DeckPicker :
 
             try {
                 // Intent is nullable because `clip.getItemAt(0).intent` always returns null
-                ImportUtils.FileImporter().handleContentProviderFile(this, uri)
+                ImportUtils.FileImporter().handleContentProviderFile(this, uri, Intent().setData(uri))
                 onResume()
             } catch (e: Exception) {
                 Timber.w(e)

AnkiDroid/src/main/java/com/ichi2/utils/ImportUtils.kt

@@ -33,6 +33,7 @@ import com.ichi2.anki.R
 import com.ichi2.anki.dialogs.DialogHandler
 import com.ichi2.anki.dialogs.DialogHandlerMessage
 import com.ichi2.anki.dialogs.ImportDialog
+import com.ichi2.anki.onSelectedCsvForImport
 import com.ichi2.anki.showImportDialog
 import com.ichi2.annotations.NeedsTest
 import com.ichi2.compat.CompatHelper
@@ -99,6 +100,9 @@ object ImportUtils {
     fun isFileAValidDeck(fileName: String): Boolean =
         FileImporter.hasExtension(fileName, "apkg") || FileImporter.hasExtension(fileName, "colpkg")
 
+    fun isFileValidTextOrCsv(fileName: String): Boolean =
+        FileImporter.hasExtension(fileName, "txt") || FileImporter.hasExtension(fileName, "csv")
+
     @SuppressWarnings("WeakerAccess")
     open class FileImporter {
         /**
@@ -200,7 +204,10 @@ object ImportUtils {
                 }
             }
             val tempOutDir: String
-            if (!isValidPackageName(filename)) {
+            if (isFileValidTextOrCsv(filename)) {
+                (context as Activity).onSelectedCsvForImport(intent!!)
+                return ImportResult.fromSuccess()
+            } else if (!isValidPackageName(filename)) {
                 return if (isAnkiDatabase(filename)) {
                     // .anki2 files aren't supported by Anki Desktop, we should eventually support them, because we can
                     // but for now, show a "nice" error.
@@ -242,6 +249,7 @@ object ImportUtils {
             return when {
                 isDeckPackage(fileName) -> true
                 isCollectionPackage(fileName) -> true
+                isFileValidTextOrCsv(fileName.toString()) -> true
                 else -> false
             }
         }