Do not copy if source path == destination path

src/main/java/com/kdanmobile/reader/copyfile/CopyFileViewModel.kt

@@ -13,6 +13,21 @@ import io.reactivex.schedulers.Schedulers
 import java.io.File
 import java.lang.Exception
 
+/**
+ * 1. if info.shouldCopyFile == false,
+ *          just call onCopySuccess() to send Event.Success(destination path)
+ * 2. if source path == destination path,
+ *          just call onCopySuccess() to send Event.Success(destination path)
+ * 3. if the application has no permission,
+ *          send Event.Failed(destination path, FileNotFoundException) and delete the destination file
+ * 4. if an IOException is thrown during copying,
+ *          send Event.Failed(destination path, FileNotFoundException) and delete the destination file
+ * 5. otherwise, when CopyFileViewModel finishes copying file,
+ *          call onCopySuccess() to send Event.Success(destination path)
+ *
+ * Finally, when CopyFileViewModel::onCleared() is called, delete the destination file if it is not complete copied
+*/
+
 class CopyFileViewModel(applicationContext: Context,
                         private val info: CopyFileInfo,
                         private val eventManager: EventManager<Event> = EventManager()
@@ -49,6 +64,11 @@ class CopyFileViewModel(applicationContext: Context,
                 null
             }
             srcFilePath = source?.getFilePath()
+
+            if (isSrcFileEqualsDstFile()) {
+                onCopySuccess()
+            }
+
             val fullFileSize = Math.max(1, source?.getFileSize() ?: 1)
             val task = CopyFileTask()
             task.setCopyMode(CopyFileTask.Mode.CREATE_NEW_FILE)
@@ -69,6 +89,15 @@ class CopyFileViewModel(applicationContext: Context,
         }
     }
 
+    //  check the destination path is the same with the source path or not
+    private fun isSrcFileEqualsDstFile(): Boolean {
+        return try {
+            (!srcFilePath.isNullOrEmpty() && File(srcFilePath).canonicalPath == File(dstFilePath).canonicalPath)
+        } catch (e: Exception) {
+            false
+        }
+    }
+
     private fun onCopyFailed(e: Throwable) {
         if (!hasCompleteCopy) {
             deleteDstFile()
@@ -87,11 +116,6 @@ class CopyFileViewModel(applicationContext: Context,
 
     private fun deleteDstFile() {
         dstFilePath?.apply {
-            //  do not delete the destination file if it is also the source file
-            try {
-                if (!srcFilePath.isNullOrEmpty() && File(srcFilePath).canonicalPath == File(dstFilePath).canonicalPath) return
-            } catch (e: Exception) {}
-
             val file = File(this)
             if (file.exists()) {
                 file.delete()