fixed a bug that caused it to send the wrong file size plus changed the way file hash gets sent from an actual hash to just file size for now for pure speed. Will see to change it in the future.

Author: GoldenDragonJD

mainwindow.cpp

@@ -90,16 +90,44 @@ QString fileChecksum(const QString &fileName, QCryptographicHash::Algorithm hash
         return "";
     }
 
+    qint64 fileSize = file.size();
     QCryptographicHash hash(hashAlgorithm);
-    if (hash.addData(&file))
-    {
-        return hash.result().toBase64();
-    }
-    else
+
+    // 1. Always hash the exact file size first to prevent collisions
+    // between files of different sizes that share the same sampled bytes.
+    hash.addData(QByteArray::number(fileSize));
+
+    // Set our sample size to 1 Megabyte
+    const qint64 sampleSize = 1024 * 1024;
+
+    // 2. If the file is 3MB or smaller, it's faster to just hash the whole thing normally.
+    if (fileSize <= sampleSize * 3)
     {
-        qDebug() << "Failed to add file data to hash engine.";
-        return "";
+        if (hash.addData(&file)) {
+            return hash.result().toBase64();
+        } else {
+            qDebug() << "Failed to add file data to hash engine.";
+            return "";
+        }
     }
+
+    // 3. --- THE CHEAT CODE: Partial Hashing for Big Files ---
+
+    // Read the first 1MB
+    file.seek(0);
+    hash.addData(file.read(sampleSize));
+
+    // Read the middle 1MB
+    qint64 middleOffset = (fileSize / 2) - (sampleSize / 2);
+    file.seek(middleOffset);
+    hash.addData(file.read(sampleSize));
+
+    // Read the last 1MB
+    qint64 endOffset = fileSize - sampleSize;
+    file.seek(endOffset);
+    hash.addData(file.read(sampleSize));
+
+    return hash.result().toBase64();
 }
 
 QByteArray MainWindow::sendEncryptionRequest()
@@ -658,7 +686,8 @@ MainWindow::MainWindow(QWidget *parent)
 
                         if (checkFile.exists())
                         {
-                            QString localHash = fileChecksum(fullLocalPath, QCryptographicHash::Sha256);
+                            QFileInfo info(fullLocalPath);
+                            QString localHash = QString::number(info.size());
                             if (localHash == remoteHash)
                             {
                                 skipList.append(relPath); // It matches! Tell sender to skip it.
@@ -1546,11 +1575,15 @@ void MainWindow::sendDirectories()
     QJsonArray folderPaths;
     QVector<QString> filesToSend;
 
+    int current_file = 0;
+
     // --- BATCHING SETUP ---
     QJsonArray manifestArray;
 
     while (itfolders.hasNext())
     {
+        QCoreApplication::processEvents();
+
         auto entity = itfolders.nextFileInfo();
 
         if (entity.isDir())
@@ -1577,8 +1610,10 @@ void MainWindow::sendDirectories()
             fileInfo["path"] = relativePath;
 
             // NOTE: You can use fileChecksum here, or info.size() + info.lastModified() for even more speed!
-            fileInfo["hash"] = fileChecksum(filePath, QCryptographicHash::Sha256);
+            fileInfo["hash"] = QString::number(entity.size());
             manifestArray.append(fileInfo);
+
+            ui->statusbar->showMessage("Computing Hash for: " + entity.fileName());
         }
     }