#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QFileDialog>
#include <QDebug>
#include <QTimer>

MainWindow::MainWindow(QWidget *parent) :
  QMainWindow(parent),
  ui(new Ui::MainWindow)
{
  ui->setupUi(this);
  buffer = new char[bufsize];
  file = new QFile;
}

MainWindow::~MainWindow()
{
  delete file;
  delete [] buffer;
  delete ui;
}

void MainWindow::on_actionOpen_triggered()
{
  QString fileName = QFileDialog::getOpenFileName(this, tr("Open File"));
  if (!fileName.isEmpty())
    openFile(fileName);
}


void MainWindow::openFile(QString filePath)
{
  ui->plainTextEdit->clear();
  file->setFileName(filePath);
  if (file->open(QFile::ReadOnly))
    QTimer::singleShot(10, this, SLOT(readFilePart()));

  startRead.start();
  ui->plainTextEdit->viewport()->setCursor(Qt::WaitCursor);
  ui->plainTextEdit->setUpdatesEnabled(false);
}


void MainWindow::readFilePart()
{
  qint64 bytesRead = file->read(buffer, bufsize - 1);
  buffer[bytesRead] = 0;
  ui->plainTextEdit->appendPlainText(buffer);

  qDebug() << "duration:" << startRead.elapsed() << ", bytesRead:" << bytesRead;

  if (bytesRead == bufsize - 1)
    QTimer::singleShot(10, this, SLOT(readFilePart()));
  else
  {
    qDebug() << "rest: {" << buffer << "}";
    QTimer::singleShot(10, this, SLOT(closeFile()));
  }
}

void MainWindow::closeFile()
{
  file->close();
  ui->plainTextEdit->setUpdatesEnabled(true);
  ui->plainTextEdit->viewport()->unsetCursor();
}