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

#include <QAction>
#include <QApplication>
#include <QClipboard>
#include <QCloseEvent>
#include <QCoreApplication>
#include <QDialog>
#include <QDialogButtonBox>
#include <QGuiApplication>
#include <QLabel>
#include <QMenu>
#include <QMessageBox>
#include <QPushButton>
#include <QSettings>
#include <QStatusBar>
#include <QStyle>
#include <QTimer>
#include <QVBoxLayout>

namespace {

  /**
   * @brief Builds a clickable HTML link for dialogs.
   * @param url URL to render.
   * @return Rich text string.
   */
  QString makeLinkHtml (const QUrl &url) {
    const QString urlText = url.toString (QUrl::FullyDecoded);
    return QStringLiteral ("<a href=\"%1\">%2</a>")
           .arg (url.toString (QUrl::FullyEncoded), urlText.toHtmlEscaped());
  }

  /**
   * @brief Returns the organization name used by QSettings.
   * @return Organization string.
   */
  QString settingsOrganization() {
    return QStringLiteral ("deeaitch");
  }

  /**
   * @brief Returns the application name used by QSettings.
   * @return Application string.
   */
  QString settingsApplication() {
    return QStringLiteral ("yourls-ui");
  }

} // namespace

/**
 * @brief Constructs the main window.
 * @param parent Parent widget.
 */
MainWindow::MainWindow (QWidget *parent)
  : QMainWindow (parent)
  , ui (new Ui::MainWindow)
  , m_trayIcon (nullptr)
  , m_trayMenu (nullptr)
  , m_cutUrlAction (nullptr)
  , m_settingsAction (nullptr)
  , m_helpAction (nullptr)
  , m_aboutAction (nullptr)
  , m_exitAction (nullptr)
  , m_yourlsClient (new YourlsClient (this)) {
  ui->setupUi (this);
  setWindowTitle (QStringLiteral ("yourls-ui settings"));
  ui->apiKeyLineEdit->setEchoMode (QLineEdit::Password);
  statusBar()->showMessage (QStringLiteral ("Configure YOURLS API settings and save."));

  setupMenuActions();
  setupTray();
  setupConnections();
  loadSettings();

  connect (m_yourlsClient, &YourlsClient::shortenSucceeded, this, &MainWindow::onShortenSucceeded);
  connect (m_yourlsClient, &YourlsClient::shortenFailed, this, &MainWindow::onShortenFailed);

  if (hasValidSettings()) {
    if (m_trayIcon != nullptr)
      m_trayIcon->show();
    QTimer::singleShot (0, this, &MainWindow::hideToTray);
  }
}

/**
 * @brief Destroys the main window.
 */
MainWindow::~MainWindow() {
  delete ui;
}

/**
 * @brief Handles close requests.
 * @param event Close event.
 */
void MainWindow::closeEvent (QCloseEvent *event) {
  if (hasValidSettings() && m_trayIcon != nullptr && m_trayIcon->isVisible()) {
    hideToTray();
    event->ignore();
    return;
  }

  QMainWindow::closeEvent (event);
}

/**
 * @brief Saves settings from the UI.
 */
void MainWindow::saveSettings() {
  const QString apiUrl = ui->urlLineEdit->text().trimmed();
  const QString apiKey = ui->apiKeyLineEdit->text().trimmed();

  if (apiUrl.isEmpty()) {
    QMessageBox::warning (this, QStringLiteral ("Missing API URL"), QStringLiteral ("Please enter the YOURLS API URL."));
    return;
  }

  if (apiKey.isEmpty()) {
    QMessageBox::warning (this, QStringLiteral ("Missing API key"), QStringLiteral ("Please enter the YOURLS API signature."));
    return;
  }

  const QUrl parsedApiUrl (apiUrl);
  if (!parsedApiUrl.isValid() || parsedApiUrl.scheme().isEmpty() || parsedApiUrl.host().isEmpty()) {
    QMessageBox::warning (this,
                          QStringLiteral ("Invalid API URL"),
                          QStringLiteral ("The configured API URL does not look valid."));
    return;
  }

  QSettings settings (settingsOrganization(), settingsApplication());
  settings.setValue (QStringLiteral ("api/url"), apiUrl);
  settings.setValue (QStringLiteral ("api/signature"), apiKey);
  settings.sync();

  if (m_trayIcon != nullptr)
    m_trayIcon->show();

  statusBar()->showMessage (QStringLiteral ("Settings saved."), 2000);
  hideToTray();
}

/**
 * @brief Shows About text.
 */
void MainWindow::showAbout() {
  QMessageBox::about (this,
                      QStringLiteral ("About yourls-ui"),
                      QStringLiteral ("yourls-ui\n\n"
                                      "Small tray utility for shortening clipboard URLs with a YOURLS API.\n\n"
                                      "Creator: deeaitch\n"
                                      "Created: 2026-03-16"));
}

/**
 * @brief Shows Help text.
 */
void MainWindow::showHelp() {
  QMessageBox::information (this,
                            QStringLiteral ("Help"),
                            QStringLiteral ("1. Open Settings and enter the YOURLS API URL and signature.\n"
                                "2. Save the settings. The application will stay in the tray.\n"
                                "3. Copy a full URL to the clipboard.\n"
                                "4. Right-click the tray icon and choose \"Cut URL\".\n"
                                "5. The short URL will be copied back to the clipboard and shown in a popup.\n\n"
                                "If something fails, the program shows detailed error information."));
}

/**
 * @brief Shows the settings window.
 */
void MainWindow::showSettingsWindow() {
  showNormal();
  raise();
  activateWindow();
}

/**
 * @brief Hides the settings window to tray when possible.
 */
void MainWindow::hideToTray() {
  if (!hasValidSettings()) {
    showSettingsWindow();
    return;
  }

  hide();
  if (m_trayIcon != nullptr && m_trayIcon->isVisible()) {
    m_trayIcon->showMessage (QStringLiteral ("yourls-ui"),
                             QStringLiteral ("The application is running in the system tray."),
                             QSystemTrayIcon::Information,
                             2000);
  }
}

/**
 * @brief Exits the application.
 */
void MainWindow::exitApplication() {
  QApplication::quit();
}

/**
 * @brief Handles tray icon activation.
 * @param reason Activation reason.
 */
void MainWindow::onTrayIconActivated (QSystemTrayIcon::ActivationReason reason) {
  if (reason == QSystemTrayIcon::DoubleClick || reason == QSystemTrayIcon::Trigger)
    showSettingsWindow();
}

/**
 * @brief Reads a URL from the clipboard and shortens it.
 */
void MainWindow::cutUrlFromClipboard() {
  if (!hasValidSettings()) {
    QMessageBox::warning (this,
                          QStringLiteral ("Settings required"),
                          QStringLiteral ("Please configure the API URL and signature first."));
    showSettingsWindow();
    return;
  }

  const QString clipboardText = QGuiApplication::clipboard()->text().trimmed();
  const QUrl longUrl = parseClipboardUrl (clipboardText);
  if (!longUrl.isValid()) {
    QMessageBox::warning (this,
                          QStringLiteral ("Invalid clipboard content"),
                          QStringLiteral ("The clipboard does not contain a valid URL."));
    return;
  }

  YourlsSettings settings;
  settings.apiUrl = ui->urlLineEdit->text().trimmed();
  settings.signature = ui->apiKeyLineEdit->text().trimmed();

  if (m_trayIcon != nullptr) {
    m_trayIcon->showMessage (QStringLiteral ("yourls-ui"),
                             QStringLiteral ("Requesting short URL..."),
                             QSystemTrayIcon::Information,
                             1200);
  }

  m_yourlsClient->shortenUrl (settings, longUrl);
}

/**
 * @brief Handles successful shortening.
 * @param shortUrl Generated short URL.
 */
void MainWindow::onShortenSucceeded (const QUrl &shortUrl) {
  QGuiApplication::clipboard()->setText (shortUrl.toString (QUrl::FullyDecoded));
  showShortUrlPopup (shortUrl);
}

/**
 * @brief Handles shortening failure.
 * @param details Detailed error text.
 */
void MainWindow::onShortenFailed (const QString &details) {
  QMessageBox::critical (this, QStringLiteral ("Failed to create short URL"), details);
}

/**
 * @brief Creates tray icon and tray menu.
 */
void MainWindow::setupTray() {
  if (!QSystemTrayIcon::isSystemTrayAvailable()) {
    QMessageBox::warning (this,
                          QStringLiteral ("System tray unavailable"),
                          QStringLiteral ("No system tray was detected. The application will stay as a normal window."));
    return;
  }

  m_trayIcon = new QSystemTrayIcon (this);
  m_trayIcon->setIcon (style()->standardIcon (QStyle::SP_DialogApplyButton));

  m_trayMenu = new QMenu (this);
  m_trayMenu->addAction (m_cutUrlAction);
  m_trayMenu->addSeparator();
  m_trayMenu->addAction (m_settingsAction);
  m_trayMenu->addAction (m_helpAction);
  m_trayMenu->addAction (m_aboutAction);
  m_trayMenu->addSeparator();
  m_trayMenu->addAction (m_exitAction);

  m_trayIcon->setContextMenu (m_trayMenu);
}

/**
 * @brief Connects UI signals to slots.
 */
void MainWindow::setupConnections() {
  connect (ui->saveBtn, &QPushButton::clicked, this, &MainWindow::saveSettings);

  connect (ui->actionHelp, &QAction::triggered, this, &MainWindow::showHelp);
  connect (ui->actionAbout, &QAction::triggered, this, &MainWindow::showAbout);
  connect (ui->actionExit, &QAction::triggered, this, &MainWindow::exitApplication);

  connect (m_cutUrlAction, &QAction::triggered, this, &MainWindow::cutUrlFromClipboard);
  connect (m_settingsAction, &QAction::triggered, this, &MainWindow::showSettingsWindow);
  connect (m_helpAction, &QAction::triggered, this, &MainWindow::showHelp);
  connect (m_aboutAction, &QAction::triggered, this, &MainWindow::showAbout);
  connect (m_exitAction, &QAction::triggered, this, &MainWindow::exitApplication);

  if (m_trayIcon != nullptr)
    connect (m_trayIcon, &QSystemTrayIcon::activated, this, &MainWindow::onTrayIconActivated);
}

/**
 * @brief Loads persisted settings into the UI.
 */
void MainWindow::loadSettings() {
  QSettings settings (settingsOrganization(), settingsApplication());
  ui->urlLineEdit->setText (settings.value (QStringLiteral ("api/url")).toString());
  ui->apiKeyLineEdit->setText (settings.value (QStringLiteral ("api/signature")).toString());
}

/**
 * @brief Returns true when all required settings are present.
 * @return True when the application can work from the tray.
 */
bool MainWindow::hasValidSettings() const {
  return !ui->urlLineEdit->text().trimmed().isEmpty()
         && !ui->apiKeyLineEdit->text().trimmed().isEmpty();
}

/**
 * @brief Validates and normalizes URL text.
 * @param text Input text.
 * @return Parsed URL.
 */
QUrl MainWindow::parseClipboardUrl (const QString &text) const {
  const QUrl url = QUrl::fromUserInput (text.trimmed());
  if (!url.isValid() || url.scheme().isEmpty() || url.host().isEmpty())
    return QUrl();
  return url;
}

/**
 * @brief Shows a popup with the generated short URL.
 * @param shortUrl Generated short URL.
 */
void MainWindow::showShortUrlPopup (const QUrl &shortUrl) {
  QDialog dialog (this);
  dialog.setWindowTitle (QStringLiteral ("Short URL created"));

  auto *layout = new QVBoxLayout (&dialog);
  auto *label = new QLabel (QStringLiteral ("Generated short URL:<br>%1").arg (makeLinkHtml (shortUrl)), &dialog);
  label->setTextFormat (Qt::RichText);
  label->setTextInteractionFlags (Qt::TextBrowserInteraction);
  label->setOpenExternalLinks (true);
  layout->addWidget (label);

  auto *buttons = new QDialogButtonBox (QDialogButtonBox::Ok, &dialog);
  QObject::connect (buttons, &QDialogButtonBox::accepted, &dialog, &QDialog::accept);
  layout->addWidget (buttons);

  dialog.exec();
}

/**
 * @brief Creates tray/menu actions.
 */
void MainWindow::setupMenuActions() {
  m_cutUrlAction = new QAction (QStringLiteral ("Cut URL"), this);
  m_settingsAction = new QAction (QStringLiteral ("Settings"), this);
  m_helpAction = new QAction (QStringLiteral ("Help"), this);
  m_aboutAction = new QAction (QStringLiteral ("About"), this);
  m_exitAction = new QAction (QStringLiteral ("Exit"), this);
}