/*
* Copyright (c) 2012-2015 Christian Surlykke, Petr Vanek
*
* This file is part of qt-lightdm-greeter 
* It is distributed under the LGPL 2.1 or later license.
* Please refer to the LICENSE file for a copy of the license.
*/
#include <QtWidgets/QApplication>
#include <QDesktopWidget>
#include <QtGlobal>
#include <QtDebug>
#include <QSettings>
#include <QIcon>
#include <QPainter>
#include <QMap>
#include <QSocketNotifier>
#include <QScreen>

#include <fcntl.h>              /* Obtain O_* constant definitions */
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>

#include <iostream>

#include "settings.h"
#include "mainwindow.h"
#include "x11util.h"
#include "global.h"

Settings *s_settings = new Settings();

static int sockets[2];

static QMap<int, MainWindow*> currentWindows;

static QTimer setupDelay;

void createSimpleBackground();

static void watch(const QScreen *scrn);

static void setupScreens();

static void messageHandler(QtMsgType type, const QMessageLogContext&, const QString& msg)
{
    std::cerr << type << ": " << msg.toUtf8().constData() << '\n';
}

static inline int size(const QRect& r)
{
    return r.width() * r.height();
}

int main(int argc, char *argv[])
{
    if (argc > 1 && QString(argv[1]) == QString("--test")) {
        Global::enableTestMode();
    }

    QApplication a(argc, argv);

    // I have no idea why, but Qt's stock qWarning() output never makes it
    // to /var/log/lightdm/x-0-greeter.log, so we use std::cerr instead..
    qInstallMessageHandler(messageHandler);

    if (!Settings::iconThemeName().isEmpty()) {
        QIcon::setThemeName(Settings::iconThemeName());
    }

    if (!Global::testMode() && !Settings::autoLoginCheckCmd().isEmpty()) {
        QProcess p;
        int ret = QProcess::execute(Settings::autoLoginCheckCmd());
        if (ret == 0) {
            if (Global::autoLoginGuest()) {
                qWarning() << "Guest login ok";
                createSimpleBackground();
                return a.exec();
            } else {
                qWarning() << "Guest login failed";
                // TODO: Set error message, display somewhere
            }
        }
    }

    QObject::connect(&setupDelay, &QTimer::timeout, []() {
        setupScreens();
    });
    setupDelay.setInterval(100);
    setupDelay.setSingleShot(true);
    setupDelay.start();

    if (!Global::testMode()) {
        for (const auto scrn : QGuiApplication::screens()) {
            watch(scrn);
        }
        QObject::connect(qApp, &QGuiApplication::screenAdded, [](const QScreen *scrn) {
            setupDelay.start();
            watch(scrn);
        });
        auto cb = [](const QScreen *) {
            setupDelay.start();
        };
        QObject::connect(qApp, &QGuiApplication::screenRemoved, cb);
        QObject::connect(qApp, &QGuiApplication::primaryScreenChanged, cb);
    }

    /*
    if (!entire.isNull()) {
        qWarning() << "Setting x background";
        AddPixmapToBackground(entire.constBits(), entire.width(), entire.height(),
                              24, entire.bytesPerLine(), entire.byteCount());
    }
    */

    return a.exec();
}

static void watch(const QScreen *scrn)
{
    QObject::connect(scrn, &QScreen::geometryChanged, [](const QRect &geom) {
        setupDelay.start();
    });
}

void createSimpleBackground()
{
    QImage img;
    if (currentWindows.isEmpty()) {
        img = Global::getConfigGradient();
        if (img.isNull()) {
            img = QImage(QApplication::desktop()->size(), QImage::Format::Format_RGB32);
        } else {
            img = img.scaled(QApplication::desktop()->size(), Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
        }
    } else {
        img = QImage(QApplication::desktop()->size(), QImage::Format::Format_RGB32);
        QPainter p(&img);
        for (auto *w : currentWindows) {
            p.drawImage(w->geometry(), w->background(), QRect(QPoint(0, 0), w->geometry().size()));
        }
    }
    AddPixmapToBackground(img.constBits(), img.width(), img.height(),
                          24, img.bytesPerLine(), img.byteCount());
}

static QList<QRect> allOld;
static int primaryOld = -1;

void setupScreens()
{
    // Get a list of non-overlapping screens, as this might lead to a broken
    // greeter with main windows covering other login forms
    QMap<int, QRect> screens;
    QList<QRect> allNew;
    if (Global::testMode()) {
        screens.insert(0, QRect(0, 0, 1024, 768));
    } else {
        for (int i = 0; i < QApplication::desktop()->screenCount(); ++i) {
            QRect r = QApplication::desktop()->screenGeometry(i);
            allNew.append(r);
            QMutableMapIterator<int, QRect>it(screens);
            while (it.hasNext()) {
                it.next();
                if (!it.value().intersects(r))
                    continue;
                // Overlap, bigger wins
                if (size(it.value()) >= size(r)) {
                    // Existing is bigger
                    goto skip_rect;
                }
                // New is bigger, remove existing and keep going
                it.remove();
            }
            // We reached here, so add new window
            screens.insert(i, r);
            skip_rect: ; // Do nothing
        }
    }

    // Spurious event?
    int primaryNew = QApplication::desktop()->primaryScreen();
    if (primaryNew == primaryOld && allOld == allNew)
        return;
    primaryOld = primaryNew;
    allOld = allNew;

    // Determine primary screen
    int primary;
    if (screens.contains(primaryNew)) {
        // Primary screen still in selection
        primary = primaryNew;
    } else {
        // Fallback to first one
        primary = screens.begin().key();
    }

    // Try to reuse as many mainwindows as possible
    QMap<int, MainWindow*> remaining = currentWindows;
    do {
        currentWindows.clear();
        QMutableMapIterator<int, QRect> it(screens);
        while (it.hasNext()) {
            it.next();
            MainWindow *old = remaining.take(it.key());
            if (old != nullptr) {
                // Existing
                qDebug() << "Re-using existing window";
                old->setGeometry(it.value());
                if (old->showLoginForm() && primary != it.key()) {
                    qDebug() << "Destroying old login form";
                    LoginForm *logForm = old->stealLoginForm();
                    if (logForm != nullptr) {
                        logForm->setParent(nullptr);
                        logForm->deleteLater();
                    }
                }
                currentWindows.insert(it.key(), old);
                it.remove();
            }
        }
    } while(0);

    // Now set up remaining screens
    QMapIterator<int, QRect> it(screens);
    while (it.hasNext()) {
        it.next();
        MainWindow *old = nullptr;
        if (!remaining.empty()) {
            qDebug() << "This should never happen, reusing old window II";
            old = remaining.take(remaining.firstKey());
            if (old != nullptr) {
                if (old->showLoginForm() && primary != it.key()) {
                    LoginForm *logForm = old->stealLoginForm();
                    if (logForm != nullptr) {
                        logForm->setParent(nullptr);
                        logForm->deleteLater();
                    }
                }
                old->setGeometry(it.value());
            }
        }
        if (old == nullptr) {
            qDebug() << "Adding a window";
            old = new MainWindow(primary == it.key(), it.key(), it.value());
            old->show();
        }
        currentWindows.insert(it.key(), old);
        if (old->showLoginForm()) {
            old->setFocus(Qt::OtherFocusReason);
            old->activateWindow();
        }
    }

    for (MainWindow *old : remaining) {
        old->deleteLater();
    }
}