#include "mainwindow/MainWindow.hpp"

#include <QAction>
#include <QCloseEvent>
#include <QCoreApplication>
#include <QHBoxLayout>
#include <QHeaderView>
#include <QItemSelectionModel>
#include <QJsonArray>
#include <QJsonObject>
#include <QKeySequence>
#include <QLabel>
#include <QLocale>
#include <QMenu>
#include <QMenuBar>
#include <QMessageBox>
#include <QSettings>
#include <QSplitter>
#include <QStatusBar>
#include <QSystemTrayIcon>
#include <QTimer>
#include <QToolBar>
#include <QTreeView>
#include <QVBoxLayout>
#include <QWidget>

#include "dialogs/AddUrlDialog.hpp"
#include "dialogs/BatchDialog.hpp"
#include "dialogs/FileInfoDialog.hpp"
#include "dialogs/GrabberWizard.hpp"
#include "dialogs/OptionsDialog.hpp"
#include "dialogs/ProgressDialog.hpp"
#include "dialogs/SchedulerDialog.hpp"
#include "dialogs/SpeedLimiterDialog.hpp"
#include "mainwindow/CategoryPanel.hpp"
#include "models/DownloadTableModel.hpp"
#include "rpc/RpcClient.hpp"
#include "tray/TrayIcon.hpp"
#include "util/Format.hpp"
#include "util/Theme.hpp"
#include "widgets/DropTargetWidget.hpp"
#include "widgets/ProgressDelegate.hpp"

#ifdef VELOX_GUI_HAVE_DBUS
#include "clipboard/GlobalShortcut.hpp"
#endif

namespace velox::gui {
namespace {

QString dotStyle(const QString &colour) {
    return QStringLiteral("color: %1; font-size: 14px;").arg(colour);
}

}  // namespace

MainWindow::MainWindow(rpc::RpcClient *client, QWidget *parent)
    : QMainWindow(parent),
      client_(client),
      model_(new DownloadTableModel(this)),
      proxy_(new DownloadFilterProxy(this)),
      view_(new QTreeView(this)),
      panel_(new CategoryPanel(this)),
      connDot_(new QLabel(QStringLiteral("●"), this)),
      connText_(new QLabel(this)),
      countsLabel_(new QLabel(this)),
      offlineBanner_(new QWidget(this)),
      countsTimer_(new QTimer(this)) {
    setWindowTitle(tr("Velox Download Manager"));
    resize(1040, 600);

    proxy_->setSourceModel(model_);
    proxy_->setSortCaseSensitivity(Qt::CaseInsensitive);

    view_->setModel(proxy_);
    view_->setRootIsDecorated(false);
    view_->setAlternatingRowColors(true);
    view_->setUniformRowHeights(true);  // keeps 10k rows scrolling at 60 fps
    view_->setSelectionBehavior(QAbstractItemView::SelectRows);
    view_->setSelectionMode(QAbstractItemView::ExtendedSelection);
    view_->setSortingEnabled(true);
    view_->setItemDelegateForColumn(DownloadTableModel::ColStatus, new ProgressDelegate(this));
    view_->setContextMenuPolicy(Qt::CustomContextMenu);
    connect(view_, &QWidget::customContextMenuRequested, this, &MainWindow::showTableContextMenu);
    connect(view_, &QAbstractItemView::doubleClicked, this,
            &MainWindow::openPropertiesForSelection);
    view_->header()->setSectionsMovable(true);
    view_->header()->setStretchLastSection(true);

    // --- offline banner (shown instead of a modal error) -----------------------------
    auto *bannerLayout = new QHBoxLayout(offlineBanner_);
    bannerLayout->setContentsMargins(10, 6, 10, 6);
    auto *bannerLabel = new QLabel(offlineBanner_);
    bannerLabel->setObjectName(QStringLiteral("offlineBannerLabel"));
    bannerLayout->addWidget(bannerLabel);
    bannerLayout->addStretch();
    offlineBanner_->setStyleSheet(
        QStringLiteral("background: %1; color: %2;")
            .arg(QLatin1String(theme::kOfflineBannerBg), QLatin1String(theme::kOfflineBannerText)));
    offlineBanner_->setVisible(false);

    auto *splitter = new QSplitter(Qt::Horizontal, this);
    splitter->addWidget(panel_);
    splitter->addWidget(view_);
    splitter->setStretchFactor(0, 0);
    splitter->setStretchFactor(1, 1);
    splitter->setSizes({220, 800});
    splitter->setChildrenCollapsible(false);

    auto *central = new QWidget(this);
    auto *layout = new QVBoxLayout(central);
    layout->setContentsMargins(0, 0, 0, 0);
    layout->setSpacing(0);
    layout->addWidget(offlineBanner_);
    layout->addWidget(splitter, 1);
    setCentralWidget(central);

    buildActions();
    buildMenus();
    buildToolBar();
    buildTray();
    buildDropTarget();

    // --- status bar -----------------------------------------------------------------
    connDot_->setStyleSheet(dotStyle(QLatin1String(theme::kDanger)));
    statusBar()->addPermanentWidget(countsLabel_, 1);
    statusBar()->addPermanentWidget(connText_);
    statusBar()->addPermanentWidget(connDot_);

    // Counts walk every row; keep that off the 4 Hz progress path.
    countsTimer_->setSingleShot(true);
    countsTimer_->setInterval(400);
    connect(countsTimer_, &QTimer::timeout, this, &MainWindow::refreshCounts);

    // --- wiring --------------------------------------------------------------------
    connect(client_, &rpc::RpcClient::stateChanged, this, &MainWindow::onConnectionState);
    connect(client_, &rpc::RpcClient::taskListReset, model_, &DownloadTableModel::resetFromJson);
    connect(client_, &rpc::RpcClient::taskProgress, model_, &DownloadTableModel::applyProgress);
    connect(client_, &rpc::RpcClient::taskAdded, model_, &DownloadTableModel::applyTaskAdded);
    connect(client_, &rpc::RpcClient::taskStateChanged, model_,
            &DownloadTableModel::applyTaskState);
    connect(client_, &rpc::RpcClient::taskRemoved, model_, &DownloadTableModel::applyTaskRemoved);
    connect(client_, &rpc::RpcClient::speedGlobal, this, &MainWindow::onSpeedGlobal);
    connect(client_, &rpc::RpcClient::settingsChanged, this, &MainWindow::onSettingsChanged);

    connect(model_, &QAbstractItemModel::modelReset, this, &MainWindow::scheduleCounts);
    connect(model_, &QAbstractItemModel::rowsInserted, this, &MainWindow::scheduleCounts);
    connect(model_, &QAbstractItemModel::rowsRemoved, this, &MainWindow::scheduleCounts);
    connect(model_, &QAbstractItemModel::dataChanged, this, &MainWindow::scheduleCounts);

    connect(panel_, &CategoryPanel::selectionChanged, this, &MainWindow::onFilterChanged);

    restoreLayout();
    onConnectionState(client_->state());
    refreshCounts();
}

MainWindow::~MainWindow() = default;

void MainWindow::buildActions() {
    actAddUrl_ = new QAction(tr("Add &URL…"), this);
    actAddUrl_->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_N));
    connect(actAddUrl_, &QAction::triggered, this, &MainWindow::openAddUrlDialog);

    actResume_ = new QAction(tr("&Resume"), this);
    actResume_->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_R));
    connect(actResume_, &QAction::triggered, this, &MainWindow::resumeSelection);

    actPause_ = new QAction(tr("&Pause"), this);
    actPause_->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_P));
    connect(actPause_, &QAction::triggered, this, &MainWindow::pauseSelection);

    actStop_ = new QAction(tr("&Stop"), this);
    connect(actStop_, &QAction::triggered, this, &MainWindow::cancelSelection);

    actRemove_ = new QAction(tr("&Delete"), this);
    actRemove_->setShortcut(QKeySequence::Delete);
    connect(actRemove_, &QAction::triggered, this, &MainWindow::removeSelection);

    actResumeAll_ = new QAction(tr("Resume A&ll"), this);
    connect(actResumeAll_, &QAction::triggered, this, &MainWindow::resumeAll);

    actPauseAll_ = new QAction(tr("Pause All"), this);
    connect(actPauseAll_, &QAction::triggered, this, &MainWindow::pauseAll);

    actProperties_ = new QAction(tr("&Properties…"), this);
    connect(actProperties_, &QAction::triggered, this, &MainWindow::openPropertiesForSelection);

    actOptions_ = new QAction(tr("&Options…"), this);
    connect(actOptions_, &QAction::triggered, this, &MainWindow::openOptionsDialog);

    actScheduler_ = new QAction(tr("&Scheduler…"), this);
    connect(actScheduler_, &QAction::triggered, this, &MainWindow::openSchedulerDialog);

    actSpeedLimiter_ = new QAction(tr("Speed &Limiter…"), this);
    connect(actSpeedLimiter_, &QAction::triggered, this, &MainWindow::openSpeedLimiterDialog);

    actBatch_ = new QAction(tr("&Batch Download…"), this);
    connect(actBatch_, &QAction::triggered, this, &MainWindow::openBatchDialog);

    actGrabber_ = new QAction(tr("Site &Grabber…"), this);
    connect(actGrabber_, &QAction::triggered, this, &MainWindow::openGrabberWizard);

    actShow_ = new QAction(tr("&Show Velox"), this);
    connect(actShow_, &QAction::triggered, this, &MainWindow::showAndRaise);
}

void MainWindow::buildMenus() {
    QMenu *tasks = menuBar()->addMenu(tr("&Tasks"));
    tasks->addAction(actAddUrl_);
    tasks->addSeparator();
    tasks->addAction(actResume_);
    tasks->addAction(actPause_);
    tasks->addAction(actStop_);
    tasks->addSeparator();
    tasks->addAction(actRemove_);
    tasks->addAction(actProperties_);
    tasks->addSeparator();
    tasks->addAction(tr("E&xit"), QKeySequence::Quit, this, &QWidget::close);

    QMenu *downloads = menuBar()->addMenu(tr("&Downloads"));
    downloads->addAction(actResumeAll_);
    downloads->addAction(actPauseAll_);
    downloads->addSeparator();
    downloads->addAction(actScheduler_);
    downloads->addAction(actSpeedLimiter_);

    QMenu *tools = menuBar()->addMenu(tr("&Tools"));
    tools->addAction(actBatch_);
    tools->addAction(actGrabber_);
    tools->addSeparator();
    tools->addAction(actOptions_);

    QMenu *view = menuBar()->addMenu(tr("&View"));
    QAction *togglePanel = view->addAction(tr("&Category Panel"));
    togglePanel->setCheckable(true);
    togglePanel->setChecked(true);
    connect(togglePanel, &QAction::toggled, panel_, &QWidget::setVisible);

    QMenu *help = menuBar()->addMenu(tr("&Help"));
    help->addAction(tr("&About Velox"), this, [this] {
        QMessageBox::about(this, tr("About Velox"),
                           tr("Velox Download Manager — GUI client (M1)."));
    });
}

void MainWindow::buildToolBar() {
    auto *tb = addToolBar(tr("Main"));
    tb->setObjectName(QStringLiteral("mainToolBar"));
    tb->setMovable(false);
    tb->addAction(actAddUrl_);
    tb->addSeparator();
    tb->addAction(actResume_);
    tb->addAction(actPause_);
    tb->addAction(actStop_);
    tb->addSeparator();
    tb->addAction(actRemove_);
    tb->addSeparator();
    tb->addAction(actScheduler_);
    tb->addAction(actOptions_);
    tb->addAction(actGrabber_);
}

void MainWindow::buildTray() {
    if (!QSystemTrayIcon::isSystemTrayAvailable()) {
        return;  // headless/mockd-only test environments, some minimal WMs
    }
    trayIcon_ = new TrayIcon(client_, actShow_, actAddUrl_, actResumeAll_, actPauseAll_, this);
    connect(trayIcon_, &TrayIcon::quitRequested, qApp, &QCoreApplication::quit);
    trayIcon_->show();
}

void MainWindow::buildDropTarget() {
    // Qt::Tool + a parent keeps it grouped with the main window (no separate taskbar
    // entry, destroyed when MainWindow is) while still floating independently per spec.
    dropTarget_ = new DropTargetWidget(this);
    connect(dropTarget_, &DropTargetWidget::urlDropped, this, &MainWindow::onUrlDropped);
    connect(dropTarget_, &DropTargetWidget::addUrlRequested, this, &MainWindow::openAddUrlDialog);

#ifdef VELOX_GUI_HAVE_DBUS
    // docs/06-risks-and-spikes.md R2, explicit path #2. Best-effort: requestBinding() is
    // silent and permanent-for-this-session on any desktop that lacks the portal or
    // declines the prompt — see GlobalShortcut's own header for why that's by design.
    globalShortcut_ = new GlobalShortcut(this);
    connect(globalShortcut_, &GlobalShortcut::activated, this, &MainWindow::openAddUrlDialog);
    globalShortcut_->requestBinding();
#endif
}

void MainWindow::closeEvent(QCloseEvent *event) {
    if (minimizeToTrayEnabled_ && trayIcon_ && trayIcon_->isVisible()) {
        hide();
        event->ignore();
        return;
    }
    saveLayout();
    QMainWindow::closeEvent(event);
    event->accept();
}

void MainWindow::onConnectionState(rpc::ConnectionState state) {
    connText_->setText(tr(rpc::toString(state)));

    QString colour = QLatin1String(theme::kDanger);
    if (state == rpc::ConnectionState::Connected) {
        colour = QLatin1String(theme::kSuccess);
    } else if (state != rpc::ConnectionState::Disconnected) {
        colour = QLatin1String(theme::kWarning);
    }
    connDot_->setStyleSheet(dotStyle(colour));

    const bool online = state == rpc::ConnectionState::Connected;
    offlineBanner_->setVisible(!online);
    if (auto *label = offlineBanner_->findChild<QLabel *>(QStringLiteral("offlineBannerLabel"))) {
        label->setText(state == rpc::ConnectionState::Reconnecting
                           ? tr("Reconnecting to the Velox service…")
                           : tr("The Velox service is not running. Downloads are unaffected; "
                                "this list is read-only until it returns."));
    }
    for (QAction *a :
         {actResume_, actPause_, actStop_, actRemove_, actResumeAll_, actPauseAll_, actAddUrl_,
          actProperties_, actScheduler_, actSpeedLimiter_, actBatch_, actGrabber_, actOptions_}) {
        a->setEnabled(online);
    }

    if (online) {
        fetchTree();
        fetchGeneralUiSettings();
    }
}

void MainWindow::fetchTree() {
    client_->call(QStringLiteral("category.list"), {}, [this](const rpc::RpcReply &reply) {
        if (reply.ok()) {
            categoriesCache_ = reply.result.toObject().value("items").toArray();
            panel_->setCategories(categoriesCache_);
        }
    });
    client_->call(QStringLiteral("queue.list"), {}, [this](const rpc::RpcReply &reply) {
        if (reply.ok()) {
            queuesCache_ = reply.result.toObject().value("items").toArray();
            panel_->setQueues(queuesCache_);
        }
    });
}

void MainWindow::fetchGeneralUiSettings() {
    client_->call(
        QStringLiteral("settings.get"),
        QJsonObject{{"keys", QJsonArray{QStringLiteral("general.minimizeToTray"),
                                        QStringLiteral("general.showDropTarget")}}},
        [this](const rpc::RpcReply &reply) {
            if (!reply.ok()) {
                return;
            }
            const QJsonObject values = reply.result.toObject().value("values").toObject();
            minimizeToTrayEnabled_ = values.value("general.minimizeToTray").toBool();
            if (dropTarget_) {
                dropTarget_->setVisible(values.value("general.showDropTarget").toBool(true));
            }
        });
}

void MainWindow::onSettingsChanged(const QJsonObject &params) {
    for (const QJsonValue &key : params.value("keys").toArray()) {
        const QString k = key.toString();
        if (k == QLatin1String("general.minimizeToTray") ||
            k == QLatin1String("general.showDropTarget")) {
            fetchGeneralUiSettings();
            break;
        }
    }
}

void MainWindow::onUrlDropped(const QString &url) {
    auto *info = new FileInfoDialog(client_, url, categoriesCache_, queuesCache_, this);
    info->setAttribute(Qt::WA_DeleteOnClose);
    info->show();
}

void MainWindow::openAddUrlDialog() {
    AddUrlDialog dlg(this);
    if (dlg.exec() != QDialog::Accepted) {
        return;
    }
    const QString url = dlg.url();
    if (url.isEmpty()) {
        return;
    }
    // Non-modal: several File Info dialogs can be open at once (spec §2), and it must
    // never block the main window while download.probe is in flight.
    auto *info = new FileInfoDialog(client_, url, categoriesCache_, queuesCache_, this);
    info->setAttribute(Qt::WA_DeleteOnClose);
    info->show();
}

void MainWindow::openPropertiesForSelection() {
    const QStringList ids = selectedTaskIds();
    if (ids.isEmpty()) {
        return;
    }
    // One Progress dialog per selected task, same as double-clicking each row.
    for (const QString &id : ids) {
        auto *dlg = new ProgressDialog(client_, id, this);
        dlg->show();
    }
}

void MainWindow::openOptionsDialog() {
    OptionsDialog dlg(client_, this);
    dlg.exec();
}

void MainWindow::openSchedulerDialog() {
    SchedulerDialog dlg(client_, this);
    dlg.exec();
}

void MainWindow::openSpeedLimiterDialog() {
    SpeedLimiterDialog dlg(client_, this);
    dlg.exec();
}

void MainWindow::openBatchDialog() {
    BatchDialog dlg(client_, categoriesCache_, queuesCache_, this);
    dlg.exec();
}

void MainWindow::openGrabberWizard() {
    auto *wizard = new GrabberWizard(client_, categoriesCache_, this);
    wizard->setAttribute(Qt::WA_DeleteOnClose);
    wizard->show();
}

void MainWindow::showAndRaise() {
    show();
    raise();
    activateWindow();
}

// docs/03-gui-spec.md §1 lists a fuller row menu (Open · Open With · Open Folder ·
// Move/Rename · Redownload · Refresh Download Address · Add to Queue ▸ · ...). Those all
// need state this build order hasn't reached yet (Options' file-type associations aren't
// per-row actions, and Batch's "Add to Queue" is a different flow than re-filing an
// existing task) — offering them now would be a fake affordance.
void MainWindow::showTableContextMenu(const QPoint &pos) {
    const QModelIndex idx = view_->indexAt(pos);
    if (idx.isValid() && view_->selectionModel() && !view_->selectionModel()->isSelected(idx)) {
        view_->selectionModel()->setCurrentIndex(
            idx, QItemSelectionModel::ClearAndSelect | QItemSelectionModel::Rows);
    }
    if (selectedTaskIds().isEmpty()) {
        return;
    }

    QMenu menu(this);
    menu.addAction(actResume_);
    menu.addAction(actPause_);
    menu.addAction(actStop_);
    menu.addSeparator();
    menu.addAction(actRemove_);
    menu.addSeparator();
    menu.addAction(actProperties_);
    menu.exec(view_->viewport()->mapToGlobal(pos));
}

void MainWindow::onFilterChanged(const TaskSelection &selection) {
    proxy_->setSelection(selection);
    // TODO(gui): also push proxy_->asTaskFilter() to a fresh download.list once the daemon
    // is serving 100k-row lists and the client should not hold them all. For M1 the whole
    // list fits and the proxy is the single source of what's shown.
    refreshCounts();
}

void MainWindow::onSpeedGlobal(const QJsonObject &params) {
    globalDownBps_ = static_cast<qint64>(params.value("downBps").toDouble());
    scheduleCounts();
}

void MainWindow::scheduleCounts() {
    // Throttle, not debounce: a restart-on-every-event timer never fires while progress
    // ticks arrive faster than its interval. Start it only when it is not already pending.
    if (!countsTimer_->isActive()) {
        countsTimer_->start();
    }
}

void MainWindow::refreshCounts() {
    const int total = model_->rowCount();
    int active = 0;
    int unfinished = 0;
    int finished = 0;
    QHash<QString, int> byCategory;
    QHash<QString, int> byQueue;
    for (int i = 0; i < total; ++i) {
        const QModelIndex idx = model_->index(i, 0);
        const QString state = idx.data(DownloadTableModel::StateRole).toString();
        if (state == QLatin1String("downloading")) {
            ++active;
        }
        if (state == QLatin1String("complete")) {
            ++finished;
        } else {
            ++unfinished;
        }
        const QString cat = idx.data(DownloadTableModel::CategoryIdRole).toString();
        if (!cat.isEmpty()) {
            ++byCategory[cat];
        }
        const QString queue = idx.data(DownloadTableModel::QueueIdRole).toString();
        if (!queue.isEmpty()) {
            ++byQueue[queue];
        }
    }

    panel_->setCounts(total, unfinished, finished, byCategory, byQueue);
    if (trayIcon_) {
        trayIcon_->setActiveCount(active);
    }

    const int shown = proxy_->rowCount();
    countsLabel_->setText(tr("%1 of %2 downloads, %3 active   ↓ %4")
                              .arg(shown)
                              .arg(total)
                              .arg(active)
                              .arg(fmt::rate(globalDownBps_)));
}

QStringList MainWindow::selectedTaskIds() const {
    QStringList ids;
    const auto rows =
        view_->selectionModel() ? view_->selectionModel()->selectedRows() : QModelIndexList{};
    ids.reserve(rows.size());
    for (const QModelIndex &proxyIdx : rows) {
        const QString id =
            proxy_->mapToSource(proxyIdx).data(DownloadTableModel::TaskIdRole).toString();
        if (!id.isEmpty()) {
            ids << id;
        }
    }
    return ids;
}

QStringList MainWindow::allTaskIds() const {
    QStringList ids;
    const int n = model_->rowCount();
    ids.reserve(n);
    for (int i = 0; i < n; ++i) {
        ids << model_->index(i, 0).data(DownloadTableModel::TaskIdRole).toString();
    }
    return ids;
}

void MainWindow::actOnTasks(const char *methodName, const QStringList &ids) {
    if (ids.isEmpty()) {
        return;
    }
    client_->call(QString::fromLatin1(methodName),
                  QJsonObject{{"taskIds", QJsonArray::fromStringList(ids)}});
}

void MainWindow::pauseSelection() {
    actOnTasks(rpc::method::kDownloadPause, selectedTaskIds());
}
void MainWindow::resumeSelection() {
    actOnTasks(rpc::method::kDownloadResume, selectedTaskIds());
}
void MainWindow::cancelSelection() {
    actOnTasks(rpc::method::kDownloadCancel, selectedTaskIds());
}

void MainWindow::removeSelection() {
    const QStringList ids = selectedTaskIds();
    if (ids.isEmpty()) {
        return;
    }
    const auto answer = QMessageBox::question(
        this, tr("Delete downloads"),
        tr("Remove %n download(s) from the list? The partial data is kept.", "", ids.size()));
    if (answer == QMessageBox::Yes) {
        actOnTasks(rpc::method::kDownloadRemove, ids);
    }
}

void MainWindow::resumeAll() {
    actOnTasks(rpc::method::kDownloadResume, allTaskIds());
}
void MainWindow::pauseAll() {
    actOnTasks(rpc::method::kDownloadPause, allTaskIds());
}

void MainWindow::restoreLayout() {
    QSettings settings;
    const QByteArray geom = settings.value(QStringLiteral("mainwindow/geometry")).toByteArray();
    if (!geom.isEmpty()) {
        restoreGeometry(geom);
    }
    const QByteArray header =
        settings.value(QStringLiteral("mainwindow/headerState")).toByteArray();
    if (!header.isEmpty()) {
        view_->header()->restoreState(header);
        return;
    }
    // First run: widths that fit the content rather than an even split. Description is the
    // stretch column, so it takes the remainder.
    view_->setColumnWidth(DownloadTableModel::ColName, 280);
    view_->setColumnWidth(DownloadTableModel::ColQueue, 32);
    view_->setColumnWidth(DownloadTableModel::ColSize, 90);
    view_->setColumnWidth(DownloadTableModel::ColStatus, 130);
    view_->setColumnWidth(DownloadTableModel::ColTimeLeft, 80);
    view_->setColumnWidth(DownloadTableModel::ColSpeed, 90);
    view_->setColumnWidth(DownloadTableModel::ColLastTry, 130);
}

void MainWindow::saveLayout() {
    QSettings settings;
    settings.setValue(QStringLiteral("mainwindow/geometry"), saveGeometry());
    settings.setValue(QStringLiteral("mainwindow/headerState"), view_->header()->saveState());
}

}  // namespace velox::gui