[DeckShare] Create temporary share links for local and server decks (#7243)

* [DeckShare] Create temporary share links for local and server decks

* [DeckShare] Address review findings and harden the share flows

Gate every share entry point on login, de-duplicate the share-link and
color-identity logic behind DeckShareUtils and an injected querier, and
replace the silent tray/status-bar notices with always-visible dialogs.

- abstract_tab_deck_editor: explain that sharing requires a connection
  instead of silently doing nothing when logged out
- tab_deck_storage: disable the share action on disconnect, reject
  folder/deck mixes and the root folder with clear warnings, re-enable
  Create on every entry/response so a dropped connection cannot leave
  the button disabled
- tab_deck_storage_visual: same login gate for the context-menu entry,
  visible success/error dialogs, and a symmetric in-flight guard
- getDeckColorIdentity now takes a CardDatabaseQuerier, dropping the
  CardDatabaseManager singleton access and enabling unit tests

* [DeckShare] Fix share-link expiry build on the minimum-supported Qt

QTimeZone::UTC (the Initialization enum) only exists since Qt 6.7, so
Debian 12 and Ubuntu 24.04 (Qt 6.4) fail to compile the share-link expiry
handling in the share dialog and the two deck-storage tabs. Mirror the
existing games_model guard and fall back to Qt::UTC on older Qt.

* [DeckShare] Use the stable server client for the visual deck storage tab

* [DeckShare] Extract the share-creation response handling into DeckShareUtils

* [DeckShare] Drop includes left unused by the share-response extraction

* [DeckShare] Format share expiry with the locale-aware short format

* [DeckShare] Build share links with QUrl and QUrlQuery for percent-encoding

* [DeckShare] Replace the duplicate computeColorIdentity with the shared getDeckColorIdentity

* [DeckShare] Recover the share controls when the server never answers

* [DeckShare] Provide the full share hint in each plural form

* [DeckShare] Join the selected-count label with a non-translatable separator

* [DeckShare] Retranslate the share button tooltip with the storage widget

* [DeckShare] Forward retranslateUi to the visual deck storage widget

* [DeckShare] Let the share bar owners supply the hint text

* [DeckShare] End the share-related headers and sources with a trailing newline

* [DeckShare] Keep the settings include in the project include block

* [DeckShare] Include the network settings header used by the share timeout

* [DeckShare] Resolve the share theme icon through themePixmap

QPixmap("theme:icons/share") has no file extension, so ThemeManager::assetPath()
is bypassed and the pixmap is always null. Use themePixmap(QStringLiteral("icons/share"))
like every other toolbar action, so the .svg (and dark/light variants) resolves.

* [DeckShare] Keep the share selection consistent with the visible decks

Filtered-out previews are hidden but kept alive, so selectedFilePaths() counted
them in the share and the selection highlight. Only decks the user can see are
now shared, and a deck that stops matching the filters is deselectd as the deck
pass runs, keeping the %n count and the highlight in sync with the screen.

* [DeckShare] Abandon an in-flight tree share on cancel

Leaving share mode never stopped the timeout timer, and a late response still
ran shareFromTreeFinished, copying the link and announcing success for a share
the user backed out of. Stopping the timer and tracking the outstanding request
by sequence number means a stale reply (or a timed-out one) after cancel is
ignored, and cancelling + re-entering share mode can no longer confuse the two
requests.

* [DeckShare] Abandon an in-flight tile share on cancel

exitShareMode() left shareTimeoutTimer running and did not abandon the pending
Command_DeckShareCreate, so a timer pop or a late success still reported the
share after the user cancelled. Stop the timer and ignore stale responses via a
sequence number, mirroring the tree tab.

* [DeckShare] Wire the status-changed handler after shareBar exists

handleConnectionChanged() dereferences shareBar->isVisible(), but the connection
was set up before shareBar was constructed and shareBar had no in-class
initializer. On any status change delivered before construction the slot read an
indeterminate pointer. Seed the connection (and the initial share availability)
after shareBar exists and give shareBar a = nullptr initializer.

* [DeckShare] Explain why a blank deck cannot be shared

A blank deck exited the share flow silently. The menu only disables the entry
via setSaveStatus(), a different predicate, so the path is reachable (e.g. add a
card and remove it again). Mirror the not-logged-in branch with a short
information dialog.

* [DeckShare] Restore the banner-text doc comment

Re-add the doc block above refreshBannerCardText() that was removed as part of
the share-selection work; it documents the coupling to refreshBannerCardToolTip.

* [DeckShare] Resolve the stable server client in the deck editor gate

actShareDeck went through tabSupervisor->getClient(), which hands back a
LocalClient while an offline game is running. LocalClient never sets its status,
so a logged-in user could not share from the deck editor during a local game,
and got a misleading "You must be connected" message. Expose the supervisor's
stable remote client and use it for the gate and the dialog, matching the other
share tabs.

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

cockatrice/src/interface/widgets/visual_deck_storage/deck_preview/deck_preview_widget.cpp

@@ -11,6 +11,7 @@
 #include "deck_preview_deck_tags_display_widget.h"
 
 #include <QFileInfo>
+#include <QFrame>
 #include <QInputDialog>
 #include <QLabel>
 #include <QMenu>
@@ -27,7 +28,7 @@ DeckPreviewWidget::DeckPreviewWidget(QWidget *_parent,
                                      VisualDeckStorageWidget *_visualDeckStorageWidget,
                                      VisualDeckStorageModel *_model,
                                      const QString &_filePath)
-    : QWidget(_parent), visualDeckStorageWidget(_visualDeckStorageWidget), model(_model), filePath(_filePath)
+    : QWidget(_parent), filePath(_filePath), visualDeckStorageWidget(_visualDeckStorageWidget), model(_model)
 {
     layout = new QVBoxLayout(this);
     setLayout(layout);
@@ -36,6 +37,8 @@ DeckPreviewWidget::DeckPreviewWidget(QWidget *_parent,
         new DeckPreviewCardPictureWidget(this, false, visualDeckStorageWidget->deckPreviewSelectionAnimationEnabled);
     pictureWidget->setFontSize(24);
     connect(pictureWidget, &DeckPreviewCardPictureWidget::imageClicked, this, &DeckPreviewWidget::imageClickedEvent);
+    connect(pictureWidget, &DeckPreviewCardPictureWidget::imageSingleClicked, this,
+            &DeckPreviewWidget::imageSingleClicked);
     connect(pictureWidget, &DeckPreviewCardPictureWidget::imageDoubleClicked, this,
             &DeckPreviewWidget::imageDoubleClickedEvent);
     bannerCardDisplayWidget = pictureWidget;
@@ -99,6 +102,15 @@ DeckPreviewWidget::DeckPreviewWidget(QWidget *_parent,
     // to keep the resize handler from searching the widget tree on every layout pass.
     fixedWidthChildren = {bannerCardDisplayWidget, colorIdentityWidget, deckTagsDisplayWidget, bannerCardLabel,
                           bannerCardComboBox};
+
+    // Child of the banner widget so the frame tracks the banner's selection animation
+    // (which animates the banner's position) instead of staying at a stale static offset.
+    selectionFrame = new QFrame(bannerCardDisplayWidget);
+    selectionFrame->setAttribute(Qt::WA_TransparentForMouseEvents);
+    selectionFrame->setStyleSheet(QStringLiteral(
+        "QFrame { border: 2px solid palette(highlight); border-radius: 4px; background: transparent; }"));
+    selectionFrame->setVisible(false);
+    bannerCardDisplayWidget->installEventFilter(this);
 }
 
 void DeckPreviewWidget::retranslateUi()
@@ -122,6 +134,63 @@ void DeckPreviewWidget::resizeEvent(QResizeEvent *event)
     for (QWidget *widget : fixedWidthChildren) {
         widget->setMaximumWidth(width);
     }
+    updateSelectionFrameGeometry();
+}
+
+bool DeckPreviewWidget::eventFilter(QObject *watched, QEvent *event)
+{
+    if (watched == bannerCardDisplayWidget && (event->type() == QEvent::Resize || event->type() == QEvent::Move)) {
+        updateSelectionFrameGeometry();
+    }
+    return QWidget::eventFilter(watched, event);
+}
+
+void DeckPreviewWidget::setShareSelectable(bool selectable)
+{
+    shareSelectable = selectable;
+    if (!selectable) {
+        setShareSelected(false);
+    }
+    updateSelectionStyle();
+}
+
+void DeckPreviewWidget::setShareSelected(bool selected)
+{
+    if (shareSelected == selected) {
+        return;
+    }
+    shareSelected = selected;
+    updateSelectionStyle();
+    emit shareSelectionToggled(selected);
+}
+
+bool DeckPreviewWidget::isShareSelected() const
+{
+    return shareSelected;
+}
+
+bool DeckPreviewWidget::isShareSelectable() const
+{
+    return shareSelectable;
+}
+
+void DeckPreviewWidget::updateSelectionFrameGeometry()
+{
+    if (selectionFrame == nullptr || bannerCardDisplayWidget == nullptr) {
+        return;
+    }
+    // Frame is a child of the banner, so it is positioned in banner coordinates and
+    // tracks the banner's selection animation automatically. A small inset keeps the
+    // highlight visible around the card art without occluding it.
+    selectionFrame->setGeometry(bannerCardDisplayWidget->rect().adjusted(1, 1, -1, -1));
+    selectionFrame->raise();
+}
+
+void DeckPreviewWidget::updateSelectionStyle()
+{
+    if (selectionFrame != nullptr) {
+        selectionFrame->setVisible(shareSelectable && isShareSelected());
+    }
 }
 
 void DeckPreviewWidget::enterEvent(QEnterEvent *event)
@@ -337,10 +406,20 @@ void DeckPreviewWidget::imageClickedEvent(QMouseEvent *event, DeckPreviewCardPic
     }
 }
 
+void DeckPreviewWidget::imageSingleClicked()
+{
+    if (isShareSelectable()) {
+        setShareSelected(!isShareSelected());
+    }
+}
+
 void DeckPreviewWidget::imageDoubleClickedEvent(QMouseEvent *event, DeckPreviewCardPictureWidget *instance)
 {
     Q_UNUSED(event);
     Q_UNUSED(instance);
+    if (isShareSelectable()) {
+        return; // in share mode a double click would just toggle a single selection
+    }
     emit deckLoadRequested(filePath);
 }
 
@@ -365,6 +444,9 @@ QMenu *DeckPreviewWidget::createRightClickMenu()
         }
     });
 
+    connect(menu->addAction(tr("Share deck...")), &QAction::triggered, this,
+            [this] { emit shareDeckRequested(filePath); });
+
     connect(menu->addAction(tr("Edit Tags")), &QAction::triggered, deckTagsDisplayWidget,
             &DeckPreviewDeckTagsDisplayWidget::openTagEditDlg);
 

cockatrice/src/interface/widgets/visual_deck_storage/deck_preview/deck_preview_widget.h

@@ -17,6 +17,7 @@
 #include <QWidget>
 
 class QEnterEvent;
+class QFrame;
 class QLabel;
 class QMenu;
 class QMouseEvent;
@@ -41,9 +42,19 @@ public:
      */
     DeckPreviewCardPictureWidget *bannerCardDisplayWidget;
 
+    /** @brief The path of the deck file backing this preview. */
+    QString filePath;
+
+    void setShareSelectable(bool selectable);
+    void setShareSelected(bool selected);
+    [[nodiscard]] bool isShareSelected() const;
+    [[nodiscard]] bool isShareSelectable() const;
+
 signals:
     void deckLoadRequested(const QString &filePath);
     void openDeckEditor(const LoadedDeck &deck);
+    void shareDeckRequested(const QString &filePath);
+    void shareSelectionToggled(bool selected);
 
 public slots:
     /**
@@ -66,6 +77,7 @@ public slots:
 protected:
     void enterEvent(QEnterEvent *event) override;
     void resizeEvent(QResizeEvent *event) override;
+    bool eventFilter(QObject *watched, QEvent *event) override;
 
 private:
     [[nodiscard]] int row() const;
@@ -76,6 +88,7 @@ private:
     QMenu *createRightClickMenu();
     void addSetBannerCardMenu(QMenu *menu);
     void imageClickedEvent(QMouseEvent *event, DeckPreviewCardPictureWidget *instance);
+    void imageSingleClicked();
     void imageDoubleClickedEvent(QMouseEvent *event, DeckPreviewCardPictureWidget *instance);
 
     void actRenameDeck();
@@ -84,7 +97,6 @@ private:
 
     VisualDeckStorageWidget *visualDeckStorageWidget;
     VisualDeckStorageModel *model;
-    QString filePath;
     QVBoxLayout *layout;
     ColorIdentityWidget *colorIdentityWidget;
     DeckPreviewDeckTagsDisplayWidget *deckTagsDisplayWidget;
@@ -92,6 +104,12 @@ private:
     QComboBox *bannerCardComboBox;
     QList<QWidget *> fixedWidthChildren; ///< Children clamped to the picture width on resize.
     int lastKnownBannerWidth = -1;       ///< The picture width last applied to the children.
+    QFrame *selectionFrame = nullptr;
+    bool shareSelectable = false;
+    bool shareSelected = false;
+
+    void updateSelectionStyle();
+    void updateSelectionFrameGeometry();
 };
 
 class NoScrollFilter : public QObject

cockatrice/src/interface/widgets/visual_deck_storage/visual_deck_storage_folder_display_widget.cpp

@@ -126,6 +126,11 @@ void VisualDeckStorageFolderDisplayWidget::continueDeckPass()
 
         const bool matches = index.data(VisualDeckStorageRoles::FilterMatchRole).toBool();
         deckPreviewWidget->setVisible(matches);
+        if (!matches) {
+            // A deck that no longer matches the filters is dropped from the selection so its
+            // highlight cannot linger on an invisible preview or be counted in the share.
+            deckPreviewWidget->setShareSelected(false);
+        }
         if (matches) {
             ++visibleDeckCount;
         }
@@ -209,6 +214,11 @@ DeckPreviewWidget *VisualDeckStorageFolderDisplayWidget::createDeckPreviewWidget
             &VisualDeckStorageWidget::deckLoadRequested);
     connect(deckPreviewWidget, &DeckPreviewWidget::openDeckEditor, visualDeckStorageWidget,
             &VisualDeckStorageWidget::openDeckEditor);
+    connect(deckPreviewWidget, &DeckPreviewWidget::shareDeckRequested, visualDeckStorageWidget,
+            &VisualDeckStorageWidget::shareDeckRequested);
+    connect(deckPreviewWidget, &DeckPreviewWidget::shareSelectionToggled, visualDeckStorageWidget,
+            &VisualDeckStorageWidget::shareSelectionChanged);
+    deckPreviewWidget->setShareSelectable(visualDeckStorageWidget->isShareSelectable());
     connect(visualDeckStorageWidget->settings(), &VisualDeckStorageQuickSettingsWidget::cardSizeChanged,
             deckPreviewWidget->bannerCardDisplayWidget, &CardInfoPictureWidget::setScaleFactor);
     deckPreviewWidget->bannerCardDisplayWidget->setScaleFactor(visualDeckStorageWidget->settings()->getCardSize());
@@ -216,6 +226,18 @@ DeckPreviewWidget *VisualDeckStorageFolderDisplayWidget::createDeckPreviewWidget
     return deckPreviewWidget;
 }
 
+void VisualDeckStorageFolderDisplayWidget::setShareSelectable(bool selectable)
+{
+    const auto previews = flowWidget->findChildren<DeckPreviewWidget *>();
+    for (DeckPreviewWidget *preview : previews) {
+        preview->setShareSelectable(selectable);
+    }
+    const auto subFolders = findChildren<VisualDeckStorageFolderDisplayWidget *>();
+    for (VisualDeckStorageFolderDisplayWidget *subFolder : subFolders) {
+        subFolder->setShareSelectable(selectable);
+    }
+}
+
 /**
  * @brief Creates, removes and keeps in sync the subfolder widgets of this folder.
  *

cockatrice/src/interface/widgets/visual_deck_storage/visual_deck_storage_folder_display_widget.h

@@ -51,6 +51,7 @@ public slots:
      */
     void scheduleReconcile();
     void updateShowFolders(bool enabled);
+    void setShareSelectable(bool selectable);
 
 signals:
     /**

cockatrice/src/interface/widgets/visual_deck_storage/visual_deck_storage_model.cpp

@@ -1,6 +1,7 @@
 #include "visual_deck_storage_model.h"
 
 #include "../../deck_loader/deck_loader.h"
+#include "../cards/additional_info/deck_color_identity.h"
 
 #include <QDir>
 #include <QDirIterator>
@@ -119,8 +120,6 @@ DeckScanResult scanDeckDirectory(const QString &deckPath)
 }
 } // namespace
 
-static QString computeColorIdentity(const LoadedDeck &deck);
-
 VisualDeckStorageModel::VisualDeckStorageModel(QObject *parent) : QAbstractListModel(parent)
 {
 }
@@ -306,7 +305,7 @@ void VisualDeckStorageModel::beginLoad(int row)
         }
         // Color identity walks every card through the database, so compute it here to
         // keep the completion handler on the UI thread cheap.
-        const QString colorIdentity = computeColorIdentity(*deck);
+        const QString colorIdentity = getDeckColorIdentity(deck->deckList, CardDatabaseManager::query());
         return DeckLoadResult{std::move(*deck), QFileInfo(filePath).lastModified(), colorIdentity};
     }));
 }
@@ -367,40 +366,6 @@ void VisualDeckStorageModel::drainPendingLoads()
     }
 }
 
-/**
- * @brief Computes the color identity of a deck in WUBRG order.
- */
-static QString computeColorIdentity(const LoadedDeck &deck)
-{
-    QStringList cardList = deck.deckList.getCardList({DECK_ZONE_MAIN, DECK_ZONE_SIDE});
-    if (cardList.isEmpty()) {
-        return {};
-    }
-
-    QSet<QChar> colorSet; // A set to collect unique color symbols (e.g., W, U, B, R, G)
-
-    for (const QString &cardName : cardList) {
-        CardInfoPtr currentCard = CardDatabaseManager::query()->getCardInfo(cardName);
-        if (currentCard) {
-            const QString colors = currentCard->getColors(); // Something like "WUB"
-            for (const QChar &color : colors) {
-                colorSet.insert(color);
-            }
-        }
-    }
-
-    // Ensure the color identity is in WUBRG order
-    QString colorIdentity;
-    const QString wubrgOrder = "WUBRG";
-    for (const QChar &color : wubrgOrder) {
-        if (colorSet.contains(color)) {
-            colorIdentity.append(color);
-        }
-    }
-
-    return colorIdentity;
-}
-
 /**
  * @brief Recomputes all derived metadata of a row from its loaded deck.
  */
@@ -414,7 +379,7 @@ void VisualDeckStorageModel::recomputeDeckMetadata(DeckPreviewData &data, bool r
     data.lastLoaded = QDateTime::fromString(deckList.getLastLoadedTimestamp());
     data.bannerCard = deckList.getBannerCard();
     if (recomputeColorIdentity) {
-        data.colorIdentity = computeColorIdentity(data.deck);
+        data.colorIdentity = getDeckColorIdentity(data.deck.deckList, CardDatabaseManager::query());
     }
 }
 

cockatrice/src/interface/widgets/visual_deck_storage/visual_deck_storage_widget.cpp

@@ -48,6 +48,12 @@ VisualDeckStorageWidget::VisualDeckStorageWidget(QWidget *parent) : QWidget(pare
     refreshButton->setFixedSize(32, 32);
     connect(refreshButton, &QPushButton::clicked, this, &VisualDeckStorageWidget::refreshIfPossible);
 
+    shareButton = new QToolButton(this);
+    shareButton->setIcon(themePixmap(QStringLiteral("icons/share")));
+    shareButton->setFixedSize(32, 32);
+    shareButton->setVisible(false);
+    connect(shareButton, &QPushButton::clicked, this, &VisualDeckStorageWidget::shareRequested);
+
     quickSettingsWidget = new VisualDeckStorageQuickSettingsWidget(this);
     connect(quickSettingsWidget, &VisualDeckStorageQuickSettingsWidget::showFoldersChanged, this,
             &VisualDeckStorageWidget::updateShowFolders);
@@ -58,6 +64,7 @@ VisualDeckStorageWidget::VisualDeckStorageWidget(QWidget *parent) : QWidget(pare
     searchAndSortLayout->addWidget(sortWidget);
     searchAndSortLayout->addWidget(searchWidget);
     searchAndSortLayout->addWidget(refreshButton);
+    searchAndSortLayout->addWidget(shareButton);
     searchAndSortLayout->addWidget(quickSettingsWidget);
 
     // tag filter box
@@ -158,11 +165,71 @@ void VisualDeckStorageWidget::retranslateUi()
     databaseLoadIndicator->setText(tr("Loading database ..."));
 
     refreshButton->setToolTip(tr("Refresh loaded files"));
+    shareButton->setToolTip(tr("Select decks to share"));
     quickSettingsWidget->setToolTip(tr("Visual Deck Storage Settings"));
 
     sortWidget->retranslateUi();
 }
 
+void VisualDeckStorageWidget::setShareSelectable(bool selectable)
+{
+    if (shareSelectable == selectable) {
+        return;
+    }
+    shareSelectable = selectable;
+    if (folderWidget != nullptr) {
+        folderWidget->setShareSelectable(selectable);
+    }
+    emit shareSelectionChanged();
+}
+
+bool VisualDeckStorageWidget::isShareSelectable() const
+{
+    return shareSelectable;
+}
+
+QStringList VisualDeckStorageWidget::selectedFilePaths() const
+{
+    QStringList selectedPaths;
+    if (folderWidget != nullptr) {
+        const auto previews = folderWidget->findChildren<DeckPreviewWidget *>();
+        for (DeckPreviewWidget *preview : previews) {
+            // Filtered-out previews stay alive hidden in their sorted place, so only decks the
+            // user can actually see are part of the share.
+            if (preview->isVisible() && preview->isShareSelected()) {
+                selectedPaths.append(preview->filePath);
+            }
+        }
+    }
+    return selectedPaths;
+}
+
+void VisualDeckStorageWidget::clearShareSelection()
+{
+    if (folderWidget != nullptr) {
+        const auto previews = folderWidget->findChildren<DeckPreviewWidget *>();
+        for (DeckPreviewWidget *preview : previews) {
+            preview->setShareSelected(false);
+        }
+    }
+}
+
+void VisualDeckStorageWidget::setShareAvailable(bool available)
+{
+    shareButton->setVisible(available);
+    shareButton->setEnabled(available);
+}
+
+void VisualDeckStorageWidget::setShareSelectedFiles(const QStringList &paths)
+{
+    if (folderWidget != nullptr) {
+        const auto previews = folderWidget->findChildren<DeckPreviewWidget *>();
+        for (DeckPreviewWidget *preview : previews) {
+            preview->setShareSelected(paths.contains(preview->filePath));
+        }
+    }
+}
+
 /**
  * Gets a const pointer to the quick settings so that the values can be accessed.
  */

cockatrice/src/interface/widgets/visual_deck_storage/visual_deck_storage_widget.h

@@ -33,6 +33,12 @@ public:
     explicit VisualDeckStorageWidget(QWidget *parent);
     void refreshIfPossible();
     void retranslateUi();
+    void setShareSelectable(bool selectable);
+    [[nodiscard]] bool isShareSelectable() const;
+    [[nodiscard]] QStringList selectedFilePaths() const;
+    void setShareSelectedFiles(const QStringList &paths);
+    void clearShareSelection();
+    void setShareAvailable(bool available);
 
     VisualDeckStorageTagFilterWidget *tagFilterWidget;
     bool deckPreviewSelectionAnimationEnabled;
@@ -63,6 +69,9 @@ public slots:
 signals:
     void deckLoadRequested(const QString &filePath);
     void openDeckEditor(const LoadedDeck &deck);
+    void shareDeckRequested(const QString &filePath);
+    void shareSelectionChanged();
+    void shareRequested();
 
 protected:
     void resizeEvent(QResizeEvent *event) override;
@@ -81,12 +90,14 @@ private:
     VisualDeckStorageSearchWidget *searchWidget;
     DeckPreviewColorIdentityFilterWidget *deckPreviewColorIdentityFilterWidget;
     QToolButton *refreshButton;
+    QToolButton *shareButton;
     VisualDeckStorageQuickSettingsWidget *quickSettingsWidget;
     QScrollArea *scrollArea;
     VisualDeckStorageFolderDisplayWidget *folderWidget = nullptr;
     VisualDeckStorageModel *storageModel = nullptr;
     VisualDeckStorageSortFilterProxyModel *storageProxyModel = nullptr;
     QTimer *refreshTimer = nullptr; ///< Coalesces the re-apply/refresh burst following a batch of deck loads.
+    bool shareSelectable = false;
 };
 
 #endif // VISUAL_DECK_STORAGE_WIDGET_H