add FieldSelectionPanel for extracting the ships/stations/debris selection

src/ui/CMakeLists.txt

@@ -9,6 +9,7 @@ SET(HDRS
     ${CMAKE_CURRENT_SOURCE_DIR}/HeaderBar.h
     ${CMAKE_CURRENT_SOURCE_DIR}/BuildButtonGrid.h
     ${CMAKE_CURRENT_SOURCE_DIR}/SelectedBuildingPanel.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/FieldSelectionPanel.h
     ${CMAKE_CURRENT_SOURCE_DIR}/BlueprintPanel.h
     ${CMAKE_CURRENT_SOURCE_DIR}/ShipLayoutDialog.h
     ${CMAKE_CURRENT_SOURCE_DIR}/ShipLayoutPreview.h
@@ -30,6 +31,7 @@ SET(SRCS
     ${CMAKE_CURRENT_SOURCE_DIR}/HeaderBar.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/BuildButtonGrid.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/SelectedBuildingPanel.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/FieldSelectionPanel.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/BlueprintPanel.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/ShipLayoutDialog.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/ShipLayoutPreview.cpp

src/ui/FieldSelectionPanel.cpp

@@ -0,0 +1,403 @@
+#include "FieldSelectionPanel.h"
+
+#include <algorithm>
+#include <map>
+#include <string>
+
+#include <QFont>
+#include <QLabel>
+#include <QStringList>
+#include <QVBoxLayout>
+
+#include "DebrisSystem.h"
+#include "DisplayName.h"
+#include "EntityAdmin.h"
+#include "FactionComponent.h"
+#include "GameConfig.h"
+#include "HealthComponent.h"
+#include "ModuleOwnerComponent.h"
+#include "SelectedBehaviorComponent.h"
+#include "ShipIdentityComponent.h"
+#include "ShipStatsCalculator.h"
+#include "ShipStatsPanel.h"
+#include "Simulation.h"
+#include "StationBodyComponent.h"
+#include "ThreatCostCalculator.h"
+#include "WeaponComponent.h"
+
+
+FieldSelectionPanel::FieldSelectionPanel(Simulation* sim,
+                                         const GameConfig* config,
+                                         QWidget* parent)
+    : QWidget(parent)
+    , m_sim(sim)
+    , m_config(config)
+{
+    // Zero margins and the same spacing as the enclosing SelectedBuildingPanel layout, so
+    // nesting the field widgets in this panel leaves their geometry unchanged.
+    m_layout = new QVBoxLayout(this);
+    m_layout->setContentsMargins(0, 0, 0, 0);
+    m_layout->setSpacing(4);
+    m_layout->setAlignment(Qt::AlignTop);
+
+    m_entityTitleLabel = new QLabel(this);
+    QFont titleFont = m_entityTitleLabel->font();
+    titleFont.setBold(true);
+    m_entityTitleLabel->setFont(titleFont);
+    m_layout->addWidget(m_entityTitleLabel);
+    m_entityTitleLabel->hide();
+
+    m_entityStatsPanel = new ShipStatsPanel(config, this);
+    m_layout->addWidget(m_entityStatsPanel);
+    m_entityStatsPanel->hide();
+
+    m_stationStatsLabel = new QLabel(this);
+    m_stationStatsLabel->setWordWrap(true);
+    m_layout->addWidget(m_stationStatsLabel);
+    m_stationStatsLabel->hide();
+
+    m_entitySummaryLabel = new QLabel(this);
+    m_entitySummaryLabel->setWordWrap(true);
+    m_layout->addWidget(m_entitySummaryLabel);
+    m_entitySummaryLabel->hide();
+
+    m_scrapLabel = new QLabel(this);
+    m_layout->addWidget(m_scrapLabel);
+    m_scrapLabel->hide();
+
+    hide();
+
+    registerForEvents();
+}
+
+FieldSelectionPanel::~FieldSelectionPanel()
+{
+    unregisterForEvents();
+}
+
+void FieldSelectionPanel::setSelectedEntities(const std::vector<entt::entity>& entities)
+{
+    m_selectedEntities = entities;
+    rebuild();
+}
+
+void FieldSelectionPanel::setSelectedDebris(const std::vector<entt::entity>& debris)
+{
+    m_selectedDebris = debris;
+    rebuild();
+}
+
+void FieldSelectionPanel::clearSelection()
+{
+    m_selectedEntities.clear();
+    m_selectedDebris.clear();
+    rebuild();
+}
+
+bool FieldSelectionPanel::hasSelection() const
+{
+    return !m_selectedEntities.empty() || !m_selectedDebris.empty();
+}
+
+void FieldSelectionPanel::hideAllWidgets()
+{
+    m_entityTitleLabel->hide();
+    m_entityStatsPanel->hide();
+    m_stationStatsLabel->hide();
+    m_entitySummaryLabel->hide();
+    m_scrapLabel->hide();
+}
+
+void FieldSelectionPanel::rebuild()
+{
+    if (!hasSelection())
+    {
+        // Nothing in the field category: take no space, leaving the panel to whatever
+        // the building category shows (REQ-UI-SELECTION-CATEGORIES).
+        hideAllWidgets();
+        hide();
+        return;
+    }
+
+    show();
+
+    EntityAdmin& admin = m_sim->getAdmin();
+
+    // A full single-object stats panel is shown only for a lone field object: one actor
+    // with no debris, or one piece of debris with no actors. As soon as the selection holds
+    // more than one object (multiple actors, multiple debris, or actors plus debris), the
+    // panel switches to the compact count summary (REQ-UI-FIELD-MULTI-SELECTION).
+    if (m_selectedEntities.size() == 1 && m_selectedDebris.empty())
+    {
+        m_entitySummaryLabel->hide();
+        m_scrapLabel->hide();
+        const entt::entity entity = m_selectedEntities.front();
+        if (admin.isValid(entity) && admin.hasAll<ShipIdentityComponent>(entity))
+        {
+            buildEntityShip(entity);
+        }
+        else if (admin.isValid(entity) && admin.hasAll<StationBodyComponent>(entity))
+        {
+            buildEntityStation(entity);
+        }
+        else
+        {
+            m_entityTitleLabel->hide();
+            m_entityStatsPanel->hide();
+            m_stationStatsLabel->hide();
+        }
+        return;
+    }
+
+    if (m_selectedEntities.empty() && m_selectedDebris.size() == 1)
+    {
+        // Single piece of debris: a "Debris" heading plus a "Scrap" stat row, styled like
+        // the ship/station stats panels (REQ-UI-DEBRIS-PANEL).
+        m_entitySummaryLabel->hide();
+        m_entityStatsPanel->hide();
+        m_stationStatsLabel->hide();
+        buildDebrisSingle();
+        return;
+    }
+
+    // More than one field object: a compact count summary. buildEntitySummary() appends the
+    // "Debris x N" and "Scrap x N" lines when debris is part of the selection.
+    m_entityTitleLabel->hide();
+    m_entityStatsPanel->hide();
+    m_stationStatsLabel->hide();
+    m_scrapLabel->hide();
+    buildEntitySummary();
+}
+
+void FieldSelectionPanel::refreshDisplay()
+{
+    if (!hasSelection()) { return; }
+
+    // Keep the live values current: the single-actor stats panel, the single-debris stats
+    // panel (whose Scrap row shrinks as it is collected), or the count summary (whose Scrap
+    // line shrinks likewise) — matching the layout chosen by rebuild()
+    // (REQ-UI-SHIP-STATS-PANEL, REQ-UI-DEBRIS-PANEL).
+    if (m_selectedEntities.size() == 1 && m_selectedDebris.empty())
+    {
+        refreshEntityStats();
+    }
+    else if (m_selectedEntities.empty() && m_selectedDebris.size() == 1)
+    {
+        buildDebrisSingle();
+    }
+    else
+    {
+        buildEntitySummary();
+    }
+}
+
+void FieldSelectionPanel::buildDebrisSingle()
+{
+    // "Debris" heading + a single "Scrap" stat row for the piece's remaining amount,
+    // mirroring the single-actor stats panels (REQ-UI-DEBRIS-PANEL).
+    m_entityTitleLabel->setText(tr("Debris"));
+    m_entityTitleLabel->show();
+    m_scrapLabel->setText(tr("Scrap: %1").arg(selectedDebrisScrapTotal()));
+    m_scrapLabel->show();
+}
+
+void FieldSelectionPanel::buildEntitySummary()
+{
+    EntityAdmin& admin = m_sim->getAdmin();
+
+    // Group actors by faction + kind + ship schematic, preserving first-seen order
+    // (REQ-UI-FIELD-MULTI-SELECTION).
+    std::vector<QString> keys;
+    std::map<QString, int> counts;
+    std::map<QString, QString> labels;
+
+    for (entt::entity entity : m_selectedEntities)
+    {
+        if (!admin.isValid(entity)) { continue; }
+        const bool isEnemy = admin.hasAll<FactionComponent>(entity)
+            && admin.get<FactionComponent>(entity).isEnemy;
+
+        QString key;
+        QString label;
+        if (admin.hasAll<ShipIdentityComponent>(entity))
+        {
+            const std::string& id = admin.get<ShipIdentityComponent>(entity).schematicId;
+            const QString name = QString::fromStdString(toDisplayName(id));
+            key = (isEnemy ? QStringLiteral("ship:enemy:") : QStringLiteral("ship:player:"))
+                + QString::fromStdString(id);
+            label = isEnemy ? tr("Enemy %1").arg(name) : name;
+        }
+        else if (admin.hasAll<StationBodyComponent>(entity))
+        {
+            key = isEnemy ? QStringLiteral("station:enemy") : QStringLiteral("station:player");
+            label = isEnemy ? tr("Enemy Defence Station") : tr("Player Defence Station");
+        }
+        else
+        {
+            continue;
+        }
+
+        if (counts.find(key) == counts.end())
+        {
+            keys.push_back(key);
+            labels[key] = label;
+        }
+        counts[key] += 1;
+    }
+
+    // One "<type> x <count>" line per group (matching the recipe tooltip and the building
+    // multi-selection). No total-count header, consistent with the building panel. When
+    // debris is part of the selection, a "Debris x <count>" line followed by a
+    // "Scrap x <total>" line are appended into the same label so the line spacing is
+    // uniform (REQ-UI-FIELD-MULTI-SELECTION, REQ-UI-DEBRIS-PANEL).
+    QStringList lines;
+    for (const QString& key : keys)
+    {
+        lines << tr("%1 x %2").arg(labels[key]).arg(counts[key]);
+    }
+    if (!m_selectedDebris.empty())
+    {
+        lines << tr("Debris x %1").arg(static_cast<int>(m_selectedDebris.size()));
+        lines << scrapTotalText();
+    }
+    m_entitySummaryLabel->setText(lines.join('\n'));
+    m_entitySummaryLabel->show();
+}
+
+void FieldSelectionPanel::buildEntityShip(entt::entity entity)
+{
+    EntityAdmin& admin = m_sim->getAdmin();
+    const ShipIdentityComponent& identity = admin.get<ShipIdentityComponent>(entity);
+    const HealthComponent& health = admin.get<HealthComponent>(entity);
+
+    m_entityTitleLabel->setText(tr("Ship: %1")
+        .arg(QString::fromStdString(identity.schematicId)));
+    m_entityTitleLabel->show();
+
+    const ShipStats stats = buildShipStatsFromEntity(admin, entity);
+    m_entityStatsPanel->refreshFromLive(stats, health.hp);
+    m_entityStatsPanel->setBehavior(
+        admin.get<SelectedBehaviorComponent>(entity).winner);
+    m_entityStatsPanel->setDebugDrawEnabled(m_debugDraw);
+
+    const ShipDef* schematicDef =
+        m_config->ships.findShipDef(identity.schematicId);
+    if (schematicDef)
+    {
+        const double threat = calculateShipThreatCost(
+            m_config->threatCosts, *m_config, schematicDef->id,
+            schematicDef->defaultModules);
+        m_entityStatsPanel->setThreatCost(threat);
+    }
+
+    m_entityStatsPanel->show();
+
+    m_stationStatsLabel->hide();
+}
+
+void FieldSelectionPanel::buildEntityStation(entt::entity entity)
+{
+    EntityAdmin& admin = m_sim->getAdmin();
+    const HealthComponent& health = admin.get<HealthComponent>(entity);
+
+    const bool isEnemy = admin.hasAll<FactionComponent>(entity)
+        && admin.get<FactionComponent>(entity).isEnemy;
+    m_entityTitleLabel->setText(isEnemy
+        ? tr("Enemy Defence Station")
+        : tr("Player Defence Station"));
+    m_entityTitleLabel->show();
+
+    float totalDps = 0.0f;
+    float maxRange = 0.0f;
+    bool hasWeapons = false;
+
+    admin.forEach<ModuleOwnerComponent, WeaponComponent>(
+        [&](entt::entity /*child*/, const ModuleOwnerComponent& owner, const WeaponComponent& w)
+        {
+            if (owner.owner != entity) { return; }
+            hasWeapons = true;
+            totalDps += w.damage * w.fireRateHz;
+            if (w.range_tiles > maxRange) { maxRange = w.range_tiles; }
+        });
+
+    QString statsText = tr("HP: %1 / %2")
+        .arg(static_cast<int>(health.hp + 0.5f))
+        .arg(static_cast<int>(health.maxHp + 0.5f));
+
+    if (hasWeapons)
+    {
+        statsText += tr("\nDPS: %1").arg(QString::number(static_cast<double>(totalDps), 'f', 1));
+        statsText += tr("\nRange: %1 tiles").arg(QString::number(static_cast<double>(maxRange), 'f', 1));
+    }
+
+    m_stationStatsLabel->setText(statsText);
+    m_stationStatsLabel->show();
+
+    m_entityStatsPanel->hide();
+}
+
+void FieldSelectionPanel::refreshEntityStats()
+{
+    // Only the single-actor stats panel needs a live refresh; the multi-actor summary is
+    // static counts, and GameWorldView prunes dead/despawned actors and re-emits the
+    // selection (REQ-UI-ENTITY-CLICK-SELECT), so the panel does not mutate it here.
+    if (m_selectedEntities.size() != 1) { return; }
+
+    EntityAdmin& admin = m_sim->getAdmin();
+    const entt::entity entity = m_selectedEntities.front();
+
+    if (!admin.isValid(entity) || !admin.hasAll<HealthComponent>(entity)) { return; }
+    const HealthComponent& health = admin.get<HealthComponent>(entity);
+    if (health.hp <= 0.0f) { return; }
+
+    if (admin.hasAll<ShipIdentityComponent>(entity))
+    {
+        const ShipStats stats = buildShipStatsFromEntity(admin, entity);
+        m_entityStatsPanel->refreshFromLive(stats, health.hp);
+        m_entityStatsPanel->setBehavior(
+            admin.get<SelectedBehaviorComponent>(entity).winner);
+    }
+    else if (admin.hasAll<StationBodyComponent>(entity))
+    {
+        buildEntityStation(entity);
+    }
+}
+
+int FieldSelectionPanel::selectedDebrisScrapTotal() const
+{
+    // Sum the remaining scrap across the still-living selected debris (REQ-UI-DEBRIS-PANEL).
+    int total = 0;
+    for (const DebrisInfo& info : m_sim->getDebrisSystem().getAllDebrisInfo())
+    {
+        if (std::find(m_selectedDebris.begin(), m_selectedDebris.end(), info.entity)
+            != m_selectedDebris.end())
+        {
+            total += info.amount;
+        }
+    }
+    return total;
+}
+
+QString FieldSelectionPanel::scrapTotalText() const
+{
+    return tr("Scrap x %1").arg(selectedDebrisScrapTotal());
+}
+
+void FieldSelectionPanel::handleEvent(std::shared_ptr<const TickAdvancedEvent> /*event*/)
+{
+    refreshDisplay();
+}
+
+void FieldSelectionPanel::handleEvent(
+    std::shared_ptr<const PlayerCommandsAppliedEvent> /*event*/)
+{
+    // Player commands are applied by a queued drain, not synchronously. When the game is
+    // paused no tick advances, so TickAdvancedEvent never fires; refresh here too.
+    refreshDisplay();
+}
+
+void FieldSelectionPanel::handleEvent(std::shared_ptr<const DebugDrawToggledEvent> event)
+{
+    m_debugDraw = event->active;
+    m_entityStatsPanel->setDebugDrawEnabled(event->active);
+}

src/ui/FieldSelectionPanel.h

@@ -0,0 +1,91 @@
+#pragma once
+
+#include <vector>
+
+#include <QString>
+#include <QWidget>
+
+#include "entt/entity/entity.hpp"
+
+#include "DebugDrawToggledEvent.h"
+#include "EventHandler.h"
+#include "PlayerCommandsAppliedEvent.h"
+#include "TickAdvancedEvent.h"
+
+struct GameConfig;
+class Simulation;
+class ShipStatsPanel;
+class QLabel;
+class QVBoxLayout;
+
+// Renders the "field" selection category — ships, defence stations and debris — as either
+// a single-object stats panel (ship, station, or debris) or a compact multi-object count
+// summary (REQ-UI-SELECTION-CATEGORIES, REQ-UI-FIELD-MULTI-SELECTION, REQ-UI-DEBRIS-PANEL).
+//
+// The panel owns its own selection state and its own widgets, and nothing else. Which of
+// the two selection categories owns the side panel is arbitrated by the parent
+// SelectedBuildingPanel: it feeds this panel through setSelectedEntities() /
+// setSelectedDebris() / clearSelection() and asks it via hasSelection(). This panel hides
+// itself whenever its selection is empty, so an inactive field category takes no space.
+class FieldSelectionPanel : public QWidget,
+                            public CombinedEventHandler<TickAdvancedEvent,
+                                                        PlayerCommandsAppliedEvent,
+                                                        DebugDrawToggledEvent>
+{
+    Q_OBJECT
+
+public:
+    FieldSelectionPanel(Simulation* sim, const GameConfig* config,
+                        QWidget* parent = nullptr);
+    ~FieldSelectionPanel() override;
+
+    // Replaces the selected actors (ships and defence stations); debris is left alone,
+    // the two coexist within the field category (REQ-UI-SELECTION-CATEGORIES).
+    void setSelectedEntities(const std::vector<entt::entity>& entities);
+    // Replaces the selected debris; the selected actors are left alone.
+    void setSelectedDebris(const std::vector<entt::entity>& debris);
+    // Drops the whole field selection — used when the building category takes over.
+    void clearSelection();
+    // True while the field category has anything selected, i.e. while this panel owns
+    // the side panel's content.
+    bool hasSelection() const;
+
+private:
+    void handleEvent(std::shared_ptr<const TickAdvancedEvent> event) override;
+    void handleEvent(std::shared_ptr<const PlayerCommandsAppliedEvent> event) override;
+    void handleEvent(std::shared_ptr<const DebugDrawToggledEvent> event) override;
+
+    // Picks the layout for the current selection and shows/hides this panel accordingly.
+    void rebuild();
+    // Keeps the live values of the layout chosen by rebuild() current.
+    void refreshDisplay();
+    void buildEntityShip(entt::entity entity);
+    void buildEntityStation(entt::entity entity);
+    void buildEntitySummary();
+    void buildDebrisSingle();
+    void refreshEntityStats();
+    void hideAllWidgets();
+    // Summed remaining scrap across the selected debris (REQ-UI-DEBRIS-PANEL).
+    int selectedDebrisScrapTotal() const;
+    // "Scrap x N" line for the multi-object summary (REQ-UI-FIELD-MULTI-SELECTION).
+    QString scrapTotalText() const;
+
+    Simulation*       m_sim;
+    const GameConfig* m_config;
+
+    bool m_debugDraw = false;
+
+    // The selected ships/defence stations. Shares the "field" selection category with
+    // debris (m_selectedDebris): both can be non-empty at once (REQ-UI-SELECTION-CATEGORIES).
+    std::vector<entt::entity> m_selectedEntities;
+    std::vector<entt::entity> m_selectedDebris;
+
+    QVBoxLayout*    m_layout;
+    QLabel*         m_entityTitleLabel;
+    ShipStatsPanel* m_entityStatsPanel;
+    QLabel*         m_stationStatsLabel;
+    QLabel*         m_entitySummaryLabel;
+    // Shows the debris "Scrap" stat row (single selection) — the scrap total for the
+    // multi-object summary lives in m_entitySummaryLabel instead.
+    QLabel*         m_scrapLabel;
+};

src/ui/SelectedBuildingPanel.cpp

@@ -9,26 +9,14 @@
 #include <QLabel>
 #include <QListWidget>
 #include <QPushButton>
-#include <QStringList>
 #include <QVBoxLayout>
 
 #include "BeltSystem.h"
 #include "Command.h"
 #include "CommandRequestedEvent.h"
-#include "DisplayName.h"
-#include "DynamicBodyComponent.h"
-#include "EntityAdmin.h"
 #include "EntitySelectionChangedEvent.h"
 #include "EventManager.h"
-#include "FactionComponent.h"
+#include "FieldSelectionPanel.h"
-#include "HealthComponent.h"
-#include "ModuleOwnerComponent.h"
-#include "SelectedBehaviorComponent.h"
-#include "ShipIdentityComponent.h"
-#include "ShipStatsCalculator.h"
-#include "ShipStatsPanel.h"
-#include "ThreatCostCalculator.h"
-#include "StationBodyComponent.h"
 #include "TickAdvancedEvent.h"
 #include "Building.h"
 #include "BuildingSystem.h"
@@ -40,10 +28,8 @@
 #include "RecipeSelectionDialog.h"
 #include "RecipeSelectionRequestedEvent.h"
 #include "Rotation.h"
-#include "DebrisSystem.h"
 #include "ShipLayoutPreview.h"
 #include "Simulation.h"
-#include "WeaponComponent.h"
 
 namespace
 {
@@ -182,30 +168,10 @@ SelectedBuildingPanel::SelectedBuildingPanel(Simulation* sim,
     connect(m_filterBList, &QListWidget::itemChanged,
             this, &SelectedBuildingPanel::onSplitterFilterChanged);
 
-    m_entityTitleLabel = new QLabel(this);
+    // The field selection renders below the building content and hides itself while
-    QFont titleFont = m_entityTitleLabel->font();
+    // nothing field-side is selected, so it costs no space then.
-    titleFont.setBold(true);
+    m_fieldSelectionPanel = new FieldSelectionPanel(sim, config, this);
-    m_entityTitleLabel->setFont(titleFont);
+    m_layout->addWidget(m_fieldSelectionPanel);
-    m_layout->addWidget(m_entityTitleLabel);
-    m_entityTitleLabel->hide();
-
-    m_entityStatsPanel = new ShipStatsPanel(config, this);
-    m_layout->addWidget(m_entityStatsPanel);
-    m_entityStatsPanel->hide();
-
-    m_stationStatsLabel = new QLabel(this);
-    m_stationStatsLabel->setWordWrap(true);
-    m_layout->addWidget(m_stationStatsLabel);
-    m_stationStatsLabel->hide();
-
-    m_entitySummaryLabel = new QLabel(this);
-    m_entitySummaryLabel->setWordWrap(true);
-    m_layout->addWidget(m_entitySummaryLabel);
-    m_entitySummaryLabel->hide();
-
-    m_scrapLabel = new QLabel(this);
-    m_layout->addWidget(m_scrapLabel);
-    m_scrapLabel->hide();
 
     buildEmpty();
 
@@ -224,13 +190,21 @@ void SelectedBuildingPanel::onSelectionChanged(const std::vector<BuildingId>& id
     {
         // A building selection is exclusive: it supersedes any field selection —
         // actors and scrap (REQ-UI-SELECTION-CATEGORIES).
-        clearEntityDisplay();
+        m_fieldSelectionPanel->clearSelection();
-        m_selectedDebris.clear();
-        m_scrapLabel->hide();
     }
     rebuild();
 }
 
+void SelectedBuildingPanel::yieldToFieldSelection()
+{
+    // The mirror image of onSelectionChanged(): a field selection — actors, debris, or
+    // both — supersedes any building selection (REQ-UI-SELECTION-CATEGORIES). An empty
+    // field selection changes nothing here: the building content, if any, keeps the panel.
+    if (!m_fieldSelectionPanel->hasSelection()) { return; }
+    m_selectedBuildingIds.clear();
+    buildEmpty();
+}
+
 void SelectedBuildingPanel::rebuild()
 {
     if (m_selectedBuildingIds.empty())
@@ -259,22 +233,14 @@ void SelectedBuildingPanel::hideAllWidgets()
     m_filterBLabel->hide();
     m_filterBList->hide();
     m_buffersLabel->hide();
-    m_scrapLabel->hide();
-}
-
-void SelectedBuildingPanel::clearContent()
-{
-    m_singleBuildingId = std::nullopt;
-    hideAllWidgets();
 }
 
 void SelectedBuildingPanel::buildEmpty()
 {
-    clearContent();
+    // Shows nothing for the building category — either because nothing is selected or
-    m_entityTitleLabel->hide();
+    // because the field category has taken the panel over.
-    m_entityStatsPanel->hide();
+    m_singleBuildingId = std::nullopt;
-    m_stationStatsLabel->hide();
+    hideAllWidgets();
-    m_entitySummaryLabel->hide();
 }
 
 void SelectedBuildingPanel::buildSingle(BuildingId id)
@@ -646,27 +612,9 @@ void SelectedBuildingPanel::handleEvent(
 
 void SelectedBuildingPanel::refreshSelectionDisplay(RefreshReason reason)
 {
-    if (!m_selectedEntities.empty() || !m_selectedDebris.empty())
+    // Only a single selected building has live content to refresh. While the field
-    {
+    // category owns the panel there is none: yieldToFieldSelection() has cleared it, so
-        // Field selection. Keep the live values current: the single-actor stats panel,
+    // this returns immediately and the field panel refreshes itself off the same events.
-        // the single-debris stats panel (whose Scrap row shrinks as it is collected), or
-        // the count summary (whose Scrap line shrinks likewise) — matching the layout
-        // chosen by buildFieldSelection() (REQ-UI-SHIP-STATS-PANEL, REQ-UI-DEBRIS-PANEL).
-        if (m_selectedEntities.size() == 1 && m_selectedDebris.empty())
-        {
-            refreshEntityStats();
-        }
-        else if (m_selectedEntities.empty() && m_selectedDebris.size() == 1)
-        {
-            buildDebrisSingle();
-        }
-        else
-        {
-            buildEntitySummary();
-        }
-        return;
-    }
-
     if (!m_singleBuildingId.has_value()) { return; }
     const Building* b = m_sim->getBuildings().findBuilding(*m_singleBuildingId);
     if (b)
@@ -904,259 +852,8 @@ void SelectedBuildingPanel::onClearBelt()
 
 void SelectedBuildingPanel::handleEvent(std::shared_ptr<const EntitySelectionChangedEvent> event)
 {
-    m_selectedEntities = event->entities;
+    m_fieldSelectionPanel->setSelectedEntities(event->entities);
-    if (!m_selectedEntities.empty())
+    yieldToFieldSelection();
-    {
-        // A field selection supersedes any building selection (REQ-UI-SELECTION-CATEGORIES).
-        m_selectedBuildingIds.clear();
-    }
-    buildFieldSelection();
-}
-
-void SelectedBuildingPanel::buildFieldSelection()
-{
-    if (m_selectedEntities.empty() && m_selectedDebris.empty())
-    {
-        // Nothing in the field category. Fall back to empty unless buildings own the panel.
-        clearEntityDisplay();
-        m_scrapLabel->hide();
-        if (m_selectedBuildingIds.empty())
-        {
-            buildEmpty();
-        }
-        return;
-    }
-
-    // A field selection owns the panel: drop any building content.
-    clearContent();
-
-    EntityAdmin& admin = m_sim->getAdmin();
-
-    // A full single-object stats panel is shown only for a lone field object: one actor
-    // with no debris, or one piece of debris with no actors. As soon as the selection holds
-    // more than one object (multiple actors, multiple debris, or actors plus debris), the
-    // panel switches to the compact count summary (REQ-UI-FIELD-MULTI-SELECTION).
-    if (m_selectedEntities.size() == 1 && m_selectedDebris.empty())
-    {
-        m_entitySummaryLabel->hide();
-        m_scrapLabel->hide();
-        const entt::entity entity = m_selectedEntities.front();
-        if (admin.isValid(entity) && admin.hasAll<ShipIdentityComponent>(entity))
-        {
-            buildEntityShip(entity);
-        }
-        else if (admin.isValid(entity) && admin.hasAll<StationBodyComponent>(entity))
-        {
-            buildEntityStation(entity);
-        }
-        else
-        {
-            m_entityTitleLabel->hide();
-            m_entityStatsPanel->hide();
-            m_stationStatsLabel->hide();
-        }
-        return;
-    }
-
-    if (m_selectedEntities.empty() && m_selectedDebris.size() == 1)
-    {
-        // Single piece of debris: a "Debris" heading plus a "Scrap" stat row, styled like
-        // the ship/station stats panels (REQ-UI-DEBRIS-PANEL).
-        m_entitySummaryLabel->hide();
-        m_entityStatsPanel->hide();
-        m_stationStatsLabel->hide();
-        buildDebrisSingle();
-        return;
-    }
-
-    // More than one field object: a compact count summary. buildEntitySummary() appends the
-    // "Debris x N" and "Scrap x N" lines when debris is part of the selection.
-    m_entityTitleLabel->hide();
-    m_entityStatsPanel->hide();
-    m_stationStatsLabel->hide();
-    m_scrapLabel->hide();
-    buildEntitySummary();
-}
-
-void SelectedBuildingPanel::buildDebrisSingle()
-{
-    // "Debris" heading + a single "Scrap" stat row for the piece's remaining amount,
-    // mirroring the single-actor stats panels (REQ-UI-DEBRIS-PANEL).
-    m_entityTitleLabel->setText(tr("Debris"));
-    m_entityTitleLabel->show();
-    m_scrapLabel->setText(tr("Scrap: %1").arg(selectedDebrisScrapTotal()));
-    m_scrapLabel->show();
-}
-
-void SelectedBuildingPanel::buildEntitySummary()
-{
-    EntityAdmin& admin = m_sim->getAdmin();
-
-    // Group actors by faction + kind + ship schematic, preserving first-seen order
-    // (REQ-UI-FIELD-MULTI-SELECTION).
-    std::vector<QString> keys;
-    std::map<QString, int> counts;
-    std::map<QString, QString> labels;
-
-    for (entt::entity entity : m_selectedEntities)
-    {
-        if (!admin.isValid(entity)) { continue; }
-        const bool isEnemy = admin.hasAll<FactionComponent>(entity)
-            && admin.get<FactionComponent>(entity).isEnemy;
-
-        QString key;
-        QString label;
-        if (admin.hasAll<ShipIdentityComponent>(entity))
-        {
-            const std::string& id = admin.get<ShipIdentityComponent>(entity).schematicId;
-            const QString name = QString::fromStdString(toDisplayName(id));
-            key = (isEnemy ? QStringLiteral("ship:enemy:") : QStringLiteral("ship:player:"))
-                + QString::fromStdString(id);
-            label = isEnemy ? tr("Enemy %1").arg(name) : name;
-        }
-        else if (admin.hasAll<StationBodyComponent>(entity))
-        {
-            key = isEnemy ? QStringLiteral("station:enemy") : QStringLiteral("station:player");
-            label = isEnemy ? tr("Enemy Defence Station") : tr("Player Defence Station");
-        }
-        else
-        {
-            continue;
-        }
-
-        if (counts.find(key) == counts.end())
-        {
-            keys.push_back(key);
-            labels[key] = label;
-        }
-        counts[key] += 1;
-    }
-
-    // One "<type> x <count>" line per group (matching the recipe tooltip and the building
-    // multi-selection). No total-count header, consistent with the building panel. When
-    // debris is part of the selection, a "Debris x <count>" line followed by a
-    // "Scrap x <total>" line are appended into the same label so the line spacing is
-    // uniform (REQ-UI-FIELD-MULTI-SELECTION, REQ-UI-DEBRIS-PANEL).
-    QStringList lines;
-    for (const QString& key : keys)
-    {
-        lines << tr("%1 x %2").arg(labels[key]).arg(counts[key]);
-    }
-    if (!m_selectedDebris.empty())
-    {
-        lines << tr("Debris x %1").arg(static_cast<int>(m_selectedDebris.size()));
-        lines << scrapTotalText();
-    }
-    m_entitySummaryLabel->setText(lines.join('\n'));
-    m_entitySummaryLabel->show();
-}
-
-void SelectedBuildingPanel::buildEntityShip(entt::entity entity)
-{
-    EntityAdmin& admin = m_sim->getAdmin();
-    const ShipIdentityComponent& identity = admin.get<ShipIdentityComponent>(entity);
-    const HealthComponent& health = admin.get<HealthComponent>(entity);
-
-    m_entityTitleLabel->setText(tr("Ship: %1")
-        .arg(QString::fromStdString(identity.schematicId)));
-    m_entityTitleLabel->show();
-
-    const ShipStats stats = buildShipStatsFromEntity(admin, entity);
-    m_entityStatsPanel->refreshFromLive(stats, health.hp);
-    m_entityStatsPanel->setBehavior(
-        admin.get<SelectedBehaviorComponent>(entity).winner);
-    m_entityStatsPanel->setDebugDrawEnabled(m_debugDraw);
-
-    const ShipDef* schematicDef =
-        m_config->ships.findShipDef(identity.schematicId);
-    if (schematicDef)
-    {
-        const double threat = calculateShipThreatCost(
-            m_config->threatCosts, *m_config, schematicDef->id,
-            schematicDef->defaultModules);
-        m_entityStatsPanel->setThreatCost(threat);
-    }
-
-    m_entityStatsPanel->show();
-
-    m_stationStatsLabel->hide();
-}
-
-void SelectedBuildingPanel::buildEntityStation(entt::entity entity)
-{
-    EntityAdmin& admin = m_sim->getAdmin();
-    const HealthComponent& health = admin.get<HealthComponent>(entity);
-
-    const bool isEnemy = admin.hasAll<FactionComponent>(entity)
-        && admin.get<FactionComponent>(entity).isEnemy;
-    m_entityTitleLabel->setText(isEnemy
-        ? tr("Enemy Defence Station")
-        : tr("Player Defence Station"));
-    m_entityTitleLabel->show();
-
-    float totalDps = 0.0f;
-    float maxRange = 0.0f;
-    bool hasWeapons = false;
-
-    admin.forEach<ModuleOwnerComponent, WeaponComponent>(
-        [&](entt::entity /*child*/, const ModuleOwnerComponent& owner, const WeaponComponent& w)
-        {
-            if (owner.owner != entity) { return; }
-            hasWeapons = true;
-            totalDps += w.damage * w.fireRateHz;
-            if (w.range_tiles > maxRange) { maxRange = w.range_tiles; }
-        });
-
-    QString statsText = tr("HP: %1 / %2")
-        .arg(static_cast<int>(health.hp + 0.5f))
-        .arg(static_cast<int>(health.maxHp + 0.5f));
-
-    if (hasWeapons)
-    {
-        statsText += tr("\nDPS: %1").arg(QString::number(static_cast<double>(totalDps), 'f', 1));
-        statsText += tr("\nRange: %1 tiles").arg(QString::number(static_cast<double>(maxRange), 'f', 1));
-    }
-
-    m_stationStatsLabel->setText(statsText);
-    m_stationStatsLabel->show();
-
-    m_entityStatsPanel->hide();
-}
-
-void SelectedBuildingPanel::refreshEntityStats()
-{
-    // Only the single-actor stats panel needs a live refresh; the multi-actor summary is
-    // static counts, and GameWorldView prunes dead/despawned actors and re-emits the
-    // selection (REQ-UI-ENTITY-CLICK-SELECT), so the panel does not mutate it here.
-    if (m_selectedEntities.size() != 1) { return; }
-
-    EntityAdmin& admin = m_sim->getAdmin();
-    const entt::entity entity = m_selectedEntities.front();
-
-    if (!admin.isValid(entity) || !admin.hasAll<HealthComponent>(entity)) { return; }
-    const HealthComponent& health = admin.get<HealthComponent>(entity);
-    if (health.hp <= 0.0f) { return; }
-
-    if (admin.hasAll<ShipIdentityComponent>(entity))
-    {
-        const ShipStats stats = buildShipStatsFromEntity(admin, entity);
-        m_entityStatsPanel->refreshFromLive(stats, health.hp);
-        m_entityStatsPanel->setBehavior(
-            admin.get<SelectedBehaviorComponent>(entity).winner);
-    }
-    else if (admin.hasAll<StationBodyComponent>(entity))
-    {
-        buildEntityStation(entity);
-    }
-}
-
-void SelectedBuildingPanel::clearEntityDisplay()
-{
-    m_selectedEntities.clear();
-    m_entityTitleLabel->hide();
-    m_entityStatsPanel->hide();
-    m_stationStatsLabel->hide();
-    m_entitySummaryLabel->hide();
 }
 
 void SelectedBuildingPanel::handleEvent(std::shared_ptr<const SelectionChangedEvent> event)
@@ -1167,38 +864,8 @@ void SelectedBuildingPanel::handleEvent(std::shared_ptr<const SelectionChangedEv
 void SelectedBuildingPanel::handleEvent(
     std::shared_ptr<const DebrisSelectionChangedEvent> event)
 {
-    m_selectedDebris = event->debris;
+    // Debris is a field object: it supersedes any building selection but coexists
-    if (!m_selectedDebris.empty())
+    // with actors (REQ-UI-SELECTION-CATEGORIES).
-    {
+    m_fieldSelectionPanel->setSelectedDebris(event->debris);
-        // Debris is a field object: it supersedes any building selection but coexists
+    yieldToFieldSelection();
-        // with actors (REQ-UI-SELECTION-CATEGORIES).
-        m_selectedBuildingIds.clear();
-    }
-    buildFieldSelection();
-}
-
-int SelectedBuildingPanel::selectedDebrisScrapTotal() const
-{
-    // Sum the remaining scrap across the still-living selected debris (REQ-UI-DEBRIS-PANEL).
-    int total = 0;
-    for (const DebrisInfo& info : m_sim->getDebrisSystem().getAllDebrisInfo())
-    {
-        if (std::find(m_selectedDebris.begin(), m_selectedDebris.end(), info.entity)
-            != m_selectedDebris.end())
-        {
-            total += info.amount;
-        }
-    }
-    return total;
-}
-
-QString SelectedBuildingPanel::scrapTotalText() const
-{
-    return tr("Scrap x %1").arg(selectedDebrisScrapTotal());
-}
-
-void SelectedBuildingPanel::handleEvent(std::shared_ptr<const DebugDrawToggledEvent> event)
-{
-    m_debugDraw = event->active;
-    m_entityStatsPanel->setDebugDrawEnabled(event->active);
 }

src/ui/SelectedBuildingPanel.h

@@ -7,12 +7,9 @@
 #include <QPoint>
 #include <QWidget>
 
-#include "entt/entity/entity.hpp"
-
 #include "BeltSystem.h"
 #include "Building.h"
 #include "BuildingId.h"
-#include "DebugDrawToggledEvent.h"
 #include "EntitySelectionChangedEvent.h"
 #include "EventHandler.h"
 #include "GameConfig.h"
@@ -26,20 +23,27 @@
 #include "TickAdvancedEvent.h"
 
 class Simulation;
+class FieldSelectionPanel;
 class ShipLayoutPreview;
-class ShipStatsPanel;
 class QLabel;
 class QListWidget;
 class QPushButton;
 class QVBoxLayout;
 
+// Shows the current selection. The building category (buildings and construction sites)
+// is rendered by this panel itself; the field category (ships, defence stations, debris)
+// is rendered by the embedded FieldSelectionPanel.
+//
+// The two categories are mutually exclusive (REQ-UI-SELECTION-CATEGORIES) and this panel
+// is the sole arbiter of which one owns the content: it listens to all three selection
+// events, forwards the field ones to the child panel, and drops the losing category's
+// content. Neither panel touches the other's widgets.
 class SelectedBuildingPanel : public QWidget,
                                public CombinedEventHandler<TickAdvancedEvent,
                                                            PlayerCommandsAppliedEvent,
                                                            EntitySelectionChangedEvent,
                                                            SelectionChangedEvent,
-                                                           DebrisSelectionChangedEvent,
+                                                           DebrisSelectionChangedEvent>
-                                                           DebugDrawToggledEvent>
 {
     Q_OBJECT
 
@@ -54,7 +58,6 @@ private:
     void handleEvent(std::shared_ptr<const EntitySelectionChangedEvent> event) override;
     void handleEvent(std::shared_ptr<const SelectionChangedEvent> event) override;
     void handleEvent(std::shared_ptr<const DebrisSelectionChangedEvent> event) override;
-    void handleEvent(std::shared_ptr<const DebugDrawToggledEvent> event) override;
 
 private slots:
     void onSelectRecipeClicked();
@@ -73,17 +76,14 @@ private:
     };
 
     void onSelectionChanged(const std::vector<BuildingId>& ids);
+    // Gives the panel to the field category once it has anything selected.
+    void yieldToFieldSelection();
     void refreshSelectionDisplay(RefreshReason reason);
     void rebuild();
     void hideAllWidgets();
-    void clearContent();
     void buildEmpty();
     void buildSingle(BuildingId id);
     void buildMulti(const std::vector<BuildingId>& ids);
-    // Summed remaining scrap across the selected debris (REQ-UI-DEBRIS-PANEL).
-    int selectedDebrisScrapTotal() const;
-    // "Scrap x N" line for the multi-object summary (REQ-UI-FIELD-MULTI-SELECTION).
-    QString scrapTotalText() const;
     void refreshBuffers(const Building* b);
     void refreshSiteProgress(const ConstructionSite* s);
     void updateShipyardLayoutWidgets(BuildingType type,
@@ -116,28 +116,7 @@ private:
     QPoint       m_splitterTile;
     std::string  m_currentRecipeId;
 
-    bool m_debugDraw = false;
+    // Renders the field selection (actors + debris) below the building content
-    // The selected ships/defence stations. Shares the "field" selection category with
+    // (REQ-UI-FIELD-MULTI-SELECTION). Hides itself while nothing field-side is selected.
-    // debris (m_selectedDebris): both can be non-empty at once (REQ-UI-SELECTION-CATEGORIES).
+    FieldSelectionPanel* m_fieldSelectionPanel;
-    std::vector<entt::entity> m_selectedEntities;
-    ShipStatsPanel* m_entityStatsPanel;
-    QLabel*         m_entityTitleLabel;
-    QLabel*         m_stationStatsLabel;
-    QLabel*         m_entitySummaryLabel;
-
-    std::vector<entt::entity> m_selectedDebris;
-    // Shows the debris "Scrap" stat row (single selection) — the scrap total for the
-    // multi-object summary lives in m_entitySummaryLabel instead.
-    QLabel*                   m_scrapLabel;
-
-    // Renders the combined field selection (actors + debris): a single-object stats panel
-    // (ship, station, or debris) or a multi-object count summary that appends the debris
-    // count and scrap total when debris is also selected (REQ-UI-FIELD-MULTI-SELECTION).
-    void buildFieldSelection();
-    void buildEntityShip(entt::entity entity);
-    void buildEntityStation(entt::entity entity);
-    void buildEntitySummary();
-    void buildDebrisSingle();
-    void refreshEntityStats();
-    void clearEntityDisplay();
 };