XCEngine/editor/src/panels/HierarchyPanel.cpp

#include "Actions/HierarchyActionRouter.h"
#include "Actions/ActionRouting.h"
#include "Commands/EntityCommands.h"
#include "HierarchyPanel.h"
#include "Core/IEditorContext.h"
#include "Core/ISceneManager.h"
#include "Core/ISelectionManager.h"
#include "Core/EditorEvents.h"
#include "Core/EventBus.h"
#include "UI/UI.h"
#include <imgui.h>

namespace {

void DrawHierarchyTreePrefix(const XCEngine::Editor::UI::TreeNodePrefixContext& context) {
    if (!context.drawList) {
        return;
    }

    const float width = context.max.x - context.min.x;
    const float height = context.max.y - context.min.y;
    const float iconExtent = XCEngine::Editor::UI::NavigationTreeIconSize();
    const float minX = context.min.x + (width - iconExtent) * 0.5f;
    const float minY = context.min.y + (height - iconExtent) * 0.5f;
    XCEngine::Editor::UI::DrawAssetIcon(
        context.drawList,
        ImVec2(minX, minY),
        ImVec2(minX + iconExtent, minY + iconExtent),
        XCEngine::Editor::UI::AssetIconKind::GameObject);
}

} // namespace

namespace XCEngine {
namespace Editor {

HierarchyPanel::HierarchyPanel() : Panel("Hierarchy") {
}

void HierarchyPanel::OnAttach() {
    if (!m_context || m_selectionHandlerId || m_renameRequestHandlerId) {
        return;
    }

    m_selectionHandlerId = m_context->GetEventBus().Subscribe<SelectionChangedEvent>(
        [this](const SelectionChangedEvent& event) {
            OnSelectionChanged(event);
        }
    );
    m_renameRequestHandlerId = m_context->GetEventBus().Subscribe<EntityRenameRequestedEvent>(
        [this](const EntityRenameRequestedEvent& event) {
            OnRenameRequested(event);
        }
    );
}

void HierarchyPanel::OnDetach() {
    if (!m_context) {
        return;
    }

    if (m_selectionHandlerId) {
        m_context->GetEventBus().Unsubscribe<SelectionChangedEvent>(m_selectionHandlerId);
        m_selectionHandlerId = 0;
    }
    if (m_renameRequestHandlerId) {
        m_context->GetEventBus().Unsubscribe<EntityRenameRequestedEvent>(m_renameRequestHandlerId);
        m_renameRequestHandlerId = 0;
    }
}

void HierarchyPanel::OnSelectionChanged(const SelectionChangedEvent& event) {
    if (m_renameState.IsActive() && event.primarySelection != m_renameState.Item()) {
        CancelRename();
    }
}

void HierarchyPanel::OnRenameRequested(const EntityRenameRequestedEvent& event) {
    if (!m_context || event.entityId == 0) {
        return;
    }

    if (auto* gameObject = m_context->GetSceneManager().GetEntity(event.entityId)) {
        BeginRename(gameObject);
    }
}

void HierarchyPanel::Render() {
    ImGui::PushStyleColor(ImGuiCol_WindowBg, UI::HierarchyInspectorPanelBackgroundColor());
    ImGui::PushStyleColor(ImGuiCol_ChildBg, UI::HierarchyInspectorPanelBackgroundColor());
    {
        UI::PanelWindowScope panel(m_name.c_str());
        if (!panel.IsOpen()) {
            ImGui::PopStyleColor(2);
            return;
        }

        Actions::ObserveFocusedActionRoute(*m_context, EditorActionRoute::Hierarchy);

        UI::PanelContentScope content("EntityList", UI::HierarchyPanelContentPadding());
        if (!content.IsOpen()) {
            ImGui::PopStyleColor(2);
            return;
        }

        auto& sceneManager = m_context->GetSceneManager();
        auto rootEntities = sceneManager.GetRootEntities();
        UI::ResetTreeLayout();

        for (auto* gameObject : rootEntities) {
            RenderEntity(gameObject);
        }

        Actions::HandleHierarchyBackgroundPrimaryClick(*m_context, m_renameState);
        Actions::RequestHierarchyBackgroundContextPopup(m_backgroundContextMenu);
        Actions::DrawHierarchyEntityContextPopup(*m_context, m_itemContextMenu);
        Actions::DrawHierarchyBackgroundContextPopup(*m_context, m_backgroundContextMenu);
        Actions::DrawHierarchyRootDropTarget(*m_context);
    }
    ImGui::PopStyleColor(2);
}

void HierarchyPanel::RenderEntity(::XCEngine::Components::GameObject* gameObject) {
    if (!gameObject) return;

    ImGui::PushID(static_cast<int>(gameObject->GetID()));

    if (m_renameState.IsEditing(gameObject->GetID())) {
        if (m_renameState.ConsumeFocusRequest()) {
            ImGui::SetKeyboardFocusHere();
        }
        
        ImGui::SetNextItemWidth(-1);
        if (ImGui::InputText(
                "##Rename",
                m_renameState.Buffer(),
                m_renameState.BufferSize(),
                ImGuiInputTextFlags_EnterReturnsTrue | ImGuiInputTextFlags_AutoSelectAll)) {
            CommitRename();
        }

        if (ImGui::IsItemActive() && ImGui::IsKeyPressed(ImGuiKey_Escape)) {
            CancelRename();
        } else if (!ImGui::IsItemActive() && ImGui::IsMouseClicked(0)) {
            CommitRename();
        }
    } else {
        UI::TreeNodeDefinition nodeDefinition;
        nodeDefinition.options.selected = m_context->GetSelectionManager().IsSelected(gameObject->GetID());
        nodeDefinition.options.leaf = gameObject->GetChildCount() == 0;
        const std::string persistenceKey = std::to_string(gameObject->GetUUID());
        nodeDefinition.persistenceKey = persistenceKey;
        nodeDefinition.style = UI::HierarchyTreeStyle();
        nodeDefinition.prefix.width = UI::NavigationTreePrefixWidth();
        nodeDefinition.prefix.draw = DrawHierarchyTreePrefix;
        nodeDefinition.callbacks.onInteraction = [this, gameObject](const UI::TreeNodeResult& node) {
            if (node.clicked) {
                Actions::HandleHierarchySelectionClick(*m_context, gameObject->GetID(), ImGui::GetIO().KeyCtrl);
            }

            if (node.secondaryClicked) {
                Actions::HandleHierarchyItemContextRequest(*m_context, gameObject, m_itemContextMenu);
            }

            if (node.doubleClicked) {
                BeginRename(gameObject);
            }
        };
        nodeDefinition.callbacks.onRenderExtras = [this, gameObject]() {
            Actions::BeginHierarchyEntityDrag(gameObject);
            Actions::AcceptHierarchyEntityDrop(*m_context, gameObject);
        };

        const UI::TreeNodeResult node = UI::DrawTreeNode(
            &m_treeState,
            (void*)gameObject->GetUUID(),
            gameObject->GetName().c_str(),
            nodeDefinition);
        
        if (node.open) {
            for (size_t i = 0; i < gameObject->GetChildCount(); i++) {
                RenderEntity(gameObject->GetChild(i));
            }
            UI::EndTreeNode();
        }
    }
    
    ImGui::PopID();
}

void HierarchyPanel::BeginRename(::XCEngine::Components::GameObject* gameObject) {
    if (!gameObject) {
        CancelRename();
        return;
    }

    m_renameState.Begin(gameObject->GetID(), gameObject->GetName().c_str());
}

void HierarchyPanel::CommitRename() {
    if (!m_renameState.IsActive()) {
        return;
    }

    const uint64_t entityId = m_renameState.Item();
    Actions::CommitEntityRename(*m_context, entityId, m_renameState.Buffer());
    CancelRename();
}

void HierarchyPanel::CancelRename() {
    m_renameState.Cancel();
}

}
}