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 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() {
    UI::PanelWindowScope panel(m_name.c_str());
    if (!panel.IsOpen()) {
        return;
    }

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

    RenderSearchBar();
    std::string filter = m_searchBuffer;

    UI::PanelContentScope content("EntityList");
    if (!content.IsOpen()) {
        return;
    }

    auto& sceneManager = m_context->GetSceneManager();
    auto rootEntities = sceneManager.GetRootEntities();
    SortEntities(const_cast<std::vector<::XCEngine::Components::GameObject*>&>(rootEntities));
    
    for (auto* gameObject : rootEntities) {
        RenderEntity(gameObject, filter);
    }
    
    if (ImGui::IsWindowHovered() && ImGui::IsMouseDown(0) && !ImGui::IsAnyItemHovered()) {
        if (!m_renameState.IsActive()) {
            m_context->GetSelectionManager().ClearSelection();
        }
    }
    
    if (UI::BeginPopupContextWindow("HierarchyContextMenu", ImGuiPopupFlags_MouseButtonRight)) {
        Actions::DrawHierarchyCreateActions(*m_context, nullptr);
        UI::EndPopup();
    }
    
    ImGui::InvisibleButton("##DragTarget", ImVec2(-1, -1));
    if (ImGui::BeginDragDropTarget()) {
        if (const ImGuiPayload* payload = ImGui::AcceptDragDropPayload("ENTITY_PTR")) {
            ::XCEngine::Components::GameObject* sourceGameObject = *(::XCEngine::Components::GameObject**)payload->Data;
            if (sourceGameObject && sourceGameObject->GetParent() != nullptr) {
                Commands::ReparentEntityPreserveWorldTransform(*m_context, sourceGameObject, 0);
            }
        }
        ImGui::EndDragDropTarget();
    }
    
}

void HierarchyPanel::RenderSearchBar() {
    UI::PanelToolbarScope toolbar("HierarchyToolbar", UI::StandardPanelToolbarHeight());
    if (!toolbar.IsOpen()) {
        return;
    }

    const float buttonWidth = UI::HierarchyOverflowButtonWidth();
    UI::ToolbarSearchField(
        "##Search",
        "Search hierarchy",
        m_searchBuffer,
        sizeof(m_searchBuffer),
        buttonWidth + UI::ToolbarSearchTrailingSpacing());
    ImGui::SameLine();
    if (UI::ToolbarButton("...", false, ImVec2(buttonWidth, 0.0f))) {
        ImGui::OpenPopup("HierarchyOptions");
    }

    if (UI::BeginPopup("HierarchyOptions")) {
        const UI::MenuCommand commands[] = {
            UI::MenuCommand::Action("Sort By Name", nullptr, m_sortMode == SortMode::Name),
            UI::MenuCommand::Action("Sort By Component Count", nullptr, m_sortMode == SortMode::ComponentCount),
            UI::MenuCommand::Action("Transform First", nullptr, m_sortMode == SortMode::TransformFirst)
        };

        UI::DrawMenuCommands(commands, [&](size_t index) {
            switch (index) {
                case 0:
                    m_sortMode = SortMode::Name;
                    break;
                case 1:
                    m_sortMode = SortMode::ComponentCount;
                    break;
                case 2:
                    m_sortMode = SortMode::TransformFirst;
                    break;
                default:
                    break;
            }
        });
        UI::EndPopup();
    }
}

void HierarchyPanel::RenderEntity(::XCEngine::Components::GameObject* gameObject, const std::string& filter) {
    if (!gameObject) return;
    
    if (!filter.empty() && !PassesFilter(gameObject, filter)) {
        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 {
        const UI::HierarchyNodeResult node = UI::DrawHierarchyNode(
            (void*)gameObject->GetUUID(),
            gameObject->GetName().c_str(),
            m_context->GetSelectionManager().IsSelected(gameObject->GetID()),
            gameObject->GetChildCount() == 0);
        
        if (node.clicked) {
            ImGuiIO& io = ImGui::GetIO();
            if (io.KeyCtrl) {
                if (!m_context->GetSelectionManager().IsSelected(gameObject->GetID())) {
                    m_context->GetSelectionManager().AddToSelection(gameObject->GetID());
                }
            } else {
                m_context->GetSelectionManager().SetSelectedEntity(gameObject->GetID());
            }
        }
        
        if (node.doubleClicked) {
            BeginRename(gameObject);
        }
        
        HandleDragDrop(gameObject);
        
        if (UI::BeginPopupContextItem("EntityContextMenu")) {
            Actions::DrawHierarchyContextActions(*m_context, gameObject);
            UI::EndPopup();
        }
        
        if (node.open) {
            for (size_t i = 0; i < gameObject->GetChildCount(); i++) {
                RenderEntity(gameObject->GetChild(i), filter);
            }
            UI::EndHierarchyNode();
        }
    }
    
    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();
    if (!m_renameState.Empty() && m_context->GetSceneManager().GetEntity(entityId)) {
        Commands::RenameEntity(*m_context, entityId, m_renameState.Buffer());
    }

    CancelRename();
}

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

void HierarchyPanel::HandleDragDrop(::XCEngine::Components::GameObject* gameObject) {
    if (ImGui::BeginDragDropSource(ImGuiDragDropFlags_None)) {
        ImGui::SetDragDropPayload("ENTITY_PTR", &gameObject, sizeof(::XCEngine::Components::GameObject*));
        ImGui::Text("%s", gameObject->GetName().c_str());
        ImGui::EndDragDropSource();
    }
    
    if (ImGui::BeginDragDropTarget()) {
        if (const ImGuiPayload* payload = ImGui::AcceptDragDropPayload("ENTITY_PTR")) {
            ::XCEngine::Components::GameObject* sourceGameObject = *(::XCEngine::Components::GameObject**)payload->Data;
            if (sourceGameObject != gameObject && Commands::CanReparentEntity(sourceGameObject, gameObject)) {
                Commands::ReparentEntityPreserveWorldTransform(*m_context, sourceGameObject, gameObject->GetID());
            }
        }
        ImGui::EndDragDropTarget();
    }
}

bool HierarchyPanel::PassesFilter(::XCEngine::Components::GameObject* gameObject, const std::string& filter) {
    if (!gameObject) return false;
    
    if (gameObject->GetName().find(filter) != std::string::npos) {
        return true;
    }
    
    for (size_t i = 0; i < gameObject->GetChildCount(); i++) {
        if (PassesFilter(gameObject->GetChild(i), filter)) {
            return true;
        }
    }
    
    return false;
}

void HierarchyPanel::SortEntities(std::vector<::XCEngine::Components::GameObject*>& entities) {
    switch (m_sortMode) {
        case SortMode::Name:
            std::sort(entities.begin(), entities.end(), [](::XCEngine::Components::GameObject* a, ::XCEngine::Components::GameObject* b) {
                return a->GetName() < b->GetName();
            });
            break;
        case SortMode::ComponentCount:
            std::sort(entities.begin(), entities.end(), [](::XCEngine::Components::GameObject* a, ::XCEngine::Components::GameObject* b) {
                return a->GetComponents<::XCEngine::Components::Component>().size() > b->GetComponents<::XCEngine::Components::Component>().size();
            });
            break;
        case SortMode::TransformFirst:
            std::sort(entities.begin(), entities.end(), [](::XCEngine::Components::GameObject* a, ::XCEngine::Components::GameObject* b) {
                bool aHasTransform = a->GetComponent<::XCEngine::Components::TransformComponent>() != nullptr;
                bool bHasTransform = b->GetComponent<::XCEngine::Components::TransformComponent>() != nullptr;
                if (aHasTransform != bHasTransform) {
                    return aHasTransform;
                }
                return a->GetName() < b->GetName();
            });
            break;
    }
}

}
}