#include <editor/Editor.h>

#include <utility>

#include <imgui.h>
#include <nlohmann/json.hpp>
#include <spdlog/spdlog.h>

#include <destrum/App.h>
#include <destrum/Assets/AssetDatabase.h>
#include <destrum/Assets/AssetTypes.h>
#include <destrum/FS/AssetFS.h>
#include <destrum/Input/InputManager.h>
#include <destrum/ObjectModel/GameObject.h>
#include <destrum/Scene/Scene.h>
#include <destrum/Scene/SceneManager.h>
#include <destrum/Serialization/PrefabSerializer.h>
#include <destrum/Serialization/SceneSerializer.h>

#include <ImGuizmo.h>

namespace {
    [[nodiscard]] bool AnyKeyReleased()
    {
        for (int key = ImGuiKey_NamedKey_BEGIN; key < ImGuiKey_NamedKey_END; ++key) {
            if (ImGui::IsKeyReleased(static_cast<ImGuiKey>(key))) {
                return true;
            }
        }
        return false;
    }
}

Editor::Editor(App& app, EditorSettings settings)
    : m_App(app),
      m_Settings(std::move(settings)),
      m_PlayMode(app),
      m_ScenePath(m_Settings.scenePath)
{
}

void Editor::onAttach()
{
    auto& assetFs = AssetFS::GetInstance();
#ifdef DESTRUM_ENGINE_ASSETS_SRC_DIR
    assetFs.SetSourceRoot("engine", DESTRUM_ENGINE_ASSETS_SRC_DIR);
#endif
    if (!m_Settings.gameAssetsSource.empty()) {
        assetFs.SetSourceRoot("game", m_Settings.gameAssetsSource);
    }
    AssetDatabase::GetInstance().Refresh();

#if defined(DESTRUM_ENGINE_ASSETS_SRC_DIR) && defined(DESTRUM_THECHEF_PATH)
    m_ShaderHotReload.Configure(DESTRUM_THECHEF_PATH, DESTRUM_ENGINE_ASSETS_SRC_DIR, assetFs.GetFullPath("engine://shaders").parent_path());
#endif

    if (m_Settings.startInEditMode) {
        m_PlayMode.EnterEditMode();
    }
    if (Scene* scene = CurrentScene()) {
        m_UndoStack.Reset(*scene);
    }
}

Scene* Editor::CurrentScene() const
{
    auto& sceneManager = SceneManager::GetInstance();
    return sceneManager.GetActiveScenes().empty() ? nullptr : &sceneManager.GetCurrentScene();
}

bool Editor::UsesEditorCamera()
{
    return m_PlayMode.IsEditing() || m_PlayMode.IsPaused() || m_App.gameCamera() == nullptr;
}

Camera* Editor::viewCamera()
{
    return UsesEditorCamera() ? &m_Camera.GetCamera() : nullptr;
}

AppLayer::InputFocus Editor::gameInputFocus() const
{
    return {
        .mouse = m_Viewport.hovered && !m_Viewport.mouseClaimed,
        .keyboard = m_Viewport.focused || m_Camera.IsLooking(),
    };
}

void Editor::onBeginFrame()
{
    ApplyViewportResize();
}

void Editor::onImGuiBegin(float dt)
{
    DrawDockSpace();
    ApplyPick();
    HandleShortcuts();

    if (UsesEditorCamera()) {
        m_Camera.Update(dt, m_Viewport.hovered || m_Viewport.focused || m_Camera.IsLooking());
    }

    if (m_ShaderHotReload.Poll(dt)) {
        const bool reloaded = m_App.getRenderer().reloadShaders(m_App.getGfxDevice());
        SetStatus(reloaded ? "Reloaded shaders" : "Shader reload failed, the old shaders stay active");
    }
}

void Editor::onImGui(float)
{
    DrawMainMenuBar();
    DrawSceneDialogs();
    DrawViewport();

    Scene* scene = CurrentScene();
    if (scene != nullptr && m_Panels.inspector) {
        ObjectId selected = scene->GetSelectedObjectId();
        m_Inspector.Draw(*scene, selected, [scene] { scene->DrawSettingsImGui(); }, &m_Panels.inspector);
        scene->SetSelectedObject(selected);
    }
    if (m_Panels.assets) {
        if (const auto opened = m_AssetBrowser.Draw(&m_Panels.assets)) {
            OnAssetDropped(*opened);
        }
    }
    if (m_Panels.stats) {
        DrawStatsPanel();
    }
    if (m_Panels.physics) {
        DrawPhysicsPanel();
    }
    if (m_Panels.imageCache) {
        m_ResourcesInspector.drawImageCacheWindow(&m_Panels.imageCache, m_App.getResources(), m_App.getImguiPass());
    }

    if (scene != nullptr && m_View.gizmos && UsesEditorCamera()) {
        GameObject* selected = scene->GetSelectedObject();
        if (selected != nullptr && !RectGizmo::CanManipulate(*selected)) {
            m_TransformGizmo.DrawToolbar();
        }
    }
}

void Editor::onEndFrame()
{
    if (m_PlayMode.ApplyPendingToggle()) {
        AfterSceneReplaced(false);
    }

    const bool itemActive = ImGui::IsAnyItemActive() || ImGuizmo::IsUsing();
    const bool gestureEnded = (m_ItemWasActive && !itemActive) || ImGui::IsMouseReleased(ImGuiMouseButton_Left) ||
                              AnyKeyReleased() || std::exchange(m_EditPending, false);
    m_ItemWasActive = itemActive;
    if (gestureEnded && !itemActive && m_PlayMode.IsEditing()) {
        RecordEdits();
    }
}

void Editor::onRender(GameRenderer& renderer)
{
    const bool picking = m_PlayMode.IsEditing() || m_PlayMode.IsPaused();
    renderer.setSelectionPassEnabled(picking);
    renderer.setHoverPixel(picking ? m_Viewport.hoverPixel : std::nullopt);

    std::vector<std::uint32_t> highlighted;
    Scene* scene = CurrentScene();
    if (scene == nullptr) {
        renderer.setHighlightedObjects(highlighted);
        return;
    }

    if (GameObject* selected = scene->GetSelectedObject(); selected != nullptr && picking) {
        std::vector<GameObject*> pending{selected};
        while (!pending.empty()) {
            GameObject* object = pending.back();
            pending.pop_back();
            highlighted.push_back(static_cast<std::uint32_t>(object->GetId()));
            for (const Transform* child : object->GetTransform().GetChildren()) {
                if (child != nullptr && child->GetOwner() != nullptr) {
                    pending.push_back(child->GetOwner());
                }
            }
        }
    }
    renderer.setHighlightedObjects(highlighted);

    if (m_View.colliders) {
        SubmitColliderLines(*scene);
    }
}

void Editor::HandleShortcuts()
{
    const ImGuiIO& io = ImGui::GetIO();
    if (io.WantTextInput) {
        return;
    }

    if (ImGui::IsKeyPressed(ImGuiKey_F5, false)) {
        m_PlayMode.RequestToggle();
    }
    if (ImGui::IsKeyPressed(ImGuiKey_F7, false) && m_PlayMode.IsPlaying()) {
        m_PlayMode.SetPaused(!m_PlayMode.IsPaused());
    }
    if (io.KeyCtrl && ImGui::IsKeyPressed(ImGuiKey_S, false)) {
        SaveScene();
    }
    if (io.KeyCtrl && ImGui::IsKeyPressed(ImGuiKey_Z)) {
        io.KeyShift ? Redo() : Undo();
    }
    if (io.KeyCtrl && ImGui::IsKeyPressed(ImGuiKey_Y)) {
        Redo();
    }

    if (!m_Viewport.focused && !m_Viewport.hovered) {
        return;
    }
    if (UsesEditorCamera() && !m_Camera.IsLooking()) {
        m_TransformGizmo.HandleShortcuts();
    }
    if (ImGui::IsKeyPressed(ImGuiKey_F, false) && !io.KeyCtrl) {
        FocusSelection();
    }
    if (ImGui::IsKeyPressed(ImGuiKey_Delete, false)) {
        DeleteSelection();
    }
    if (io.KeyCtrl && ImGui::IsKeyPressed(ImGuiKey_D, false)) {
        DuplicateSelection();
    }
}

void Editor::Undo()
{
    Scene* scene = CurrentScene();
    if (scene == nullptr || !m_PlayMode.IsEditing()) {
        return;
    }
    if (m_UndoStack.Undo(*scene)) {
        m_App.collectUnusedResources();
        m_App.onPlayModeChanged(false);
    }
}

void Editor::Redo()
{
    Scene* scene = CurrentScene();
    if (scene == nullptr || !m_PlayMode.IsEditing()) {
        return;
    }
    if (m_UndoStack.Redo(*scene)) {
        m_App.collectUnusedResources();
        m_App.onPlayModeChanged(false);
    }
}

void Editor::RecordEdits()
{
    if (Scene* scene = CurrentScene()) {
        m_UndoStack.Record(*scene);
    }
}

void Editor::AfterSceneReplaced(bool resetHistory)
{
    m_App.collectUnusedResources();
    Scene* scene = CurrentScene();
    if (scene == nullptr) {
        return;
    }
    if (resetHistory) {
        m_UndoStack.Reset(*scene);
    } else {
        m_UndoStack.Rebase(*scene);
    }
}

void Editor::DeleteSelection()
{
    Scene* scene = CurrentScene();
    GameObject* selected = scene != nullptr ? scene->GetSelectedObject() : nullptr;
    if (selected == nullptr) {
        return;
    }
    selected->Destroy();
    scene->SetSelectedObject(InvalidObjectId);
    m_EditPending = true;
}

void Editor::DuplicateSelection()
{
    Scene* scene = CurrentScene();
    GameObject* selected = scene != nullptr ? scene->GetSelectedObject() : nullptr;
    if (selected == nullptr) {
        return;
    }
    if (const GameObject* copy = PrefabSerializer::Duplicate(*selected)) {
        scene->SetSelectedObject(copy->GetId());
        m_EditPending = true;
    }
}

void Editor::FocusSelection()
{
    Scene* scene = CurrentScene();
    if (GameObject* selected = scene != nullptr ? scene->GetSelectedObject() : nullptr) {
        m_Camera.Focus(ComputeWorldBounds(*selected, m_App.getResources()));
    }
}

void Editor::SetStatus(std::string status)
{
    spdlog::info("{}", status);
    m_Status = std::move(status);
}

bool Editor::WriteScene(Scene& scene, std::string_view path)
{
    const AssetDatabase::MetaFileScope createMetaFiles;
    const auto root = SceneSerializer::Capture(scene);
    if (!root || !AssetFS::GetInstance().WriteFile(path, root->dump(4))) {
        SetStatus("Could not save the scene to " + std::string{path});
        return false;
    }
    SetStatus("Saved " + std::string{path});
    return true;
}

bool Editor::SaveScene()
{
    if (!m_PlayMode.IsEditing()) {
        SetStatus("Stop play mode before saving, the scene is the play copy right now");
        return false;
    }
    if (m_ScenePath.empty()) {
        m_SaveAsDialog = true;
        return false;
    }
    Scene* scene = CurrentScene();
    return scene != nullptr && WriteScene(*scene, m_ScenePath);
}

bool Editor::SaveSceneAs(std::string_view path)
{
    std::string target{path};
    if (!AssetTypes::IsScene(target)) {
        target += AssetTypes::SceneExtension;
    }
    m_ScenePath = target;
    return SaveScene();
}

bool Editor::OpenScene(std::string_view path)
{
    Scene* scene = CurrentScene();
    if (scene == nullptr) {
        return false;
    }
    if (!m_PlayMode.IsEditing()) {
        SetStatus("Stop play mode before opening another scene");
        return false;
    }

    if (!SceneSerializer::Load(*scene, AssetFS::GetInstance().GetFullPath(path))) {
        SetStatus("Could not open " + std::string{path});
        return false;
    }
    m_ScenePath = path;
    m_PlayMode.EnterEditMode();
    AfterSceneReplaced(true);
    SetStatus("Opened " + std::string{path});
    return true;
}

void Editor::NewScene()
{
    Scene* scene = CurrentScene();
    if (scene == nullptr || !m_PlayMode.IsEditing()) {
        return;
    }
    const nlohmann::json empty{{"name", "Untitled"}, {"objects", nlohmann::json::array()}};
    if (SceneSerializer::LoadFromJson(*scene, empty)) {
        m_ScenePath.clear();
        m_PlayMode.EnterEditMode();
        AfterSceneReplaced(true);
    }
}