#include <destrum/Scene/SceneManager.h>

#include <algorithm>
#include <iterator>
#include <stdexcept>

#include <destrum/Scene/Scene.h>
#include <destrum/Util/DeltaTime.h>

Scene& SceneManager::GetCurrentScene() const {
    if (m_activeScenes.empty()) {
        throw std::out_of_range("No active scenes are available");
    }
    return *m_activeScenes.front();
}

void SceneManager::Update(float dt) {
    for (const auto& scene : m_activeScenes) {
        if (m_playing) {
            scene->Update(dt);
        } else {
            scene->CommitPendingAdditions();
        }
    }
}

void SceneManager::FixedUpdate(float dt) {
    if (!m_playing) {
        return;
    }
    for (const auto& scene : m_activeScenes) {
        scene->FixedUpdate(dt);
    }
}

void SceneManager::LateUpdate(float dt) {
    if (!m_playing) {
        return;
    }
    for (const auto& scene : m_activeScenes) {
        scene->LateUpdate(dt);
    }
}

void SceneManager::Render(const RenderContext& ctx) {
    for (const auto& scene : m_activeScenes) {
        scene->Render(ctx);
    }
}

void SceneManager::RenderImgui(bool* open) {
    for (const auto& scene : m_activeScenes) {
        scene->RenderImgui(open);
    }
}

void SceneManager::HandleGameObjectDestroy() {
    for (const auto& scene : m_scenes) {
        scene->CleanupDestroyedGameObjects();
    }
}

void SceneManager::DestroyGameObjects() {
    for (const auto& scene : m_scenes) {
        scene->DestroyGameObjects();
    }
}

void SceneManager::UnloadAllScenes() {
    for (const auto& scene : m_scenes) {
        scene->Unload();
    }
}

void SceneManager::HandleSceneDestroy() {
    for (auto it = m_scenes.begin(); it != m_scenes.end();) {
        if ((*it)->IsBeingUnloaded()) {
            const auto activeIt = std::find(m_activeScenes.begin(), m_activeScenes.end(), *it);
            if (activeIt != m_activeScenes.end()) {
                m_activeScenes.erase(activeIt);
            }
            it = m_scenes.erase(it);
        } else {
            ++it;
        }
    }

    // Remove any stale active scenes that are no longer in the scene list.
    std::erase_if(m_activeScenes, [this](const auto& scene) {
        return std::find(m_scenes.begin(), m_scenes.end(), scene) == m_scenes.end();
    });
}

void SceneManager::HandleScene() {
    HandleGameObjectDestroy();
    HandleSceneDestroy();
}

void SceneManager::Destroy() {
    if (m_scenes.empty()) {
        return;
    }

    UnloadAllScenes();
    DestroyGameObjects();
    HandleGameObjectDestroy();
    HandleSceneDestroy();
}

void SceneManager::SwitchScene(int index) {
    if (index < 0 || index >= static_cast<int>(m_scenes.size())) {
        throw std::out_of_range("Scene index out of range");
    }

    for (const auto& scene : m_activeScenes) {
        scene->UnloadBindings();
    }
    m_activeScenes.clear();
    m_activeScenes.push_back(m_scenes[static_cast<std::size_t>(index)]);
    m_activeScenes.back()->LoadBindings();
}

void SceneManager::AddActiveScene(int index) {
    if (index < 0 || index >= static_cast<int>(m_scenes.size())) {
        throw std::out_of_range("Scene index out of range");
    }

    const auto& scene = m_scenes[static_cast<std::size_t>(index)];
    if (std::find(m_activeScenes.begin(), m_activeScenes.end(), scene) == m_activeScenes.end()) {
        scene->LoadBindings();
        m_activeScenes.push_back(scene);
    }
}

void SceneManager::RemoveActiveScene(int index) {
    if (index < 0 || index >= static_cast<int>(m_scenes.size())) {
        throw std::out_of_range("Scene index out of range");
    }

    const auto& scene = m_scenes[static_cast<std::size_t>(index)];
    const auto it = std::find(m_activeScenes.begin(), m_activeScenes.end(), scene);
    if (it != m_activeScenes.end()) {
        (*it)->UnloadBindings();
        m_activeScenes.erase(it);
    }
}

int SceneManager::GetActiveSceneId() const {
    if (m_scenes.empty() || m_activeScenes.empty()) {
        return -1;
    }

    const auto it = std::find(m_scenes.begin(), m_scenes.end(), m_activeScenes.front());
    if (it == m_scenes.end()) {
        return -1;
    }
    return static_cast<int>(std::distance(m_scenes.begin(), it));
}

Scene& SceneManager::CreateScene(const std::string& name) {
    const auto scene = std::shared_ptr<Scene>(new Scene(name));
    m_scenes.push_back(scene);
    if (m_scenes.size() == 1) {
        m_activeScenes.push_back(scene);
    }
    return *scene;
}