#pragma once

#include "rhi.h"
#include "scene/scene_types.h"   // BlackHoleParams, SceneObject
#include <glm/glm.hpp>
#include <vector>

namespace Donut
{
    // The black-hole view, written ONCE against the RHI. Each frame it ray-traces
    // the geodesic shader into an off-screen target (progressive resolution: a
    // small target while the camera moves, a larger one once it settles) and then
    // upscales that target onto the swapchain. The Application owns the camera and
    // the HDRI cubemap and passes them in.
    struct GeodesicView
    {
        glm::vec3 position, right, up, forward;
        float tan_half_fov = 1.0f;
        float aspect       = 16.0f / 9.0f;
        bool  moving       = false;
        float time         = 0.0f;
    };

    class BlackHoleRenderer
    {
    public:
        static constexpr int GEO_LO_W = 480, GEO_LO_H = 270;
        static constexpr int GEO_HI_W = 960, GEO_HI_H = 540;

        auto init(RHI::Device& device) -> bool;

        // Off-screen geodesic pass (opens/closes its own render pass). Call before
        // the swapchain pass; `cubemap` is the shared HDRI environment. `objects`
        // are the Scene's spheres — ray-traced as lensed spheres around the hole
        // (1 scene unit = 1 Schwarzschild radius). Grid units == r_s.
        auto render_geodesic(RHI::CommandList& cmd, const GeodesicView& view,
                             const BlackHoleParams& params,
                             const std::vector<SceneObject>& objects, RHI::Texture* cubemap) -> void;

        // Upscales the geodesic target onto the swapchain (call inside the open
        // swapchain render pass, before ImGui).
        auto blit(RHI::CommandList& cmd, int fb_width, int fb_height) -> void;

    private:
        RHI::Device* m_device = nullptr;

        Ref<RHI::Pipeline>     m_geo_pipeline;
        Ref<RHI::RenderTarget> m_geo_lo;
        Ref<RHI::RenderTarget> m_geo_hi;
        Ref<RHI::Buffer>       m_quad_vb;
        Ref<RHI::Buffer>       m_cam_ubo;
        Ref<RHI::Buffer>       m_disk_ubo;
        Ref<RHI::Buffer>       m_obj_ubo;
        Ref<RHI::Buffer>       m_sim_ubo;

        Ref<RHI::Pipeline>     m_present_pipeline;
        RHI::RenderTarget*     m_last_target = nullptr;   // target chosen this frame
    };
}