#pragma once

#include <SDL3/SDL_gpu.h>

// ============================================================================
// PostFXUniforms — pushed to the fragment stage each frame via
//   SDL_PushGPUFragmentUniformData(pass, 0, &uniforms, sizeof(PostFXUniforms))
// MSL binding: constant PostFXUniforms& u [[buffer(0)]]
// ============================================================================
struct PostFXUniforms {
    float vignette_strength;   // 0 = none, 1.5 = default subtle
    float chroma_strength;     // 0 = off, 1 = full chromatic aberration
    float scanline_strength;   // 0 = off, 1 = full scanlines
    float time;                // accumulated seconds (for future animations)
};

// ============================================================================
// GpuPipeline — Creates and owns the graphics pipelines used by the engine.
//
//  sprite_pipeline_ : textured quads, alpha blending.
//                     Vertex layout: GpuVertex (pos float2, uv float2, col float4).
//  ball_pipeline_   : instanced ball rendering, alpha blending.
//                     Vertex layout: BallGPUData as per-instance data (input_rate=INSTANCE).
//                     6 procedural vertices per instance (no index buffer).
//  postfx_pipeline_ : full-screen triangle, no vertex buffer, no blend.
//                     Reads offscreen texture, writes to swapchain.
//                     Accepts PostFXUniforms via fragment uniform buffer slot 0.
// ============================================================================
class GpuPipeline {
public:
    // target_format: pass SDL_GetGPUSwapchainTextureFormat() result.
    // offscreen_format: format of the offscreen render target.
    bool init(SDL_GPUDevice* device,
              SDL_GPUTextureFormat target_format,
              SDL_GPUTextureFormat offscreen_format);
    void destroy(SDL_GPUDevice* device);

    SDL_GPUGraphicsPipeline* spritePipeline() const { return sprite_pipeline_; }
    SDL_GPUGraphicsPipeline* ballPipeline()   const { return ball_pipeline_; }
    SDL_GPUGraphicsPipeline* postfxPipeline() const { return postfx_pipeline_; }

private:
    SDL_GPUShader* createShader(SDL_GPUDevice* device,
                                const char* msl_source,
                                const char* entrypoint,
                                SDL_GPUShaderStage stage,
                                Uint32 num_samplers,
                                Uint32 num_uniform_buffers,
                                Uint32 num_storage_buffers = 0);

    SDL_GPUShader* createShaderSPIRV(SDL_GPUDevice* device,
                                     const uint8_t* spv_code,
                                     size_t spv_size,
                                     const char* entrypoint,
                                     SDL_GPUShaderStage stage,
                                     Uint32 num_samplers,
                                     Uint32 num_uniform_buffers,
                                     Uint32 num_storage_buffers = 0);

    SDL_GPUGraphicsPipeline* sprite_pipeline_ = nullptr;
    SDL_GPUGraphicsPipeline* ball_pipeline_   = nullptr;
    SDL_GPUGraphicsPipeline* postfx_pipeline_ = nullptr;
};