#ifndef OPTICS_H
#define OPTICS_H

#include <stddef.h>
#include <stdio.h>

typedef struct { double r, g, b; } LinearRgb;
typedef struct {
  double fwhm_pixels;
  double moffat_beta;
} PointSpreadFunction;

/* One immutable process-wide kernel for the one PSF parameter pair accepted
 * by the current renderer.  Its storage remains private to optics.c. */
typedef struct {
  double fwhm_pixels, moffat_beta, alpha_pixels;
  double max_radius_pixels, build_seconds;
  float *weights;
  int phase_resolution, radius_pixels;
  int ready;
} PsfKernelCache;

typedef struct {
  size_t cached_splats;
  size_t direct_fallbacks;
} PsfSplatStats;

/* Integrate a Planck spectrum into absolute linear-sRGB spectral radiance
 * (W m^-2 sr^-1), before catalog amplitude and display exposure. */
LinearRgb blackbody_to_linear_rgb(double temperature_K);
int psf_kernel_cache_init(PsfKernelCache *cache,
                          const PointSpreadFunction *psf);
void psf_kernel_cache_destroy(PsfKernelCache *cache);
void psf_kernel_cache_report_ready(const PsfKernelCache *cache, FILE *stream);
void psf_kernel_cache_report(const PsfKernelCache *cache,
                             const PsfSplatStats *stats, FILE *stream);
/* Reference implementation: pixel-area-integrated Moffat with the same tail
 * budgets as the cache-aware renderer. */
void splat_moffat_direct(double *hdr, int width, int height, double x, double y,
                         LinearRgb color, double flux,
                         const PointSpreadFunction *psf);
void splat_moffat(double *hdr, int width, int height, double x, double y,
                  LinearRgb color, double flux,
                  const PointSpreadFunction *psf);
/* Returns nonzero when this event used the direct reference fallback. */
int splat_moffat_cached(double *hdr, int width, int height, double x, double y,
                        LinearRgb color, double flux,
                        const PointSpreadFunction *psf,
                        const PsfKernelCache *cache);
/* Writes PNG when built with libpng; non-libpng builds use PPM fallback. */
int write_tonemapped_image(const char *path, const double *hdr, int width,
                           int height);
#ifdef ENABLE_HDR_DEBUG
/* Test-build-only: writes the pre-tone-mapping framebuffer as 32-bit RGB FITS. */
int write_hdr_fits(const char *path, const double *hdr, int width, int height,
                   double horizontal_fov_deg);
#endif

#endif