/*
 * eph_provider.h -- Ephemeris provider dispatch for pg_orrery
 *
 * Manages the optional JPL DE ephemeris alongside the compiled-in
 * VSOP87 and ELP2000-82B theories.
 *
 * Key design constraints:
 *   - Per-backend lazy initialization (never in _PG_init/postmaster)
 *   - ICRS equatorial -> ecliptic J2000 frame rotation at the boundary
 *   - Automatic VSOP87 fallback on any DE error
 *   - No shared state between PostgreSQL backends
 */

#ifndef PG_ORRERY_EPH_PROVIDER_H
#define PG_ORRERY_EPH_PROVIDER_H

#include "postgres.h"
#include "types.h"

/*
 * Ephemeris provider identifiers.
 */
typedef enum
{
    EPH_VSOP87,     /* compiled-in VSOP87 / ELP2000-82B (always available) */
    EPH_JPL_DE      /* JPL DE binary file (optional, STABLE) */
} EphProvider;


/*
 * Initialize the GUC variable (pg_orrery.ephemeris_path).
 * Called from _PG_init(). Does NOT open the DE file.
 */
void eph_register_gucs(void);

/*
 * Cleanup callback for on_proc_exit.
 * Closes the DE file descriptor if open.
 */
void eph_cleanup(int code, Datum arg);

/*
 * Attempt to initialize the DE reader for this backend.
 * Returns true if DE is available and ready, false otherwise.
 * On first call, opens the file and validates. On subsequent calls,
 * returns cached status.
 *
 * Thread-safe per backend (each backend has its own static state).
 */
bool eph_de_available(void);

/*
 * Which provider is currently active?
 */
EphProvider eph_current_provider(void);

/*
 * Get the configured ephemeris file path (or NULL if not set).
 */
const char *eph_get_path(void);


/*
 * Get planet heliocentric ecliptic J2000 position via DE.
 *
 * body_id: pg_orrery body ID (1=Mercury..8=Neptune)
 * jd:      Julian date (TDB)
 * xyz[6]:  output position (AU) in ecliptic J2000 frame
 *          (xyz[3..5] are zero — velocity not yet implemented)
 *
 * Returns true on success. On failure, xyz is unchanged and
 * caller should fall back to VSOP87.
 */
bool eph_de_planet(int body_id, double jd, double xyz[6]);

/*
 * Get Earth heliocentric ecliptic J2000 position via DE.
 *
 * jd:      Julian date (TDB)
 * xyz[6]:  output position (AU) in ecliptic J2000 frame
 *
 * Returns true on success.
 */
bool eph_de_earth(double jd, double xyz[6]);

/*
 * Get Moon geocentric ecliptic J2000 position via DE.
 *
 * jd:      Julian date (TDB)
 * xyz[3]:  output position (AU) in ecliptic J2000 frame
 *
 * Returns true on success. On failure, caller falls back to ELP2000-82B.
 */
bool eph_de_moon(double jd, double xyz[3]);

/*
 * Get Sun "heliocentric" position (always 0,0,0 but consistent API).
 */
bool eph_de_sun(double jd, double xyz[6]);

/*
 * DE metadata accessors (for pg_orrery_ephemeris_info).
 * Return 0/0.0 if DE is not loaded.
 */
double eph_de_start_jd(void);
double eph_de_end_jd(void);
int    eph_de_version(void);
double eph_de_au_km(void);

#endif /* PG_ORRERY_EPH_PROVIDER_H */