pg_orrery/sql/pg_orbit--0.1.0.sql

-- pg_orbit -- Orbital mechanics types and functions for PostgreSQL
--
-- Types: tle, eci_position, geodetic, topocentric, observer, pass_event
-- Provides SGP4/SDP4 propagation, coordinate transforms, pass prediction,
-- and GiST indexing on altitude bands for conjunction screening.
--
-- All propagation uses WGS-72 constants (matching TLE mean element fitting).
-- Coordinate output uses WGS-84 (matching modern geodetic standards).

-- ============================================================
-- Shell types (forward declarations)
-- ============================================================

CREATE TYPE tle;
CREATE TYPE eci_position;
CREATE TYPE geodetic;
CREATE TYPE topocentric;
CREATE TYPE observer;
CREATE TYPE pass_event;


-- ============================================================
-- TLE type: Two-Line Element set
-- ============================================================

CREATE FUNCTION tle_in(cstring) RETURNS tle
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION tle_out(tle) RETURNS cstring
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION tle_recv(internal) RETURNS tle
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION tle_send(tle) RETURNS bytea
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE TYPE tle (
    INPUT = tle_in,
    OUTPUT = tle_out,
    RECEIVE = tle_recv,
    SEND = tle_send,
    INTERNALLENGTH = 112,
    ALIGNMENT = double,
    STORAGE = plain
);

COMMENT ON TYPE tle IS 'Two-Line Element set — parsed mean orbital elements for SGP4/SDP4 propagation';

-- TLE accessor functions

CREATE FUNCTION tle_epoch(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_epoch(tle) IS 'TLE epoch as Julian date (UTC)';

CREATE FUNCTION tle_norad_id(tle) RETURNS int4
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_norad_id(tle) IS 'NORAD catalog number';

CREATE FUNCTION tle_inclination(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_inclination(tle) IS 'Orbital inclination in degrees';

CREATE FUNCTION tle_eccentricity(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_eccentricity(tle) IS 'Orbital eccentricity (dimensionless)';

CREATE FUNCTION tle_raan(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_raan(tle) IS 'Right ascension of ascending node in degrees';

CREATE FUNCTION tle_arg_perigee(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_arg_perigee(tle) IS 'Argument of perigee in degrees';

CREATE FUNCTION tle_mean_anomaly(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_mean_anomaly(tle) IS 'Mean anomaly in degrees';

CREATE FUNCTION tle_mean_motion(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_mean_motion(tle) IS 'Mean motion in revolutions per day';

CREATE FUNCTION tle_bstar(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_bstar(tle) IS 'B* drag coefficient (1/earth-radii)';

CREATE FUNCTION tle_period(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_period(tle) IS 'Orbital period in minutes';

CREATE FUNCTION tle_age(tle, timestamptz) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_age(tle, timestamptz) IS 'TLE age in days (positive = past epoch, negative = before epoch)';

CREATE FUNCTION tle_perigee(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_perigee(tle) IS 'Perigee altitude in km above WGS-72 ellipsoid';

CREATE FUNCTION tle_apogee(tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_apogee(tle) IS 'Apogee altitude in km above WGS-72 ellipsoid';

CREATE FUNCTION tle_intl_desig(tle) RETURNS text
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_intl_desig(tle) IS 'International designator (COSPAR ID)';

CREATE FUNCTION tle_from_lines(text, text) RETURNS tle
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_from_lines(text, text) IS
    'Construct TLE from separate line1/line2 text columns';


-- ============================================================
-- ECI position type: True Equator Mean Equinox (TEME) frame
-- ============================================================

CREATE FUNCTION eci_in(cstring) RETURNS eci_position
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION eci_out(eci_position) RETURNS cstring
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION eci_recv(internal) RETURNS eci_position
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION eci_send(eci_position) RETURNS bytea
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE TYPE eci_position (
    INPUT = eci_in,
    OUTPUT = eci_out,
    RECEIVE = eci_recv,
    SEND = eci_send,
    INTERNALLENGTH = 48,
    ALIGNMENT = double,
    STORAGE = plain
);

COMMENT ON TYPE eci_position IS 'Earth-Centered Inertial position and velocity in TEME frame (km, km/s)';

-- ECI accessor functions

CREATE FUNCTION eci_x(eci_position) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION eci_y(eci_position) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION eci_z(eci_position) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION eci_vx(eci_position) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION eci_vy(eci_position) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION eci_vz(eci_position) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION eci_speed(eci_position) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION eci_speed(eci_position) IS 'Velocity magnitude in km/s';

CREATE FUNCTION eci_altitude(eci_position) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION eci_altitude(eci_position) IS 'Approximate geocentric altitude in km (radius - WGS72_AE)';


-- ============================================================
-- Geodetic type: WGS-84 latitude/longitude/altitude
-- ============================================================

CREATE FUNCTION geodetic_in(cstring) RETURNS geodetic
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION geodetic_out(geodetic) RETURNS cstring
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION geodetic_recv(internal) RETURNS geodetic
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION geodetic_send(geodetic) RETURNS bytea
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE TYPE geodetic (
    INPUT = geodetic_in,
    OUTPUT = geodetic_out,
    RECEIVE = geodetic_recv,
    SEND = geodetic_send,
    INTERNALLENGTH = 24,
    ALIGNMENT = double,
    STORAGE = plain
);

COMMENT ON TYPE geodetic IS 'Geodetic coordinates on WGS-84 ellipsoid (lat/lon in degrees, altitude in km)';

CREATE FUNCTION geodetic_lat(geodetic) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION geodetic_lon(geodetic) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION geodetic_alt(geodetic) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;


-- ============================================================
-- Topocentric type: observer-relative az/el/range
-- ============================================================

CREATE FUNCTION topocentric_in(cstring) RETURNS topocentric
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION topocentric_out(topocentric) RETURNS cstring
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION topocentric_recv(internal) RETURNS topocentric
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION topocentric_send(topocentric) RETURNS bytea
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE TYPE topocentric (
    INPUT = topocentric_in,
    OUTPUT = topocentric_out,
    RECEIVE = topocentric_recv,
    SEND = topocentric_send,
    INTERNALLENGTH = 32,
    ALIGNMENT = double,
    STORAGE = plain
);

COMMENT ON TYPE topocentric IS 'Topocentric coordinates relative to observer (azimuth, elevation, range, range rate)';

CREATE FUNCTION topo_azimuth(topocentric) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION topo_azimuth(topocentric) IS 'Azimuth in degrees (0=N, 90=E, 180=S, 270=W)';

CREATE FUNCTION topo_elevation(topocentric) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION topo_elevation(topocentric) IS 'Elevation in degrees (0=horizon, 90=zenith)';

CREATE FUNCTION topo_range(topocentric) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION topo_range(topocentric) IS 'Slant range in km';

CREATE FUNCTION topo_range_rate(topocentric) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION topo_range_rate(topocentric) IS 'Range rate in km/s (positive = receding)';


-- ============================================================
-- Observer type: ground station location
-- ============================================================

CREATE FUNCTION observer_in(cstring) RETURNS observer
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION observer_out(observer) RETURNS cstring
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION observer_recv(internal) RETURNS observer
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION observer_send(observer) RETURNS bytea
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE TYPE observer (
    INPUT = observer_in,
    OUTPUT = observer_out,
    RECEIVE = observer_recv,
    SEND = observer_send,
    INTERNALLENGTH = 24,
    ALIGNMENT = double,
    STORAGE = plain
);

COMMENT ON TYPE observer IS 'Ground observer location (accepts: 40.0N 105.3W 1655m or decimal degrees)';

CREATE FUNCTION observer_lat(observer) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION observer_lat(observer) IS 'Latitude in degrees (positive = North)';

CREATE FUNCTION observer_lon(observer) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION observer_lon(observer) IS 'Longitude in degrees (positive = East)';

CREATE FUNCTION observer_alt(observer) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION observer_alt(observer) IS 'Altitude in meters above WGS-84 ellipsoid';

CREATE FUNCTION observer_from_geodetic(float8, float8, float8 DEFAULT 0.0) RETURNS observer
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION observer_from_geodetic(float8, float8, float8) IS
    'Construct observer from lat (deg), lon (deg), altitude (meters). Avoids text formatting round-trips.';


-- ============================================================
-- Pass event type: satellite visibility window
-- ============================================================

CREATE FUNCTION pass_event_in(cstring) RETURNS pass_event
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION pass_event_out(pass_event) RETURNS cstring
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION pass_event_recv(internal) RETURNS pass_event
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION pass_event_send(pass_event) RETURNS bytea
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE TYPE pass_event (
    INPUT = pass_event_in,
    OUTPUT = pass_event_out,
    RECEIVE = pass_event_recv,
    SEND = pass_event_send,
    INTERNALLENGTH = 48,
    ALIGNMENT = double,
    STORAGE = plain
);

COMMENT ON TYPE pass_event IS 'Satellite pass event (AOS/MAX/LOS times, max elevation, AOS/LOS azimuths)';

CREATE FUNCTION pass_aos_time(pass_event) RETURNS timestamptz
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION pass_aos_time(pass_event) IS 'Acquisition of signal time';

CREATE FUNCTION pass_max_el_time(pass_event) RETURNS timestamptz
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION pass_max_el_time(pass_event) IS 'Maximum elevation time';

CREATE FUNCTION pass_los_time(pass_event) RETURNS timestamptz
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION pass_los_time(pass_event) IS 'Loss of signal time';

CREATE FUNCTION pass_max_elevation(pass_event) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION pass_max_elevation(pass_event) IS 'Maximum elevation in degrees';

CREATE FUNCTION pass_aos_azimuth(pass_event) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION pass_aos_azimuth(pass_event) IS 'AOS azimuth in degrees (0=N)';

CREATE FUNCTION pass_los_azimuth(pass_event) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION pass_los_azimuth(pass_event) IS 'LOS azimuth in degrees (0=N)';

CREATE FUNCTION pass_duration(pass_event) RETURNS interval
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION pass_duration(pass_event) IS 'Pass duration (LOS - AOS)';


-- ============================================================
-- SGP4/SDP4 propagation functions
-- ============================================================

CREATE FUNCTION sgp4_propagate(tle, timestamptz) RETURNS eci_position
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION sgp4_propagate(tle, timestamptz) IS
    'Propagate TLE to a point in time using SGP4 (near-earth) or SDP4 (deep-space). Returns TEME ECI position/velocity.';

CREATE FUNCTION sgp4_propagate_safe(tle, timestamptz) RETURNS eci_position
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE PARALLEL SAFE;
COMMENT ON FUNCTION sgp4_propagate_safe(tle, timestamptz) IS
    'Like sgp4_propagate but returns NULL on error instead of raising an exception. For batch queries with potentially invalid TLEs.';

CREATE FUNCTION sgp4_propagate_series(tle, timestamptz, timestamptz, interval)
    RETURNS TABLE(t timestamptz, x float8, y float8, z float8, vx float8, vy float8, vz float8)
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE
    ROWS 100;
COMMENT ON FUNCTION sgp4_propagate_series(tle, timestamptz, timestamptz, interval) IS
    'Propagate TLE over a time range at regular intervals. Returns time series of TEME positions.';

CREATE FUNCTION tle_distance(tle, tle, timestamptz) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION tle_distance(tle, tle, timestamptz) IS
    'Euclidean distance in km between two TLEs at a reference time';


-- ============================================================
-- Coordinate transform functions
-- ============================================================

CREATE FUNCTION eci_to_geodetic(eci_position, timestamptz) RETURNS geodetic
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION eci_to_geodetic(eci_position, timestamptz) IS
    'Convert TEME ECI position to WGS-84 geodetic coordinates at given time';

CREATE FUNCTION eci_to_topocentric(eci_position, observer, timestamptz) RETURNS topocentric
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION eci_to_topocentric(eci_position, observer, timestamptz) IS
    'Convert TEME ECI position to topocentric (az/el/range) relative to observer';

CREATE FUNCTION subsatellite_point(tle, timestamptz) RETURNS geodetic
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION subsatellite_point(tle, timestamptz) IS
    'Subsatellite (nadir) point on WGS-84 ellipsoid at given time';

CREATE FUNCTION ground_track(tle, timestamptz, timestamptz, interval)
    RETURNS TABLE(t timestamptz, lat float8, lon float8, alt float8)
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE
    ROWS 100;
COMMENT ON FUNCTION ground_track(tle, timestamptz, timestamptz, interval) IS
    'Ground track as time series of subsatellite points (lat/lon in degrees, alt in km)';

CREATE FUNCTION observe(tle, observer, timestamptz) RETURNS topocentric
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION observe(tle, observer, timestamptz) IS
    'Propagate TLE and compute observer-relative look angles in one call. Returns topocentric (az/el/range/range_rate).';

CREATE FUNCTION observe_safe(tle, observer, timestamptz) RETURNS topocentric
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE PARALLEL SAFE;
COMMENT ON FUNCTION observe_safe(tle, observer, timestamptz) IS
    'Like observe() but returns NULL on propagation error. For batch queries with potentially invalid/decayed TLEs.';


-- ============================================================
-- Pass prediction functions
-- ============================================================

CREATE FUNCTION next_pass(tle, observer, timestamptz) RETURNS pass_event
    AS 'MODULE_PATHNAME' LANGUAGE C STABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION next_pass(tle, observer, timestamptz) IS
    'Find the next satellite pass over observer (searches up to 7 days ahead)';

CREATE FUNCTION predict_passes(tle, observer, timestamptz, timestamptz, float8 DEFAULT 0.0)
    RETURNS SETOF pass_event
    AS 'MODULE_PATHNAME' LANGUAGE C STABLE STRICT PARALLEL SAFE
    ROWS 10;
COMMENT ON FUNCTION predict_passes(tle, observer, timestamptz, timestamptz, float8) IS
    'Predict all satellite passes over observer in time window. Optional min_elevation in degrees.';

CREATE FUNCTION pass_visible(tle, observer, timestamptz, timestamptz) RETURNS boolean
    AS 'MODULE_PATHNAME' LANGUAGE C STABLE STRICT PARALLEL SAFE;
COMMENT ON FUNCTION pass_visible(tle, observer, timestamptz, timestamptz) IS
    'True if any pass occurs over observer in the time window';


-- ============================================================
-- GiST operator support functions
-- ============================================================

-- Overlap operator: do altitude bands intersect?
CREATE FUNCTION tle_overlap(tle, tle) RETURNS boolean
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

-- Altitude distance operator
CREATE FUNCTION tle_alt_distance(tle, tle) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE OPERATOR && (
    LEFTARG = tle,
    RIGHTARG = tle,
    FUNCTION = tle_overlap,
    COMMUTATOR = &&,
    RESTRICT = areasel,
    JOIN = areajoinsel
);

COMMENT ON OPERATOR && (tle, tle) IS 'Altitude band overlap — necessary condition for conjunction';

CREATE OPERATOR <-> (
    LEFTARG = tle,
    RIGHTARG = tle,
    FUNCTION = tle_alt_distance,
    COMMUTATOR = <->
);

COMMENT ON OPERATOR <-> (tle, tle) IS 'Minimum altitude-band separation in km (0 if overlapping)';


-- ============================================================
-- GiST operator class for altitude-band indexing
-- ============================================================

-- GiST internal support functions
CREATE FUNCTION gist_tle_compress(internal) RETURNS internal
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION gist_tle_decompress(internal) RETURNS internal
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION gist_tle_consistent(internal, tle, smallint, oid, internal) RETURNS boolean
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION gist_tle_union(internal, internal) RETURNS internal
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION gist_tle_penalty(internal, internal, internal) RETURNS internal
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION gist_tle_picksplit(internal, internal) RETURNS internal
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION gist_tle_same(internal, internal, internal) RETURNS internal
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE FUNCTION gist_tle_distance(internal, tle, smallint, oid, internal) RETURNS float8
    AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;

CREATE OPERATOR CLASS tle_ops
    DEFAULT FOR TYPE tle USING gist AS
        OPERATOR  3   && ,
        OPERATOR  15  <-> (tle, tle) FOR ORDER BY float_ops,
        FUNCTION  1   gist_tle_consistent(internal, tle, smallint, oid, internal),
        FUNCTION  2   gist_tle_union(internal, internal),
        FUNCTION  3   gist_tle_compress(internal),
        FUNCTION  4   gist_tle_decompress(internal),
        FUNCTION  5   gist_tle_penalty(internal, internal, internal),
        FUNCTION  6   gist_tle_picksplit(internal, internal),
        FUNCTION  7   gist_tle_same(internal, internal, internal),
        FUNCTION  8   gist_tle_distance(internal, tle, smallint, oid, internal);