astrology-insights/panchang/src/birthchart/core/planets.ts

Comprehensive Vedic astrology engine for Node.js — Panchang, birth charts (Kundli), Vimshottari Dasha, divisional charts, dosha analysis, and planetary remedies. Swiss Ephemeris precision, validated against Drik Panchang.

/**
 * Planetary Position Calculator
 * Calculate sidereal positions for all 9 Vedic grahas.
 */

import { Ephemeris } from '../../calculations/ephemeris';
import { GrahaName, GrahaPosition, ALL_GRAHAS } from '../types';
import { SIGN_NAMES } from './constants';
import { determineDignity, getDignitySymbol, determineCombustion } from './states';

// Nakshatra data (inline to avoid circular deps)
const NAKSHATRA_DATA: Array<{ name: string; lord: string }> = [
  { name: 'Ashwini',           lord: 'Ketu' },
  { name: 'Bharani',           lord: 'Venus' },
  { name: 'Krittika',          lord: 'Sun' },
  { name: 'Rohini',            lord: 'Moon' },
  { name: 'Mrigashira',        lord: 'Mars' },
  { name: 'Ardra',             lord: 'Rahu' },
  { name: 'Punarvasu',         lord: 'Jupiter' },
  { name: 'Pushya',            lord: 'Saturn' },
  { name: 'Ashlesha',          lord: 'Mercury' },
  { name: 'Magha',             lord: 'Ketu' },
  { name: 'Purva Phalguni',    lord: 'Venus' },
  { name: 'Uttara Phalguni',   lord: 'Sun' },
  { name: 'Hasta',             lord: 'Moon' },
  { name: 'Chitra',            lord: 'Mars' },
  { name: 'Swati',             lord: 'Rahu' },
  { name: 'Vishakha',          lord: 'Jupiter' },
  { name: 'Anuradha',          lord: 'Saturn' },
  { name: 'Jyeshtha',          lord: 'Mercury' },
  { name: 'Mula',              lord: 'Ketu' },
  { name: 'Purva Ashadha',     lord: 'Venus' },
  { name: 'Uttara Ashadha',    lord: 'Sun' },
  { name: 'Shravana',          lord: 'Moon' },
  { name: 'Dhanishtha',        lord: 'Mars' },
  { name: 'Shatabhisha',       lord: 'Rahu' },
  { name: 'Purva Bhadrapada',  lord: 'Jupiter' },
  { name: 'Uttara Bhadrapada', lord: 'Saturn' },
  { name: 'Revati',            lord: 'Mercury' },
];

function normalizeAngle(a: number): number {
  let n = a % 360;
  if (n < 0) n += 360;
  return n;
}

function computeNakshatra(lon: number): {
  name: string; number: number; pada: number; lord: string;
} {
  const oneNak = 360 / 27;
  const onePada = oneNak / 4;
  const norm = normalizeAngle(lon);
  const idx = Math.floor(norm / oneNak);
  const posInNak = norm - idx * oneNak;
  const pada = Math.min(Math.floor(posInNak / onePada) + 1, 4);
  const nk = NAKSHATRA_DATA[idx] || { name: 'Unknown', lord: 'Unknown' };
  return { name: nk.name, number: idx + 1, pada, lord: nk.lord };
}

/**
 * Calculate sidereal positions for all 9 grahas.
 */
export function calculateAllPlanets(
  utcDate: Date,
  ayanamsa: number,
  ephemeris: Ephemeris,
): GrahaPosition[] {
  const positions: GrahaPosition[] = [];

  // First, calculate Sun position (needed for combustion checks)
  let sunSiderealLon = 0;

  for (const graha of ALL_GRAHAS) {
    const pos = ephemeris.calculatePosition(utcDate, graha);
    const siderealLon = normalizeAngle(pos.longitude - ayanamsa);

    // Get speed via the Ephemeris speed method
    const speed = getGrahaSpeed(utcDate, graha, ephemeris);

    // Rahu & Ketu are always retrograde
    let retrograde: boolean;
    if (graha === 'Rahu' || graha === 'Ketu') {
      retrograde = true;
    } else {
      retrograde = speed < 0;
    }

    const signNumber = Math.floor(siderealLon / 30) + 1;
    const degreeInSign = siderealLon - (signNumber - 1) * 30;
    const nak = computeNakshatra(siderealLon);

    const dignity = determineDignity(graha, signNumber, degreeInSign);
    const symbol = getDignitySymbol(dignity);

    if (graha === 'Sun') {
      sunSiderealLon = siderealLon;
    }

    positions.push({
      name: graha,
      longitude: Math.round(siderealLon * 10000) / 10000,
      latitude: pos.latitude,
      speed: Math.round(speed * 10000) / 10000,
      retrograde,
      signName: SIGN_NAMES[signNumber] || 'Unknown',
      signNumber,
      degreeInSign: Math.round(degreeInSign * 100) / 100,
      nakshatra: nak.name,
      nakshatraNumber: nak.number,
      nakshatraPada: nak.pada,
      nakshatraLord: nak.lord,
      dignity,
      isCombust: false, // will be filled below
      combustOrb: 0,
      symbol,
    });
  }

  // Now compute combustion for each planet (need Sun's position)
  for (const gp of positions) {
    if (gp.name === 'Sun') {
      sunSiderealLon = gp.longitude;
      break;
    }
  }

  for (const gp of positions) {
    const comb = determineCombustion(gp.name, gp.longitude, sunSiderealLon, gp.retrograde);
    gp.isCombust = comb.isCombust;
    gp.combustOrb = comb.orb;
  }

  return positions;
}

/**
 * Get the speed (degrees/day) for a graha.
 * Uses swe_calc_ut with SEFLG_SPEED.
 */
function getGrahaSpeed(utcDate: Date, graha: GrahaName, ephemeris: Ephemeris): number {
  try {
    const result = ephemeris.calculatePositionWithSpeed(utcDate, graha);
    return result.speed;
  } catch {
    // Fallback speeds (mean daily motion)
    const defaultSpeeds: Record<string, number> = {
      Sun: 0.9856,
      Moon: 13.176,
      Mars: 0.524,
      Mercury: 1.383,
      Jupiter: 0.083,
      Venus: 1.602,
      Saturn: 0.034,
      Rahu: -0.053,  // always retrograde
      Ketu: -0.053,
    };
    return defaultSpeeds[graha] || 0;
  }
}