import { config } from '../config/Config.js';
import { Rng } from '../utils/Rng.js';
import { NameGenerator, ordinalLabel } from '../utils/NameGenerator.js';

const clamp = (v, lo, hi) => Math.min(hi, Math.max(lo, v));

/**
 * Turns a lightweight galaxy record (id, name, type, x, y) into a fully
 * generated system: star, planets, moons, debris belt, hazard flag.
 *
 * Deterministic contract:
 *   same galaxy seed + same record id ⇒ identical content, every time.
 * The draw stream is derived from (seed, 'system', id) — NOT from the
 * galaxy-level sequence — so a system generated when the player arrives
 * is byte-for-byte identical to one generated during an up-front
 * generateAll(). That's what makes lazy generation safe.
 *
 * What the system actually contains is steered by the TYPE'S ATTRIBUTES
 * in data/systems.json (`types.<id>.attributes`): star classes, binary
 * chance, planet count spread, planet class weights, moon/belt chances,
 * habitability, hazard. Theme (`types.<id>.theme`) is for UI. Add new
 * attribute keys here + in the JSON and types become richer without
 * touching the galaxy generator.
 */
export function generateSystemContent(galaxy, record, typeDefs = null) {
  const defs = typeDefs ?? config.get('systems.types', {});
  const type = defs[record.type] ?? { label: record.type, attributes: {} };
  const attr = type.attributes ?? {};
  const rng = Rng.derive(galaxy.seed, 'system', record.id);

  // --- Star -------------------------------------------------------------
  const starClasses = attr.star?.classes ?? { G: 30, K: 35, M: 35 };
  const massTable = attr.star?.mass ?? {};
  const starClass = rng.weighted(starClasses, 'M');
  const mass = Array.isArray(massTable[starClass]) ? massTable[starClass] : [0.3, 1.2];
  const star = {
    name: NameGenerator.star(rng),
    class: starClass,
    mass: Number(rng.range(mass[0], mass[1]).toFixed(2)),
    binary: false,
  };
  if (rng.chance(attr.binaryChance ?? 0.05)) {
    star.binary = true;
    star.secondary = {
      name: NameGenerator.star(rng),
      class: rng.weighted(starClasses, starClass),
    };
  }

  // --- Planets ----------------------------------------------------------
  const pc = attr.planetCount ?? { min: 3, max: 8, mean: 5 };
  const count = Math.round(
    clamp(pc.mean + (rng.next() - 0.5) * (pc.max - pc.min), pc.min, pc.max),
  );
  const classWeights = attr.planetClasses ?? { rocky: 45, gas: 25, ice: 18, lava: 12 };
  const planets = [];
  for (let i = 1; i <= count; i++) {
    const pclass = rng.weighted(classWeights, 'rocky');
    let moons = 0;
    if (rng.chance(attr.moonChance ?? 0.3)) {
      // Jovian/ice worlds drag moon systems; terrestrials mostly don't.
      moons = pclass === 'gas' || pclass === 'ice' ? rng.int(1, 6) : rng.int(0, 2);
    }
    planets.push({
      name: `${NameGenerator.planetRoot(rng)} ${ordinalLabel(i)}`,
      ordinal: i,
      class: pclass,
      moons,
      habitable: pclass === 'rocky' && rng.chance(attr.habitability ?? 0.1),
    });
  }

  // --- Debris belt & system-level hazard --------------------------------
  const belt = {
    present: rng.chance(attr.beltChance ?? 0.35),
    kind: rng.pick(['asteroid', 'debris']) ?? 'asteroid',
  };
  const hazard = rng.chance(attr.hazard ?? 0.1);

  return {
    name: record.name,
    type: record.type,
    star,
    planets,
    belt,
    hazard,
  };
}