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

const clamp = (v, lo, hi) => Math.min(hi, Math.max(lo, v));
const TAU = Math.PI * 2;
const DEG = Math.PI / 180;

/**
 * Turns a lightweight galaxy record (id, name, type, x, y, rNorm) into a
 * fully generated system: star, planets, moons, SETTLEMENTS, 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 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, and — the lived-in layer — `settlements` (chance
 * + required planet class per settlement kind). Settlement kinds and their
 * population ranges live in data/settlements.json; the core→rim density
 * gradient in data/galaxy.json (`settlements.gradient`).
 *
 * The galaxy is ALREADY LIVED IN: it was settled long before the player.
 * Colonies on habitable worlds, mining stations over resource worlds,
 * cloud bases riding gas giants, stations adrift in open space — and a
 * fair number of charted-but-unclaimed systems. Nothing here is hostile
 * yet: `owner` on every settlement is a reserved seam for the factions
 * and pirates we'll introduce later.
 *
 * Place identity (the reputation/trading/faction keys): every planet and
 * settlement carries a stable `id`, seed-deterministic because it is
 * built from the system id + the object's position in its generated list:
 *   planets      `<systemId>-p<ordinal>`   (p1…pn, orbital order)
 *   settlements  `<systemId>-s<n>`         (s1…, draw order: planet-bound
 *                                           kinds in orbital order, then
 *                                           free-space)
 * Same seed ⇒ same ids ⇒ a reputation saved against them lines up with
 * the regenerated galaxy (see js/reputation/Reputation.js). The player's
 * home world is not one of the generated planets — it has the fixed key
 * 'home'.
 */
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 };
  // Planet names come from a curated bank (data/naming.json → banks.planet),
  // dealt out per-system without repeats (see NameGenerator.planetDeck).
  // A dedicated derived stream keeps this order-independent (lazy === eager).
  const planetDeck = NameGenerator.planetDeck(
    Rng.derive(galaxy.seed, 'system', record.id, 'names', 'planets')
  );
  // The player's home world sits at the origin of the STARTING system and is
  // not one of the generated planets. It takes the first name off that
  // system's deck so it can never clash with a planet; the planets then draw
  // from the rest of the deck (all distinct within the system).
  const isHome = record.id === galaxy?.currentSystemId;
  const homeName = isHome ? planetDeck[0] : null;
  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({
      id: `${record.id}-p${i}`, // reputation/trading key (stable per seed)
      name: planetDeck[(isHome ? i : i - 1) % planetDeck.length],
      ordinal: i,
      class: pclass,
      moons,
      habitable: pclass === 'rocky' && rng.chance(attr.habitability ?? 0.1),
    });
  }
  // --- Settlements (the lived-in layer) ---------------------------------
  const settlements = generateSettlements({
    rng,
    systemId: record.id,
    kindDefs: config.get('settlements.kinds', {}),
    spec: attr.settlements ?? {},
    planets,
    stationDeck: NameGenerator.stationDeck(
      Rng.derive(galaxy.seed, 'system', record.id, 'names', 'stations')
    ),
    density: settlementDensity(galaxy, record),
  });

  // --- Layout: orbits around the home world -----------------------------
  // Planets and free-space stations are the system's layout objects — each
  // gets an x/y (see layoutSystem for the spacing rules and the N=11 case).
  const freeSpace = settlements.filter((s) => s.anchor?.type === 'space');
  layoutSystem(galaxy.seed, record.id, planets, freeSpace);

  // --- Asteroid clusters ------------------------------------------------
  // Loose groups of slowly tumbling rocks scattered through the void.
  // Generated AFTER the layout (so every placed object is a spacing
  // obstacle) from the dedicated stream (seed, 'system', id, 'asteroids')
  // — independent of the star/planet/settlement/layout draws above, so
  // lazy (on-arrival) === eager (generateAll) is preserved.
  const asteroids = generateAsteroidClusters(galaxy, record, planets, freeSpace);

  // --- 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);

  const content = {
    name: record.name,
    type: record.type,
    star,
    planets,
    settlements,
    asteroids,
    belt,
    hazard,
  };
  if (isHome) content.homeName = homeName; // the player's home world (starting system only)
  return content;
}

/**
 * Top-down layout of a system's objects — its planets and its free-space
 * stations — as one or two ORBITS (rings) around the home world, which
 * always sits at the system origin (the game renders a solid world there;
 * see GameScene).
 *
 * Each object gains x, y (world position). Planets also gain scale (size
 * multiplier, data/planets.json → classScale — the spacing rules below are
 * center-to-center, but the rendered discs still scale by class).
 *
 * The hard spacing rules (data/planets.json → solarSystem):
 *   minSpacing  — no two objects (planets, space stations, the home world)
 *                 may be closer than this, center to center;
 *   maxNeighbor — whenever a system holds more than one object, every
 *                 object must be within this of at least one other.
 *
 * A ring of k objects at radius R around the origin satisfies both at once:
 *   - object ⇄ home-world distance is R, so R ∈ [minSpacing, maxNeighbor]
 *     takes care of the home world's own pair of constraints;
 *   - the closest object-object pair on a regular k-gon is an edge,
 *     2·R·sin(π/k) — an edge is the shortest chord (vertices further around
 *     are further), so edge ≥ minSpacing covers every pair;
 *   - every object's nearest neighbor is then the home world, at
 *     R ≤ maxNeighbor.
 * That radius range is non-empty for k ≤ 10 (k = 11 would need
 * R ≥ 10905, which already strands the home world beyond maxNeighbor). So
 * the 11-object maximum (9 planets + 2 stations — the most the current
 * data can produce) gets two orbits: an inner 3-ring and an outer 8-ring.
 * The outer ring's near neighbor is its ring-mate (edge stays in
 * [minSpacing, maxNeighbor]); the inner ring keeps the home world within
 * maxNeighbor; and any inner/outer pair is at least R_outer − R_inner ≥
 * minSpacing apart. Smaller N all share one orbit. (Defensively, beyond
 * 11 objects the orbits chain outward — rings of ≤ 10, and a lone world
 * always fits radially outside the previous orbit — so this terminates
 * for any N.)
 *
 * What counts as an object: planets (all of them) and free-space
 * settlements (anchor.type 'space' — deep-space stations, waypoints).
 * Planet-bound settlements are features OF their planet (a colony sits on
 * it) and so are not layout objects of their own.
 *
 * Determinism: draws come from the dedicated fork (seed, 'system', id,
 * 'layout') — layout never perturbs the star/planet/settlement draws
 * above, and lazy (on-arrival) === eager (generateAll) is preserved.
 */
function layoutSystem(seed, systemId, planets, freeSpace) {
  const band = config.get('planets.solarSystem', {});
  if (band.enabled === false) return;
  const MIN_SEP = band.minSpacing ?? 6144;
  const MAX_NBR = band.maxNeighbor ?? 10240;

  // Rendered size per class (visual only — the spacing rules are
  // center-to-center, not edge-to-edge).
  for (const p of planets) {
    p.scale = config.get(`planets.classScale.${p.class}`, 1) ?? 1;
  }

  // Slot assignment order: planets in orbital order, then free-space
  // stations in generation order (deep-space station, then waypoint) —
  // stable per system, so lazy === eager.
  const objects = [...planets, ...freeSpace];
  const N = objects.length;
  if (N === 0) return;

  const TAU = Math.PI * 2;
  const lay = Rng.derive(seed, 'system', systemId, 'layout');
  const edgeFactor = (k) => (k <= 1 ? 1 : 2 * Math.sin(Math.PI / k));
  const slots = [];
  let prevR = 0;
  let prevAngle = 0;

  const placeRing = (k, lo, hi) => {
    const R = lay.range(lo, hi);
    // A LONE object on an outer orbit sits radially outside an
    // already-placed one: its guaranteed neighbor is then exactly
    // R − prevR away, whereas a random angle could leave it more than
    // maxNeighbor from every inner object.
    const th0 = k === 1 && prevR > 0 ? prevAngle : lay.range(0, TAU);
    for (let i = 0; i < k; i++) {
      const th = th0 + (k === 1 ? 0 : (TAU * i) / k);
      slots.push({ x: R * Math.cos(th), y: R * Math.sin(th) });
    }
    prevR = R;
    prevAngle = th0;
  };

  if (N <= 10) {
    // One orbit around the home world (k = 1: a single object, whose only
    // neighbor is the home world — fine, it's still within [MIN_SEP, MAX_NBR]).
    const f = edgeFactor(N);
    placeRing(N, Math.max(MIN_SEP, MIN_SEP / f), MAX_NBR);
  } else if (N === 11) {
    // Inner 3-ring: the home world must stay within MAX_NBR of it (R1 ≤
    // MAX_NBR), and the outer 8-ring must sit at least MIN_SEP beyond it
    // at a radius where its edge is still ≤ MAX_NBR:
    //   R1 ≤ MAX_NBR / edgeFactor(8) − MIN_SEP.
    const f8 = edgeFactor(8);
    placeRing(
      3,
      Math.max(MIN_SEP, MIN_SEP / edgeFactor(3)),
      Math.min(MAX_NBR, MAX_NBR / f8 - MIN_SEP),
    );
    const R1 = prevR;
    // Outer 8-ring: ring-mates are its near neighbors (edge in
    // [MIN_SEP, MAX_NBR]); every inner object is ≥ R2 − R1 ≥ MIN_SEP away.
    placeRing(
      8,
      Math.max(MIN_SEP / f8, R1 + MIN_SEP),
      Math.min(MAX_NBR / f8, R1 + MAX_NBR),
    );
  } else {
    // Beyond the data maximum: chain orbits outward. A ring of ≤ 10
    // objects always has a valid radius as ring 1, a lone world always
    // fits on any outer orbit — the loop terminates for any N.
    let rem = N;
    while (rem > 0) {
      const k = Math.min(rem, 10);
      const f = edgeFactor(k);
      const lo = prevR === 0 ? Math.max(MIN_SEP, MIN_SEP / f) : Math.max(MIN_SEP / f, prevR + MIN_SEP);
      const hi = prevR === 0 ? MAX_NBR : Math.min(MAX_NBR / f, prevR + MAX_NBR);
      if (lo <= hi) {
        placeRing(k, lo, hi);
        rem -= k;
      } else {
        placeRing(1, prevR + MIN_SEP, prevR + MAX_NBR);
        rem -= 1;
      }
    }
  }

  for (let i = 0; i < objects.length; i++) {
    objects[i].x = slots[i].x;
    objects[i].y = slots[i].y;
  }
}

/**
 * Asteroid clusters — the system's loose rock fields (data/asteroids.json).
 *
 * A cluster is a GROUP of 4–8 rocks (data → cluster.groupSize), each 64–128
 * px (cluster.sizes) with at least one full-size rock, sitting within
 * `cluster.spread` of the cluster center, and kept a small gap apart from
 * each other (cluster.gapFactor — the generator relaxes any overlap so no
 * two rocks interpenetrate). Every rock tumbles on its own
 * slow spin (its own speed and direction — cluster.spin), and the whole
 * group drifts slowly around its center (cluster.groupSpin) — the render
 * (js/entities/AsteroidCluster.js) reads these straight off the record.
 *
 * The rules (all from data/asteroids.json):
 *   - COUNT vs PLANETS — clusterCount ≈ targetObjects − planetCount (±
 *     jitter, clamped to [minClusters, maxClusters]): the more planets a
 *     system has, the fewer asteroid clusters, and vice versa. The
 *     STARTING system always gets at least startingSystemMinClusters, and
 *     those first ones are placed inside the player's initial tether
 *     (tether.level1Radius × radiusGrowth^(homeLevel−1), whole cluster,
 *     minus placement.tetherMargin) so the player can reach them.
 *   - SPACING — no cluster center may sit closer than
 *     placement.minObjectSpacing (1024 px, center-to-center) to ANY other
 *     object: the home world (origin), every planet, every free-space
 *     station, and every other cluster.
 *   - SCATTER — other clusters land anywhere in the annulus
 *     [placement.minRadius, placement.maxRadius] around the origin, picked
 *     by seeded rejection sampling (uniform in area) — sprinkled through
 *     the void, inside and outside the planet orbits.
 *   - FRAMES — each rock is a random sheet frame, with NO frame repeated
 *     twice in the same cluster (a seeded shuffle of the frame pool).
 *   - NAMES — synthesised (NameGenerator.asteroid) and never repeating a
 *     name already used in the system (planets, stations, other clusters).
 *
 * Determinism: every draw comes from the dedicated forks
 *   Rng.derive(seed, 'system', id, 'asteroids')  — members, spins, placement
 *   Rng.derive(seed, 'system', id, 'names', 'asteroids') — names
 * — so clusters are seed-deterministic, independent of the other streams,
 * and lazy === eager (see generateSystemContent).
 *
 * Record shape (one per cluster):
 *   {
 *     id, name, x, y,          // cluster center + identity
 *     bound,                   // max extent from center = discovery radius
 *     tint,                    // per-cluster starlight tint (int, or null)
 *     groupSpin, groupPhase,   // the loose group's slow drift (rad/s, rad)
 *     debrisPhase, debris: [], // dust motes (local px, size, alpha)
 *     asteroids: [{ frame, x, y, size, spin, phase }] // rocks, local px
 *   }
 */
function generateAsteroidClusters(galaxy, record, planets, freeSpace) {
  const cfg = config.section('asteroids', {});
  if (cfg.enabled === false) return [];
  // Without the solar-system layout there are no placed objects to space
  // against — no clusters either (the scene renders nothing else anyway).
  if (config.get('planets.solarSystem.enabled', true) === false) return [];

  const clusterCfg = cfg.cluster ?? {};
  const dist = cfg.distribution ?? {};
  const placement = cfg.placement ?? {};
  const isHome = record.id === galaxy?.currentSystemId;

  // --- How many clusters: the inverse of the planet count ---------------
  const target = dist.targetObjects ?? 9;
  const jitter = dist.jitter ?? 1;
  const minC = Math.max(1, Math.floor(dist.minClusters ?? 1));
  const maxC = Math.max(minC, Math.floor(dist.maxClusters ?? 6));
  const homeMin = isHome ? Math.max(minC, Math.floor(dist.startingSystemMinClusters ?? 2)) : minC;

  const rng = Rng.derive(galaxy.seed, 'system', record.id, 'asteroids');
  const count = clamp(
    Math.round(target - planets.length + rng.range(-jitter, jitter)),
    homeMin, maxC,
  );
  if (count === 0) return [];

  // --- Parameter plumbing (every value steerable from data/asteroids.json)
  const frameCount = Math.max(1, Math.floor(cfg.frameCount ?? 10));
  const sizeMin = Math.floor(clusterCfg.sizes?.min ?? 64);
  const sizeMax = Math.max(sizeMin, Math.floor(clusterCfg.sizes?.max ?? 128));
  const groupMin = Math.max(1, Math.floor(clusterCfg.groupSize?.min ?? 4));
  const groupMax = Math.max(groupMin, Math.floor(clusterCfg.groupSize?.max ?? 8));
  const spread = clusterCfg.spread ?? 140;
  const spinMin = Math.max(0, clusterCfg.spin?.minDegPerSec ?? 0.3) * DEG;
  const spinMax = Math.max(spinMin, clusterCfg.spin?.maxDegPerSec ?? 1.6) * DEG;
  const gspinMin = Math.max(0, clusterCfg.groupSpin?.minDegPerSec ?? 0.12) * DEG;
  const gspinMax = Math.max(gspinMin, clusterCfg.groupSpin?.maxDegPerSec ?? 0.4) * DEG;
  const tintAnchors =
    clusterCfg.tint?.enabled === false ? [] : (clusterCfg.tint?.anchors ?? ['#dfe9ff', '#ffe9d6', '#e8e4f8']);
  const tintStrength = clamp(clusterCfg.tint?.strength ?? 0.5, 0, 1);
  const debrisCfg = clusterCfg.debris ?? {};

  // --- Placement rules ---------------------------------------------------
  const rMin = placement.minRadius ?? 2048;
  const rMax = Math.max(rMin, placement.maxRadius ?? 18432);
  const minSep = placement.minObjectSpacing ?? 1024;
  const maxAttempts = Math.max(1, Math.floor(placement.maxPlacementAttempts ?? 400));
  const tetherMargin = placement.tetherMargin ?? 96;
  const tetherRadius = homeTetherRadius();
  const homeSlots = isHome ? Math.min(count, homeMin) : 0;

  // Names already taken in this system (planets + stations).
  const nameRng = Rng.derive(galaxy.seed, 'system', record.id, 'names', 'asteroids');
  const usedNames = new Set();
  for (const p of planets) if (p.name) usedNames.add(p.name);
  for (const s of freeSpace) if (s.name) usedNames.add(s.name);

  // Spacing obstacles: the home world (origin) + every placed object.
  const placed = [{ x: 0, y: 0 }];
  for (const p of planets) if (typeof p.x === 'number' && typeof p.y === 'number') placed.push({ x: p.x, y: p.y });
  for (const s of freeSpace) if (typeof s.x === 'number' && typeof s.y === 'number') placed.push({ x: s.x, y: s.y });

  const clusters = [];
  for (let i = 0; i < count; i++) {
    // --- The group's rocks ---------------------------------------------
    const memberCount = rng.int(groupMin, groupMax);

    // Frames: a random subset of the sheet — NO frame twice in this cluster.
    const frames = rng.shuffle(Array.from({ length: frameCount }, (_, k) => k)).slice(0, memberCount);

    // Sizes: random in [sizeMin, sizeMax]; at least minFullSize full-size.
    const sizes = Array.from({ length: memberCount }, () => rng.int(sizeMin, sizeMax));
    const fullRocks = Math.min(Math.max(0, Math.floor(clusterCfg.minFullSize ?? 1)), memberCount);
    for (let k = 0; k < fullRocks; k++) sizes[rng.int(0, memberCount - 1)] = sizeMax;

    // Offsets: a dense random blob around the center (uniform in area),
    // then a relaxation pass enforces a small gap between EVERY pair of
    // rocks (cluster.gapFactor — 1.12 ≈ a subtle gap): only pairs that
    // would overlap move, each by half the shortfall, so the group keeps
    // its random look and stays compact while no rocks interpenetrate.
    const gapFactor = Math.max(1, clusterCfg.gapFactor ?? 1.12);
    const members = [];
    for (let k = 0; k < memberCount; k++) {
      const a = rng.range(0, TAU);
      const r = spread * Math.sqrt(rng.next()); // uniform in area
      members.push({ x: Math.cos(a) * r, y: Math.sin(a) * r, size: sizes[k] });
    }
    relaxRockGaps(members, gapFactor);
    const bound = Math.max(...members.map((m) => Math.hypot(m.x, m.y) + m.size / 2));

    // Spins: each rock tumbles on its own — its own slow speed, its own
    // direction, its own starting phase.
    const spins = members.map(() => (rng.chance(0.5) ? 1 : -1) * rng.range(spinMin, spinMax));
    const phases = members.map(() => rng.range(0, TAU));

    // Dust: a fine halo of motes orbiting just outside the rocks.
    const debris = [];
    if (debrisCfg.enabled !== false) {
      const n = rng.int(debrisCfg.count?.[0] ?? 14, debrisCfg.count?.[1] ?? 30);
      const rIn = bound * (debrisCfg.inner ?? 1.0);
      const rOut = Math.max(rIn, bound * (debrisCfg.outer ?? 2.1));
      for (let k = 0; k < n; k++) {
        const a = rng.range(0, TAU);
        const r = Math.sqrt(rng.range(rIn * rIn, rOut * rOut));
        debris.push({
          x: Math.cos(a) * r,
          y: Math.sin(a) * r,
          size: rng.range(debrisCfg.size?.[0] ?? 0.8, debrisCfg.size?.[1] ?? 2.4),
          alpha: rng.range(debrisCfg.alpha?.[0] ?? 0.12, debrisCfg.alpha?.[1] ?? 0.4),
        });
      }
    }

    // Starlight: a subtle warm/cool shift, per cluster.
    const tint = tintAnchors.length
      ? mixTint(tintAnchors[rng.int(0, tintAnchors.length - 1)] ?? tintAnchors[0], tintStrength)
      : null;

    // Name: synthesised, unique within the system.
    let name = NameGenerator.asteroid(nameRng);
    for (let tries = 0; tries < 10 && usedNames.has(name); tries++) name = NameGenerator.asteroid(nameRng);
    usedNames.add(name);

    // --- Where: sprinkle it in the void --------------------------------
    // The starting system's first clusters live INSIDE the initial tether
    // (whole group: center + bound + margin ≤ tether radius); the rest —
    // and every cluster elsewhere — go anywhere in the scatter annulus.
    const zoneMax =
      i < homeSlots ? Math.max(rMin, Math.min(rMax, tetherRadius - bound - tetherMargin)) : rMax;
    const pos = placeInAnnulus(rng, rMin, zoneMax, placed, minSep, maxAttempts);
    placed.push(pos);

    clusters.push({
      id: `asteroid-${i + 1}`,
      name,
      x: pos.x,
      y: pos.y,
      bound,
      tint,
      groupSpin: (rng.chance(0.5) ? 1 : -1) * rng.range(gspinMin, gspinMax),
      groupPhase: rng.range(0, TAU),
      debrisPhase: rng.range(0, TAU),
      // The dust glides on its OWN slow orbit (0.2–0.5 deg/s, random way)
      // — fine particles drifting around the rocks, not locked to them.
      debrisSpin: (rng.next() < 0.5 ? 1 : -1) * rng.range(0.2, 0.5) * DEG,
      debris,
      asteroids: members.map((m, k) => ({
        frame: frames[k],
        x: m.x,
        y: m.y,
        size: m.size,
        spin: spins[k],
        phase: phases[k],
      })),
    });
  }
  return clusters;
}

/**
 * A random point in the annulus [rMin, rMax] around the origin (uniform in
 * AREA) that is ≥ minSep from every placed object — seeded rejection
 * sampling. If the annulus is hopelessly crowded (it isn't, at these
 * numbers) it returns the best candidate rather than failing.
 */
function placeInAnnulus(rng, rMin, rMax, placed, minSep, maxAttempts) {
  let best = null;
  for (let attempt = 0; attempt < maxAttempts; attempt++) {
    const a = rng.range(0, TAU);
    const r = Math.sqrt(rng.range(rMin * rMin, rMax * rMax));
    const x = Math.cos(a) * r;
    const y = Math.sin(a) * r;
    let ok = true;
    let worst = Infinity;
    for (const p of placed) {
      const d = Math.hypot(x - p.x, y - p.y);
      if (d < minSep) {
        ok = false;
        if (d < worst) worst = d;
      }
    }
    if (ok) return { x, y };
    if (best === null || worst > best.worst) best = { x, y, worst }; // best = furthest from the closest object
  }
  return { x: best.x, y: best.y };
}

/**
 * Enforce the generator's gap rule: after the pass, every pair of rocks is
 * ≥ gapFactor × (r1 + r2) apart (centers) — a small visible edge-gap
 * (1.0 = touching). Iterative pairwise separation: each violator moves half
 * the shortfall, only violating pairs move (minimal displacement), and a
 * few dozen sweeps settle any rock count. Fully deterministic (fixed pair
 * order, fixed iteration cap).
 */
function relaxRockGaps(members, gapFactor, maxIter = 96) {
  for (let it = 0; it < maxIter; it++) {
    let worst = 0;
    for (let i = 0; i < members.length; i++) {
      for (let j = i + 1; j < members.length; j++) {
        const a = members[i];
        const b = members[j];
        let dx = b.x - a.x;
        let dy = b.y - a.y;
        let d = Math.hypot(dx, dy);
        const need = gapFactor * (a.size / 2 + b.size / 2);
        if (d >= need) continue;
        if (d < 1e-9) { dx = 1; dy = 0; d = 1; } // coincident: deterministic axis
        const push = (need - d) / 2;
        a.x -= (dx / d) * push;
        a.y -= (dy / d) * push;
        b.x += (dx / d) * push;
        b.y += (dy / d) * push;
        worst = Math.max(worst, need - d);
      }
    }
    if (worst <= 1e-6) break;
  }
}

/** The starting system's initial tether radius (home world's level). */
function homeTetherRadius() {
  const level = Math.max(1, Math.floor(config.get('tether.homeLevel', 1)));
  const base = config.get('tether.level1Radius', 5120);
  const growth = config.get('tether.radiusGrowth', 1.25);
  return base * Math.pow(growth, level - 1);
}

/**
 * Blend a hex tint anchor toward white by `strength` (0 = white, 1 = the
 * anchor) → a 24-bit canvas tint. Pure (no Phaser — this runs in Node).
 */
function mixTint(hex, strength) {
  let h = String(hex ?? '').trim().replace(/^#/, '');
  if (h.length === 3) h = h.split('').map((c) => c + c).join('');
  const n = parseInt(h, 16);
  if (!Number.isFinite(n)) return null;
  const mix = (c) => Math.round(255 + (c - 255) * strength);
  return (mix((n >> 16) & 255) << 16) | (mix((n >> 8) & 255) << 8) | mix(n & 255);
}

/**
 * Core→rim density: the settled heart of the galaxy has more activity per
 * system; the rim is thinner, lonelier. `factor` scales every settlement
 * chance (clamped to a floor so the rim isn't dead). 0 = no gradient.
 */
function settlementDensity(galaxy, record) {
  const g = galaxy?.params?.settlements?.gradient ?? {};
  const falloff = Math.max(0, g.falloff ?? 0.7);
  const floor = clamp(g.floor ?? 0.22, 0, 1);
  const rNorm = clamp(record?.rNorm ?? 0, 0, 1);
  return clamp(1 - rNorm * falloff, floor, 1);
}

/**
 * Draw settlements for one system. Stable draw order: planet-bound kinds in
 * orbital order (colony, mining, cloud), then free-floating (deep-space
 * station, waypoint). Every roll goes through the system's own stream.
 * Each settlement gets a stable `id` (`<systemId>-s<n>`, n = its position
 * in this order) — the reputation/factions key.
 */
function generateSettlements({ rng, systemId, kindDefs, spec, planets, stationDeck, density }) {
  const out = [];
  let nameIndex = 0; // next station name from the system's deck (no repeats)

  const make = (kind, anchor) => {
    const def = kindDefs[kind] ?? {};
    out.push({
      id: `${systemId}-s${out.length + 1}`, // reputation/factions key (stable per seed)
      kind,
      name: stationDeck[nameIndex++ % stationDeck.length],
      anchor,
      population: logPopulation(rng, def.population),
      owner: null, // reserved: factions / pirates claim settlements later
    });
  };

  // Planet-bound, in orbital order.
  for (const p of planets) {
    if (p.habitable && roll(rng, spec.colony?.chance ?? 0.3, density)) {
      make('colony', { type: 'planet', ordinal: p.ordinal });
    }
    if (needs(p, spec.miningStation?.needs, ['rocky', 'lava', 'ice']) &&
        roll(rng, spec.miningStation?.chance ?? 0.2, density)) {
      make('miningStation', { type: 'planet', ordinal: p.ordinal });
    }
    if (needs(p, spec.cloudBase?.needs, ['gas']) &&
        roll(rng, spec.cloudBase?.chance ?? 0.15, density)) {
      make('cloudBase', { type: 'planet', ordinal: p.ordinal });
    }
  }

  // Free-floating, out in the dark.
  if (roll(rng, spec.deepSpaceStation?.chance ?? 0.12, density)) {
    make('deepSpaceStation', { type: 'space' });
  }
  if (roll(rng, spec.waypoint?.chance ?? 0.2, density)) {
    make('waypoint', { type: 'space' });
  }

  return out;
}

/** One deterministic roll, scaled by the core→rim density factor. */
function roll(rng, chance, density) {
  return rng.chance(chance * density);
}

/** Does the planet satisfy the kind's requirements? */
function needs(planet, needsList, defaults) {
  const list = Array.isArray(needsList) && needsList.length ? needsList : defaults;
  return list.includes(planet.class);
}

/** Log-uniform population in [min, max] (a few towns to a few megacities). */
function logPopulation(rng, pop) {
  const min = pop?.min ?? 1;
  const max = Math.max(min, pop?.max ?? min);
  if (min <= 0 && rng.chance(0.5)) return 0; // e.g. unmanned waypoints
  return Math.round(Math.exp(rng.range(Math.log(Math.max(1, min)), Math.log(max))));
}