function distanceSquared(left, right) {
  const dx = left[0] - right[0];
  const dy = left[1] - right[1];
  const dz = left[2] - right[2];
  return dx * dx + dy * dy + dz * dz;
}

export function orderBossObjectives(rawBosses, entrance, configuredOrder) {
  if (!configuredOrder) {
    return {
      ordered: [...rawBosses].sort((left, right) => (
        distanceSquared(left.position, entrance) - distanceSquared(right.position, entrance)
        || left.id.localeCompare(right.id)
      )),
      provenance: {
        authoritative: false,
        kind: "healerMan-distance-derived",
        evidence: ["scripts/runewaker-pipeline/build-population.mjs"],
      },
    };
  }

  if (configuredOrder.kind !== "source-authored") {
    throw new Error("bossObjectiveOrder.kind must be source-authored.");
  }
  if (!Array.isArray(configuredOrder.evidence) || !configuredOrder.evidence.length
    || configuredOrder.evidence.some((entry) => typeof entry !== "string" || !entry.trim())) {
    throw new Error("Source-authored bossObjectiveOrder requires nonempty evidence paths.");
  }
  if (!Array.isArray(configuredOrder.spawnIds)
    || configuredOrder.spawnIds.some((id) => !Number.isInteger(id) || id <= 0)) {
    throw new Error("Source-authored bossObjectiveOrder requires positive integer spawnIds.");
  }
  const configuredIds = new Set(configuredOrder.spawnIds);
  if (configuredIds.size !== configuredOrder.spawnIds.length) {
    throw new Error("Source-authored bossObjectiveOrder contains duplicate spawnIds.");
  }
  const bySourceSpawnId = new Map(rawBosses.map((boss) => [boss.sourceSpawnId, boss]));
  if (configuredIds.size !== bySourceSpawnId.size
    || [...configuredIds].some((id) => !bySourceSpawnId.has(id))) {
    throw new Error("Source-authored bossObjectiveOrder must list every runtime boss spawn exactly once.");
  }
  return {
    ordered: configuredOrder.spawnIds.map((id) => bySourceSpawnId.get(id)),
    provenance: {
      authoritative: true,
      kind: "source-authored",
      evidence: [...configuredOrder.evidence],
      sourceSpawnIds: [...configuredOrder.spawnIds],
    },
  };
}