src/entities/element/lib/formatElementMass.ts - dev - 45case/ptable

src/entities/element/lib/formatElementMass.ts
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24 июл 2026, 11:54
24 июл 2026, 11:543cf1d48
import { ptableAtomicMassAbridgedByZ } from "./ptableAtomicMassAbridged";

/**
 * Format atomic mass for UI.
 * - Default: ptable-style abridged card label (≤ 5 significant figures).
 * - `full: true`: raw `weight` string from JSON (full precision).
 * Parentheses around mass numbers (Tc, Mt, …) are omitted.
 */
export function formatElementMass(
  value: number | null,
  options?: {
    /** Atomic number — used to look up the exact ptable abridged label. */
    atomicNumber?: number | null;
    /** Original ptable `weight` string; preferred for `full` and as fallback. */
    source?: string | null;
    /** Show the full JSON weight string instead of the abridged card label. */
    full?: boolean;
    /** Appended after the formatted mass, e.g. `"u"`. */
    unit?: string;
  },
) {
  const unit = options?.unit ? ` ${options.unit}` : "";
  const source = options?.source?.trim();

  if (options?.full) {
    if (source) {
      return `${stripMassParentheses(source).replace(".", ",")}${unit}`;
    }

    if (value == null || !Number.isFinite(value)) {
      return value == null ? "—" : `—${unit}`;
    }

    return `${String(value).replace(".", ",")}${unit}`;
  }

  const atomicNumber = options?.atomicNumber;

  if (atomicNumber != null) {
    const abridged = ptableAtomicMassAbridgedByZ[atomicNumber];
    if (abridged) {
      return `${stripMassParentheses(abridged).replace(".", ",")}${unit}`;
    }
  }

  if (source) {
    return `${abridgeWeightSource(source).replace(".", ",")}${unit}`;
  }

  if (value == null) {
    return "—";
  }

  if (!Number.isFinite(value)) {
    return `—${unit}`;
  }

  if (Number.isInteger(value)) {
    return `${value}${unit}`;
  }

  return `${abridgeWeightValue(value).replace(".", ",")}${unit}`;
}

function stripMassParentheses(label: string): string {
  return label.replace(/^\((.+)\)$/, "$1");
}

function countSignificantFigures(decimalStr: string): number {
  const cleaned = decimalStr.replace(/^[+-]/, "").toLowerCase();
  if (cleaned.includes("e")) {
    return countSignificantFigures(cleaned.split("e")[0]!);
  }

  const digits = cleaned.replace(".", "").replace(/^0+/, "");
  return digits.length || 1;
}

/** Fallback abridgment when no Z lookup is available. */
function abridgeWeightSource(source: string): string {
  const value = Number(source);
  if (!Number.isFinite(value)) {
    return source;
  }

  if (!source.includes(".")) {
    return String(Math.trunc(value));
  }

  if (countSignificantFigures(source) < 5) {
    return source;
  }

  return abridgeWeightValue(value);
}

function abridgeWeightValue(value: number): string {
  if (value === 0) {
    return "0";
  }

  const abs = Math.abs(value);
  const order = Math.floor(Math.log10(abs));
  const decimals = Math.max(0, 5 - 1 - order);
  // Round via string to reduce binary float drift (e.g. 50.9415 → 50.942).
  const fixed = abs.toFixed(decimals + 2);
  const [wholePart, fracPart = ""] = fixed.split(".") as [string, string];
  const digits = `${wholePart}${fracPart}`.replace(/^0+/, "") || "0";
  const roundedDigits = roundDigitString(digits, 5);
  const sign = value < 0 ? "-" : "";

  if (order >= 4) {
    return `${sign}${roundedDigits}`;
  }

  if (order >= 0) {
    const wholeLength = order + 1;
    const whole = roundedDigits.slice(0, wholeLength) || "0";
    const frac = roundedDigits.slice(wholeLength).padEnd(decimals, "0").slice(0, decimals);
    return frac ? `${sign}${whole}.${frac}` : `${sign}${whole}`;
  }

  const precision = value.toPrecision(5);
  return /[eE]/.test(precision) ? String(Number(precision)) : precision;
}

function roundDigitString(digits: string, significantFigures: number): string {
  if (digits.length <= significantFigures) {
    return digits.padEnd(significantFigures, "0");
  }

  const head = digits.slice(0, significantFigures);
  const next = Number(digits[significantFigures] ?? "0");
  if (next < 5) {
    return head;
  }

  const asNumber = BigInt(head) + 1n;
  return asNumber.toString().padStart(significantFigures, "0");
}