// 수식은 실행 가능한 JavaScript로 변환하지 않고 토큰과 구문 트리로 평가한다.
const EstExpression = (() => {
  function evaluate(input, resolve = () => undefined, settings = {}) {
    const text = String(input)
      .replace(/×|·/g, "*")
      .replace(/÷/g, "/")
      .replace(/−|－/g, "-")
      .replace(/＋/g, "+")
      .replace(/％/g, "%")
      .replace(/√\s*\(/g, "SQRT(")
      .replace(/π/g, "PI")
      .replace(/(?<=[\d\u0370-\u03ff])\s*(?=\()/g, "*")
      .replace(/(?<=[\d.)])\s*[xX]\s*(?=[\d.(A-Za-z])/g, "*")
      .replace(/(?<=[A-Z])x(?=[A-Z])/g, "*")
      .replace(/(?<=\d),(?=\d{3}(?:\D|$))/g, "");
    const tokens = [];
    const pattern =
      /\s+|(?:\d+\.?\d*|\.\d+)(?:[eE][+-]?\d+)?|\[[^\]]+\]|[A-Za-z_가-힣\u0370-\u03ff][A-Za-z_0-9가-힣\u0370-\u03ff.]*|[+*/^%(),:~=-]/y;
    let at = 0;
    while (at < text.length) {
      pattern.lastIndex = at;
      const match = pattern.exec(text);
      if (!match) throw Error(`수식 문자 오류 (${at + 1}): ${text.slice(at, at + 12)}`);
      if (match[0].trim()) tokens.push(match[0]);
      at = pattern.lastIndex;
    }
    let position = 0;
    const functions = {
      ABS: Math.abs,
      SQRT: Math.sqrt,
      MIN: Math.min,
      MAX: Math.max,
      ROUND: (n, d = 0) => EstMath.floating(n, d, 1),
      TRUNC: (n, d = 0) => EstMath.floating(n, d, 2),
      FLOOR: Math.floor,
      CEIL: Math.ceil,
      SUM: (...args) => args.reduce((a, b) => a + b, 0),
    };
    function value(token, force = false) {
      const key = token.startsWith("[") ? token.slice(1, -1) : token;
      const resolved = resolve(key);
      const numeric = /^(?:\d+\.?\d*|\.\d+)(?:[eE][+-]?\d+)?$/.test(key);
      if (resolved !== undefined && (!numeric || force || settings.numericReferences))
        return Number(resolved);
      if (numeric && !force) return Number(key);
      if (key === "PI") return Math.PI;
      throw Error(`참조 항목 없음: ${key}`);
    }
    function atom() {
      const token = tokens[position++];
      if (token === undefined) throw Error("수식이 끝나지 않았습니다.");
      if (token === "+" || token === "-") return (token === "-" ? -1 : 1) * atom();
      let n;
      if (token === "(") {
        n = sum();
        if (tokens[position++] !== ")") throw Error("괄호가 맞지 않습니다.");
      } else if (functions[token.toUpperCase()] && tokens[position] === "(") {
        position++;
        const args = [];
        if (tokens[position] !== ")") {
          args.push(sum());
          while (tokens[position] === ",") {
            position++;
            args.push(sum());
          }
        }
        if (tokens[position++] !== ")") throw Error("함수 괄호 오류");
        n = functions[token.toUpperCase()](...args);
      } else if ([":", "~"].includes(tokens[position])) {
        position++;
        const end = tokens[position++];
        if (!settings.range) throw Error("범위 참조를 사용할 수 없습니다.");
        n = settings.range(token.replace(/^\[|\]$/g, ""), end?.replace(/^\[|\]$/g, ""));
      } else n = value(token, token.startsWith("["));
      while (tokens[position] === "%") {
        position++;
        n /= 100;
      }
      return n;
    }
    function power() {
      const n = atom();
      if (tokens[position] === "^") {
        position++;
        return n ** power();
      }
      return n;
    }
    function product() {
      let n = power();
      while (["*", "/"].includes(tokens[position])) {
        const op = tokens[position++],
          v = power();
        if (op === "/" && v === 0) throw Error("0으로 나눌 수 없습니다.");
        n = op === "*" ? n * v : n / v;
      }
      return n;
    }
    function sum() {
      let n = product();
      while (["+", "-"].includes(tokens[position])) {
        const op = tokens[position++],
          v = product();
        n = op === "+" ? n + v : n - v;
      }
      return n;
    }
    const result = sum();
    if (position !== tokens.length || !Number.isFinite(result))
      throw Error("수식 결과가 유효하지 않습니다.");
    return result;
  }
  return { evaluate };
})();