/**
 * 公式编译
 */
class Formula {
  private formula = "";
  private watchers: string[] = [];
  private ast: string[] = [];
  constructor(_formula) {
    this.formula = _formula;
    this.compile();
  }
  private compile() {
    // eslint-disable-next-line no-useless-escape
    const ast = this.formula.split(/([\+\-\*\/\(\)])/);
    this.ast = ast.filter((it) => it !== "");
    this.ast.forEach((char) => {
      if (this.isSymbol(char) || this.isStatic(char)) {
        return;
      }
      this.watchers.push(char.split(/[\.\[]/)[0]);
    });
  }
  private isSymbol(char: string) {
    return /^[\+\-\*\/\(\)]{1}$/g.test(char);
  }
  private isStatic(char: string) {
    return /[\"\']/.test(char) || /^\d+$/.test(char);
  }
  shouldUpdate(watcher: string) {
    return this.watchers.includes(watcher);
  }
  result(_context: NonNullable<unknown>) {
    const ast = this.ast.map((char) => {
      if (this.isSymbol(char) || this.isStatic(char)) {
        return char;
      }
      return char.replace(/(^[\.\[]*)/, "_context.$1");
    });
    return eval(ast.join(""));
  }
  destroy() {
    this.formula = "";
    this.watchers = [];
    this.ast = [];
  }
}

export { Formula };