// SymbolicOperator matches the symbolic operators supported by ts-rsql
type SymbolicOperator = "<" | "<=" | ">" | ">=" | "==" | "!=";

// NamedOperator defines what this library uses for named operators.
type NamedOperator = `=${"lt" | "le" | "gt" | "ge" | "in" | "out"}=`;

// KnownOperator defines the operators that this lib supports
/**
 * @internal
 */
export type KnownOperator = SymbolicOperator | NamedOperator;

/**
 * @internal
 */
export const toSqlOperator = (operator: KnownOperator): string => {
  switch (operator) {
    case "==":
      return "like";
    case "!=":
      return "<>";
    case "<":
    case "=lt=":
      return "<";
    case "<=":
    case "=le=":
      return "<=";
    case ">":
    case "=gt=":
      return ">";
    case ">=":
    case "=ge=":
      return ">=";
    case "=in=":
      return "in";
    case "=out=":
      return "not in";
    default: {
      const invalid: never = operator;
      throw Error(invalid);
    }
  }
};

export const isKnownOperator = (maybe: string): maybe is KnownOperator => {
  try {
    toSqlOperator(maybe as NamedOperator);
    return true;
  } catch {
    return false;
  }
};