"""Command-line interface: python calc.py "<expression>"

Result printing rule:
  - If the result is a whole number (e.g. 2.0), print as int (e.g. "2").
  - Otherwise print as float (e.g. "3.5").
"""

import sys
from calc.lexer import tokenize, LexError
from calc.parser import parse, ParseError
from calc.evaluator import evaluate, EvalError


def _format(value) -> str:
    if isinstance(value, float) and value.is_integer():
        return str(int(value))
    return str(value)


def main():
    if len(sys.argv) != 2:
        print(f"usage: {sys.argv[0]} <expression>", file=sys.stderr)
        sys.exit(1)
    expr = sys.argv[1]
    try:
        tokens = tokenize(expr)
        ast = parse(tokens)
        result = evaluate(ast)
        print(_format(result))
    except (LexError, ParseError, EvalError) as exc:
        print(f"error: {exc}", file=sys.stderr)
        sys.exit(1)


if __name__ == "__main__":
    main()