from datetime import datetime


def print_header(title: str) -> None:
    print(f"\n--- {title} ---\n")


def print_table(headers: list[str], rows: list[list[str]]) -> None:
    if not rows:
        print("  (empty)")
        return
    all_rows = [headers] + [[str(c) for c in row] for row in rows]
    widths = [max(len(r[i]) for r in all_rows) for i in range(len(headers))]
    fmt = " | ".join(f"{{:<{w}}}" for w in widths)
    print(fmt.format(*headers))
    print("-+-".join("-" * w for w in widths))
    for row in all_rows[1:]:
        print(fmt.format(*row))


def prompt_int(
    prompt: str,
    required: bool = True,
    min_val: int | None = None,
    max_val: int | None = None,
) -> int | None:
    while True:
        val = input(prompt).strip()
        if not val:
            if not required:
                return None
            print("This field is required.")
            continue
        try:
            n = int(val)
        except ValueError:
            print("Please enter a valid integer.")
            continue
        if min_val is not None and n < min_val:
            print(f"Must be at least {min_val}.")
            continue
        if max_val is not None and n > max_val:
            print(f"Must be at most {max_val}.")
            continue
        return n


def prompt_str(prompt: str, required: bool = True) -> str | None:
    while True:
        val = input(prompt).strip()
        if not val:
            if not required:
                return None
            print("This field is required.")
            continue
        return val


def prompt_datetime(prompt: str, default_now: bool = True) -> str:
    while True:
        default = datetime.now().strftime("%Y-%m-%d %H")
        val = input(f"{prompt} [{default}]: ").strip()
        if not val:
            if default_now:
                return default
        else:
            try:
                datetime.strptime(val, "%Y-%m-%d %H")
                return val
            except ValueError:
                print("Invalid format. Use YYYY-MM-DD HH.")
                continue


def confirm(prompt: str) -> bool:
    val = input(f"{prompt} [y/N]: ").strip().lower()
    return val == "y"