from __future__ import annotations


def format_bytes(n: int | None) -> str:
    if n is None or n < 0:
        return "N/A"
    if n < 1024:
        return f"{n} B"
    if n < 1024**2:
        return f"{n / 1024:.1f} KB"
    if n < 1024**3:
        return f"{n / 1024 ** 2:.1f} MB"
    return f"{n / 1024 ** 3:.2f} GB"


def format_duration(microseconds: int | None) -> str:
    if microseconds is None:
        return "N/A"
    if microseconds < 1000:
        return f"{microseconds} us"
    ms = microseconds / 1000
    if ms < 1000:
        return f"{ms:.1f} ms"
    sec = ms / 1000
    if sec < 60:
        return f"{sec:.1f} s"
    minutes = int(sec // 60)
    remaining_sec = sec % 60
    return f"{minutes}m {remaining_sec:.0f}s"


def truncate(s: str | None, max_len: int = 200) -> str:
    if s is None:
        return ""
    if len(s) <= max_len:
        return s
    return s[:max_len] + "..."