#!/usr/bin/env python3
from pathlib import Path
from datetime import datetime


def now_str() -> str:
    return datetime.now().strftime("%Y-%m-%d %H:%M:%S")


def nots(line: str) -> str:
    if line.startswith("[") and "]" in line:
        return line.split("]", 1)[1].lstrip()
    return line


def tail_lines(path: Path, n: int) -> list[str]:
    # grabs the last n lines without reading the whole file into memory first,
    # since memory.txt only ever grows and reading it fully every message doesn't scale
    if n <= 0:
        return []
    avg_line_bytes = 200
    with path.open("rb") as f:
        f.seek(0, 2)
        file_size = f.tell()
        if file_size == 0:
            return []
        block_size = n * avg_line_bytes
        data = b""
        lines = []
        while True:
            seek_pos = max(file_size - block_size, 0)
            f.seek(seek_pos)
            data = f.read(file_size - seek_pos)
            lines = data.splitlines()
            if len(lines) > n or seek_pos == 0:
                break
            block_size *= 2
    return [l.decode("utf-8", errors="ignore").strip() for l in lines[-n:] if l.strip()]