from typing import List
import os
from line import Line


class LogFileModel:
    def __init__(self, file):
        self._file = file

    def data(self, byte_offset:int, lines: int) -> List[Line]:
        result : List[Line] = []

        # TODO handle lines longer than 4096 bytes
        with open(self._file, 'r') as f:
            offset = max(0, byte_offset - 4096)
            offset = offset - offset % 4096 # align to blocks of 4kb
            f.seek(offset)
            while l := f.readline():
                new_offset = f.tell()
                if offset >= byte_offset:
                    line = Line(offset, new_offset-1, l)
                    result.append(line)
                offset = new_offset
                if len(result) >= lines:
                    break

        return result

    def byte_count(self) -> int:
        return os.stat(self._file).st_size