from pathlib import Path
from typing import Iterable, List

from app.core.config import ENCODING_UTF8, NEWLINE
from app.core.crypto import DataCipher, load_encryption_key


class FileManager:
    _cipher_instance: DataCipher | None = None

    def __init__(self, file_path: Path) -> None:
        self.file_path = file_path
        self.file_path.parent.mkdir(parents=True, exist_ok=True)
        self.file_path.touch(exist_ok=True)
        self._cipher = self._get_cipher()

    @classmethod
    def _get_cipher(cls) -> DataCipher:
        if cls._cipher_instance is None:
            cls._cipher_instance = DataCipher(load_encryption_key())
        return cls._cipher_instance

    def _decode_line(self, raw: str) -> str:
        try:
            return self._cipher.decrypt(raw)
        except Exception:
            return raw

    def _encode_line(self, plain: str) -> str:
        return self._cipher.encrypt(plain)

    def read_lines(self) -> List[str]:
        with self.file_path.open("r", encoding=ENCODING_UTF8) as file:
            decoded: List[str] = []
            for line in file:
                if not line.strip():
                    continue
                decoded.append(self._decode_line(line.rstrip(NEWLINE)))
            return decoded

    def write_lines(self, lines: Iterable[str]) -> None:
        with self.file_path.open("w", encoding=ENCODING_UTF8) as file:
            for line in lines:
                file.write(f"{self._encode_line(line)}{NEWLINE}")

    def append_line(self, line: str) -> None:
        with self.file_path.open("a", encoding=ENCODING_UTF8) as file:
            file.write(f"{self._encode_line(line)}{NEWLINE}")