"""Rotating file logging for the tracker CLI."""

from __future__ import annotations

import logging
import sys
from logging.handlers import RotatingFileHandler
from pathlib import Path
from typing import TextIO


DEFAULT_LOG_DIR = "logs/tracker"
DEFAULT_LOG_MAX_BYTES = 10 * 1024 * 1024
DEFAULT_LOG_BACKUP_COUNT = 5
TRACKER_LOGGER_NAME = "meshnet.tracker"


class _ExactLevelFilter(logging.Filter):
    def __init__(self, level: int) -> None:
        super().__init__()
        self._level = level

    def filter(self, record: logging.LogRecord) -> bool:
        return record.levelno == self._level


class _TeeStream:
    def __init__(self, stream: TextIO, logger: logging.Logger, level: int) -> None:
        self._stream = stream
        self._logger = logger
        self._level = level
        self._buffer = ""

    def write(self, text: str) -> int:
        self._stream.write(text)
        self._stream.flush()
        self._buffer += text
        while "\n" in self._buffer:
            line, self._buffer = self._buffer.split("\n", 1)
            line = line.rstrip()
            if line:
                self._logger.log(self._level, line)
        return len(text)

    def flush(self) -> None:
        self._stream.flush()
        line = self._buffer.rstrip()
        if line:
            self._logger.log(self._level, line)
        self._buffer = ""

    def isatty(self) -> bool:
        return self._stream.isatty()


def _make_handler(path: Path, level: int, *, max_bytes: int, backup_count: int) -> RotatingFileHandler:
    handler = RotatingFileHandler(
        path,
        maxBytes=max_bytes,
        backupCount=backup_count,
        encoding="utf-8",
    )
    handler.setLevel(level)
    handler.addFilter(_ExactLevelFilter(level))
    handler.setFormatter(logging.Formatter("%(asctime)s %(levelname)s %(message)s"))
    return handler


def configure_tracker_file_logging(
    log_dir: str | Path = DEFAULT_LOG_DIR,
    *,
    max_bytes: int = DEFAULT_LOG_MAX_BYTES,
    backup_count: int = DEFAULT_LOG_BACKUP_COUNT,
    tee_stdio: bool = True,
) -> Path:
    """Configure rotatable info/warning/error log files and return the directory."""

    path = Path(log_dir).expanduser()
    path.mkdir(parents=True, exist_ok=True)

    logger = logging.getLogger(TRACKER_LOGGER_NAME)
    logger.setLevel(logging.INFO)
    logger.propagate = False
    logger.handlers.clear()
    logger.addHandler(_make_handler(path / "info.log", logging.INFO, max_bytes=max_bytes, backup_count=backup_count))
    logger.addHandler(_make_handler(path / "warning.log", logging.WARNING, max_bytes=max_bytes, backup_count=backup_count))
    logger.addHandler(_make_handler(path / "error.log", logging.ERROR, max_bytes=max_bytes, backup_count=backup_count))

    if tee_stdio:
        if not isinstance(sys.stdout, _TeeStream):
            sys.stdout = _TeeStream(sys.stdout, logger, logging.INFO)  # type: ignore[assignment]
        if not isinstance(sys.stderr, _TeeStream):
            sys.stderr = _TeeStream(sys.stderr, logger, logging.ERROR)  # type: ignore[assignment]

    return path


def tracker_logger() -> logging.Logger:
    return logging.getLogger(TRACKER_LOGGER_NAME)