"""Logging setup for AYN Antivirus.

Provides a one-call ``setup_logging()`` function that configures a
rotating file handler and an optional console handler with consistent
formatting across the entire application.
"""

from __future__ import annotations

import logging
import os
import sys
from logging.handlers import RotatingFileHandler
from pathlib import Path
from typing import Optional

from ayn_antivirus.constants import DEFAULT_LOG_PATH

# ---------------------------------------------------------------------------
# Format
# ---------------------------------------------------------------------------
_LOG_FORMAT = "[%(asctime)s] %(levelname)s %(name)s: %(message)s"
_DATE_FORMAT = "%Y-%m-%d %H:%M:%S"

# Rotating handler defaults.
_MAX_BYTES = 10 * 1024 * 1024  # 10 MB
_BACKUP_COUNT = 5


def setup_logging(
    log_dir: str | Path = DEFAULT_LOG_PATH,
    level: int | str = logging.INFO,
    console: bool = True,
    filename: str = "ayn-antivirus.log",
) -> logging.Logger:
    """Configure the root ``ayn_antivirus`` logger.

    Parameters
    ----------
    log_dir:
        Directory for the rotating log file.  Created automatically.
    level:
        Logging level (``logging.DEBUG``, ``"INFO"``, etc.).
    console:
        If ``True``, also emit to stderr.
    filename:
        Name of the log file inside *log_dir*.

    Returns
    -------
    logging.Logger
        The configured ``ayn_antivirus`` logger.
    """
    if isinstance(level, str):
        level = getattr(logging, level.upper(), logging.INFO)

    root = logging.getLogger("ayn_antivirus")
    root.setLevel(level)

    # Avoid duplicate handlers on repeated calls.
    if root.handlers:
        return root

    formatter = logging.Formatter(_LOG_FORMAT, datefmt=_DATE_FORMAT)

    # --- Rotating file handler ---
    log_path = Path(log_dir)
    try:
        log_path.mkdir(parents=True, exist_ok=True)
        fh = RotatingFileHandler(
            str(log_path / filename),
            maxBytes=_MAX_BYTES,
            backupCount=_BACKUP_COUNT,
            encoding="utf-8",
        )
        fh.setLevel(level)
        fh.setFormatter(formatter)
        root.addHandler(fh)
    except OSError:
        # If we can't write to the log dir, fall back to console only.
        pass

    # --- Console handler ---
    if console:
        ch = logging.StreamHandler(sys.stderr)
        ch.setLevel(level)
        ch.setFormatter(formatter)
        root.addHandler(ch)

    return root


def get_logger(name: str) -> logging.Logger:
    """Return a child logger under the ``ayn_antivirus`` namespace.

    Example::

        logger = get_logger("scanners.file")
        # → logging.getLogger("ayn_antivirus.scanners.file")
    """
    return logging.getLogger(f"ayn_antivirus.{name}")