"""
Logging system: in-memory ring buffer + file output.
"""
from __future__ import annotations

import logging
import time
from collections import deque
from pathlib import Path
from typing import Optional


class RingBufferHandler(logging.Handler):
    """Keeps last N log lines in memory for UI display."""

    def __init__(self, maxlen: int = 500):
        super().__init__()
        self._buffer: deque[str] = deque(maxlen=maxlen)

    def emit(self, record: logging.LogRecord) -> None:
        msg = self.format(record)
        self._buffer.append(msg)

    def get_lines(self, last: int = 100) -> list[str]:
        lines = list(self._buffer)
        return lines[-last:] if last else lines

    def get_text(self, last: int = 100) -> str:
        return "\n".join(self.get_lines(last))

    def clear(self) -> None:
        self._buffer.clear()


class AppLogger:
    _instance: Optional["AppLogger"] = None

    def __init__(self, log_dir: Path = Path("output")):
        self.log_dir = log_dir
        self.log_dir.mkdir(parents=True, exist_ok=True)
        self.log_file = log_dir / "logs.txt"

        self.ring = RingBufferHandler(maxlen=1000)
        self.ring.setFormatter(logging.Formatter("%(asctime)s %(levelname)s %(message)s", "%H:%M:%S"))

        file_handler = logging.FileHandler(self.log_file, encoding="utf-8")
        file_handler.setFormatter(logging.Formatter("%(asctime)s %(levelname)s %(name)s %(message)s"))

        root = logging.getLogger()
        root.setLevel(logging.INFO)
        root.addHandler(self.ring)
        root.addHandler(file_handler)

    @classmethod
    def get(cls, log_dir: Path = Path("output")) -> "AppLogger":
        if cls._instance is None:
            cls._instance = cls(log_dir)
        return cls._instance

    def ui_log(self, msg: str) -> None:
        """Add a message directly to the ring buffer (bypassing Python log level)."""
        ts = time.strftime("%H:%M:%S")
        self.ring._buffer.append(f"{ts} {msg}")

    def get_ui_text(self, last: int = 200) -> str:
        return self.ring.get_text(last)