"""内存日志缓冲:供后台「系统日志」页查看应用运行日志。

把应用日志(stdout)同时捕获到进程内环形缓冲(deque),提供级别/关键字/条数
过滤查询。缓冲在进程重启后清零;需要持久化的审计请另行落库。
"""
from __future__ import annotations

import logging
from collections import deque

_BUFFER: deque[dict] = deque(maxlen=2000)

_LEVEL_ORDER = {"DEBUG": 10, "INFO": 20, "WARNING": 30, "ERROR": 40, "CRITICAL": 50}


class MemoryLogHandler(logging.Handler):
    """把日志记录写入内存环形缓冲。"""

    def __init__(self) -> None:
        super().__init__()
        # format() 会在有 exc_info 时自动附带异常堆栈文本
        self.setFormatter(logging.Formatter("%(message)s"))

    def emit(self, record: logging.LogRecord) -> None:
        try:
            entry = {
                "ts": record.created,
                "level": record.levelname,
                "logger": record.name,
                "message": self.format(record),
            }
            _BUFFER.append(entry)
        except Exception:  # noqa: BLE001  日志采集绝不影响业务
            self.handleError(record)


class _SQLNoiseFilter(logging.Filter):
    """过滤 SQLAlchemy 的 DEBUG/INFO 回显(只留警告以上)。"""

    def filter(self, record: logging.LogRecord) -> bool:
        return not (
            record.name.startswith("sqlalchemy.") and record.levelno < logging.WARNING
        )


def get_entries(
    min_level: str | None = None,
    keyword: str | None = None,
    limit: int = 200,
) -> list[dict]:
    """按条件查询缓冲日志,最新在前。"""
    min_no = _LEVEL_ORDER.get((min_level or "").upper(), 0)
    kw = (keyword or "").strip().lower()
    items = list(_BUFFER)
    items.reverse()
    out: list[dict] = []
    for e in items:
        if _LEVEL_ORDER.get(e["level"], 0) < min_no:
            continue
        if kw and kw not in e["message"].lower() and kw not in e["logger"].lower():
            continue
        out.append(e)
        if len(out) >= limit:
            break
    return out


def setup_memory_logging(level: str = "INFO") -> None:
    """挂载内存 handler 到 root logger(幂等),并确保 root 级别不低于 INFO。"""
    root = logging.getLogger()
    if any(isinstance(h, MemoryLogHandler) for h in root.handlers):
        return
    handler = MemoryLogHandler()
    handler.setLevel(logging.INFO)
    handler.addFilter(_SQLNoiseFilter())
    root.addHandler(handler)
    if root.level == logging.NOTSET or root.level > logging.INFO:
        root.setLevel(getattr(logging, level.upper(), logging.INFO))