# for_admin_catch_log.py
# 管理员日志查看：读取 bot-utility 的 systemd 日志或指定日志文件。
import asyncio
import os
import subprocess

LOG_PATH = os.environ.get("BOT_LOG_PATH", "")
LOG_UNIT = os.environ.get("BOT_LOG_UNIT", "bot-utility.service")
DEFAULT_LINES = 5
MAX_LINES = 100

LOG_ENCODING = os.environ.get("BOT_LOG_ENCODING", "utf-8")


def _admin_list():
    from channel import admin_list
    return [x for n in ("qq", "tg") for x in admin_list(n)]


def _tail_log(lines):
    """读取最后 lines 行；未指定 BOT_LOG_PATH 时使用 journal，返回 (ok, text)。"""
    if not LOG_PATH:
        return _tail_journal(lines)
    if not os.path.exists(LOG_PATH):
        return False, f"日志文件不存在: {LOG_PATH}"
    try:
        # 从文件尾部倒着读块, 避免一次性载入大文件
        with open(LOG_PATH, "rb") as f:
            f.seek(0, os.SEEK_END)
            size = f.tell()
            block = 8192
            pos = size
            buf = b""
            while pos > 0 and buf.count(b"\n") < lines + 1:
                read_len = min(block, pos)
                pos -= read_len
                f.seek(pos)
                buf = f.read(read_len) + buf
            tail_bytes = buf
        text = tail_bytes.decode(LOG_ENCODING, errors="replace")
        rows = text.splitlines()
        if len(rows) > lines:
            rows = rows[-lines:]
        body = "\n".join(rows).strip()
        if not body:
            return False, "日志为空"
        return True, body
    except Exception as e:
        return False, f"读取日志异常: {str(e)[:200]}"


def _tail_journal(lines):
    try:
        result = subprocess.run(
            ["journalctl", "--unit", LOG_UNIT, "--lines", str(lines),
             "--no-pager", "--output=cat", "--quiet"],
            capture_output=True, text=True, encoding="utf-8", errors="replace",
            timeout=10, check=False,
        )
        if result.returncode or "permission" in result.stderr.lower():
            return False, f"读取 systemd 日志失败: {result.stderr.strip()[:200]}"
        body = result.stdout.strip()
        return (True, body) if body else (False, "日志为空")
    except (OSError, subprocess.TimeoutExpired) as e:
        return False, f"读取 systemd 日志异常: {str(e)[:200]}"


def _dedupe_merge(text):
    """合并连续重复行: 相同行连续出现 N 次时只保留一行并标注 (xN)"""
    rows = text.splitlines()
    if not rows:
        return ""
    merged = []
    prev = rows[0]
    count = 1
    for row in rows[1:]:
        if row == prev:
            count += 1
        else:
            merged.append(f"{prev} (x{count})" if count > 1 else prev)
            prev = row
            count = 1
    merged.append(f"{prev} (x{count})" if count > 1 else prev)
    return "\n".join(merged)


def _clip(text):
    """限制输出长度, 避免刷屏 (QQ 单条消息上限约 4000 字符)"""
    if len(text) > 3800:
        text = text[-3800:]
    return text


HELP_TEXT = (
    "日志查看指令\n"
    "━━━━━━━━━━━━\n"
    "• .log help       显示本帮助\n"
    "• .log <int>      获取最近的 N 条日志 (最大 100, 默认 5)\n"
)


async def handle_command(ws, msg_type, target_id, raw_text):
    from channel import send_message
    parts = raw_text.split(maxsplit=1)
    arg = parts[1].strip() if len(parts) >= 2 else ""

    if arg.lower() == "help":
        await send_message(ws, msg_type, target_id, HELP_TEXT)
        return

    if arg == "":
        lines = DEFAULT_LINES
    else:
        try:
            lines = int(arg)
        except ValueError:
            await send_message(ws, msg_type, target_id,
                               "参数必须为整数, 例如 .log 10 或 .log help")
            return
        if lines < 1:
            await send_message(ws, msg_type, target_id, "日志条数至少为 1")
            return
        if lines > MAX_LINES:
            lines = MAX_LINES

    ok, text = await asyncio.to_thread(_tail_log, lines)
    if not ok:
        await send_message(ws, msg_type, target_id, text)
        return

    body = _clip(_dedupe_merge(text))
    await send_message(ws, msg_type, target_id,
                       f"最近 {lines} 条日志:\n━━━━━━━━━━━━\n{body}")