"""Watchdog service: report loading, process checks, trigger bookkeeping.

Mostly pure (no Flask imports). `trigger_watchdog_run` uses subprocess only;
the caller (route) is responsible for flash/redirect.
"""

import logging
import os
import sqlite3
import subprocess
import time

import config
from repositories import watchdog_repo

logger = logging.getLogger(__name__)

# 简单防重: 模块级变量记录上次触发时间戳, cooldown 秒内重复 POST 返回失败
_last_trigger_ts = 0.0


def parse_days(raw, default=7):
    """Clamp days query param to 1-90; non-numeric falls back to default."""
    try:
        value = int(raw)
    except (TypeError, ValueError):
        return default
    return max(1, min(90, value))


def load_watchdog_reports(watchdog_conn, days=7):
    """Return recent watchdog reports; [] when db/table missing or unreadable."""
    if not os.path.exists(config.WATCHDOG_DB):
        return []
    try:
        return watchdog_repo.list_reports(watchdog_conn, days=days)
    except sqlite3.Error:
        logger.exception("failed to read watchdog db")
        return []


def is_watchdog_running():
    """True if a python process running daily_watchdog.py already exists."""
    try:
        out = subprocess.run(
            ["pgrep", "-f", "daily_watchdog.py"],
            capture_output=True, text=True, timeout=5,
        ).stdout
    except Exception:
        logger.exception("watchdog pgrep failed")
        return False
    for pid in out.split():
        try:
            with open(f"/proc/{pid}/cmdline", "rb") as f:
                argv0 = f.read().split(b"\x00")[0].decode(errors="replace")
        except OSError:
            continue
        if os.path.basename(argv0).startswith("python"):
            return True
    return False


def trigger_watchdog_run(cooldown=None):
    """Attempt to launch scripts/daily_watchdog.py in the background.

    Returns (ok, status, message):
      - (True,  "started",  msg)  launched successfully
      - (False, "cooldown", msg)  hit the anti-repeat cooldown
      - (False, "running",  msg)  an instance is already running
      - (False, "error",    msg)  subprocess launch failed
    """
    global _last_trigger_ts
    cooldown = config.WATCHDOG_RUN_COOLDOWN if cooldown is None else cooldown

    now = time.time()
    if now - _last_trigger_ts < cooldown:
        return False, "cooldown", "操作太频繁, 请稍后再试"
    _last_trigger_ts = now

    if is_watchdog_running():
        return False, "running", "daily_watchdog.py 已在运行中, 本次触发被忽略"

    try:
        os.makedirs(os.path.dirname(config.WATCHDOG_RUN_LOG), exist_ok=True)
        log_f = open(config.WATCHDOG_RUN_LOG, "a", encoding="utf-8")
        env = dict(os.environ)
        env["HOME"] = "/home/yi"
        subprocess.Popen(
            ["/usr/bin/python3", config.WATCHDOG_SCRIPT],
            stdout=log_f, stderr=subprocess.STDOUT,
            cwd=config.BASE_DIR, env=env, start_new_session=True,
        )
        return True, "started", "已触发, 约 1-2 分钟后刷新页面查看新报告"
    except Exception as exc:
        logger.exception("failed to launch daily_watchdog.py")
        return False, "error", f"触发失败: {exc}"