"""Per-user sandbox 容器池(DESIGN §7.5)。

命名:`zcbot-sandbox-<user_id>`(user_id = UUID 标准串带 dash,与 bind mount
源路径 `<workspace>/users/<user_id>/` 对齐 ── `docker ps` 看到容器名能直接 grep
出 workspace 目录)。

生命周期:
- `ensure(user_id)`:per-user `asyncio.Lock` 串行化 → `docker inspect` 探测 → 已 running
  直接返;exists-but-stopped 先 `rm -f` 重起(保证 iptables 重新 apply);不存在 `docker run`
- `mark_active(user_id)`:exec 完更新 in-memory `_last_active[uid]=now`(docker labels
  不可运行时修改 ── Docker 23+ 移除 `docker update --label-add` 支持)
- `reap_idle()`:周期任务,扫 `_last_active` dict,>`idle_ttl` 的 `docker rm -f`
- `shutdown_all()`:app 启动时清前驱孤儿(`docker ps --filter label=zcbot.product=sandbox`)

幂等性:
- ensure 在重复调用时跨 daemon round-trip < 100ms(纯 `docker inspect`);per-user lock
  防同 user 两并发 `docker run --name` 撞 "Conflict"(虽然 docker 本身会 reject,提前
  锁更干净)
- reaper 只杀 dict 里有记录的容器 ── 重启后 dict 空 → 不杀历史孤儿(这条由 startup
  `shutdown_all` 兜底)

Step 2 范围:仅 pool / lifecycle。Tools(shell / run_python)在 Step 3 接入。
"""
from __future__ import annotations

import asyncio
import os
import subprocess
import time
from pathlib import Path
from typing import Dict, List, Optional
from uuid import UUID

from .network import NETWORK_NAME, ensure_network


CONTAINER_NAME_PREFIX = "zcbot-sandbox-"
LABEL_PRODUCT_KEY = "zcbot.product"
LABEL_PRODUCT_VALUE = "sandbox"
LABEL_USER_ID_KEY = "zcbot.user_id"

DEFAULT_IMAGE = "zcbot-sandbox:latest"
DEFAULT_IDLE_TTL_SECONDS = 300


def container_name(user_id: UUID) -> str:
    return f"{CONTAINER_NAME_PREFIX}{user_id}"


def _now() -> int:
    return int(time.time())


def _container_exists(name: str) -> bool:
    """任何 state(running / exited / created)都算存在。"""
    r = subprocess.run(
        ["docker", "inspect", "--type=container", name],
        capture_output=True, text=True,
    )
    return r.returncode == 0


def _container_running(name: str) -> bool:
    r = subprocess.run(
        ["docker", "inspect", "--type=container",
         "--format={{.State.Running}}", name],
        capture_output=True, text=True,
    )
    return r.returncode == 0 and r.stdout.strip() == "true"


class SandboxPool:
    def __init__(
        self,
        user_root_base: Path,
        image: Optional[str] = None,
        runtime: Optional[str] = None,
        idle_ttl: Optional[int] = None,
        pg_ips: Optional[str] = None,
    ) -> None:
        """
        user_root_base: per-user 子树父目录,典型 `<workspace>/users`。bind mount 源
                        = `user_root_base / <user_id>`,目标 `/workspace`。
        image:         sandbox 镜像 tag(默 env `ZCBOT_SANDBOX_IMAGE`)
        runtime:       `docker run --runtime` 值(runc / runsc / kata 等);空 = 默认
                        (env `ZCBOT_SANDBOX_RUNTIME`)。§7.5 #5 / §7.9 升级表 ── 切
                        gVisor / Firecracker 时改这一项即可,应用层零改动。
        idle_ttl:      秒;`mark_active` 时间戳 < now - ttl 的容器被 reap_idle 杀
                        (env `ZCBOT_SANDBOX_IDLE_TTL`,默 300)
        pg_ips:        逗号分隔的 PG IP 串,塞容器 `ZCBOT_PG_IPS` env,init.sh 加 DROP 规则
                        (env `ZCBOT_PG_IPS`)。defense-in-depth ── 即便落内网三段。
        """
        self.user_root_base = user_root_base
        self.image = image or os.getenv("ZCBOT_SANDBOX_IMAGE", DEFAULT_IMAGE)
        self.runtime = runtime or os.getenv("ZCBOT_SANDBOX_RUNTIME") or ""
        self.idle_ttl = idle_ttl if idle_ttl is not None else int(
            os.getenv("ZCBOT_SANDBOX_IDLE_TTL", str(DEFAULT_IDLE_TTL_SECONDS))
        )
        self.pg_ips = pg_ips if pg_ips is not None else os.getenv("ZCBOT_PG_IPS", "")
        self._locks: Dict[UUID, asyncio.Lock] = {}
        self._last_active: Dict[UUID, int] = {}

    def _lock_for(self, user_id: UUID) -> asyncio.Lock:
        if user_id not in self._locks:
            self._locks[user_id] = asyncio.Lock()
        return self._locks[user_id]

    async def ensure(self, user_id: UUID) -> str:
        """返回容器名;create-or-reuse 原子。"""
        async with self._lock_for(user_id):
            name = container_name(user_id)
            if _container_running(name):
                self._last_active[user_id] = _now()
                return name
            if _container_exists(name):
                # stopped / crashed ── rm 重起。iptables 规则随容器生命周期重新 apply。
                subprocess.run(
                    ["docker", "rm", "-f", name],
                    capture_output=True, check=False,
                )
            await asyncio.to_thread(self._docker_run, user_id, name)
            self._last_active[user_id] = _now()
            return name

    def _docker_run(self, user_id: UUID, name: str) -> None:
        """同步阻塞;由 ensure 在 to_thread 里调。"""
        user_root = self.user_root_base / str(user_id)
        user_root.mkdir(parents=True, exist_ok=True)

        cmd: List[str] = [
            "docker", "run", "-d",
            "--name", name,
            "--label", f"{LABEL_PRODUCT_KEY}={LABEL_PRODUCT_VALUE}",
            "--label", f"{LABEL_USER_ID_KEY}={user_id}",
            "--network", NETWORK_NAME,
            # §7.5 硬限制(任一缺失视为 hardening 未完成)
            "--read-only",                                  # rootfs read-only
            "--tmpfs", "/tmp:exec,size=512m,mode=1777",     # 可写临时区,exec 允许 (run_python 写脚本)
            "--cap-drop=ALL",                               # 默全丢
            "--cap-add=NET_ADMIN",                          # init.sh 配 iptables 需要;exec 进来的 uid 1000 拿不到
            "--security-opt=no-new-privileges",
            "--pids-limit=256",
            "--memory=2g",
            "--cpus=1.0",
            "-v", f"{user_root}:/workspace",
            "-e", f"ZCBOT_PG_IPS={self.pg_ips}",
            "--restart=no",
        ]
        if self.runtime:
            cmd += ["--runtime", self.runtime]
        cmd.append(self.image)

        r = subprocess.run(cmd, capture_output=True, text=True)
        if r.returncode != 0:
            raise RuntimeError(
                f"docker run {name} failed (rc={r.returncode}): {r.stderr.strip()}"
            )

    def mark_active(self, user_id: UUID) -> None:
        """每次 `docker exec` 完调一次,刷新 idle 计时。"""
        self._last_active[user_id] = _now()

    def reap_idle(self) -> List[str]:
        """杀超过 idle_ttl 没活跃的容器。返回已杀容器名列表(供日志 / 审计)。"""
        removed: List[str] = []
        cutoff = _now() - self.idle_ttl
        for uid, ts in list(self._last_active.items()):
            if ts < cutoff:
                name = container_name(uid)
                r = subprocess.run(
                    ["docker", "rm", "-f", name],
                    capture_output=True, text=True,
                )
                if r.returncode == 0:
                    removed.append(name)
                # 无论 rm 成功与否,从 dict 移除 ── 失败则下次启动靠 shutdown_all 兜底
                del self._last_active[uid]
        return removed

    def shutdown_all(self) -> List[str]:
        """杀所有 label=zcbot.product=sandbox 的容器。

        典型用途:① app 启动时清前驱进程留下的孤儿 ② 测试 / 维护手动调。
        """
        list_r = subprocess.run(
            ["docker", "ps", "-aq", "--filter",
             f"label={LABEL_PRODUCT_KEY}={LABEL_PRODUCT_VALUE}"],
            capture_output=True, text=True,
        )
        if list_r.returncode != 0 or not list_r.stdout.strip():
            return []
        ids = list_r.stdout.strip().splitlines()
        subprocess.run(
            ["docker", "rm", "-f", *ids],
            capture_output=True, text=True,
        )
        # 反查容器名给调用方记日志(rm 前先 inspect)── 这里简化只返 id
        self._last_active.clear()
        return ids


def setup_pool(user_root_base: Path) -> SandboxPool:
    """app 启动便捷入口:ensure 网络存在 + 返回 pool 实例。

    典型用法(lifespan 启动钩子):
        pool = setup_pool(workspace / "users")
        pool.shutdown_all()        # 清前驱孤儿
        # 后台 reaper task 周期跑 pool.reap_idle()
    """
    ensure_network()
    return SandboxPool(user_root_base=user_root_base)