import docker

_client = None


def _c():
    global _client
    if _client is None:
        _client = docker.DockerClient(base_url="unix:///var/run/docker.sock", timeout=15)
    return _client


def host_info():
    try:
        import shutil
        client = _c()
        info = client.info()
        containers = client.containers.list(all=True, sparse=True)
        running = sum(1 for c in containers if c.status == "running")
        images = len(client.images.list())
        mem_total = info.get("MemTotal", 0)
        mem_used = 0
        try:
            with open("/proc/meminfo") as f:
                mem = {}
                for line in f.read().splitlines():
                    if ":" in line:
                        parts = line.split()
                        mem[parts[0].rstrip(":")] = int(parts[1]) * 1024
            mem_total = mem.get("MemTotal", mem_total)
            mem_used = mem_total - mem.get("MemAvailable", mem.get("MemFree", 0))
        except Exception:
            pass
        disk_total = disk_used = 0
        try:
            d = shutil.disk_usage("/")
            disk_total, disk_used = d.total, d.used
        except Exception:
            pass
        return {
            "name": info.get("Name", "?"),
            "os": info.get("OperatingSystem", "?"),
            "version": info.get("ServerVersion", "?"),
            "kernel": info.get("KernelVersion", "?"),
            "cpu": info.get("NCPU", 0),
            "memory": mem_total,
            "mem_used": mem_used,
            "mem_total": mem_total,
            "running": running,
            "containers": len(containers),
            "images": images,
            "disk_total": disk_total,
            "disk_used": disk_used,
            "storage": info.get("DriverStatus", [["?", "?"]])[0][1] if info.get("DriverStatus") else "?",
            "error": None,
        }
    except Exception as e:
        return {"name": "?", "running": 0, "containers": 0, "images": 0, "error": str(e)}


def list_containers():
    try:
        client = _c()
        return [
            {
                "id": c.short_id,
                "name": c.name,
                "image": c.image.tags[0] if c.image.tags else c.image.short_id[:19],
                "status": c.status,
                "ports": c.ports,
                "created": c.attrs.get("Created", "")[:19],
            }
            for c in client.containers.list(all=True)
        ]
    except Exception as e:
        return {"error": str(e)}


def list_images():
    try:
        client = _c()
        return [{"id": i.short_id, "tags": i.tags, "size": i.attrs.get("Size", 0)} for i in client.images.list()]
    except Exception as e:
        return {"error": str(e)}


def container_action(cid, action):
    try:
        client = _c()
        c = client.containers.get(cid)
        if action == "start":
            c.start()
        elif action == "stop":
            c.stop(timeout=10)
        elif action == "restart":
            c.restart(timeout=10)
        else:
            return {"error": f"unknown action {action}"}
        return {"status": f"{action}ed", "name": c.name}
    except Exception as e:
        return {"error": str(e)}


def container_stats(cid):
    try:
        client = _c()
        c = client.containers.get(cid)
        s = c.stats(stream=False)
        mem_usage = s["memory_stats"].get("usage", 0)
        mem_limit = s["memory_stats"].get("limit", 1)
        cpu_delta = s["cpu_stats"]["cpu_usage"]["total_usage"] - s["precpu_stats"]["cpu_usage"]["total_usage"]
        system_delta = s["cpu_stats"]["system_cpu_usage"] - s["precpu_stats"]["system_cpu_usage"]
        cpu_percent = (cpu_delta / system_delta) * 100.0 * s["cpu_stats"].get("online_cpus", 1) if system_delta > 0 else 0
        return {
            "memory_usage": mem_usage,
            "memory_limit": mem_limit,
            "memory_pct": round(mem_usage / mem_limit * 100, 1) if mem_limit else 0,
            "cpu_pct": round(cpu_percent, 1),
            "pids": s["pids_stats"].get("current", 0),
            "network_rx": s.get("networks", {}).get("eth0", {}).get("rx_bytes", 0),
            "network_tx": s.get("networks", {}).get("eth0", {}).get("tx_bytes", 0),
        }
    except Exception as e:
        return {"error": str(e)}