"""
MTG Agent — лёгкий HTTP агент для каждой ноды.
Читает метрики MTG контейнеров через Docker SDK и отдаёт через REST API.
Порт: 8081 (внутри docker сети)
"""
import os
from fastapi import FastAPI, HTTPException, Header
from fastapi.responses import JSONResponse
import docker

app = FastAPI(title="MTG Agent", version="1.0.0")

AGENT_TOKEN = os.environ.get("AGENT_TOKEN", "mtg-agent-secret")

client = docker.from_env()


def get_mtg_containers():
    try:
        return [c for c in client.containers.list(all=True) if c.name.startswith("mtg-") and c.name != "mtg-agent"]
    except Exception:
        return []


def get_connections(container) -> int:
    try:
        container.reload()
        pid = container.attrs.get("State", {}).get("Pid", 0)
        if not pid:
            return 0

        MTG_PORT_HEX = "0C38"  # 3128 in hex

        tcp6_path = f"/proc/{pid}/net/tcp6"
        try:
            with open(tcp6_path) as f:
                lines = f.readlines()[1:]
        except Exception:
            tcp_path = f"/proc/{pid}/net/tcp"
            with open(tcp_path) as f:
                lines = f.readlines()[1:]

        remote_ips = set()
        for line in lines:
            parts = line.split()
            if len(parts) < 4:
                continue
            state = parts[3]
            local_addr = parts[1]
            remote_addr = parts[2]
            local_port = local_addr.split(":")[1] if ":" in local_addr else ""
            if state == "01" and local_port == MTG_PORT_HEX:
                remote_ip = remote_addr.rsplit(":", 1)[0] if ":" in remote_addr else remote_addr
                remote_ips.add(remote_ip)

        return len(remote_ips)
    except Exception:
        return 0


def get_traffic(container) -> dict:
    try:
        stats = container.stats(stream=False)
        nets = stats.get("networks", {})
        total_rx = sum(v.get("rx_bytes", 0) for v in nets.values())
        total_tx = sum(v.get("tx_bytes", 0) for v in nets.values())

        def fmt(b: int) -> str:
            if b >= 1_073_741_824:
                return f"{b / 1_073_741_824:.2f}GB"
            if b >= 1_048_576:
                return f"{b / 1_048_576:.2f}MB"
            if b >= 1024:
                return f"{b / 1024:.2f}KB"
            return f"{b}B"

        return {"rx": fmt(total_rx), "tx": fmt(total_tx), "rx_bytes": total_rx, "tx_bytes": total_tx}
    except Exception:
        return {"rx": "—", "tx": "—", "rx_bytes": 0, "tx_bytes": 0}


@app.get("/health")
def health():
    return {"status": "ok", "version": "1.0.0"}


@app.get("/metrics")
def metrics(x_agent_token: str = Header(default="")):
    if x_agent_token != AGENT_TOKEN:
        raise HTTPException(status_code=401, detail="Unauthorized")

    containers = get_mtg_containers()
    result = []

    for c in containers:
        name = c.name
        running = c.status == "running"
        devices = get_connections(c) if running else 0
        traffic = get_traffic(c) if running else {"rx": "—", "tx": "—", "rx_bytes": 0, "tx_bytes": 0}

        result.append({
            "name": name,
            "running": running,
            "status": c.status,
            "connections": devices,
            "devices": devices,
            "is_online": devices > 0,
            "traffic": traffic,
        })

    return JSONResponse({"containers": result, "total": len(result)})