#!/usr/bin/env node
// gateway: 直接运行开发用 native browser gateway；不依赖 systemd。
import { spawn, execFileSync } from "node:child_process";
import { existsSync, readFileSync } from "node:fs";
import net from "node:net";
import os from "node:os";
import path from "node:path";
import { fileURLToPath } from "node:url";

const root = path.dirname(path.dirname(fileURLToPath(import.meta.url)));

function readEnvFile(filePath) {
  if (!existsSync(filePath)) return {};
  const values = {};
  for (const line of readFileSync(filePath, "utf8").split("\n")) {
    const match = /^([A-Za-z_][A-Za-z0-9_]*)=(.*)$/.exec(line.trim());
    if (match) values[match[1]] = match[2];
  }
  return values;
}

const rootEnv = readEnvFile(path.join(root, ".env"));
const gatewayEnvPath = process.env.CREATORHUB_BROWSER_GATEWAY_ENV
  ?? path.join(os.homedir(), ".config", "creatorhub", "browser-gateway.env");
const gatewayEnv = readEnvFile(gatewayEnvPath);
const env = { ...process.env, ...rootEnv, ...gatewayEnv };
if (!env.LISTEN_ADDR) env.LISTEN_ADDR = "127.0.0.1:28187";
if (!env.GATEWAY_TOKEN) env.GATEWAY_TOKEN = "dev-creatorhub-gateway-token";

// 与 Python 侧 split_listen_address 对齐。
function splitListenAddr(value) {
  let rest = value;
  let host = "";
  if (rest.startsWith(":")) {
    rest = rest.slice(1);
  } else if (rest.startsWith("[")) {
    const closing = rest.indexOf("]:");
    if (closing <= 1) throw new Error(`LISTEN_ADDR 必须是 host:port：${value}`);
    host = rest.slice(1, closing);
    rest = rest.slice(closing + 2);
  } else {
    const sep = rest.lastIndexOf(":");
    if (sep < 0) throw new Error(`LISTEN_ADDR 必须是 host:port：${value}`);
    host = rest.slice(0, sep);
    rest = rest.slice(sep + 1);
  }
  const port = Number(rest);
  if (!Number.isInteger(port) || port < 1 || port > 65535) {
    throw new Error(`LISTEN_ADDR 端口必须是 1..65535：${value}`);
  }
  return { host, port };
}

function probePort(host, port) {
  return new Promise((resolve) => {
    const server = net.createServer();
    server.once("error", (err) => resolve(err));
    server.listen({ host: host || undefined, port, exclusive: true }, () => {
      server.close(() => resolve(null));
    });
  });
}

// 通过 ss -ltnp 找出占用端口的进程；失败或拿不到进程信息时返回 []。
function findOccupants(port) {
  try {
    const out = execFileSync("ss", ["-ltnp"], { encoding: "utf8" });
    const occupants = [];
    for (const line of out.split("\n")) {
      if (!line.includes(`:${port} `)) continue;
      for (const match of line.matchAll(/"([^"]+)",pid=(\d+)/g)) {
        occupants.push(`${match[1]} (pid ${match[2]})`);
      }
    }
    return [...new Set(occupants)];
  } catch {
    return [];
  }
}

async function assertListenAddrFree(value) {
  const { host, port } = splitListenAddr(value);
  const shown = host || "0.0.0.0";
  const err = await probePort(host, port);
  if (!err) return;
  if (err.code !== "EADDRINUSE") return; // 其余错误交给 Python 侧原样报出。
  const occupants = findOccupants(port);
  console.error(`[gateway] 监听地址 ${shown}:${port} 已被占用，gateway 无法启动。`);
  if (occupants.length > 0) {
    console.error(`[gateway] 占用进程：${occupants.join("、")}（常见原因：上一个 gateway 实例还在运行）。`);
    console.error(`[gateway] 处理：先停掉占用进程，或用 LISTEN_ADDR 换一个端口（优先级：~/.config/creatorhub/browser-gateway.env > .env）。`);
  } else {
    console.error(`[gateway] 无法识别占用进程（可能需要 root 才能查看），可用命令：ss -ltnp | grep :${port}`);
  }
  process.exit(1);
}

await assertListenAddrFree(env.LISTEN_ADDR);

const gateway = spawn("python3", ["-m", "browser_gateway.server.http"], {
  cwd: root,
  env,
  stdio: "inherit",
});

for (const signal of ["SIGINT", "SIGTERM"]) {
  process.on(signal, () => gateway.kill(signal));
}

gateway.on("exit", (code, signal) => {
  if (signal) process.exit(1);
  process.exit(code ?? 0);
});