import { execFile as _execFile, spawn } from "node:child_process";
import { mkdir, readFile, stat, symlink, writeFile } from "node:fs/promises";
import { homedir } from "node:os";
import { join } from "node:path";
import { promisify } from "node:util";
const execFile = promisify(_execFile);

/**
 * @typedef {object} Alpine
 * @prop {(packages: string[]) => Promise<void>} install
 * @prop {(runlevel: string, service: string) => Promise<void>} rcUpdate
 */

/**
 * Initialize an Alpine 3.18 rootfs at `root`
 * @param {string} root
 * @returns {Promise<Alpine>}
 */
export async function init(root) {
  await runInContainer(
    root,
    `
mkdir -p /rootfs/etc/apk
cp -r /etc/apk/keys /rootfs/etc/apk/
echo https://dl-cdn.alpinelinux.org/alpine/v3.18/main >> /rootfs/etc/apk/repositories
echo https://dl-cdn.alpinelinux.org/alpine/v3.18/community >> /rootfs/etc/apk/repositories
ln -s /var/cache/apk /rootfs/etc/apk/cache
apk add --initdb --root /rootfs alpine-base
    `
  );
  return {
    async install(packages) {
      const worldPath = join(root, "/etc/apk/world");
      const oldWorld = (await readFile(worldPath, "utf-8")).split("\n");
      const newWorld = oldWorld.concat(packages);
      await writeFile(worldPath, newWorld.join("\n"));

      await runInContainer(root, `apk fix --root /rootfs`);
    },
    async rcUpdate(runlevel, service) {
      const servicePath = `/etc/init.d/${service}`;
      try {
        await stat(join(root, servicePath));
      } catch (error) {
        throw new Error(`Can't stat service ${service}: ${error}`);
      }
      await symlink(
        servicePath,
        join(root, `/etc/runlevels/`, runlevel, service)
      );
    },
  };
}

const IS_DEV = process.env.NODE_ENV === "development";
/**
 * Run script inside an Alpine 3.18 container with `root` mounted in /rootfs
 * @param {string} root
 * @param {string} script
 */
async function runInContainer(root, script) {
  const cacheDir = join(homedir(), ".cache/apkit");
  await mkdir(cacheDir, { recursive: true });
  const proc = spawn(
    "podman",
    [
      "run",
      "-i",
      "--rm",
      "-v",
      `${root}:/rootfs:Z`,
      "-v",
      `${cacheDir}:/var/cache/apk:Z`,
      "docker.io/alpine:3.18",
      "sh",
      "-ec",
      script,
    ],
    { stdio: IS_DEV ? "inherit" : "pipe" }
  );
  await new Promise((resolve, reject) =>
    proc.on("exit", (code) => (code === 0 ? resolve(void 0) : reject(code)))
  );
}