import { copyFile, readFile, rm, writeFile } from "node:fs/promises";
import path from "node:path";
import { Alpine } from "./alpine.js";
import { execFile } from "./helpers/better-api.js";

export type Kind = "lts" | "virt";
export type Kernel = {
  initramfs: string;
  vmlinuz: string;
  kind: Kind;
};

export async function setupKernel(
  alpine: Alpine,
  output: string
): Promise<Kernel> {
  const kind: Kind = "virt";

  await alpine.writeFile(
    "/etc/update-extlinux.conf",
    `# configuration for extlinux config builder

# Overwrite current /boot/extlinux.conf.
overwrite=1

# vesa_menu
# use fancy vesa menu (vesamenu.c32) menus, won't work with serial
vesa_menu=1

#default_kernel_opts=quiet
default_kernel_opts=
modules=loop,squashfs,sd-mod,usb-storage,ext4,vfat

# root device - if not specified, will be guessed using
# blkid -o export /dev/root
root=/dev/sda

# if set to non-zero, update-extlinux will be a lot more verbose.
verbose=0

hidden=0
timeout=3
default=lts
`
  );

  const features = [
    "squashfs",
    "ata",
    "base",
    "cdrom",
    "ext4",
    "keymap",
    "kms",
    "mmc",
    "nvme",
    "scsi",
    "usb",
    ...(kind === "virt" ? ["virtio"] : []),
  ];

  await alpine.writeFile(
    "/etc/mkinitfs/mkinitfs.conf",
    `features="${features.join(" ")}"
disable_trigger=yes`
  );

  await alpine.installPackages([`linux-${kind}`, "zstd"]);

  // patch mkinitfs to use faster zstd
  const mkinitfs = alpine.path("/sbin/mkinitfs");
  const newMkinitfs = (await readFile(mkinitfs, "utf-8")).replace(
    'comp="zstd -19"',
    'comp="zstd -3"'
  );
  await writeFile(mkinitfs, newMkinitfs);

  const kernelRelease = (
    await readFile(
      alpine.path(`/usr/share/kernel/${kind}/kernel.release`),
      "utf-8"
    )
  ).trim();
  // TODO: poner en un mejor lugar
  await alpine.writeExecutable(
    "/etc/mkinitfs/init",
    await readFile("./initramfs-init", "utf-8")
  );
  // run mkinitfs manually as trigger was diabled
  await execFile("chroot", [
    alpine.dir,
    "mkinitfs",
    "-C",
    "zstd",
    "-o",
    `/boot/initramfs-${kind}`,
    "-i",
    "/etc/mkinitfs/init",
    kernelRelease,
  ]);

  const initramfs = path.join(alpine.dir, `/boot/initramfs-${kind}`);
  const vmlinuz = path.join(alpine.dir, `/boot/vmlinuz-${kind}`);

  const kernel: Kernel = {
    kind,
    initramfs: path.join(output, "initramfs"),
    vmlinuz: path.join(output, "vmlinuz"),
  };

  await copyFile(initramfs, kernel.initramfs);
  await copyFile(vmlinuz, kernel.vmlinuz);
  await rm(initramfs);
  await rm(vmlinuz);
  return kernel;
}