import type { InstallContext } from "../types/context";
import { runMutating } from "../lib/process";
import { ensureDiagnosticsStorageRoot } from "../lib/diagnosticsStorage";

async function userExists(user: string): Promise<boolean> {
  try {
    await runMutating`id -u ${user} >/dev/null 2>&1`;
    return true;
  } catch {
    return false;
  }
}

async function getUserField(user: string, field: number): Promise<string> {
  return (await runMutating`getent passwd ${user} | cut -d: -f${field}`).trim();
}

async function getPrimaryGroup(user: string): Promise<string> {
  return (await runMutating`id -gn ${user}`).trim();
}

async function ensureDir(path: string, mode: string, ownerGroup: string): Promise<void> {
  await runMutating`install -d -m ${mode} -o ${ownerGroup.split(":")[0]} -g ${ownerGroup.split(":")[1]} ${path}`;
}

async function makeUser(user: string, expectedHome: string): Promise<void> {
  await runMutating`useradd --system --home ${expectedHome} --shell /usr/sbin/nologin ${user}`;
}

async function ensureRuntimeIdentity(user: string, expectedHome: string): Promise<void> {
  if (!(await userExists(user))) {
    await makeUser(user, expectedHome);
    return;
  }

  const shell = await getUserField(user, 7);
  const home = await getUserField(user, 6);
  const group = await getPrimaryGroup(user);

  if (shell !== "/usr/sbin/nologin" && shell !== "/bin/false") {
    throw new Error(`existing user '${user}' has unsupported shell: ${shell}`);
  }
  if (group !== user) {
    throw new Error(`existing user '${user}' must have primary group '${user}', got: ${group}`);
  }
  if (home !== expectedHome) {
    throw new Error(`existing user '${user}' has unexpected home: ${home} (expected ${expectedHome})`);
  }
}

export async function prepareFilesystem(context: InstallContext): Promise<void> {
  await ensureRuntimeIdentity("hysteria", "/var/lib/hysteria");
  await ensureRuntimeIdentity("hy2xs-admin", context.config.dataDir);
  await ensureDir("/etc/hy2xs", "0700", "root:root");
  await ensureDir("/etc/hysteria", "0755", "root:root");
  await ensureDir("/var/lib/hysteria", "0750", "hysteria:hysteria");
  await ensureDir(context.config.dataDir, "0750", "hy2xs-admin:hy2xs-admin");
  await ensureDir(context.config.logDir, "0750", "hy2xs-admin:hy2xs-admin");
  await ensureDir(context.config.installDir, "0755", "root:root");
  await ensureDir("/usr/local/lib/hy2xs", "0755", "root:root");
  await ensureDir("/etc/nftables.d", "0755", "root:root");
  await ensureDiagnosticsStorageRoot();
  await runMutating`chmod -R go-w ${context.config.installDir}`;
}