// What the mesh delivered to home-assistant's provisions step, and the step's own small memory.
//
// Per provision it requires, the mesh writes two files beside each other (the manifest's `binds` and
// `secrets`): `<provision>.json`, the binding — where the provider is (`at`), what it serves (`port`,
// `scheme`, …) and the login this module presents (`as`) — and `<provision>.secret`, the pair
// credential. Nothing here guesses a host, a port or a key.

import { mkdir, readFile, rename, writeFile } from "node:fs/promises";
import { join } from "node:path";

import type { Binding, Marks } from "./connections.js";

/** A file the mesh wrote, or undefined when it is not there. */
export async function readIfThere(path: string | undefined): Promise<string | undefined> {
  if (!path) return undefined;
  return readFile(path, "utf8").catch(() => undefined);
}

/** A binding file parsed, or undefined when absent or not JSON. */
export async function readBinding(path: string): Promise<Binding | undefined> {
  const raw = await readIfThere(path);
  if (raw === undefined) return undefined;
  try {
    return JSON.parse(raw) as Binding;
  } catch {
    return undefined;
  }
}

export function marksIn(dir: string): Marks {
  return {
    async get(name) {
      return (await readIfThere(join(dir, `${name}.digest`)))?.trim() || undefined;
    },
    async set(name, value) {
      await mkdir(dir, { recursive: true, mode: 0o700 });
      const path = join(dir, `${name}.digest`);
      await writeFile(`${path}.tmp`, `${value}\n`, { mode: 0o600 });
      await rename(`${path}.tmp`, path);
    },
  };
}