import { createRepo, uploadFiles, downloadFile, whoAmI } from "@huggingface/hub";
import type { AppData, SyncableSettings } from "./store";
import { validateData } from "./store";

/** Optional sync of the app data to a private HF dataset owned by the user.
 *  Requires a user-pasted fine-grained token (write access to the dataset);
 *  the host shell's OAuth token is short-lived and read-only, so it can't be
 *  used for this. The token never leaves the browser except toward hf.co. */

const DATASET_NAME = "cookaiware-data";
const DATA_FILE = "cookaiware-data.json";
const SETTINGS_FILE = "cookaiware-settings.json";

export interface HfSyncIdentity {
  userName: string;
  repoId: string;
}

export async function resolveIdentity(token: string): Promise<HfSyncIdentity> {
  const me = await whoAmI({ accessToken: token });
  return { userName: me.name, repoId: `datasets/${me.name}/${DATASET_NAME}` };
}

async function ensureRepo(token: string, repoId: string): Promise<void> {
  try {
    await createRepo({ repo: repoId, accessToken: token, private: true });
  } catch (err) {
    // The repo usually already exists (every save after the first), and the
    // Hub wording for that error varies — so never fail the save here. If the
    // repo is genuinely missing/unreachable, uploadFiles will raise the real
    // error right after and that one is surfaced.
    console.debug("[hf-sync] createRepo skipped:", err instanceof Error ? err.message : err);
  }
}

export async function uploadData(
  token: string,
  data: AppData,
  settings?: SyncableSettings,
): Promise<HfSyncIdentity> {
  const identity = await resolveIdentity(token);
  await ensureRepo(token, identity.repoId);
  const files = [
    { path: DATA_FILE, content: new Blob([JSON.stringify(data, null, 2)], { type: "application/json" }) },
  ];
  if (settings) {
    files.push({
      path: SETTINGS_FILE,
      content: new Blob([JSON.stringify(settings, null, 2)], { type: "application/json" }),
    });
  }
  await uploadFiles({
    repo: identity.repoId,
    accessToken: token,
    files,
    commitTitle: "Update CookAIware data",
  });
  return identity;
}

export async function downloadData(token: string): Promise<AppData | null> {
  const identity = await resolveIdentity(token);
  const res = await downloadFile({ repo: identity.repoId, path: DATA_FILE, accessToken: token });
  if (!res) return null;
  return validateData(JSON.parse(await res.text()));
}

/** Fetch the synced settings subset, or null if none has been uploaded yet
 *  (older datasets, or a device that never enabled sync). */
export async function downloadSettings(token: string): Promise<unknown | null> {
  try {
    const identity = await resolveIdentity(token);
    const res = await downloadFile({ repo: identity.repoId, path: SETTINGS_FILE, accessToken: token });
    if (!res) return null;
    return JSON.parse(await res.text());
  } catch (err) {
    console.debug("[hf-sync] no settings file:", err instanceof Error ? err.message : err);
    return null;
  }
}