// Desktop auto-update — prompt-on-update flow.
//
// Runs ONLY inside the Tauri desktop shell; a plain browser has no updater, so
// this is a guarded no-op there. On launch it checks the configured update
// endpoint (tauri.conf.json → plugins.updater); if a signed newer version is
// available it asks the operator, then downloads + installs and relaunches.
//
// The plugins are imported dynamically so the browser build never bundles them
// and never tries to resolve the Tauri APIs. Offline-first: a failed check (no
// network — the appliance is usually offline) is swallowed; updates only happen
// when someone has brought the box online (e.g. a phone hotspot) on purpose.

/** True when running inside the Tauri webview (not a normal browser). */
function inTauri(): boolean {
  return typeof window !== "undefined" && "__TAURI_INTERNALS__" in window;
}

export interface UpdatePrompt {
  /** Newer version string offered by the server. */
  version: string;
  /** Release notes, if the server provided them. */
  notes?: string;
}

/**
 * Check for an update. If one is available, calls `confirm` (your UI) with the
 * version/notes; when it resolves true, downloads + installs and relaunches.
 * No-op (resolves silently) in the browser or when no update / offline.
 */
export async function checkForDesktopUpdate(
  confirm: (info: UpdatePrompt) => Promise<boolean>,
): Promise<void> {
  if (!inTauri()) return;
  try {
    const { check } = await import("@tauri-apps/plugin-updater");
    const update = await check();
    if (!update) return; // up to date

    const accepted = await confirm({ version: update.version, notes: update.body });
    if (!accepted) return;

    // Download + install the signed update (signature verified against the
    // pubkey in tauri.conf.json), then relaunch into the new version.
    try {
      await update.downloadAndInstall();
    } catch (err) {
      // A real update WAS found and accepted — this is a genuine install
      // failure (bad signature, corrupted download, disk/permission issue),
      // not "offline". Surface it instead of silently reverting to the old
      // version with no explanation.
      console.error("desktop update download/install failed:", err);
      throw err;
    }
    const { relaunch } = await import("@tauri-apps/plugin-process");
    await relaunch();
  } catch (err) {
    // Offline / endpoint unreachable / no update server yet → ignore. The app
    // keeps running on the current version; checking again next launch. Still
    // log it so a real install failure (rethrown above) isn't invisible.
    console.warn("desktop update check/apply skipped:", err);
  }
}