/**
 * Centralised copy-to-clipboard with a single, module-scope auto-clear
 * timer.
 *
 * Why module scope: tying the timer to a React component (via `useRef`)
 * means it gets cancelled when the screen unmounts — which happens
 * routinely (auto-lock on tab-switch, navigation to another item). The
 * user's just-completed copy then either gets wiped immediately
 * (component cleanup runs `setStringAsync("")`) or sits indefinitely.
 *
 * Behaviour:
 *   * `copyToClipboard(value)` writes the value, returns `true` on
 *     success.
 *   * On success, schedules a 30-second auto-wipe.
 *   * Subsequent copies cancel the prior timer and reschedule, so the
 *     wipe is always 30 seconds from the *last* copy regardless of
 *     which screen issued it.
 *
 * Limitation: we don't read the clipboard back (would require the
 * clipboard-read permission), so if the user copies from another app
 * between our copy and the auto-clear firing, we'll still wipe their
 * value at the 30s mark. Acceptable trade-off for a password manager.
 */

import * as Clipboard from "expo-clipboard";

const AUTO_CLEAR_MS = 30_000;

let clearTimer: ReturnType<typeof setTimeout> | null = null;

/** Write `value` to the clipboard. Returns `true` if the write succeeded. */
export async function copyToClipboard(value: string): Promise<boolean> {
  let ok: boolean;
  try {
    ok = await Clipboard.setStringAsync(value);
  } catch {
    ok = false;
  }
  if (!ok) {
    return false;
  }

  if (clearTimer !== null) {
    clearTimeout(clearTimer);
  }
  clearTimer = setTimeout(() => {
    clearTimer = null;
    void Clipboard.setStringAsync("").catch(() => {
      // Best-effort.
    });
  }, AUTO_CLEAR_MS);
  return true;
}

/**
 * Wipe the clipboard now (e.g. on explicit logout). Cancels the pending
 * auto-clear so we don't fire a redundant wipe later.
 */
export async function clearClipboardNow(): Promise<void> {
  if (clearTimer !== null) {
    clearTimeout(clearTimer);
    clearTimer = null;
  }
  try {
    await Clipboard.setStringAsync("");
  } catch {
    // Best-effort.
  }
}