// Version: 1.0.0 | Created: 2026-07-04
// Post-login prompt: if the account has secret storage (key backup) and this
// fresh device cannot read encrypted history yet, offer the recovery-key
// restore straight away instead of leaving it buried in Profile > Security.
//
// Shown at most once per login session. "Later" keeps the old behaviour
// (restore manually from the Profile tab).

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:matrix/matrix.dart';

import 'key_restore_dialog.dart';

bool _promptedThisSession = false;

/// Reset when a new login happens (called from the login flow if needed).
void resetKeyRestorePrompt() => _promptedThisSession = false;

/// Checks whether the freshly logged-in session needs a key restore and,
/// if so, asks the user. Safe to call multiple times; only fires once.
Future<void> maybePromptKeyRestore(BuildContext context, Client client) async {
  if (_promptedThisSession) return;
  _promptedThisSession = true;

  try {
    // Wait for the first sync so account data (secret storage config) exists.
    if (client.prevBatch == null) {
      await client.onSync.stream.first.timeout(const Duration(seconds: 30));
    }
  } on TimeoutException {
    debugPrint('[KeyRestorePrompt] first sync timed out — skipping');
    return;
  }

  final enc = client.encryption;
  if (enc == null) return;

  // No secret storage on the account → nothing to restore from.
  final hasSecretStorage =
      client.accountData.containsKey('m.secret_storage.default_key');
  if (!hasSecretStorage) return;

  // Keys already cached (or session verified) → nothing to do.
  var cached = false;
  try {
    cached = await enc.keyManager.isCached();
  } on Exception catch (e) {
    debugPrint('[KeyRestorePrompt] isCached failed: $e');
  }
  if (cached && !client.isUnknownSession) return;

  if (!context.mounted) return;

  final wantsRestore = await showDialog<bool>(
    context: context,
    builder: (ctx) => AlertDialog(
      title: const Text('Restore encrypted messages?'),
      content: const Text(
        'This device cannot read your older encrypted messages yet. '
        'Enter your recovery key now to unlock them, or do it later '
        'from Profile > Security & Privacy.',
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.of(ctx).pop(false),
          child: const Text('Later'),
        ),
        FilledButton(
          onPressed: () => Navigator.of(ctx).pop(true),
          child: const Text('Enter recovery key'),
        ),
      ],
    ),
  );

  if (wantsRestore != true || !context.mounted) return;
  await showKeyRestoreDialog(context, client);
}