import 'package:flutter/material.dart';
import 'package:lucide_icons_flutter/lucide_icons.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
import 'package:get/get.dart';
import 'package:miler/views/helpers/widgets/page_transitions.dart';
import 'package:miler/views/onboardscreens/otp_page.dart';
import 'package:miler/views/onboardscreens/auth_scaffold.dart';
import 'package:miler/helpers/rider_shell.dart';
import 'package:miler/controllers/auth.dart';
import 'package:shared_preferences/shared_preferences.dart';

/// ─────────────────────────────────────────────────────────────────────────
/// UNLOCK — the returning rider's front door.
///
/// Deliberately **not** given a step indicator. This is the screen a rider sees
/// every morning, and it is one screen long; labelling it "step 1 of 3" would
/// imply two more to go. The step rail belongs to the one-time sign-up flow.
///
/// ── What changed and why ──
///
/// **It says whose account it is.** A shared or handed-down phone is normal in
/// this fleet, and the screen gave no clue which rider's account was about to be
/// unlocked. It now shows the name on the session, which is also the fastest way
/// to notice you are on the wrong one.
///
/// **The boxes match the rest of the flow.** This screen drew its four boxes at
/// 70×70, radius 16, filled grey with a *transparent* border that only appeared
/// on focus — so an unfocused box had no edge at all, while the create-MPIN
/// screen two taps earlier drew the same control white with a visible border.
/// Both now use the shared [AuthCodeRow].
///
/// **"Access your account securely" is gone.** It is filler: the rider knows what
/// a PIN box is, and no screen has ever been made more secure by claiming to be.
/// ─────────────────────────────────────────────────────────────────────────
class Mpin extends GetResponsiveView {
  Mpin({super.key});

  @override
  Widget builder() {
    return const _MpinView();
  }
}

class _MpinView extends StatefulWidget {
  const _MpinView();

  @override
  State<_MpinView> createState() => _MpinViewState();
}

class _MpinViewState extends State<_MpinView> {
  final AuthController _auth = Get.put(AuthController());
  final List<TextEditingController> _mpinControllers = List.generate(
    4,
    (_) => TextEditingController(),
  );
  final List<FocusNode> _focusNodes = List.generate(4, (_) => FocusNode());

  bool isVerifying = false;
  bool _rejected = false;

  /// What actually went wrong, from [AuthController.lastPinFailure].
  ///
  /// This screen used to hard-code "Incorrect MPIN. Try again." for every
  /// failure the controller reported — including the ones that never reached
  /// the server. A rider whose sign-in was dying on a device-id lookup was told
  /// his PIN was wrong, so the one thing he could report was the one thing that
  /// was not true. Whatever the controller knows, the screen now says.
  String? _failure;
  String _riderName = '';

  @override
  void initState() {
    super.initState();
    _loadRider();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      _focusNodes[0].requestFocus();
    });
  }

  Future<void> _loadRider() async {
    try {
      final prefs = await SharedPreferences.getInstance();
      final name = (prefs.getString('user_name') ?? '').trim();
      if (mounted && name.isNotEmpty) {
        setState(() => _riderName = name.split(' ').first);
      }
    } catch (_) {
      // Non-essential: the screen works without a name.
    }
  }

  @override
  void dispose() {
    for (var c in _mpinControllers) {
      c.dispose();
    }
    for (var f in _focusNodes) {
      f.dispose();
    }
    super.dispose();
  }

  bool get _isComplete => _mpinControllers.every((c) => c.text.isNotEmpty);

  void _onMpinChange(String value, int index) {
    if (value.isNotEmpty && index < 3) {
      _focusNodes[index + 1].requestFocus();
    } else if (value.isEmpty && index > 0) {
      _focusNodes[index - 1].requestFocus();
    }

    setState(() {
      if (_rejected) {
        _rejected = false;
        _failure = null;
      }
    });

    if (_isComplete) {
      FocusScope.of(context).unfocus();
      _submitMpin();
    }
  }

  /// Wired to [AuthController.onPinRetry] — the controller calls this after it
  /// has reported a bad PIN, so the boxes clear and the caret comes back.
  void _clearMpinAndFocus() {
    for (final c in _mpinControllers) {
      c.clear();
    }
    _focusNodes[0].requestFocus();
    if (mounted) {
      setState(() {
        _rejected = true;
        _failure = _auth.lastPinFailure;
      });
    }
  }

  Future<void> _submitMpin() async {
    if (!mounted || isVerifying) return;
    _auth.onPinRetry = _clearMpinAndFocus;
    setState(() => isVerifying = true);

    final ok = await _auth.verifyPinWithServer(
      _mpinControllers.map((c) => c.text).join(),
    );

    if (!mounted) return;
    setState(() {
      isVerifying = false;
      // Say it on the screen, not only inside a sheet the rider dismisses.
      if (!ok) {
        _rejected = true;
        _failure = _auth.lastPinFailure;
      }
    });

    if (ok) {
      // Straight to the app. There used to be a "Go on duty" gate between the
      // PIN and the tabs, which made every launch a two-step sign-in for a
      // decision the rider can make — and change — from the switch in Home's
      // app bar at any moment of the shift.
      //
      // Which app depends on the tenant the login just resolved: `loginParsed`
      // persists `tenantid`/`tenantname` and calls `TenantController.load()`
      // before returning, so by this line the answer is settled. A delivery
      // rider lands in the ported Xpress flow, everyone else in the parcel
      // dashboard. See [riderShell].
      Get.offAll(() => riderShell());
    }
  }

  @override
  Widget build(BuildContext context) {
    return AuthScaffold(
      onBack: () => Get.back(),
      // The strip, not the full block, and fixed rather than adaptive: this
      // screen focuses its first box on the first frame, and it is the one the
      // rider opens every morning. See [AuthBrandBanner].
      //
      // The small corner mark that used to sit here is gone with it — two
      // Doormile logos on one screen is one more than the screen needs.
      banner: const AuthBrandBanner(compact: true),
      title: _riderName.isEmpty
          ? 'Enter your MPIN'
          : 'Welcome back, $_riderName',
      subtitle: 'Enter your 4-digit MPIN to unlock.',
      footer: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          AuthPrimaryButton(
            label: 'Unlock',
            icon: LucideIcons.lockOpen,
            loading: isVerifying,
            onPressed: isVerifying || !_isComplete ? null : _submitMpin,
          ),
          SizedBox(height: 6.h),
          AuthTextAction(
            label: 'Forgot MPIN?',
            onPressed: isVerifying
                ? null
                : () async {
                    await _auth.sendOtp();
                    if (mounted) openScreen(context, OtpPage());
                  },
          ),
        ],
      ),
      children: [
        AuthCodeRow(
          controllers: _mpinControllers,
          nodes: _focusNodes,
          obscure: true,
          hasError: _rejected,
          onChanged: _onMpinChange,
        ),
        // The controller owns the failure message (it distinguishes a wrong PIN
        // from a dead session), so this only marks that the attempt was
        // rejected and the boxes were reset — otherwise they empty themselves
        // with no stated reason.
        AuthInlineError(
          message: _rejected
              ? (_failure ?? 'Incorrect MPIN. Try again.')
              : null,
        ),
      ],
    );
  }
}