import 'dart:async';
import 'package:flutter/material.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/helpers/constants/Font_constant.dart';
import 'package:miler/views/helpers/constants/Colorconstants.dart';
import 'package:miler/controllers/auth.dart';
import 'package:miler/views/onboardscreens/Creat_mpin.dart';
import 'package:miler/views/onboardscreens/auth_scaffold.dart';
import 'package:sms_autofill/sms_autofill.dart';

/// ─────────────────────────────────────────────────────────────────────────
/// VERIFY — step 2 of 3.
///
/// ── What changed and why ──
///
/// **The number is now on screen.** The old copy said "Enter the 6-digit code
/// sent to your device", which is the one screen in the flow where the rider
/// most needs to check a fact — *which* number did it go to — and it did not
/// tell him. If he fat-fingered a digit on the previous screen, he waits out a
/// 60-second timer for a code that was never coming, with no way to tell. It now
/// echoes the number with a "Change" action beside it, which is what every app
/// that has thought about this does.
///
/// **Failure is visible.** A wrong or expired code silently cleared all six
/// boxes and dropped a floating `SnackBar` at the bottom of the screen —
/// underneath the keyboard, which is up by definition here. The rider saw six
/// boxes empty themselves for no stated reason. The boxes now turn red and the
/// reason is printed under them.
///
/// **The decorative tile is gone**, along with the 64px tinted SMS glyph inside
/// it: it pushed the code boxes a third of the way down the screen to illustrate
/// a word already in the heading.
/// ─────────────────────────────────────────────────────────────────────────
class OtpPage extends GetResponsiveView {
  OtpPage({super.key});

  @override
  Widget builder() => const _OtpPageLayout();
}

class _OtpPageLayout extends StatefulWidget {
  const _OtpPageLayout();

  @override
  State<_OtpPageLayout> createState() => _OtpPageLayoutState();
}

class _OtpPageLayoutState extends State<_OtpPageLayout> with CodeAutoFill {
  final AuthController _auth = Get.put(AuthController());
  final List<TextEditingController> _otpControllers = List.generate(
    6,
    (_) => TextEditingController(),
  );
  final List<FocusNode> _focusNodes = List.generate(6, (_) => FocusNode());

  bool isVerifying = false;
  String? _error;
  int _secondsRemaining = 60;
  Timer? _timer;

  @override
  void initState() {
    super.initState();
    _startTimer();
    listenForCode();
    WidgetsBinding.instance.addPostFrameCallback(
      (_) => _focusNodes[0].requestFocus(),
    );
  }

  void _startTimer() {
    _secondsRemaining = 60;
    _timer?.cancel();
    _timer = Timer.periodic(const Duration(seconds: 1), (timer) {
      if (!mounted) {
        timer.cancel();
        return;
      }
      if (_secondsRemaining > 0) {
        setState(() => _secondsRemaining--);
      } else {
        timer.cancel();
      }
    });
  }

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

  String get _code => _otpControllers.map((c) => c.text).join();

  Future<void> _autoVerify() async {
    if (isVerifying || !_isComplete) return;
    setState(() {
      isVerifying = true;
      _error = null;
    });

    final ok = await _auth.verifyOtp(_code);

    if (!mounted) return;
    setState(() => isVerifying = false);

    if (ok) {
      openScreen(context, CreateMpin());
    } else {
      // Clear and refocus as before, but say so — see the class note.
      for (final c in _otpControllers) {
        c.clear();
      }
      _focusNodes[0].requestFocus();
      setState(() {
        _error = _secondsRemaining == 0
            ? 'That code is incorrect or has expired. Request a new one.'
            : 'That code is incorrect. Check the SMS and try again.';
      });
    }
  }

  @override
  void codeUpdated() {
    final received = code ?? '';
    if (received.length >= 6) {
      for (int i = 0; i < 6; i++) {
        _otpControllers[i].text = received[i];
      }
      setState(() => _error = null);
      _autoVerify();
    }
  }

  void _onDigitChanged(String val, int index) {
    if (val.isNotEmpty && index < 5) {
      _focusNodes[index + 1].requestFocus();
    }
    if (val.isEmpty && index > 0) {
      _focusNodes[index - 1].requestFocus();
    }
    // Typing again clears a previous rejection — the red boxes refer to the code
    // he just replaced, not the one he is entering now.
    setState(() {
      if (_error != null) _error = null;
    });
    if (_isComplete) _autoVerify();
  }

  /// `+91 98765 43210`, grouped so a rider can actually proof-read it.
  String get _maskedPhone {
    final raw = (_auth.currentPhone ?? '').replaceAll(RegExp(r'\D'), '');
    if (raw.length != 10) return 'your mobile number';
    return '+91 ${raw.substring(0, 5)} ${raw.substring(5)}';
  }

  @override
  void dispose() {
    for (var c in _otpControllers) {
      c.dispose();
    }
    for (var f in _focusNodes) {
      f.dispose();
    }
    _timer?.cancel();
    cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final canResend = _secondsRemaining == 0;

    return AuthScaffold(
      onBack: () => Get.back(),
      // 1 of 2, not 2 of 3: the number screen no longer counts itself, and a
      // counter whose first sighting is "step 2" is a counter the rider has
      // already lost track of. See the note at the top of `Sign_in`.
      step: 1,
      totalSteps: 2,
      // Compact, for the same reason as the two screens either side of it: the
      // first box takes focus on the first frame. Included so the flow does not
      // gain and lose its masthead between the number screen and the PIN one.
      banner: const AuthBrandBanner(compact: true),
      title: 'Enter the 6-digit code',
      footer: AuthPrimaryButton(
        label: 'Verify & continue',
        loading: isVerifying,
        onPressed: isVerifying || !_isComplete ? null : _autoVerify,
      ),
      children: [
        // ── Which number, and a way out ──
        // The single most useful fact on this screen, and the old version left
        // it off entirely.
        Padding(
          padding: EdgeInsets.only(bottom: 26.h),
          child: Row(
            children: [
              Expanded(
                child: Text.rich(
                  TextSpan(
                    style: AuthType.subtitle,
                    children: [
                      const TextSpan(text: 'Sent by SMS to '),
                      TextSpan(
                        text: _maskedPhone,
                        style: TextStyle(
                          fontWeight: FontWeight.w800,
                          color: ColorConstants.slateText,
                          fontFamily: FontConstants.fontFamily,
                        ),
                      ),
                    ],
                  ),
                ),
              ),
              SizedBox(width: 8.w),
              AuthTextAction(
                label: 'Change',
                onPressed: isVerifying ? null : () => Get.back(),
              ),
            ],
          ),
        ),

        AuthCodeRow(
          controllers: _otpControllers,
          nodes: _focusNodes,
          hasError: _error != null,
          onChanged: _onDigitChanged,
        ),
        AuthInlineError(message: _error),

        SizedBox(height: 22.h),

        // ── Resend ──
        //
        // The countdown used to be a disabled `TextButton` reading
        // "Resend in 00:42", so the affordance and the timer were the same
        // control and it looked broken for its first sixty seconds. The wait is
        // now a plain sentence, and the button only exists once it can be used.
        Center(
          child: canResend
              ? AuthTextAction(
                  label: 'Send a new code',
                  icon: Icons.refresh_rounded,
                  onPressed: () async {
                    setState(() => _error = null);
                    _startTimer();
                    await _auth.sendOtp();
                  },
                )
              : Text(
                  'You can request a new code in '
                  '0:${_secondsRemaining.toString().padLeft(2, '0')}',
                  style: AuthType.meta,
                ),
        ),
      ],
    );
  }
}