import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:lucide_icons_flutter/lucide_icons.dart';

import '../core/theme.dart';
import '../state/session_controller.dart';
import '../widgets/common.dart';

/// Step 1 of 2: the mobile number a shift manager would text.
class PhoneScreen extends ConsumerStatefulWidget {
  const PhoneScreen({super.key});

  @override
  ConsumerState<PhoneScreen> createState() => _PhoneScreenState();
}

class _PhoneScreenState extends ConsumerState<PhoneScreen> {
  final _controller = TextEditingController();
  bool get _valid =>
      _controller.text.replaceAll(RegExp(r'\D'), '').length >= 10;

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  void _send() {
    final phone = '+1 ${_controller.text.trim()}';
    ref.read(sessionProvider.notifier).sendCode(phone);
    context.push('/otp');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(leading: const BackButton()),
      body: SafeArea(
        child: SingleChildScrollView(
          padding: const EdgeInsets.fromLTRB(20, 4, 20, 24),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              const SectionLabel('Step 1 of 2'),
              const Text(
                "What's your\nmobile number?",
                style: TextStyle(
                  fontSize: 29,
                  fontWeight: FontWeight.w700,
                  height: 1.1,
                  letterSpacing: -1,
                ),
              ),
              const SizedBox(height: 10),
              const Text(
                'Shift managers text you here, and we will send a 6-digit code '
                'to confirm it is yours.',
                style: TextStyle(
                  fontSize: 14,
                  height: 1.55,
                  color: KrowPalette.mute,
                ),
              ),
              const SizedBox(height: 24),
              TextField(
                controller: _controller,
                autofocus: true,
                keyboardType: TextInputType.phone,
                onChanged: (_) => setState(() {}),
                inputFormatters: [
                  FilteringTextInputFormatter.allow(RegExp(r'[0-9 ]')),
                  LengthLimitingTextInputFormatter(14),
                ],
                style: const TextStyle(
                  fontSize: 17,
                  fontWeight: FontWeight.w600,
                  letterSpacing: 0.6,
                ),
                decoration: const InputDecoration(
                  hintText: '408 555 0148',
                  prefixIcon: Padding(
                    padding: EdgeInsets.fromLTRB(16, 15, 10, 15),
                    child: Text(
                      '+1',
                      style: TextStyle(
                        fontSize: 16,
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                  ),
                  prefixIconConstraints: BoxConstraints(minWidth: 0),
                ),
              ),
              const SizedBox(height: 10),
              const Text(
                'Message and data rates may apply. Reply STOP any time to opt '
                'out.',
                style: TextStyle(
                  fontSize: 12,
                  height: 1.5,
                  color: Color(0xFF949FA5),
                ),
              ),
              const SizedBox(height: 26),
              FilledButton(
                onPressed: _valid ? _send : null,
                child: const Text('Send code'),
              ),
              const SizedBox(height: 10),
              Center(
                child: TextButton(
                  onPressed: () => ScaffoldMessenger.of(context).showSnackBar(
                    const SnackBar(
                      content: Text('Email sign-in is coming soon'),
                    ),
                  ),
                  child: const Text('Verify with email instead'),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

/// Step 2 of 2: the code, with a resend countdown and a limited try budget.
class OtpScreen extends ConsumerStatefulWidget {
  const OtpScreen({super.key});

  @override
  ConsumerState<OtpScreen> createState() => _OtpScreenState();
}

class _OtpScreenState extends ConsumerState<OtpScreen> {
  final _controller = TextEditingController();
  Timer? _timer;
  int _secondsLeft = 30;
  int _triesLeft = 3;
  String? _error;

  @override
  void initState() {
    super.initState();
    _startCountdown();
  }

  @override
  void dispose() {
    _timer?.cancel();
    _controller.dispose();
    super.dispose();
  }

  void _startCountdown() {
    _timer?.cancel();
    setState(() => _secondsLeft = 30);
    _timer = Timer.periodic(const Duration(seconds: 1), (t) {
      if (!mounted) return;
      if (_secondsLeft <= 1) {
        t.cancel();
        setState(() => _secondsLeft = 0);
      } else {
        setState(() => _secondsLeft--);
      }
    });
  }

  void _verify() {
    final ok = ref.read(sessionProvider.notifier).verifyCode(_controller.text);
    if (ok) {
      context.go('/verified');
      return;
    }
    setState(() {
      _triesLeft--;
      _error = _triesLeft > 0
          ? 'That code does not match. Check the most recent text - older '
                'codes stop working. $_triesLeft tries left.'
          : 'Too many attempts. Request a new code to try again.';
    });
  }

  @override
  Widget build(BuildContext context) {
    final phone = ref.watch(sessionProvider).phone ?? '';
    final canVerify = _controller.text.length == 6 && _triesLeft > 0;

    return Scaffold(
      appBar: AppBar(leading: const BackButton()),
      body: SafeArea(
        child: SingleChildScrollView(
          padding: const EdgeInsets.fromLTRB(20, 4, 20, 24),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              const SectionLabel('Step 2 of 2'),
              const Text(
                'Enter the code',
                style: TextStyle(
                  fontSize: 29,
                  fontWeight: FontWeight.w700,
                  letterSpacing: -1,
                ),
              ),
              const SizedBox(height: 10),
              Row(
                children: [
                  Text(
                    'Texted to $phone',
                    style: const TextStyle(
                      fontSize: 13.5,
                      color: KrowPalette.mute,
                    ),
                  ),
                  TextButton(
                    onPressed: () => context.pop(),
                    child: const Text('Change'),
                  ),
                ],
              ),
              const SizedBox(height: 8),
              TextField(
                controller: _controller,
                autofocus: true,
                keyboardType: TextInputType.number,
                textAlign: TextAlign.center,
                maxLength: 6,
                onChanged: (_) => setState(() => _error = null),
                inputFormatters: [FilteringTextInputFormatter.digitsOnly],
                style: const TextStyle(
                  fontSize: 30,
                  fontWeight: FontWeight.w700,
                  letterSpacing: 14,
                ),
                decoration: InputDecoration(
                  counterText: '',
                  hintText: '------',
                  errorText: _error,
                  errorMaxLines: 3,
                  hintStyle: const TextStyle(
                    fontSize: 30,
                    letterSpacing: 14,
                    color: Color(0xFFC4D4C9),
                  ),
                ),
              ),
              const SizedBox(height: 14),
              const InfoBanner('Demo build: the code is always 123456.'),
              const SizedBox(height: 16),
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  const Text(
                    "Didn't get the text?",
                    style: TextStyle(fontSize: 13, color: KrowPalette.mute),
                  ),
                  if (_secondsLeft > 0)
                    Text(
                      'Resend in 0:${_secondsLeft.toString().padLeft(2, '0')}',
                      style: const TextStyle(
                        fontSize: 12.5,
                        color: Color(0xFF949FA5),
                      ),
                    )
                  else
                    TextButton(
                      onPressed: () {
                        setState(() {
                          _triesLeft = 3;
                          _error = null;
                        });
                        _startCountdown();
                        ScaffoldMessenger.of(context).showSnackBar(
                          const SnackBar(content: Text('New code sent')),
                        );
                      },
                      child: const Text('Resend code'),
                    ),
                ],
              ),
              const SizedBox(height: 18),
              FilledButton(
                onPressed: canVerify ? _verify : null,
                child: const Text('Verify number'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

/// Confirmation, plus the two things still standing between the worker and
/// their first shift.
class VerifiedScreen extends ConsumerWidget {
  const VerifiedScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final phone = ref.watch(sessionProvider).phone ?? '';
    return Scaffold(
      backgroundColor: KrowPalette.blue,
      body: Column(
        children: [
          Expanded(
            child: SafeArea(
              bottom: false,
              child: Padding(
                padding: const EdgeInsets.symmetric(horizontal: 26),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Container(
                      width: 86,
                      height: 86,
                      decoration: const BoxDecoration(
                        color: KrowPalette.yellow,
                        shape: BoxShape.circle,
                      ),
                      child: const Icon(
                        LucideIcons.check,
                        size: 40,
                        color: KrowPalette.ink,
                      ),
                    ),
                    const SizedBox(height: 26),
                    const Text(
                      'Number verified',
                      style: TextStyle(
                        fontSize: 30,
                        fontWeight: FontWeight.w700,
                        letterSpacing: -1,
                        color: Colors.white,
                      ),
                    ),
                    const SizedBox(height: 10),
                    Text(
                      phone,
                      style: const TextStyle(
                        fontSize: 15,
                        fontWeight: FontWeight.w600,
                        color: KrowPalette.yellow,
                      ),
                    ),
                    const SizedBox(height: 14),
                    Text(
                      'Two things left before you can accept shifts.',
                      textAlign: TextAlign.center,
                      style: TextStyle(
                        fontSize: 14,
                        height: 1.55,
                        color: Colors.white.withValues(alpha: 0.62),
                      ),
                    ),
                    const SizedBox(height: 26),
                    const _TodoRow(
                      title: 'Upload your ID',
                      subtitle: 'State ID or passport',
                      badge: '2 min',
                    ),
                    const SizedBox(height: 10),
                    const _TodoRow(
                      title: 'Set your availability',
                      subtitle: 'So we only send shifts you can work',
                      badge: '1 min',
                    ),
                  ],
                ),
              ),
            ),
          ),
          Container(
            width: double.infinity,
            decoration: const BoxDecoration(
              color: KrowPalette.sage,
              borderRadius: BorderRadius.vertical(top: Radius.circular(24)),
            ),
            child: SafeArea(
              top: false,
              child: Padding(
                padding: const EdgeInsets.fromLTRB(20, 22, 20, 16),
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    FilledButton(
                      onPressed: () => context.go('/permissions'),
                      child: const Text('Continue'),
                    ),
                  ],
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class _TodoRow extends StatelessWidget {
  const _TodoRow({
    required this.title,
    required this.subtitle,
    required this.badge,
  });

  final String title;
  final String subtitle;
  final String badge;

  @override
  Widget build(BuildContext context) {
    return Container(
      padding: const EdgeInsets.all(14),
      decoration: BoxDecoration(
        color: Colors.white.withValues(alpha: 0.08),
        borderRadius: BorderRadius.circular(14),
        border: Border.all(color: Colors.white24),
      ),
      child: Row(
        children: [
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  title,
                  style: const TextStyle(
                    fontSize: 16,
                    fontWeight: FontWeight.w700,
                    color: Colors.white,
                  ),
                ),
                const SizedBox(height: 2),
                Text(
                  subtitle,
                  style: TextStyle(
                    fontSize: 12.5,
                    color: Colors.white.withValues(alpha: 0.55),
                  ),
                ),
              ],
            ),
          ),
          StatusChip(badge, tone: ChipTone.yellow),
        ],
      ),
    );
  }
}

class _Permission {
  const _Permission(this.icon, this.step, this.title, this.body, this.reasons);

  final IconData icon;
  final String step;
  final String title;
  final String body;
  final List<String> reasons;
}

/// The three-step permission run. Each grant is recorded in the session so the
/// app knows what it is allowed to do later.
class PermissionsScreen extends ConsumerStatefulWidget {
  const PermissionsScreen({super.key});

  @override
  ConsumerState<PermissionsScreen> createState() => _PermissionsScreenState();
}

class _PermissionsScreenState extends ConsumerState<PermissionsScreen> {
  int _step = 0;

  static const _permissions = [
    _Permission(
      LucideIcons.mapPin,
      'Step 1 of 3',
      'Let KROW see where you are',
      'Clock-in is locked until you are within 150 m of the venue. Without '
          'location you cannot start a shift.',
      [
        'Unlocks clock in when you arrive',
        'Sorts shifts by distance from you',
        'Only read while a shift is active',
      ],
    ),
    _Permission(
      LucideIcons.bell,
      'Step 2 of 3',
      'Turn on notifications',
      'Shift offers are first-come. If your phone is silent someone else takes '
          'the shift.',
      [
        'New shift offers matched to you',
        'Clock-in reminders 30 min before',
        'Pay alerts when money lands',
      ],
    ),
    _Permission(
      LucideIcons.camera,
      'Step 3 of 3',
      'Camera and photos',
      'Attire and document checks need a photo of the real item. Nothing is '
          'uploaded until you tap send.',
      [
        'Photograph your uniform items',
        'Capture ID and certificates',
        'Nothing is stored on our servers unsent',
      ],
    ),
  ];

  void _advance({required bool granted}) {
    final notifier = ref.read(sessionProvider.notifier);
    if (granted) {
      switch (_step) {
        case 0:
          notifier.grantLocation();
        case 1:
          notifier.grantNotifications();
        case 2:
          notifier.grantCamera();
      }
    }
    if (_step == _permissions.length - 1) {
      context.go('/today');
    } else {
      setState(() => _step++);
    }
  }

  @override
  Widget build(BuildContext context) {
    final p = _permissions[_step];
    return Scaffold(
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.fromLTRB(22, 24, 22, 16),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              // The copy scrolls if it has to; the actions stay pinned, so a
              // short screen or a large text scale can never push them off.
              Expanded(
                child: SingleChildScrollView(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Container(
                        width: 60,
                        height: 60,
                        decoration: BoxDecoration(
                          color: KrowPalette.blue,
                          borderRadius: BorderRadius.circular(18),
                        ),
                        child: Icon(p.icon, size: 27, color: Colors.white),
                      ),
                      SectionLabel(p.step),
                      Text(
                        p.title,
                        style: const TextStyle(
                          fontSize: 25,
                          fontWeight: FontWeight.w700,
                          height: 1.15,
                          letterSpacing: -0.9,
                        ),
                      ),
                      const SizedBox(height: 10),
                      Text(
                        p.body,
                        style: const TextStyle(
                          fontSize: 14,
                          height: 1.55,
                          color: KrowPalette.mute,
                        ),
                      ),
                      const SizedBox(height: 18),
                      for (final reason in p.reasons)
                        Padding(
                          padding: const EdgeInsets.only(bottom: 12),
                          child: Row(
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: [
                              Container(
                                width: 20,
                                height: 20,
                                // Nudged to sit on the first line's optical
                                // centre, so wrapped reasons stay top-aligned.
                                margin: const EdgeInsets.only(top: 1),
                                decoration: BoxDecoration(
                                  color: KrowPalette.blueTint,
                                  borderRadius: BorderRadius.circular(7),
                                ),
                                child: const Icon(
                                  LucideIcons.check,
                                  size: 12,
                                  color: KrowPalette.blue,
                                ),
                              ),
                              const SizedBox(width: 11),
                              Expanded(
                                child: Text(
                                  reason,
                                  style: const TextStyle(
                                    fontSize: 13,
                                    height: 1.45,
                                    color: KrowPalette.mute,
                                  ),
                                ),
                              ),
                            ],
                          ),
                        ),
                    ],
                  ),
                ),
              ),
              const SizedBox(height: 16),
              FilledButton(
                onPressed: () => _advance(granted: true),
                child: Text(switch (_step) {
                  0 => 'Allow location',
                  1 => 'Turn on notifications',
                  _ => 'Allow camera',
                }),
              ),
              const SizedBox(height: 4),
              // Full width so the secondary action shares the primary's edges
              // rather than hugging the left.
              TextButton(
                onPressed: () => _advance(granted: false),
                style: TextButton.styleFrom(
                  minimumSize: const Size.fromHeight(44),
                ),
                child: const Text('Not now'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}