import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import '../../../core/api/api_client_provider.dart';
import '../../../core/constants.dart';
import '../../../core/theme/halo_tokens.dart';
import '../../../core/theme/widgets/halo_button.dart';
import '../state/payment_draft_provider.dart';

/// "Cara bayar" — QRIS-first list of payment methods. On tap of `bayar`:
/// 1. POST `/api/client/payment-sessions` with the draft + chosen method.
/// 2. Push `/payment/waiting/:paymentId`.
class PaymentMethodScreen extends ConsumerStatefulWidget {
  const PaymentMethodScreen({super.key});

  @override
  ConsumerState<PaymentMethodScreen> createState() => _PaymentMethodScreenState();
}

enum _PayMethod {
  qris('qris', 'QRIS', 'semua e-wallet & m-banking', '🔲', recommended: true),
  ovo('ovo', 'OVO', 'saldo OVO', '🟣'),
  gopay('gopay', 'GoPay', 'saldo GoPay', '🟢'),
  dana('dana', 'DANA', 'saldo DANA', '🔵'),
  shopee('shopee', 'ShopeePay', 'saldo ShopeePay', '🟠');

  final String id;
  final String label;
  final String sub;
  final String icon;
  final bool recommended;

  const _PayMethod(
    this.id,
    this.label,
    this.sub,
    this.icon, {
    this.recommended = false,
  });
}

class _PaymentMethodScreenState extends ConsumerState<PaymentMethodScreen> {
  _PayMethod _selected = _PayMethod.qris;
  bool _submitting = false;
  String? _error;

  Future<void> _onPay() async {
    if (_submitting) return;
    final draft = ref.read(paymentDraftNotifierProvider);
    if (draft.durationMinutes == null || draft.priceIDR == null) {
      setState(() => _error = 'Pilih durasi dulu sebelum bayar.');
      return;
    }
    setState(() {
      _submitting = true;
      _error = null;
    });
    final api = ref.read(apiClientProvider);
    try {
      final body = <String, dynamic>{
        'mode': draft.mode.value,
        'duration_minutes': draft.durationMinutes,
        'price_idr': draft.priceIDR,
        'is_first_session_discount': draft.isFirstSessionDiscount,
        'method': _selected.id,
      };
      // Trailing slash matches the existing payment_notifier path — Fastify
      // is not configured with `ignoreTrailingSlash`.
      final response = await api.post('/api/client/payment-sessions/', data: body);
      final data = response['data'] as Map<String, dynamic>;
      final paymentId = data['id'] as String;
      ref.read(paymentDraftNotifierProvider.notifier).setPaymentId(paymentId);
      if (!mounted) return;
      context.push('/payment/waiting/$paymentId');
    } on DioException catch (e) {
      if (!mounted) return;
      setState(() {
        _submitting = false;
        _error = _humanError(e);
      });
    } catch (_) {
      if (!mounted) return;
      setState(() {
        _submitting = false;
        _error = 'Gagal membuat sesi pembayaran.';
      });
    }
  }

  String _humanError(DioException e) {
    final code = e.response?.data?['error']?['code'] as String?;
    final status = e.response?.statusCode;
    if (status == 422 || code == 'VALIDATION_ERROR' || code == 'INVALID_TIER') {
      return 'Pilihan durasi tidak valid.';
    }
    if (status == 403) return 'Sesi tidak diizinkan.';
    if (status == 404) return 'Sesi pembayaran tidak ditemukan.';
    return 'Gagal membuat sesi pembayaran.';
  }

  @override
  Widget build(BuildContext context) {
    final draft = ref.watch(paymentDraftNotifierProvider);
    final amount = draft.priceIDR ?? 0;
    final durationLabel = draft.durationMinutes != null
        ? 'sesi ${draft.durationMinutes} menit'
        : 'sesi';
    final amountLabel = formatRupiah(amount);
    final recommended = _PayMethod.values.where((m) => m.recommended).toList();
    final others = _PayMethod.values.where((m) => !m.recommended).toList();

    return Scaffold(
      backgroundColor: HaloTokens.bg,
      appBar: AppBar(
        backgroundColor: HaloTokens.bg,
        elevation: 0,
        leading: IconButton(
          icon: const Icon(Icons.chevron_left, color: HaloTokens.brandDark),
          onPressed: () {
            if (context.canPop()) {
              context.pop();
            } else {
              context.go('/payment/duration-pick');
            }
          },
        ),
        title: const Text(
          'cara bayar',
          style: TextStyle(
            fontFamily: HaloTokens.fontDisplay,
            fontSize: 18,
            fontWeight: FontWeight.w700,
            color: HaloTokens.brandDark,
          ),
        ),
        centerTitle: false,
      ),
      body: Column(
        children: [
          Padding(
            padding: const EdgeInsets.fromLTRB(
              HaloSpacing.s24,
              HaloSpacing.s4,
              HaloSpacing.s24,
              HaloSpacing.s12,
            ),
            child: Container(
              padding: const EdgeInsets.all(HaloSpacing.s12),
              decoration: BoxDecoration(
                color: HaloTokens.surface,
                borderRadius: HaloRadius.lg,
                border: Border.all(color: HaloTokens.border),
              ),
              child: Row(
                children: [
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        const Text(
                          'total bayar',
                          style: TextStyle(fontSize: 11.5, color: HaloTokens.inkSoft),
                        ),
                        Text(
                          durationLabel,
                          style: const TextStyle(fontSize: 11, color: HaloTokens.inkMuted),
                        ),
                      ],
                    ),
                  ),
                  Text(
                    amountLabel,
                    style: const TextStyle(
                      fontFamily: HaloTokens.fontDisplay,
                      fontSize: 22,
                      fontWeight: FontWeight.w700,
                      color: HaloTokens.brandDark,
                      letterSpacing: -0.5,
                    ),
                  ),
                ],
              ),
            ),
          ),
          Expanded(
            child: ListView(
              padding: const EdgeInsets.fromLTRB(
                HaloSpacing.s20,
                HaloSpacing.s8,
                HaloSpacing.s20,
                HaloSpacing.s16,
              ),
              children: [
                const _SectionLabel('paling cepat'),
                ...recommended.map((m) => _MethodTile(
                      method: m,
                      selected: _selected == m,
                      onTap: () => setState(() => _selected = m),
                      large: true,
                    )),
                const SizedBox(height: HaloSpacing.s8),
                const _SectionLabel('e-wallet lain'),
                ...others.map((m) => _MethodTile(
                      method: m,
                      selected: _selected == m,
                      onTap: () => setState(() => _selected = m),
                    )),
              ],
            ),
          ),
          if (_error != null)
            Container(
              margin: const EdgeInsets.fromLTRB(
                HaloSpacing.s24,
                0,
                HaloSpacing.s24,
                HaloSpacing.s8,
              ),
              padding: const EdgeInsets.all(HaloSpacing.s12),
              decoration: BoxDecoration(
                color: const Color(0xFFFFEBEB),
                borderRadius: HaloRadius.md,
                border: Border.all(color: HaloTokens.danger),
              ),
              child: Row(
                children: [
                  const Icon(Icons.error_outline, color: HaloTokens.danger, size: 18),
                  const SizedBox(width: HaloSpacing.s8),
                  Expanded(
                    child: Text(
                      _error!,
                      style: const TextStyle(color: HaloTokens.danger, fontSize: 13),
                    ),
                  ),
                ],
              ),
            ),
          Container(
            padding: const EdgeInsets.fromLTRB(
              HaloSpacing.s24,
              HaloSpacing.s12,
              HaloSpacing.s24,
              HaloSpacing.s32,
            ),
            decoration: const BoxDecoration(
              color: HaloTokens.bg,
              border: Border(top: BorderSide(color: HaloTokens.border)),
            ),
            child: HaloButton(
              label: _submitting ? 'memproses...' : 'bayar $amountLabel',
              size: HaloButtonSize.lg,
              fullWidth: true,
              onPressed: _submitting ? null : _onPay,
            ),
          ),
        ],
      ),
    );
  }
}

class _SectionLabel extends StatelessWidget {
  final String label;
  const _SectionLabel(this.label);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.fromLTRB(4, HaloSpacing.s8, 4, HaloSpacing.s8),
      child: Text(
        label,
        style: const TextStyle(
          fontSize: 11,
          fontWeight: FontWeight.w600,
          color: HaloTokens.inkSoft,
          letterSpacing: 0.6,
        ),
      ),
    );
  }
}

class _MethodTile extends StatelessWidget {
  final _PayMethod method;
  final bool selected;
  final VoidCallback onTap;
  final bool large;

  const _MethodTile({
    required this.method,
    required this.selected,
    required this.onTap,
    this.large = false,
  });

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(bottom: HaloSpacing.s8),
      child: Material(
        color: selected ? HaloTokens.brandSofter : HaloTokens.surface,
        borderRadius: HaloRadius.lg,
        child: InkWell(
          borderRadius: HaloRadius.lg,
          onTap: onTap,
          child: AnimatedContainer(
            duration: HaloMotion.fast,
            padding: EdgeInsets.all(large ? HaloSpacing.s16 : HaloSpacing.s12),
            decoration: BoxDecoration(
              border: Border.all(
                color: selected ? HaloTokens.brand : HaloTokens.border,
                width: selected ? 2 : 1,
              ),
              borderRadius: HaloRadius.lg,
            ),
            child: Row(
              children: [
                Container(
                  width: large ? 40 : 36,
                  height: large ? 40 : 36,
                  decoration: BoxDecoration(
                    color: HaloTokens.surface,
                    borderRadius: HaloRadius.md,
                    border: Border.all(color: HaloTokens.border),
                  ),
                  alignment: Alignment.center,
                  child: Text(method.icon, style: TextStyle(fontSize: large ? 20 : 18)),
                ),
                const SizedBox(width: HaloSpacing.s12),
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Row(
                        children: [
                          Text(
                            method.label,
                            style: TextStyle(
                              fontSize: large ? 14.5 : 13.5,
                              fontWeight: FontWeight.w600,
                              color: HaloTokens.ink,
                            ),
                          ),
                          if (method.recommended) ...[
                            const SizedBox(width: HaloSpacing.s8),
                            Container(
                              padding: const EdgeInsets.symmetric(
                                horizontal: HaloSpacing.s8,
                                vertical: 2,
                              ),
                              decoration: const BoxDecoration(
                                color: HaloTokens.mint,
                                borderRadius: HaloRadius.pill,
                              ),
                              child: const Text(
                                'DIREKOMENDASIKAN',
                                style: TextStyle(
                                  fontSize: 9,
                                  fontWeight: FontWeight.w700,
                                  color: Color(0xFF1F4D34),
                                  letterSpacing: 0.4,
                                ),
                              ),
                            ),
                          ],
                        ],
                      ),
                      const SizedBox(height: 2),
                      Text(
                        method.sub,
                        style: TextStyle(
                          fontSize: large ? 11.5 : 11,
                          color: HaloTokens.inkSoft,
                        ),
                      ),
                    ],
                  ),
                ),
                Container(
                  width: large ? 20 : 18,
                  height: large ? 20 : 18,
                  decoration: BoxDecoration(
                    shape: BoxShape.circle,
                    border: Border.all(
                      color: selected ? HaloTokens.brand : HaloTokens.border,
                      width: 2,
                    ),
                    color: selected ? HaloTokens.brand : HaloTokens.surface,
                  ),
                  child: selected
                      ? Center(
                          child: Container(
                            width: large ? 8 : 6,
                            height: large ? 8 : 6,
                            decoration: const BoxDecoration(
                              shape: BoxShape.circle,
                              color: Colors.white,
                            ),
                          ),
                        )
                      : null,
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}