import 'package:auto_route/auto_route.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_spinkit/flutter_spinkit.dart';

import '../../../application/voucher/voucher_loader/voucher_loader_bloc.dart';
import '../../../application/voucher/voucher_redemption_loader/voucher_redemption_loader_bloc.dart';
import '../../../application/wallet/wallet_loader/wallet_loader_bloc.dart';
import '../../../common/extension/extension.dart';
import '../../../common/theme/theme.dart';
import '../../../domain/wallet/wallet.dart';
import '../../../injection.dart';
import '../../components/button/button.dart';
import '../../components/toast/flushbar.dart';
import '../../router/app_router.gr.dart';
import '../wallet/wallet_ui.dart';
import 'widgets/redemption_card.dart';
import 'widgets/redemption_detail_sheet.dart';
import 'widgets/voucher_card.dart';

/// EnakReward: tukar EnakPoint ke voucher (§9.1) dan "Voucher saya" (§9.3).
@RoutePage()
class RewardPage extends StatefulWidget implements AutoRouteWrapper {
  const RewardPage({super.key});

  @override
  State<RewardPage> createState() => _RewardPageState();

  @override
  Widget wrappedRoute(BuildContext context) => MultiBlocProvider(
    providers: [
      BlocProvider(
        create: (_) =>
            getIt<VoucherLoaderBloc>()..add(const VoucherLoaderEvent.fetched()),
      ),
      BlocProvider(
        create: (_) =>
            getIt<VoucherRedemptionLoaderBloc>()
              ..add(const VoucherRedemptionLoaderEvent.refreshed()),
      ),
    ],
    child: this,
  );
}

class _RewardPageState extends State<RewardPage>
    with SingleTickerProviderStateMixin {
  late final TabController _tabController = TabController(
    length: 2,
    vsync: this,
  );

  @override
  void initState() {
    super.initState();
    // Tombol Tukar nonaktif bila saldo EnakPoint kurang.
    context.read<WalletLoaderBloc>().add(const WalletLoaderEvent.fetched());
  }

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

  /// Katalog, voucher saya, dan saldo dimuat ulang setiap kembali dari detail:
  /// stok bisa berubah, dan voucher yang habis harus hilang dari katalog.
  Future<void> _openDetail(Voucher voucher) async {
    final redeemed = await context.router.push<bool>(
      RewardDetailRoute(voucher: voucher),
    );
    if (!mounted) return;

    context.read<VoucherLoaderBloc>().add(const VoucherLoaderEvent.fetched());
    context.read<VoucherRedemptionLoaderBloc>().add(
      const VoucherRedemptionLoaderEvent.refreshed(),
    );
    context.read<WalletLoaderBloc>().add(const WalletLoaderEvent.fetched());
    if (redeemed == true) _tabController.animateTo(1);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppColor.background,
      appBar: AppBar(
        title: const Text('EnakReward'),
        bottom: TabBar(
          controller: _tabController,
          tabs: const [
            Tab(text: 'Tukar voucher'),
            Tab(text: 'Voucher saya'),
          ],
        ),
      ),
      body: TabBarView(
        controller: _tabController,
        children: [
          _CatalogTab(onOpen: _openDetail),
          _RedemptionTab(onBrowse: () => _tabController.animateTo(0)),
        ],
      ),
    );
  }
}

class _CatalogTab extends StatelessWidget {
  const _CatalogTab({required this.onOpen});

  final ValueChanged<Voucher> onOpen;

  Future<void> _onRefresh(BuildContext context) async {
    context.read<WalletLoaderBloc>().add(const WalletLoaderEvent.fetched());
    final bloc = context.read<VoucherLoaderBloc>();
    bloc.add(const VoucherLoaderEvent.fetched());
    await bloc.stream.firstWhere((s) => !s.isFetching);
  }

  @override
  Widget build(BuildContext context) {
    return BlocBuilder<VoucherLoaderBloc, VoucherLoaderState>(
      builder: (context, state) {
        if (!state.hasLoaded) {
          return state.failureOption.fold(
            () => const Center(
              child: SpinKitFadingCircle(color: AppColor.primary, size: 36),
            ),
            (f) => _ErrorView(
              message: walletFailureMessage(f),
              onRetry: () => context.read<VoucherLoaderBloc>().add(
                const VoucherLoaderEvent.fetched(),
              ),
            ),
          );
        }

        return BlocBuilder<WalletLoaderBloc, WalletLoaderState>(
          builder: (context, walletState) => RefreshIndicator(
            color: AppColor.primary,
            onRefresh: () => _onRefresh(context),
            child: ListView(
              padding: const EdgeInsets.fromLTRB(16, 16, 16, 32),
              children: [
                _PointBalanceCard(walletState: walletState),
                const SizedBox(height: 16),
                if (state.vouchers.isEmpty)
                  const _EmptyView(
                    icon: Icons.confirmation_number_outlined,
                    message: 'Belum ada voucher yang bisa ditukar',
                  )
                else
                  ...state.vouchers.map(
                    (voucher) => Padding(
                      padding: const EdgeInsets.only(bottom: 12),
                      child: VoucherCard(
                        voucher: voucher,
                        canAfford:
                            !walletState.hasLoaded ||
                            walletState.summary.pointBalance >=
                                voucher.pointCost,
                        onTap: () => onOpen(voucher),
                      ),
                    ),
                  ),
              ],
            ),
          ),
        );
      },
    );
  }
}

class _RedemptionTab extends StatelessWidget {
  const _RedemptionTab({required this.onBrowse});

  final VoidCallback onBrowse;

  Future<void> _onRefresh(BuildContext context) async {
    final bloc = context.read<VoucherRedemptionLoaderBloc>();
    bloc.add(const VoucherRedemptionLoaderEvent.refreshed());
    await bloc.stream.firstWhere((s) => !s.isFetching);
  }

  @override
  Widget build(BuildContext context) {
    return BlocConsumer<
      VoucherRedemptionLoaderBloc,
      VoucherRedemptionLoaderState
    >(
      listenWhen: (p, c) =>
          p.failureOption != c.failureOption && c.items.isNotEmpty,
      listener: (context, state) => state.failureOption.fold(
        () {},
        (f) => AppFlushbar.showError(context, walletFailureMessage(f)),
      ),
      builder: (context, state) {
        if (!state.hasLoaded) {
          return state.failureOption.fold(
            () => const Center(
              child: SpinKitFadingCircle(color: AppColor.primary, size: 36),
            ),
            (f) => _ErrorView(
              message: walletFailureMessage(f),
              onRetry: () => context.read<VoucherRedemptionLoaderBloc>().add(
                const VoucherRedemptionLoaderEvent.refreshed(),
              ),
            ),
          );
        }

        return RefreshIndicator(
          color: AppColor.primary,
          onRefresh: () => _onRefresh(context),
          child: NotificationListener<ScrollNotification>(
            onNotification: (notification) {
              final metrics = notification.metrics;
              if (metrics.pixels >= metrics.maxScrollExtent - 200) {
                context.read<VoucherRedemptionLoaderBloc>().add(
                  const VoucherRedemptionLoaderEvent.loadedMore(),
                );
              }
              return false;
            },
            child: state.items.isEmpty
                ? ListView(
                    padding: const EdgeInsets.all(16),
                    children: [
                      _EmptyView(
                        icon: Icons.local_activity_outlined,
                        message: 'Belum ada voucher',
                        actionLabel: 'Tukar EnakPoint sekarang',
                        onAction: onBrowse,
                      ),
                    ],
                  )
                : ListView.separated(
                    padding: const EdgeInsets.fromLTRB(16, 16, 16, 32),
                    itemCount: state.items.length + (state.hasMore ? 1 : 0),
                    separatorBuilder: (_, _) => const SizedBox(height: 12),
                    itemBuilder: (context, index) {
                      if (index >= state.items.length) {
                        return const Padding(
                          padding: EdgeInsets.all(16),
                          child: Center(
                            child: SpinKitFadingCircle(
                              color: AppColor.primary,
                              size: 24,
                            ),
                          ),
                        );
                      }
                      final redemption = state.items[index];
                      return RedemptionCard(
                        redemption: redemption,
                        onTap: () =>
                            RedemptionDetailSheet.show(context, redemption),
                      );
                    },
                  ),
          ),
        );
      },
    );
  }
}

/// Saldo EnakPoint, selalu "setara potongan", tidak pernah "saldo Rp".
class _PointBalanceCard extends StatelessWidget {
  const _PointBalanceCard({required this.walletState});

  final WalletLoaderState walletState;

  @override
  Widget build(BuildContext context) {
    final summary = walletState.summary;

    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        gradient: const LinearGradient(
          colors: AppColor.primaryGradient,
          begin: Alignment.topLeft,
          end: Alignment.bottomRight,
        ),
        borderRadius: BorderRadius.circular(16),
      ),
      child: Row(
        children: [
          Container(
            width: 44,
            height: 44,
            padding: const EdgeInsets.all(6),
            decoration: const BoxDecoration(
              color: AppColor.white,
              shape: BoxShape.circle,
            ),
            child: const WalletCurrencyIcon(
              currency: WalletCurrency.point,
              size: 32,
            ),
          ),
          const SizedBox(width: 12),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  'EnakPoint kamu',
                  style: AppStyle.sm.copyWith(
                    color: AppColor.textWhite.withOpacity(0.9),
                  ),
                ),
                Text(
                  walletState.hasLoaded
                      ? summary.pointBalance.thousandFormat
                      : '…',
                  style: AppStyle.h5.copyWith(
                    color: AppColor.textWhite,
                    fontWeight: FontWeight.w700,
                  ),
                ),
                if (walletState.hasLoaded)
                  Text(
                    pointDiscountLabel(summary.pointDiscountValue),
                    style: AppStyle.xs.copyWith(
                      color: AppColor.textWhite.withOpacity(0.9),
                    ),
                  ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

class _EmptyView extends StatelessWidget {
  const _EmptyView({
    required this.icon,
    required this.message,
    this.actionLabel,
    this.onAction,
  });

  final IconData icon;
  final String message;
  final String? actionLabel;
  final VoidCallback? onAction;

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(top: 48),
      child: Column(
        children: [
          Icon(icon, size: 56, color: AppColor.textLight),
          const SizedBox(height: 12),
          Text(
            message,
            textAlign: TextAlign.center,
            style: AppStyle.md.copyWith(color: AppColor.textSecondary),
          ),
          if (actionLabel != null) ...[
            const SizedBox(height: 16),
            AppOutlineButton(
              title: actionLabel!,
              width: 220,
              onPressed: onAction,
            ),
          ],
        ],
      ),
    );
  }
}

class _ErrorView extends StatelessWidget {
  const _ErrorView({required this.message, required this.onRetry});

  final String message;
  final VoidCallback onRetry;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(24),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(message, style: AppStyle.md, textAlign: TextAlign.center),
            const SizedBox(height: 16),
            AppOutlineButton(
              title: 'Coba lagi',
              width: 160,
              onPressed: onRetry,
            ),
          ],
        ),
      ),
    );
  }
}