import 'dart:async';

import 'package:easy_localization/easy_localization.dart';
import 'package:flutter/material.dart';
import 'package:mohem_flutter_app/api/offers_and_discounts_api_client.dart';
import 'package:mohem_flutter_app/app_state/app_state.dart';
import 'package:mohem_flutter_app/classes/colors.dart';
import 'package:mohem_flutter_app/classes/consts.dart';
import 'package:mohem_flutter_app/classes/utils.dart';
import 'package:mohem_flutter_app/config/routes.dart';
import 'package:mohem_flutter_app/extensions/string_extensions.dart';
import 'package:mohem_flutter_app/generated/locale_keys.g.dart';
import 'package:mohem_flutter_app/models/generic_response_model.dart';
import 'package:mohem_flutter_app/models/offers_and_discounts/wala_plus_retailer_model.dart';
import 'package:mohem_flutter_app/ui/mazaya/widgets/mazaya_bottom_nav.dart';
import 'package:mohem_flutter_app/ui/mazaya/widgets/wala_plus_retailer_grid.dart';
import 'package:mohem_flutter_app/widgets/app_bar_widget.dart';

// Mazaya Saved tab - full-screen version of what was FavoriteMerchantsBottomSheet (a modal
// bottom sheet). Same fetch/search/pagination/toggle-favorite logic, now its own pushed route
// with the shared MazayaBottomNav instead of a dismissible sheet - matches Discover's "own
// route, fetches fresh on mount" pattern.
class SavedRetailersScreen extends StatefulWidget {
  const SavedRetailersScreen({Key? key}) : super(key: key);

  @override
  State<SavedRetailersScreen> createState() => _SavedRetailersScreenState();
}

class _SavedRetailersScreenState extends State<SavedRetailersScreen> {
  List<WalaPlusRetailerModel> favoriteRetailers = <WalaPlusRetailerModel>[];
  bool isLoading = true;
  bool isLoadingMore = false;
  bool hasMore = true;
  bool _isFetchingPage = false;
  int currentPage = 1;
  int totalPages = 1;
  final int pageSize = 10;
  String searchQuery = "";
  Timer? _debounceTimer;
  final TextEditingController _searchController = TextEditingController();
  final ScrollController _scrollController = ScrollController();

  @override
  void initState() {
    super.initState();
    _scrollController.addListener(_scrollListener);
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (mounted) fetchFavorites();
    });
  }

  @override
  void dispose() {
    _debounceTimer?.cancel();
    _scrollController.removeListener(_scrollListener);
    _scrollController.dispose();
    _searchController.dispose();
    super.dispose();
  }

  void _scrollListener() {
    if (!_scrollController.hasClients) return;
    double maxScroll = _scrollController.position.maxScrollExtent;
    double currentScroll = _scrollController.position.pixels;
    if (currentScroll >= maxScroll - 35) {
      if (!isLoading && !isLoadingMore && !_isFetchingPage && hasMore) {
        fetchNextPage();
      }
    }
  }

  String? _getUserReferenceForFavorites() {
    String ref = OffersAndDiscountsApiClient().resolveUserReference();
    if (ref.trim().isNotEmpty) return ref.trim();
    String? userName = AppState().getUserName;
    if (userName != null && userName.trim().isNotEmpty) return userName.trim();
    return null;
  }

  Future<void> fetchFavorites({String? query}) async {
    if (query != null) searchQuery = query;
    setState(() {
      isLoading = true;
      currentPage = 1;
      hasMore = true;
    });
    try {
      String? queryParam =
          searchQuery.trim().isNotEmpty ? searchQuery.trim() : null;
      String? userRef = _getUserReferenceForFavorites();
      WalaPlusRetailersResponse? response = await OffersAndDiscountsApiClient()
          .getWalaPlusRetailers(
            categoryId: "",
            page: 1,
            perPage: pageSize,
            offerType: null,
            query: queryParam,
            sortBy: null,
            radius: null,
            minDiscount: null,
            context: null,
            userReference: userRef,
          );
      favoriteRetailers = response?.retailers ?? <WalaPlusRetailerModel>[];
      for (WalaPlusRetailerModel r in favoriteRetailers) {
        r.isFavorite = true;
      }
      currentPage = 1;
      totalPages = response?.pagesCount ?? 1;
      hasMore =
          currentPage < totalPages &&
          (response?.retailers?.isNotEmpty ?? false);
    } catch (e) {
      debugPrint("MazayaSavedScreen: error fetching favorites: $e");
      favoriteRetailers = <WalaPlusRetailerModel>[];
    } finally {
      if (mounted) setState(() => isLoading = false);
    }
  }

  Future<void> fetchNextPage() async {
    if (isLoading || isLoadingMore || _isFetchingPage || !hasMore) return;
    _isFetchingPage = true;
    setState(() => isLoadingMore = true);
    try {
      int nextPage = currentPage + 1;
      String? queryParam =
          searchQuery.trim().isNotEmpty ? searchQuery.trim() : null;
      String? userRef = _getUserReferenceForFavorites();
      WalaPlusRetailersResponse? response = await OffersAndDiscountsApiClient()
          .getWalaPlusRetailers(
            categoryId: "",
            page: nextPage,
            perPage: pageSize,
            offerType: null,
            query: queryParam,
            sortBy: null,
            radius: null,
            minDiscount: null,
            context: null,
            userReference: userRef,
          );
      List<WalaPlusRetailerModel> newRetailers =
          response?.retailers ?? <WalaPlusRetailerModel>[];
      if (newRetailers.isNotEmpty) {
        for (WalaPlusRetailerModel r in newRetailers) {
          r.isFavorite = true;
        }
        currentPage = nextPage;
        totalPages = response?.pagesCount ?? totalPages;
        hasMore = currentPage < totalPages;
        favoriteRetailers.addAll(newRetailers);
      } else {
        hasMore = false;
      }
    } catch (e) {
      debugPrint("MazayaSavedScreen: error fetching next page: $e");
    } finally {
      _isFetchingPage = false;
      if (mounted) setState(() => isLoadingMore = false);
    }
  }

  void _onSearchChanged(String query) {
    _debounceTimer?.cancel();
    searchQuery = query;
    if (query.trim().isEmpty) {
      fetchFavorites(query: "");
    } else {
      _debounceTimer = Timer(const Duration(milliseconds: 600), () {
        fetchFavorites(query: query.trim());
      });
    }
  }

  Future<void> _toggleFavorite(WalaPlusRetailerModel item) async {
    String retailerId = item.id ?? "";
    if (retailerId.isEmpty) return;

    bool currentFav = item.isFavorite ?? true;
    bool targetFav = !currentFav;

    setState(() {
      item.isFavorite = targetFav;
      if (!targetFav) {
        favoriteRetailers.removeWhere(
          (WalaPlusRetailerModel r) => r.id == item.id,
        );
      }
    });
    Utils.showLoading(context);

    try {
      GenericResponseModel? response;
      String? userRef = _getUserReferenceForFavorites();
      if (targetFav) {
        response = await OffersAndDiscountsApiClient().addWalaPlusFavorite(
          retailerId: retailerId,
          context: context,
          userReference: userRef,
        );
      } else {
        response = await OffersAndDiscountsApiClient().removeWalaPlusFavorite(
          retailerId: retailerId,
          context: context,
          userReference: userRef,
        );
      }

      Utils.hideLoading(context);

      if (response != null && response.errorMessage == null) {
        bool isAr = AppState().isArabic(context);
        String msg =
            isAr
                ? (targetFav
                    ? LocaleKeys.favoriteAddedSuccess.tr()
                    : LocaleKeys.favoriteRemovedSuccess.tr())
                : (response.wpFavoritesAddRemoveMessage ??
                    (targetFav
                        ? LocaleKeys.favoriteAddedSuccess.tr()
                        : LocaleKeys.favoriteRemovedSuccess.tr()));
        Utils.showToast(msg, isSuccess: true);
      } else {
        Utils.showToast(
          response?.errorEndUserMessage ??
              response?.errorMessage ??
              LocaleKeys.favoriteError.tr(),
        );
        await fetchFavorites(query: _searchController.text);
      }
    } catch (e) {
      Utils.hideLoading(context);
      debugPrint("MazayaSavedScreen: error toggling favorite: $e");
      Utils.showToast(LocaleKeys.favoriteError.tr());
      await fetchFavorites(query: _searchController.text);
    }
  }

  void _openRetailer(WalaPlusRetailerModel item) async {
    await Navigator.pushNamed(
      context,
      AppRoutes.retailerDetailsScreen,
      arguments: item,
    );
    if (mounted) {
      await fetchFavorites(query: _searchController.text);
    }
  }

  @override
  Widget build(BuildContext context) {
    bool isAr = AppState().isArabic(context);
    return Scaffold(
      backgroundColor: Colors.white,
      appBar: AppBarWidget(
        context,
        title: LocaleKeys.favoriteOffers.tr(),
        showHomeButton: false,
        // Reached from the Mazaya bottom nav - same as Discover, no back button for a
        // dependent-login session since this is one of their root tabs, not a pushed screen.
        showBackButton: false,
      ),
      bottomNavigationBar: const MazayaBottomNav(currentTab: MazayaTab.saved),
      body: Column(
        children: <Widget>[
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
            child: Container(
              width: double.infinity,
              height: 70,
              padding: const EdgeInsets.only(
                top: 14,
                right: 16,
                bottom: 14,
                left: 16,
              ),
              decoration: BoxDecoration(
                color: Colors.white,
                borderRadius: BorderRadius.circular(16),
                border: Border.all(color: const Color(0xFFE8E8E8), width: 1.0),
                boxShadow: <BoxShadow>[
                  BoxShadow(
                    color: const Color(0xFF000000).withOpacity(0.0314),
                    offset: const Offset(0, 2),
                    blurRadius: 5,
                    spreadRadius: 0,
                  ),
                ],
              ),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  LocaleKeys.search.tr().toText12(
                    isBold: true,
                    color: const Color(0xFF2A333C),
                  ),
                  const SizedBox(height: 2),
                  TextField(
                    controller: _searchController,
                    onChanged: _onSearchChanged,
                    onSubmitted: (String val) {
                      _debounceTimer?.cancel();
                      fetchFavorites(query: val.trim());
                    },
                    textInputAction: TextInputAction.search,
                    decoration: InputDecoration(
                      isDense: true,
                      contentPadding: EdgeInsets.zero,
                      hintText: LocaleKeys.searchItems.tr(),
                      hintStyle: const TextStyle(
                        color: Color(0xFFACAFB1),
                        fontSize: 14,
                        fontWeight: FontWeight.w400,
                        height: 1.2,
                      ),
                      border: InputBorder.none,
                      suffixIcon: ValueListenableBuilder<TextEditingValue>(
                        valueListenable: _searchController,
                        builder: (
                          BuildContext context,
                          TextEditingValue value,
                          Widget? child,
                        ) {
                          if (value.text.isEmpty)
                            return const SizedBox.shrink();
                          return InkWell(
                            child: const Icon(
                              Icons.clear,
                              size: 18,
                              color: Color(0xFF848486),
                            ),
                            onTap: () {
                              _searchController.clear();
                              _onSearchChanged("");
                            },
                          );
                        },
                      ),
                      suffixIconConstraints: const BoxConstraints(
                        maxWidth: 24,
                        maxHeight: 28,
                      ),
                    ),
                    style: const TextStyle(
                      color: Color(0xFF2A333C),
                      fontSize: 14,
                      fontWeight: FontWeight.w400,
                    ),
                  ),
                ],
              ),
            ),
          ),
          Expanded(
            child: RefreshIndicator(
              onRefresh: () => fetchFavorites(query: _searchController.text),
              color: MyColors.textMixColor,
              child: SingleChildScrollView(
                controller: _scrollController,
                physics: const AlwaysScrollableScrollPhysics(
                  parent: BouncingScrollPhysics(),
                ),
                padding: const EdgeInsets.symmetric(
                  horizontal: 16,
                  vertical: 8,
                ),
                child: Column(
                  children: <Widget>[
                    WalaPlusRetailerGrid(
                      isLoading: isLoading,
                      retailers: favoriteRetailers,
                      isAr: isAr,
                      isLoadingMore: isLoadingMore,
                      onTapRetailer: _openRetailer,
                      onFavoriteTap: _toggleFavorite,
                    ),
                    const SizedBox(height: 20),
                  ],
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}