import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:outbag_app/backend/permissions.dart';
import 'package:outbag_app/backend/request.dart';
import 'package:outbag_app/backend/room.dart';
import 'package:outbag_app/backend/user.dart';
import 'package:outbag_app/components/category_chip.dart';
import 'package:outbag_app/components/category_picker.dart';
import 'package:outbag_app/components/labeled_divider.dart';
import 'package:outbag_app/components/product_picker.dart';
import 'package:outbag_app/tools/fetch_wrapper.dart';
import 'package:provider/provider.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';

class ShoppingListPage extends StatefulWidget {
  final RoomInfo? info;
  final Room? room;

  const ShoppingListPage(this.room, this.info, {super.key});

  @override
  State<StatefulWidget> createState() => _ShoppingListPageState();
}

class _ShoppingListPageState extends State<ShoppingListPage> {
  List<RoomItem> list = [];
  List<RoomItem> cart = [];
  Map<int, int> weights = {};
  List<RoomCategory> categories = [];
  List<RoomProduct> products = [];

  void fetchItems() {
    final user = context.read<User>();

    // TODO: load cached items first

    doNetworkRequest(ScaffoldMessenger.of(context),
      req: () => postWithCreadentials(
        credentials: user,
        target: user.server,
        path: 'getItems',
        body: {'room': widget.room?.id, 'server': widget.room?.serverTag}),
      onOK: (body) async {
        final resp = body['data']
        .map<RoomItem>((raw) => RoomItem.fromJSON(raw))
        .toList();

        final List<RoomItem> l = [];
        final List<RoomItem> c = [];

        for (RoomItem item in resp) {
          if (item.state == 0) {
            l.add(item);
          } else {
            c.add(item);
          }
        }

        // TODO: cache items

        setState(() {
            list = l;
            cart = c;

            sortAll();
        });
    });
  }

  void sortAll() {
    for (List<RoomItem> input in [list, cart]) {
      setState(() {
          input.sort((a, b) {
              if (a.category == b.category) {
                return 0;
              }
              if (a.category == null) {
                // b should be below
                return -1;
              }
              if (b.category == null) {
                // a should be below
                return 1;
              }

              final weightA = weights[a.category];
              final weightB = weights[b.category];
              // both could be null now,
              // so we have to check agein
              if (weightA == weightB) {
                return 0;
              }
              if (weightA == null) {
                // b should be below
                return -1;
              }
              if (weightB == null) {
                // a should be below
                return 1;
              }

              return weightA.compareTo(weightB);
          });
      });
    }
  }

  void fetchCategories() {
    final user = context.read<User>();

    // TODO: load cached categories first

    doNetworkRequest(ScaffoldMessenger.of(context),
      req: () => postWithCreadentials(
        credentials: user,
        target: user.server,
        path: 'getCategories',
        body: {'room': widget.room?.id, 'server': widget.room?.serverTag}),
      onOK: (body) async {
        final resp = body['data']
        .map<RoomCategory>((raw) => RoomCategory.fromJSON(raw))
        .toList();

        Map<int, int> map = {};
        for (int i = 0; i < resp.length; i++) {
          map[resp[i].id] = i;
        }
        setState(() {
            weights = map;
            categories = resp;
            sortAll();
        });
    });
  }

  void fetchProducts() {
    final user = context.read<User>();

    // TODO: load cached products first

    doNetworkRequest(ScaffoldMessenger.of(context),
      req: () => postWithCreadentials(
        credentials: user,
        target: user.server,
        path: 'getProducts',
        body: {'room': widget.room?.id, 'server': widget.room?.serverTag}),
      onOK: (body) async {
        final resp = body['data']
        .map<RoomProduct>((raw) => RoomProduct.fromJSON(raw))
        .toList();

        setState(() {
            products = resp;
        });
    });
  }

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

    WidgetsBinding.instance.addPostFrameCallback((_) {
        fetchItems();
        fetchCategories();
        fetchProducts();
    });
  }

  void changeItemState(RoomItem item) {
    final user = context.read<User>();
    doNetworkRequest(ScaffoldMessenger.of(context),
      req: () => postWithCreadentials(
        credentials: user,
        target: user.server,
        path: 'changeItemState',
        body: {
          'room': widget.room?.id,
          'server': widget.room?.serverTag,
          'listItemID': item.id,
          'state': item.state
    }));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ListView(children: [
          LabeledDivider(AppLocalizations.of(context)!.shoppingList),
          ListView.builder(
            shrinkWrap: true,
            physics: const ClampingScrollPhysics(),
            itemCount: list.length,
            itemBuilder: (context, index) {
              final item = list[index];

              return ShoppingListItem(
                name: item.name,
                description: item.description,
                category: (item.category != null)
                ? categories[item.category!]
                : RoomCategory.other(context),
                key: Key(item.id.toString()),
                inCart: item.state != 0,
                onDismiss: () {
                  // move to cart
                  item.state = 1;

                  setState(() {
                      list.removeAt(index);
                      cart.add(item);
                      sortAll();
                  });

                  // network request
                  // NOTE: for now we do not care if it is successfull,
                  // because the shopping cart is supposed to work even
                  // without network
                  changeItemState(item);
                },
                onTap: () {
                  // TODO: show modal bottom sheet
                  // containing
                  // - item info
                  // - option to view linked product (if available)
                  // - edit item (if allowed)
                  // - delete item (if allowed)
                  // - move to/from shopping cart?
                  showModalBottomSheet(
                    context: context,
                    builder: (context) => ShoppingListItemInfo(
                      products: products,
                      categories: categories,
                      item: item,
                      room: widget.room!.id,
                      server: widget.room!.serverTag));
              });
            },
          ),
          LabeledDivider(AppLocalizations.of(context)!.shoppingCart),
          ListView.builder(
            itemCount: cart.length,
            shrinkWrap: true,
            physics: const ClampingScrollPhysics(),
            itemBuilder: (context, index) {
              final item = cart[index];

              return ShoppingListItem(
                name: item.name,
                description: item.description,
                category: (item.category != null)
                ? categories[item.category!]
                : RoomCategory.other(context),
                key: Key(item.id.toString()),
                inCart: item.state != 0,
                onDismiss: () {
                  // move back to list
                  item.state = 0;
                  setState(() {
                      cart.removeAt(index);
                      list.add(item);
                      sortAll();
                  });

                  // network request
                  // NOTE: for now we do not care if it is successfull,
                  // because the shopping cart is supposed to work even
                  // without network
                  changeItemState(item);
                },
                onTap: () {
                  // TODO: show modal bottom sheet
                  // containing
                  // - item info
                  // - option to view linked product (if available)
                  // - edit item (if allowed)
                  // - delete item (if allowed)
                  // - move to/from shopping cart?
                  showModalBottomSheet(
                    context: context,
                    builder: (context) => ShoppingListItemInfo(
                      products: products,
                      categories: categories,
                      item: item,
                      room: widget.room!.id,
                      server: widget.room!.serverTag));
              });
            },
          )
      ]),
      floatingActionButton: ((widget.info?.isAdmin ?? false) ||
        (widget.info?.isOwner ?? false) ||
        ((widget.info?.permissions)! & RoomPermission.editRoomContent !=
          0))
      ? FloatingActionButton.extended(
        icon: const Icon(Icons.add),
        label: Text(AppLocalizations.of(context)!.newItemShort),
        tooltip: AppLocalizations.of(context)!.newItemLong,
        onPressed: () {
          // show new category popup
          context.pushNamed('new-item', params: {
              'server': widget.room!.serverTag,
              'id': widget.room!.id,
          });
        },
      )
      : null,
    );
  }
}

class ShoppingListItem extends StatelessWidget {
  String name;
  RoomCategory category;
  String description;
  bool inCart;
  final Key _key;
  Function()? onDismiss;
  Function()? onTap;

  ShoppingListItem(
    {required this.name,
      required this.category,
      required this.inCart,
      required this.description,
      required key,
      this.onDismiss,
      this.onTap})
  : _key = key;

  @override
  Widget build(BuildContext context) {
    return Dismissible(
      key: Key('item-$_key'),
      dismissThresholds: const {
        // NOTE: value might need updating
        // maybe we could calculate this using the screen width
        DismissDirection.horizontal: 500.0,
      },
      confirmDismiss: (_) async {
        if (onDismiss != null) {
          onDismiss!();
        }

        // keep item in list
        // NOTE: might want to set this to true/variable
        // if in-shopping-cart items have a second screen
        return true;
      },
      background:
      Icon(!inCart ? Icons.shopping_cart : Icons.remove_shopping_cart),
      child: ListTile(
        enabled: !inCart,
        title: Text(name),
        subtitle: Text(description),
        trailing: CategoryChip(category: category,),
        onTap: () {
          if (onTap != null) {
            onTap!();
          }
        },
      ),
    );
  }
}

class ShoppingListItemInfo extends StatelessWidget {
  RoomItem item;
  String server;
  String room;
  List<RoomCategory> categories = [];
  List<RoomProduct> products = [];

  ShoppingListItemInfo(
    {required this.item,
      required this.server,
      required this.room,
      required this.categories,
      required this.products});

  @override
  Widget build(BuildContext context) {
    final textTheme = Theme.of(context).textTheme;
    return BottomSheet(
      onClosing: () {},
      builder: (context) => Column(
        children: [
          Padding(
            padding: const EdgeInsets.all(14),
            child: Center(
              child: Column(children: [
                  Text(item.name, style: textTheme.headlineLarge),
                  Text(item.description, style: textTheme.titleMedium),
                  CategoryPicker(
                    label: AppLocalizations.of(context)!.selectCategoryLabel,
                    categories: categories,
                    selected: item.category,
                    enabled: false),
                  ProductPicker(
                    label:AppLocalizations.of(context)!.selectLinkedProductLabel,
                    help:AppLocalizations.of(context)!.selectLinkedProductHelp,
                    products: products,
                    selected: item.link,
                    enabled: false)

                  // TODO: show more info
          ]))),
          ...(item.link != null)
          ? [
            ListTile(
              title: Text(AppLocalizations.of(context)!
                .itemShowLinkedProductTitle),
              subtitle: Text(AppLocalizations.of(context)!
                .itemShowLinkedProductSubtitle),
              trailing: const Icon(Icons.chevron_right),
              onTap: () {
                // launch "view-product" page for specific product
                context.pushNamed('view-product', params: {
                    'server': server,
                    'id': room,
                    'product': item.id.toString()
                });
              },
            )
          ]
          : []
        ],
      ),
    );
  }
}