checkout_provider.dart

import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:habanero/models/models.dart';

class CartItem {
  final MenuItem item;
  int count = 0;

  double get total => item.price * count;

  CartItem(this.item);
}

class CartProvider extends ChangeNotifier {
  final List<CartItem> cartItems = [];

  // for ui
  CartItem focused;

  // debounce
  Timer debouncer;

  double get itemsTotal {
    if (cartItems.length < 1) {
      return 0;
    }
    return cartItems.map((e) => e.total).reduce((a, b) => a + b);
  }

  void add(MenuItem item) {
    final cartItem = cartItems.firstWhere((ci) => ci.item.id == item.id,
        orElse: () => CartItem(item));

    if (cartItem.count == 0) {
      cartItem.count = 1;
      cartItems.add(cartItem);
    } else {
      cartItem.count += 1;
    }

    notifyListeners();

    if (focused != null) {
      hideAfter();
    }
  }

  void remove(MenuItem item) {
    final cartItem =
        cartItems.firstWhere((ci) => ci.item.id == item.id, orElse: () => null);

    if (cartItem != null) {
      if (cartItem.count == 1) {
        cartItems.remove(cartItem);
      } else {
        cartItem.count -= 1;
      }
    }

    notifyListeners();

    if (focused != null) {
      hideAfter();
    }
  }

  void removeAll(MenuItem item) {
    final cartItem =
        cartItems.firstWhere((ci) => ci.item.id == item.id, orElse: () => null);

    if (cartItem != null) {
      cartItems.remove(cartItem);

      notifyListeners();
    }

    if (focused != null) {
      hideAfter();
    }
  }

  void toggle(MenuItem item) {
    if (contains(item)) {
      removeAll(item);
    } else {
      add(item);
    }
  }

  void reset() {
    cartItems.clear();

    notifyListeners();
  }

  void select(CartItem item) {
    focused = item;
    notifyListeners();

    hideAfter();
  }

  void hideAfter() {
    debouncer?.cancel();
    debouncer = Timer(Duration(seconds: 10), () {
      focused = null;
      notifyListeners();
    });
  }

  bool contains(MenuItem item) =>
      cartItems.firstWhere(
        (el) => el.item == item,
        orElse: () => null,
      ) !=
      null;
}