119 lines
3.9 KiB
Kotlin
119 lines
3.9 KiB
Kotlin
/*
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* Copyright (C) 2023 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.cupcake.ui
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import androidx.lifecycle.ViewModel
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import com.example.cupcake.data.OrderUiState
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import kotlinx.coroutines.flow.MutableStateFlow
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import kotlinx.coroutines.flow.StateFlow
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import kotlinx.coroutines.flow.asStateFlow
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import kotlinx.coroutines.flow.update
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import java.text.NumberFormat
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import java.text.SimpleDateFormat
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import java.util.Calendar
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import java.util.Locale
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/** Price for a single cupcake */
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private const val PRICE_PER_CUPCAKE = 2.00
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/** Additional cost for same day pickup of an order */
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private const val PRICE_FOR_SAME_DAY_PICKUP = 3.00
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/**
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* [OrderViewModel] holds information about a cupcake order in terms of quantity, flavor, and
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* pickup date. It also knows how to calculate the total price based on these order details.
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*/
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class OrderViewModel : ViewModel() {
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/**
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* Cupcake state for this order
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*/
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private val _uiState = MutableStateFlow(OrderUiState(pickupOptions = pickupOptions()))
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val uiState: StateFlow<OrderUiState> = _uiState.asStateFlow()
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/**
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* Set the quantity [numberCupcakes] of cupcakes for this order's state and update the price
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*/
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fun setQuantity(numberCupcakes: Int) {
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_uiState.update { currentState ->
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currentState.copy(
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quantity = numberCupcakes,
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price = calculatePrice(quantity = numberCupcakes)
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)
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}
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}
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/**
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* Set the [desiredFlavor] of cupcakes for this order's state.
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* Only 1 flavor can be selected for the whole order.
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*/
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fun setFlavor(desiredFlavor: String) {
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_uiState.update { currentState ->
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currentState.copy(flavor = desiredFlavor)
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}
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}
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/**
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* Set the [pickupDate] for this order's state and update the price
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*/
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fun setDate(pickupDate: String) {
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_uiState.update { currentState ->
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currentState.copy(
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date = pickupDate,
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price = calculatePrice(pickupDate = pickupDate)
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)
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}
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}
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/**
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* Reset the order state
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*/
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fun resetOrder() {
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_uiState.value = OrderUiState(pickupOptions = pickupOptions())
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}
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/**
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* Returns the calculated price based on the order details.
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*/
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private fun calculatePrice(
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quantity: Int = _uiState.value.quantity,
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pickupDate: String = _uiState.value.date
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): String {
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var calculatedPrice = quantity * PRICE_PER_CUPCAKE
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// If the user selected the first option (today) for pickup, add the surcharge
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if (pickupOptions()[0] == pickupDate) {
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calculatedPrice += PRICE_FOR_SAME_DAY_PICKUP
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}
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val formattedPrice = NumberFormat.getCurrencyInstance().format(calculatedPrice)
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return formattedPrice
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}
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/**
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* Returns a list of date options starting with the current date and the following 3 dates.
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*/
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private fun pickupOptions(): List<String> {
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val dateOptions = mutableListOf<String>()
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val formatter = SimpleDateFormat("E MMM d", Locale.getDefault())
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val calendar = Calendar.getInstance()
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// add current date and the following 3 dates.
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repeat(4) {
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dateOptions.add(formatter.format(calendar.time))
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calendar.add(Calendar.DATE, 1)
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}
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return dateOptions
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}
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}
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