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TaskDetailViewModel.kt
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TaskDetailViewModel.kt
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/*
* Copyright 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.architecture.blueprints.todoapp.taskdetail
import androidx.lifecycle.SavedStateHandle
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.example.android.architecture.blueprints.todoapp.R
import com.example.android.architecture.blueprints.todoapp.TodoDestinationsArgs
import com.example.android.architecture.blueprints.todoapp.data.Task
import com.example.android.architecture.blueprints.todoapp.data.TaskRepository
import com.example.android.architecture.blueprints.todoapp.util.Async
import com.example.android.architecture.blueprints.todoapp.util.WhileUiSubscribed
import dagger.hilt.android.lifecycle.HiltViewModel
import javax.inject.Inject
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.catch
import kotlinx.coroutines.flow.combine
import kotlinx.coroutines.flow.map
import kotlinx.coroutines.flow.stateIn
import kotlinx.coroutines.launch
/**
* UiState for the Details screen.
*/
data class TaskDetailUiState(
val task: Task? = null,
val isLoading: Boolean = false,
val userMessage: Int? = null,
val isTaskDeleted: Boolean = false
)
/**
* ViewModel for the Details screen.
*/
@HiltViewModel
class TaskDetailViewModel @Inject constructor(
private val taskRepository: TaskRepository,
savedStateHandle: SavedStateHandle
) : ViewModel() {
val taskId: String = savedStateHandle[TodoDestinationsArgs.TASK_ID_ARG]!!
private val _userMessage: MutableStateFlow<Int?> = MutableStateFlow(null)
private val _isLoading = MutableStateFlow(false)
private val _isTaskDeleted = MutableStateFlow(false)
private val _taskAsync = taskRepository.getTaskStream(taskId)
.map { handleTask(it) }
.catch { emit(Async.Error(R.string.loading_task_error)) }
val uiState: StateFlow<TaskDetailUiState> = combine(
_userMessage, _isLoading, _isTaskDeleted, _taskAsync
) { userMessage, isLoading, isTaskDeleted, taskAsync ->
when (taskAsync) {
Async.Loading -> {
TaskDetailUiState(isLoading = true)
}
is Async.Error -> {
TaskDetailUiState(
userMessage = taskAsync.errorMessage,
isTaskDeleted = isTaskDeleted
)
}
is Async.Success -> {
TaskDetailUiState(
task = taskAsync.data,
isLoading = isLoading,
userMessage = userMessage,
isTaskDeleted = isTaskDeleted
)
}
}
}
.stateIn(
scope = viewModelScope,
started = WhileUiSubscribed,
initialValue = TaskDetailUiState(isLoading = true)
)
fun deleteTask() = viewModelScope.launch {
taskRepository.deleteTask(taskId)
_isTaskDeleted.value = true
}
fun setCompleted(completed: Boolean) = viewModelScope.launch {
val task = uiState.value.task ?: return@launch
if (completed) {
taskRepository.completeTask(task.id)
showSnackbarMessage(R.string.task_marked_complete)
} else {
taskRepository.activateTask(task.id)
showSnackbarMessage(R.string.task_marked_active)
}
}
fun refresh() {
_isLoading.value = true
viewModelScope.launch {
taskRepository.refreshTask(taskId)
_isLoading.value = false
}
}
fun snackbarMessageShown() {
_userMessage.value = null
}
private fun showSnackbarMessage(message: Int) {
_userMessage.value = message
}
private fun handleTask(task: Task?): Async<Task?> {
if (task == null) {
return Async.Error(R.string.task_not_found)
}
return Async.Success(task)
}
}