public abstract class TaskViewModel extends BaseObservable
implements TasksDataSource.GetTaskCallback {
public final ObservableField<String> snackbarText = new ObservableField<>();
public final ObservableField<String> title = new ObservableField<>();
public final ObservableField<String> description = new ObservableField<>();
private final ObservableField<Task> mTaskObservable = new ObservableField<>();
private final TasksRepository mTasksRepository;
private final Context mContext;
private boolean mIsDataLoading;
public TaskViewModel(Context context, TasksRepository tasksRepository) {
mContext = context.getApplicationContext(); // Force use of Application Context.
mTasksRepository = tasksRepository;
// Exposed observables depend on the mTaskObservable observable:
mTaskObservable.addOnPropertyChangedCallback(new OnPropertyChangedCallback() {
@Override
public void onPropertyChanged(Observable observable, int i) {
Task task = mTaskObservable.get();
if (task != null) {
title.set(task.getTitle());
description.set(task.getDescription());
} else {
title.set(mContext.getString(R.string.no_data));
description.set(mContext.getString(R.string.no_data_description));
}
}
});
}
public void start(String taskId) {
if (taskId != null) {
mIsDataLoading = true;
mTasksRepository.getTask(taskId, this);
}
}
public void setTask(Task task) {
mTaskObservable.set(task);
}
// "completed" is two-way bound, so in order to intercept the new value, use a @Bindable
// annotation and process it in the setter.
@Bindable
public boolean getCompleted() {
Task task = mTaskObservable.get();
return task != null && task.isCompleted();
}
public void setCompleted(boolean completed) {
if (mIsDataLoading) {
return;
}
Task task = mTaskObservable.get();
// Notify repository and user
if (completed) {
mTasksRepository.completeTask(task);
snackbarText.set(mContext.getResources().getString(R.string.task_marked_complete));
} else {
mTasksRepository.activateTask(task);
snackbarText.set(mContext.getResources().getString(R.string.task_marked_active));
}
}
@Bindable
public boolean isDataAvailable() {
return mTaskObservable.get() != null;
}
@Bindable
public boolean isDataLoading() {
return mIsDataLoading;
}
// This could be an observable, but we save a call to Task.getTitleForList() if not needed.
@Bindable
public String getTitleForList() {
if (mTaskObservable.get() == null) {
return "No data";
}
return mTaskObservable.get().getTitleForList();
}
@Override
public void onTaskLoaded(Task task) {
mTaskObservable.set(task);
mIsDataLoading = false;
notifyChange(); // For the @Bindable properties
}
@Override
public void onDataNotAvailable() {
mTaskObservable.set(null);
mIsDataLoading = false;
}
public void deleteTask() {
if (mTaskObservable.get() != null) {
mTasksRepository.deleteTask(mTaskObservable.get().getId());
}
}
public void onRefresh() {
if (mTaskObservable.get() != null) {
start(mTaskObservable.get().getId());
}
}
public String getSnackbarText() {
return snackbarText.get();
}
@Nullable
protected String getTaskId() {
return mTaskObservable.get().getId();
}
}
