LehrerApp/LehrerApp.Desktop/ViewModels/Students/StudentPickerDialogViewModel.cs

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LehrerApp.Core.Interfaces;
using LehrerApp.Core.Models;
using LehrerApp.Desktop.ViewModels.Groups;
using System.Collections.ObjectModel;

namespace LehrerApp.Desktop.ViewModels.Students;

/// <summary>Einfacher "einen Schüler wählen"-Dialog für Einstiegspunkte ohne bereits geöffneten
/// Schüler (z.B. das Formulare-Menü) - anders als <see cref="Groups.AddStudentToGroupDialogViewModel"/>
/// ohne Gruppenbezug/Mitgliedschaftszeitraum, einfach alle Schüler durchsuchbar.</summary>
public partial class StudentPickerDialogViewModel : ObservableObject
{
    private readonly IStudentRepository _students;

    [ObservableProperty] private string _searchText = "";
    [ObservableProperty] private StudentPickerItem? _selectedStudent;
    [ObservableProperty] private string _validationMessage = "";

    public ObservableCollection<StudentPickerItem> Students { get; } = [];
    public Student? Result { get; private set; }

    public StudentPickerDialogViewModel(IStudentRepository students)
    {
        _students = students;
        LoadStudents();
    }

    partial void OnSearchTextChanged(string value) => LoadStudents();

    private void LoadStudents()
    {
        var matches = _students.GetAll()
            .Where(s => string.IsNullOrWhiteSpace(SearchText) ||
                        s.FullName.Contains(SearchText, StringComparison.OrdinalIgnoreCase))
            .OrderBy(s => s.FullName, StringComparer.CurrentCultureIgnoreCase);
        Students.Clear();
        foreach (var student in matches) Students.Add(new StudentPickerItem(student));
    }

    [RelayCommand]
    private void Select()
    {
        if (SelectedStudent is null) { ValidationMessage = "Bitte einen Schüler auswählen."; return; }
        Result = _students.GetById(SelectedStudent.Id);
    }
}