chapter-organizer/WebApp/Components/Features/Students/EventRankingEdit.razor

@page "/students/event-ranking-edit/{StudentId:int}"
@attribute [Authorize]
@using Microsoft.EntityFrameworkCore
@using BlazorSortableList
@using WebApp.Models
@using WebApp.Components.Shared.Components
@inject AppDbContext Context
@inject NavigationManager NavigationManager
@inject ISnackbar Snackbar
@inject ILogger<EventRankingEdit> Logger

@if (_student == null)
{
    <p><em>Loading...</em></p>
}
else
{
    <PageHeader
        Title="Student Event Ranks"
        Subtitle="@_student.Name"
        Icon="@AppIcons.EventRank"
        ShowBackButton="true"
        BackButtonUrl="/students/event-ranking">
        <ActionButtons>
            <MudTooltip Text="Save Rankings">
                <MudButton StartIcon="@Icons.Material.Filled.Save"
                           OnClick="Save"
                           Color="Color.Primary"
                           Variant="Variant.Filled">
                    Save Rankings
                </MudButton>
            </MudTooltip>
        </ActionButtons>
    </PageHeader>

    @* https://github.com/AlexNek/BlazorSortableList *@
    <MudGrid Class="mt-2">
        <MudItem xs="12" md="6" xl="4">
            <MudPaper Class="pa-3 mb-3" Elevation="2">
                <div class="d-flex align-center mb-1">
                    <MudIcon Icon="@Icons.Material.Filled.FormatListNumbered" Class="mr-2" Color="Color.Primary" />
                    <MudText Typo="Typo.h6" Color="Color.Primary">Ranked Events</MudText>
                </div>
                <MudText Typo="Typo.caption" Color="Color.Secondary">Drag events here in order of preference</MudText>
            </MudPaper>
                <SortableList
                    Group="GroupId" Id="ListId1" Context="item"
                    Items="_rankedEvents" OnRemove="RankedEventsRemove"  OnUpdate="Update">
                    <SortableItemTemplate>
                        <MudCard Outlined="true" Class="mb-2">
                            <MudCardContent Class="pa-2">
                                <div class="d-flex align-center">
                                    <MudBadge Content="@(_rankedEvents.IndexOf(item) + 1)" Color="Color.Primary" Overlap="true" Class="mr-3">
                                        <MudIcon Icon="@Icons.Material.Filled.DragIndicator" />
                                    </MudBadge>
                                    <div class="flex-grow-1">
                                        <MudText Typo="Typo.body2"><strong>@item.Name</strong></MudText>
                                        <MudText Typo="Typo.caption">
                                            @AppIcons.EventAttributes(item) @AppIcons.EventEffort(item)
                                        </MudText>
                                    </div>
                                </div>
                            </MudCardContent>
                        </MudCard>
                    </SortableItemTemplate>
            </SortableList>
        </MudItem>
        <MudItem xs="12" md="6" xl="4">
            <MudPaper Class="pa-3 mb-3" Elevation="2">
                <div class="d-flex align-center mb-1">
                    <MudIcon Icon="@AppIcons.Events" Class="mr-2" />
                    <MudText Typo="Typo.h6">Available Events</MudText>
                </div>
                <MudText Typo="Typo.caption" Color="Color.Secondary">Drag events to rank them</MudText>
            </MudPaper>
                <SortableList
                    Group="GroupId" Id="ListId2" Context="item"
                    Items="_availableEvents" OnRemove="AvailableEventsRemove" Sort="false">
                    <SortableItemTemplate>
                        <MudCard Outlined="true" Class="mb-2">
                            <MudCardContent Class="pa-2">
                                <MudText Typo="Typo.body2"><strong>@item.Name</strong></MudText>
                                <MudText Typo="Typo.caption">
                                    @AppIcons.EventAttributes(item) @AppIcons.EventEffort(item)
                                </MudText>
                            </MudCardContent>
                        </MudCard>
                    </SortableItemTemplate>
            </SortableList>
        </MudItem>
    </MudGrid>
}

@code {

    private const string ListId1 = "SharedListId1";
    private const string ListId2 = "SharedListId2";
    private const string GroupId = "CommonGroup";

    [Parameter] public int? StudentId { get; set; }

    private Student? _student;
    private List<EventDefinition>? _events;

    public List<EventDefinition> _rankedEvents = [];
    public List<EventDefinition> _availableEvents = [];

    private void RankedEventsRemove((int oldIndex, int newIndex) indices)
    {
        // get the item at the old index in list 1
        var item = _rankedEvents[indices.oldIndex];

        // add it to the new index in list 2
        _availableEvents.Insert(indices.newIndex, item);

        // remove the item from the old index in list 1
        _rankedEvents.Remove(_rankedEvents[indices.oldIndex]);
    }

    private void AvailableEventsRemove((int oldIndex, int newIndex) indices)
    {
        // get the item at the old index in list 2
        var item = _availableEvents[indices.oldIndex];

        // add it to the new index in list 1
        _rankedEvents.Insert(indices.newIndex, item);

        // remove the item from the old index in list 2
        _availableEvents.Remove(_availableEvents[indices.oldIndex]);
    }

    protected override async Task OnInitializedAsync()
    {
        _student =
            await Context.Students
                .Include(e => e.EventRankings)
                .Where(e => e.Id == StudentId).FirstAsync();
        _events =
            await Context.Events
                .OrderBy(e => e.Name)
            .ToListAsync();

        _rankedEvents = _student.EventRankings.OrderBy(e => e.Rank).Select(e => e.EventDefinition).ToList();
        _availableEvents = _events.Where(e => !_rankedEvents.Contains(e)).ToList();
    }

    private void Update((int oldIndex, int newIndex) indices)
    {
        var (oldIndex, newIndex) = indices;

        var items = _rankedEvents;
        var itemToMove = items[oldIndex];
        items.RemoveAt(oldIndex);

        if (newIndex < items.Count)
        {
            items.Insert(newIndex, itemToMove);
        }
        else
        {
            items.Add(itemToMove);
        }

        StateHasChanged();
    }


    async Task Save()
    {
        if (_student == null)
            return;

        try
        {
            _student.EventRankings.Clear();
            for (var index = 0; index < _rankedEvents.Count; index++)
            {
                var evt = _rankedEvents[index];
                _student.EventRankings.Add(new StudentEventRanking
                {
                    EventDefinition = evt,
                    Student = _student,
                    Rank = index + 1
                });
            }

            Context.Students.Update(_student);
            await Context.SaveChangesAsync();

            Snackbar.Add($"Event rankings saved for {_student.Name}", Severity.Success);
            NavigationManager.NavigateTo("/students/event-ranking");
        }
        catch (Exception e)
        {
            Snackbar.Add("Error saving rankings. Please try again.", Severity.Error);
            Logger.LogError(e, "Error saving event rankings for student {StudentId}", StudentId);
        }
    }
}