@page "/students"
@attribute [Authorize]
@implements IAsyncDisposable
@using Microsoft.EntityFrameworkCore
@using WebApp.Authentication
@using WebApp.Models
@using WebApp.Components.Shared.Components
@inject AppDbContext Context
@inject IDialogService DialogService
@inject ISnackbar Snackbar
@inject INotesService NotesService
@inject IConfiguration Configuration
@inject IJSRuntime JSRuntime
@using Core.Notes
@using Core.Parsers
@using WebApp.Services

<PageHeader Title="Students">
    <ActionButtons>
        <MudTooltip Text="Create New">
            <MudButton StartIcon="@Icons.Material.Filled.Create" Href="students/create" Variant="Variant.Filled" Color="Color.Primary">Create New</MudButton>
        </MudTooltip>
        <AuthorizeView Roles="@AuthRoles.Administrator">
            <MudButtonGroup Variant="Variant.Outlined">
                <MudTooltip Text="Add new students from CSV. Existing names are skipped; leftover columns merge into student notes.">
                    <MudButton StartIcon="@Icons.Material.Filled.UploadFile" Href="/students/import">Import</MudButton>
                </MudTooltip>
                <MudMenu Icon="@Icons.Material.Filled.ArrowDropDown"
                         AriaLabel="More import actions"
                         AnchorOrigin="Origin.BottomRight"
                         TransformOrigin="Origin.TopRight">
                    <MudMenuItem Icon="@Icons.Material.Filled.Download"
                                 OnClick="DownloadStudentImportTemplate">
                        Download CSV template
                    </MudMenuItem>
                </MudMenu>
            </MudButtonGroup>
        </AuthorizeView>
        <MudTooltip Text="Event Rankings">
            <MudButton StartIcon="@AppIcons.EventRank" Href="students/event-ranking" Variant="Variant.Outlined">Event Rankings</MudButton>
        </MudTooltip>
        <MudTooltip Text="Registration">
            <MudButton StartIcon="@AppIcons.Registration" Href="students/teams" Variant="Variant.Outlined">Registration</MudButton>
        </MudTooltip>
    </ActionButtons>
</PageHeader>

<MudPaper Elevation="2" Class="pa-3 pa-md-6">
    <MudDataGrid T="Student"
                 @key="NoteFieldColumnsKey"
                 ServerData="ServerReload"
                 @ref="_dataGrid"
                 Filterable="true"
                 RowsPerPage="25"
                 Dense="true"
                 Striped="true"
                 Hover="true"
                 Loading="@_isLoading"
                 LoadingProgressColor="Color.Primary">
        <Columns>
            <PropertyColumn Property="@(e => e.LastName)" Title="Name" Sortable="true">
                <CellTemplate>
                    <MudStack Row="true" AlignItems="AlignItems.Center" Justify="Justify.SpaceBetween" Spacing="1">
                        <MudStack Row="true" AlignItems="AlignItems.Center" Spacing="1" Wrap="Wrap.Wrap">
                            <MudLink Href="@($"/students/details?id={context.Item.Id}&returnUrl=/students")"
                                     Underline="Underline.Hover"
                                     Color="Color.Primary">
                                @context.Item.LastNameFirstName
                            </MudLink>
                            @if (context.Item.OfficerRole != null)
                            {
                                <MudChip T="string" Size="Size.Small" Icon="@(AppIcons.OfficerRoleIcon(context.Item.OfficerRole.Value))">@context.Item.OfficerRole</MudChip>
                            }
                        </MudStack>
                        <MudStack Row="true" AlignItems="AlignItems.Center" Spacing="1">
                            <IconButtonWithTooltip Icon="@Icons.Material.Filled.Edit"
                                                   TooltipText="Edit"
                                                   Href="@($"/students/edit?id={context.Item.Id}&returnUrl=/students")" />
                            <IconButtonWithTooltip Icon="@Icons.Material.Outlined.Delete"
                                                   TooltipText="Delete"
                                                   HoverColor="Color.Error"
                                                   OnClick="() => DeleteStudent(context.Item!)" />
                        </MudStack>
                    </MudStack>
                </CellTemplate>
            </PropertyColumn>
            <PropertyColumn Property="@(e => e.Grade)" Title="Grade (TSA Year)" Sortable="true">
                <CellTemplate>
                    <span style="white-space: nowrap;">@((MarkupString)AppIcons.GetOrdinalSuperscript(context.Item.Grade))</span> (@context.Item.TsaYear)
                </CellTemplate>
            </PropertyColumn>
            @foreach (var field in _noteFieldColumns)
            {
                var fieldName = field;
                <TemplateColumn Title="@fieldName" Sortable="false" Filterable="false">
                    <CellTemplate>
                        @GetNoteField(context.Item.Id, fieldName)
                    </CellTemplate>
                </TemplateColumn>
            }
        </Columns>
        <PagerContent>
            <MudDataGridPager T="Student"></MudDataGridPager>
        </PagerContent>
    </MudDataGrid>
</MudPaper>

@code {
    MudDataGrid<Student> _dataGrid = null!;
    private bool _isLoading = true;
    private CancellationTokenSource? _cancellationTokenSource;
    private bool _isDisposed = false;
    private List<string> _noteFieldColumns = [];
    private Dictionary<int, string?> _noteContentByStudentId = [];
    private string NoteFieldColumnsKey => string.Join('\u001f', _noteFieldColumns);

    protected override void OnInitialized()
    {
        _cancellationTokenSource = new CancellationTokenSource();
    }

    protected override void OnParametersSet()
    {
        _noteFieldColumns = WebApp.Models.ChapterSettings.ReadIndexNoteFields(Configuration);
    }

    private async Task<GridData<Student>> ServerReload(GridState<Student> state)
    {
        if (_isDisposed)
        {
            return new GridData<Student> { TotalItems = 0, Items = [] };
        }

        _isLoading = true;
        try
        {
            var cancellationToken = _cancellationTokenSource?.Token ?? CancellationToken.None;

            var query = 
                Context.Students
                    .AsNoTracking()
                    .OrderBy(e => e.LastName)
                    .Where(state.FilterDefinitions).OrderBy(state.SortDefinitions);

            var totalItems = await query.CountAsync(cancellationToken);
            var pagedData = await query.Skip(state.Page * state.PageSize).Take(state.PageSize).ToArrayAsync(cancellationToken);

            var notes = await NotesService.GetStudentNotesAsync(pagedData.Select(s => s.Id));
            _noteContentByStudentId = notes.ToDictionary(k => k.Key, v => v.Value.Content);

            return new GridData<Student>
            {
                TotalItems = totalItems,
                Items = pagedData
            };
        }
        catch (TaskCanceledException)
        {
            return new GridData<Student> { TotalItems = 0, Items = [] };
        }
        catch (JSDisconnectedException)
        {
            return new GridData<Student> { TotalItems = 0, Items = [] };
        }
        finally
        {
            if (!_isDisposed)
            {
                _isLoading = false;
            }
        }
    }

    private async Task DeleteStudent(Student student)
    {
        if (_isDisposed) return;

        try
        {
            var cancellationToken = _cancellationTokenSource?.Token ?? CancellationToken.None;

            var result = await DialogService
                .ShowMessageBox("Delete student",
                    (MarkupString)$"Are you sure want to delete <b>{student.Name}</b>? This cannot be undone.",
                    yesText:"Yes",
                    noText:"Cancel");

            if (_isDisposed) return;

            if (result == true)
            {
                // Load the student fresh from database with tracking to avoid tracking conflicts
                var studentToDelete = await Context.Students
                    .FirstOrDefaultAsync(s => s.Id == student.Id, cancellationToken);

                if (_isDisposed) return;

                if (studentToDelete == null)
                {
                    if (!_isDisposed)
                    {
                        Snackbar.Add("Student not found or already deleted", Severity.Warning);
                    }
                    return;
                }

                await NotesService.SoftDeleteStudentNotesAsync([studentToDelete.Id], cancellationToken);
                Context.Students.Remove(studentToDelete);
                await Context.SaveChangesAsync(cancellationToken);
                
                if (!_isDisposed)
                {
                    Snackbar.Add($"Student {studentToDelete.Name} deleted", Severity.Info);
                }
            }

            if (!_isDisposed)
            {
                StateHasChanged();
                await _dataGrid.ReloadServerData();
            }
        }
        catch (TaskCanceledException)
        {
            // Component was disposed, ignore
        }
        catch (JSDisconnectedException)
        {
            // JS connection lost, ignore
        }
        catch (Exception ex)
        {
            if (!_isDisposed)
            {
                Snackbar.Add($"Error deleting student: {ex.Message}", Severity.Error);
            }
        }
    }

    public async ValueTask DisposeAsync()
    {
        if (!_isDisposed)
        {
            _isDisposed = true;
            _cancellationTokenSource?.Cancel();
            _cancellationTokenSource?.Dispose();
            _cancellationTokenSource = null;
        }
        await ValueTask.CompletedTask;
    }

    private async Task DownloadStudentImportTemplate()
    {
        if (_isDisposed)
            return;

        try
        {
            var cancellationToken = _cancellationTokenSource?.Token ?? CancellationToken.None;
            var fromNotes = await NotesService.GetImportedFieldNamesAsync(cancellationToken);
            var leftover = _noteFieldColumns
                .Concat(fromNotes)
                .Distinct(StringComparer.OrdinalIgnoreCase);
            var csv = StudentImportCsvTemplate.Build(leftover);
            byte[] bytes = [..System.Text.Encoding.UTF8.GetPreamble(), ..System.Text.Encoding.UTF8.GetBytes(csv)];
            var base64 = Convert.ToBase64String(bytes);
            await JSRuntime.InvokeVoidAsync("tsaDownload.fromBase64", "student-import-template.csv", "text/csv;charset=utf-8", base64);
        }
        catch (JSDisconnectedException)
        {
        }
        catch (TaskCanceledException)
        {
        }
        catch (Exception ex)
        {
            if (!_isDisposed)
                Snackbar.Add($"Could not download template: {ex.Message}", Severity.Error);
        }
    }

    private string GetNoteField(int studentId, string fieldName)
    {
        if (!_noteContentByStudentId.TryGetValue(studentId, out var content))
            return string.Empty;

        return ImportedFieldsTable.GetFieldValue(content, fieldName) ?? string.Empty;
    }
}