DbFirst/DbFirst.BlazorWebApp/Components/CatalogsGrid.razor

@using Microsoft.AspNetCore.Components.Forms
@inject CatalogApiClient Api

<style>
    .action-panel { margin-bottom: 16px; }
    .grid-section { margin-top: 12px; }
    .catalog-edit-popup {
        min-width: 720px;
    }
</style>

@if (!string.IsNullOrWhiteSpace(errorMessage))
{
    <div class="alert alert-danger" role="alert">@errorMessage</div>
}
else if (!string.IsNullOrWhiteSpace(infoMessage))
{
    <div class="alert alert-success" role="alert">@infoMessage</div>
}

@if (isLoading)
{
    <p><em>Lade Daten...</em></p>
}
else if (items.Count == 0)
{
    <p>Keine Einträge vorhanden.</p>
}
else
{
    <div class="grid-section">
        <DxGrid Data="@items"
                TItem="CatalogReadDto"
                KeyFieldName="@nameof(CatalogReadDto.Guid)"
                ShowFilterRow="true"
                PageSize="10"
                CssClass="mb-4 catalog-grid"
                EditMode="GridEditMode.PopupEditForm"
                PopupEditFormCssClass="catalog-edit-popup"
                CustomizeEditModel="OnCustomizeEditModel"
                EditModelSaving="OnEditModelSaving"
                DataItemDeleting="OnDataItemDeleting">
            <Columns>
                <DxGridCommandColumn Width="120px" />
                <DxGridDataColumn FieldName="@nameof(CatalogReadDto.Guid)" Caption="Id" Width="140px" SortIndex="0" SortOrder="GridColumnSortOrder.Ascending" />
                <DxGridDataColumn FieldName="@nameof(CatalogReadDto.CatTitle)" Caption="Titel" />
                <DxGridDataColumn FieldName="@nameof(CatalogReadDto.CatString)" Caption="String" />
                <DxGridDataColumn FieldName="@nameof(CatalogReadDto.AddedWho)" Caption="Angelegt von" ReadOnly="true" />
                <DxGridDataColumn FieldName="@nameof(CatalogReadDto.AddedWhen)" Caption="Angelegt am" ReadOnly="true" />
                <DxGridDataColumn FieldName="@nameof(CatalogReadDto.ChangedWho)" Caption="Geändert von" ReadOnly="true" />
                <DxGridDataColumn FieldName="@nameof(CatalogReadDto.ChangedWhen)" Caption="Geändert am" ReadOnly="true" />
            </Columns>
            <EditFormTemplate Context="editFormContext">
                @{ SetEditContext(editFormContext.EditContext); var editModel = (CatalogEditModel)editFormContext.EditModel; }
                <DxFormLayout ColCount="2">
                    <DxFormLayoutItem Caption="Titel">
                        <DxTextBox @bind-Text="editModel.CatTitle" Width="100%" />
                    </DxFormLayoutItem>
                    <DxFormLayoutItem Caption="Kennung">
                        <DxTextBox @bind-Text="editModel.CatString" Width="100%" />
                    </DxFormLayoutItem>
                    <DxFormLayoutItem Caption="Update-Prozedur">
                        <DxComboBox Data="@procedureOptions"
                                    TData="ProcedureOption"
                                    TValue="int"
                                    TextFieldName="Text"
                                    ValueFieldName="Value"
                                    @bind-Value="editModel.UpdateProcedure"
                                    Width="100%" />
                    </DxFormLayoutItem>
                    <DxFormLayoutItem ColSpanMd="12">
                        <ValidationSummary />
                    </DxFormLayoutItem>
                </DxFormLayout>
            </EditFormTemplate>
        </DxGrid>
    </div>
}

@code {
    private List<CatalogReadDto> items = new();
    private bool isLoading;
    private string? errorMessage;
    private string? infoMessage;
    private EditContext? editContext;
    private ValidationMessageStore? validationMessageStore;

    private readonly List<ProcedureOption> procedureOptions = new()
    {
        new() { Value = 0, Text = "PRTBMY_CATALOG_UPDATE" },
        new() { Value = 1, Text = "PRTBMY_CATALOG_SAVE" }
    };

    protected override async Task OnInitializedAsync()
    {
        await LoadCatalogs();
    }

    private void SetEditContext(EditContext context)
    {
        if (editContext == context)
        {
            return;
        }

        if (editContext != null)
        {
            editContext.OnFieldChanged -= OnEditFieldChanged;
        }

        editContext = context;
        validationMessageStore = new ValidationMessageStore(editContext);
        editContext.OnFieldChanged += OnEditFieldChanged;
    }

    private void OnEditFieldChanged(object? sender, FieldChangedEventArgs e)
    {
        if (validationMessageStore == null || editContext == null)
        {
            return;
        }

        if (e.FieldIdentifier.FieldName == nameof(CatalogEditModel.UpdateProcedure) ||
            e.FieldIdentifier.FieldName == nameof(CatalogEditModel.CatTitle))
        {
            validationMessageStore.Clear();
            editContext.NotifyValidationStateChanged();
        }
    }

    private void OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
    {
        if (e.IsNew)
        {
            e.EditModel = new CatalogEditModel();
            return;
        }

        var item = (CatalogReadDto)e.DataItem;
        e.EditModel = new CatalogEditModel
        {
            Guid = item.Guid,
            CatTitle = item.CatTitle,
            CatString = item.CatString,
            UpdateProcedure = 0,
            OriginalCatTitle = item.CatTitle
        };
    }

    private async Task LoadCatalogs()
    {
        isLoading = true;
        errorMessage = null;
        try
        {
            items = await Api.GetAllAsync();
        }
        catch (Exception ex)
        {
            errorMessage = $"Kataloge konnten nicht geladen werden: {ex.Message}";
        }
        finally
        {
            isLoading = false;
            StateHasChanged();
        }
    }

    private async Task OnEditModelSaving(GridEditModelSavingEventArgs e)
    {
        errorMessage = null;
        infoMessage = null;

        validationMessageStore?.Clear();
        editContext?.NotifyValidationStateChanged();

        var editModel = (CatalogEditModel)e.EditModel;
        if (!ValidateEditModel(editModel, e.IsNew))
        {
            e.Cancel = true;
            return;
        }

        var dto = new CatalogWriteDto
        {
            CatTitle = editModel.CatTitle,
            CatString = editModel.CatString,
            UpdateProcedure = editModel.UpdateProcedure
        };

        try
        {
            if (e.IsNew)
            {
                var created = await Api.CreateAsync(dto);
                if (!created.Success || created.Value == null)
                {
                    if (!string.IsNullOrWhiteSpace(created.Error))
                    {
                        AddValidationError(editModel, nameof(CatalogEditModel.CatTitle), created.Error);
                    }
                    else
                    {
                        errorMessage = "Anlegen fehlgeschlagen.";
                    }

                    e.Cancel = true;
                    return;
                }

                infoMessage = "Katalog angelegt.";
            }
            else
            {
                var updated = await Api.UpdateAsync(editModel.Guid, dto);
                if (!updated.Success)
                {
                    errorMessage = updated.Error ?? "Aktualisierung fehlgeschlagen.";
                    e.Cancel = true;
                    return;
                }

                infoMessage = "Katalog aktualisiert.";
            }

            await LoadCatalogs();
        }
        catch (Exception ex)
        {
            errorMessage = $"Fehler beim Speichern: {ex.Message}";
            e.Cancel = true;
        }
    }

    private void AddValidationError(CatalogEditModel editModel, string fieldName, string message)
    {
        if (editContext == null || validationMessageStore == null)
        {
            return;
        }

        var field = new FieldIdentifier(editModel, fieldName);
        validationMessageStore.Add(field, message);
        editContext.NotifyValidationStateChanged();
    }

    private bool ValidateEditModel(CatalogEditModel editModel, bool isNew)
    {
        if (isNew)
        {
            return true;
        }

        if (editModel.UpdateProcedure == 0 &&
            !string.Equals(editModel.CatTitle, editModel.OriginalCatTitle, StringComparison.OrdinalIgnoreCase))
        {
            AddValidationError(editModel, nameof(CatalogEditModel.CatTitle), "Titel kann nicht geändert werden.");
            return false;
        }

        return true;
    }

    private async Task OnDataItemDeleting(GridDataItemDeletingEventArgs e)
    {
        errorMessage = null;
        infoMessage = null;

        var item = (CatalogReadDto)e.DataItem;

        try
        {
            var deleted = await Api.DeleteAsync(item.Guid);
            if (!deleted.Success)
            {
                errorMessage = deleted.Error ?? "Löschen fehlgeschlagen.";
                e.Cancel = true;
                return;
            }

            infoMessage = "Katalog gelöscht.";
            await LoadCatalogs();
        }
        catch (Exception ex)
        {
            errorMessage = $"Fehler beim Löschen: {ex.Message}";
            e.Cancel = true;
        }
    }

    private sealed class CatalogEditModel
    {
        public int Guid { get; set; }
        public string CatTitle { get; set; } = string.Empty;
        public string CatString { get; set; } = string.Empty;
        public int UpdateProcedure { get; set; }
        public string OriginalCatTitle { get; set; } = string.Empty;
    }

    private sealed class ProcedureOption
    {
        public int Value { get; set; }
        public string Text { get; set; } = string.Empty;
    }
}