DbFirst/DbFirst.BlazorWebApp/Components/CatalogsGrid.razor

@using System.Text.Json
@using Microsoft.AspNetCore.Components
@using Microsoft.AspNetCore.Components.Rendering
@using Microsoft.AspNetCore.Components.Forms
@using DevExpress.Blazor
@inject CatalogApiClient Api
@inject LayoutApiClient LayoutApi
@inject IJSRuntime JsRuntime

<style>
    .action-panel { margin-bottom: 16px; }
    .grid-section { margin-top: 12px; }
    .catalog-edit-popup {
        min-width: 720px;
    }
    .band-editor {
        display: grid;
        gap: 12px;
        margin-bottom: 16px;
    }
    .band-controls {
        display: flex;
        flex-wrap: wrap;
        gap: 8px;
        align-items: center;
    }
    .band-row {
        display: flex;
        gap: 8px;
        align-items: center;
    }
    .band-columns {
        max-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="band-editor">
        <div class="band-controls">
            <DxButton Text="Band hinzufügen" Click="AddBand" />
            <DxButton Text="Layout speichern" Click="SaveLayoutAsync" Enabled="@CanSaveBandLayout" />
            <DxButton Text="Band-Layout zurücksetzen" Click="ResetBandLayoutAsync" />
        </div>
        @foreach (var band in bandLayout.Bands)
        {
            <div class="band-row">
                <DxTextBox Text="@band.Caption" TextChanged="@(value => UpdateBandCaption(band, value))" />
                <DxButton Text="Entfernen" Click="@(() => RemoveBand(band))" />
            </div>
        }
        <DxFormLayout CssClass="band-columns" ColCount="2">
            @foreach (var column in columnDefinitions)
            {
                <DxFormLayoutItem Caption="@column.Caption">
                    <DxComboBox Data="@bandOptions"
                                TData="BandOption"
                                TValue="string"
                                TextFieldName="Caption"
                                ValueFieldName="Id"
                                Value="@GetColumnBand(column.FieldName)"
                                ValueChanged="@(value => UpdateColumnBand(column.FieldName, value))"
                                Width="100%" />
                </DxFormLayoutItem>
            }
        </DxFormLayout>
    </div>

    <div class="grid-section">
        <DxGrid Data="@items"
                TItem="CatalogReadDto"
                KeyFieldName="@nameof(CatalogReadDto.Guid)"
                ShowGroupPanel="true"
                ShowGroupedColumns="true"
                AllowGroup="true"
                ShowFilterRow="true"
                AllowColumnResize="true"
                ColumnResizeMode="GridColumnResizeMode.ColumnsContainer"
                AllowColumnReorder="true"
                PageSize="10"
                CssClass="mb-4 catalog-grid"
                EditMode="GridEditMode.PopupEditForm"
                PopupEditFormCssClass="catalog-edit-popup"
                PopupEditFormHeaderText="@popupHeaderText"
                CustomizeEditModel="OnCustomizeEditModel"
                EditModelSaving="OnEditModelSaving"
                DataItemDeleting="OnDataItemDeleting"
                @ref="gridRef">
            <Columns>
                @RenderColumns()
            </Columns>
            <EditFormTemplate Context="editFormContext">
                @{ SetEditContext(editFormContext.EditContext); var editModel = (CatalogEditModel)editFormContext.EditModel; SetPopupHeaderText(editModel.IsNew); }
                <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>
                    @if (!editModel.IsNew)
                    {
                        <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 IGrid? gridRef;
    private string popupHeaderText = "Edit";
    private const string LayoutType = "GRID_BANDS";
    private const string LayoutKey = "CatalogsGrid";
    private const string LayoutUserStorageKey = "layoutUser";
    private string? layoutUser;
    private BandLayout bandLayout = new();
    private Dictionary<string, string> columnBandAssignments = new();
    private List<BandOption> bandOptions = new();
    private Dictionary<string, ColumnDefinition> columnLookup = new();
    private readonly JsonSerializerOptions jsonOptions = new(JsonSerializerDefaults.Web);
    private List<ColumnDefinition> columnDefinitions = new()
    {
        new() { FieldName = nameof(CatalogReadDto.Guid), Caption = "Id", Width = "140px", FilterType = ColumnFilterType.Text },
        new() { FieldName = nameof(CatalogReadDto.CatTitle), Caption = "Titel", FilterType = ColumnFilterType.Text },
        new() { FieldName = nameof(CatalogReadDto.CatString), Caption = "String", FilterType = ColumnFilterType.Text },
        new() { FieldName = nameof(CatalogReadDto.AddedWho), Caption = "Angelegt von", ReadOnly = true, FilterType = ColumnFilterType.Text },
        new() { FieldName = nameof(CatalogReadDto.AddedWhen), Caption = "Angelegt am", ReadOnly = true, FilterType = ColumnFilterType.Date },
        new() { FieldName = nameof(CatalogReadDto.ChangedWho), Caption = "Geändert von", ReadOnly = true, FilterType = ColumnFilterType.Text },
        new() { FieldName = nameof(CatalogReadDto.ChangedWhen), Caption = "Geändert am", ReadOnly = true, FilterType = ColumnFilterType.Date }
    };

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

    private bool CanSaveBandLayout => !string.IsNullOrWhiteSpace(layoutUser);

    protected override async Task OnInitializedAsync()
    {
        columnLookup = columnDefinitions.ToDictionary(column => column.FieldName, StringComparer.OrdinalIgnoreCase);
        await EnsureLayoutUserAsync();
        await LoadBandLayoutAsync();
        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))
        {
            validationMessageStore.Clear();
            editContext.NotifyValidationStateChanged();
            return;
        }

        if (e.FieldIdentifier.FieldName == nameof(CatalogEditModel.CatTitle))
        {
            var field = new FieldIdentifier(editContext.Model, nameof(CatalogEditModel.CatTitle));
            validationMessageStore.Clear(field);
            editContext.NotifyValidationStateChanged();
        }
    }

    private void SetPopupHeaderText(bool isNew)
    {
        popupHeaderText = isNew ? "Neu" : "Edit";
    }

    private void OnCustomizeEditModel(GridCustomizeEditModelEventArgs e)
    {
        popupHeaderText = e.IsNew ? "Neu" : "Edit";
        if (e.IsNew)
        {
            e.EditModel = new CatalogEditModel { IsNew = true };
            return;
        }

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

    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 async Task EnsureLayoutUserAsync()
    {
        layoutUser = await JsRuntime.InvokeAsync<string?>("localStorage.getItem", LayoutUserStorageKey);
        if (string.IsNullOrWhiteSpace(layoutUser))
        {
            layoutUser = Guid.NewGuid().ToString("N");
            await JsRuntime.InvokeVoidAsync("localStorage.setItem", LayoutUserStorageKey, layoutUser);
        }
    }

    private async Task SaveLayoutAsync()
    {
        if (string.IsNullOrWhiteSpace(layoutUser))
        {
            return;
        }

        try
        {
            CaptureColumnLayoutFromGrid();

            var layoutData = JsonSerializer.Serialize(bandLayout, jsonOptions);
            await LayoutApi.UpsertAsync(new LayoutDto
            {
                LayoutType = LayoutType,
                LayoutKey = LayoutKey,
                UserName = layoutUser,
                LayoutData = layoutData
            });
            infoMessage = "Layout gespeichert.";
            errorMessage = null;
        }
        catch (Exception ex)
        {
            errorMessage = $"Layout konnte nicht gespeichert werden: {ex.Message}";
        }
    }

    private void CaptureColumnLayoutFromGrid()
    {
        if (gridRef == null)
        {
            return;
        }

        var layout = gridRef.SaveLayout();
        bandLayout.GridLayout = layout;

        var orderedColumns = layout.Columns
            .Where(column => !string.IsNullOrWhiteSpace(column.FieldName))
            .OrderBy(column => column.VisibleIndex)
            .ToList();

        bandLayout.ColumnOrder = orderedColumns
            .Select(column => column.FieldName)
            .ToList();

        bandLayout.ColumnWidths = orderedColumns
            .Where(column => !string.IsNullOrWhiteSpace(column.Width))
            .ToDictionary(column => column.FieldName, column => column.Width, StringComparer.OrdinalIgnoreCase);
    }

    private async Task LoadBandLayoutAsync()
    {
        if (string.IsNullOrWhiteSpace(layoutUser))
        {
            bandLayout = new BandLayout();
            UpdateBandOptions();
            return;
        }

        var stored = await LayoutApi.GetAsync(LayoutType, LayoutKey, layoutUser);
        if (stored != null && !string.IsNullOrWhiteSpace(stored.LayoutData))
        {
            var parsed = JsonSerializer.Deserialize<BandLayout>(stored.LayoutData, jsonOptions);
            bandLayout = NormalizeBandLayout(parsed);
        }
        else
        {
            bandLayout = new BandLayout();
        }

        columnBandAssignments = BuildAssignmentsFromLayout(bandLayout);
        ApplyColumnLayoutFromStorage();
        UpdateBandOptions();
    }

    private void AddBand()
    {
        bandLayout.Bands.Add(new BandDefinition
        {
            Id = Guid.NewGuid().ToString("N"),
            Caption = "Band"
        });
        UpdateBandOptions();
    }

    private void RemoveBand(BandDefinition band)
    {
        bandLayout.Bands.Remove(band);
        var removedColumns = columnBandAssignments.Where(pair => pair.Value == band.Id)
            .Select(pair => pair.Key)
            .ToList();
        foreach (var column in removedColumns)
        {
            columnBandAssignments.Remove(column);
        }
        UpdateBandOptions();
        SyncBandsFromAssignments();
    }

    private void UpdateBandCaption(BandDefinition band, string value)
    {
        band.Caption = value;
        UpdateBandOptions();
    }

    private void UpdateColumnBand(string fieldName, string? bandId)
    {
        if (string.IsNullOrWhiteSpace(bandId))
        {
            columnBandAssignments.Remove(fieldName);
        }
        else
        {
            columnBandAssignments[fieldName] = bandId;
        }

        SyncBandsFromAssignments();
    }

    private string GetColumnBand(string fieldName)
    {
        return columnBandAssignments.TryGetValue(fieldName, out var bandId) ? bandId : string.Empty;
    }

    private void SyncBandsFromAssignments()
    {
        foreach (var band in bandLayout.Bands)
        {
            band.Columns = columnDefinitions
                .Where(column => columnBandAssignments.TryGetValue(column.FieldName, out var bandId) && bandId == band.Id)
                .Select(column => column.FieldName)
                .ToList();
        }

        StateHasChanged();
    }

    private void UpdateBandOptions()
    {
        bandOptions = new List<BandOption> { new() { Id = string.Empty, Caption = "Ohne Band" } };
        bandOptions.AddRange(bandLayout.Bands.Select(band => new BandOption { Id = band.Id, Caption = band.Caption }));
    }

    private BandLayout NormalizeBandLayout(BandLayout? layout)
    {
        layout ??= new BandLayout();
        layout.Bands ??= new List<BandDefinition>();
        layout.ColumnOrder ??= new List<string>();
        layout.ColumnWidths ??= new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase);
        foreach (var band in layout.Bands)
        {
            if (string.IsNullOrWhiteSpace(band.Id))
            {
                band.Id = Guid.NewGuid().ToString("N");
            }

            if (string.IsNullOrWhiteSpace(band.Caption))
            {
                band.Caption = "Band";
            }

            band.Columns = band.Columns?.Where(columnLookup.ContainsKey).ToList() ?? new List<string>();
        }

        return layout;
    }

    private Dictionary<string, string> BuildAssignmentsFromLayout(BandLayout layout)
    {
        var assignments = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
        foreach (var band in layout.Bands)
        {
            foreach (var column in band.Columns)
            {
                assignments[column] = band.Id;
            }
        }

        return assignments;
    }

    private RenderFragment RenderColumns() => builder =>
    {
        var seq = 0;
        builder.OpenComponent<DxGridCommandColumn>(seq++);
        builder.AddAttribute(seq++, "Width", "120px");
        builder.CloseComponent();

        var grouped = bandLayout.Bands.SelectMany(band => band.Columns).ToHashSet(StringComparer.OrdinalIgnoreCase);
        foreach (var column in columnDefinitions.Where(column => !grouped.Contains(column.FieldName)))
        {
            BuildDataColumn(builder, ref seq, column);
        }

        foreach (var band in bandLayout.Bands)
        {
            if (band.Columns.Count == 0)
            {
                continue;
            }

            builder.OpenComponent<DxGridBandColumn>(seq++);
            builder.AddAttribute(seq++, "Caption", band.Caption);
            builder.AddAttribute(seq++, "Columns", (RenderFragment)(bandBuilder =>
            {
                var bandSeq = 0;
                foreach (var columnName in band.Columns)
                {
                    if (columnLookup.TryGetValue(columnName, out var column))
                    {
                        BuildDataColumn(bandBuilder, ref bandSeq, column);
                    }
                }
            }));
            builder.CloseComponent();
        }
    };

    private void BuildDataColumn(RenderTreeBuilder builder, ref int seq, ColumnDefinition column)
    {
        builder.OpenComponent<DxGridDataColumn>(seq++);
        builder.AddAttribute(seq++, "FieldName", column.FieldName);
        builder.AddAttribute(seq++, "Caption", column.Caption);
        if (!string.IsNullOrWhiteSpace(column.Width))
        {
            builder.AddAttribute(seq++, "Width", column.Width);
        }

        if (!string.IsNullOrWhiteSpace(column.DisplayFormat))
        {
            builder.AddAttribute(seq++, "DisplayFormat", column.DisplayFormat);
        }

        if (column.ReadOnly)
        {
            builder.AddAttribute(seq++, "ReadOnly", true);
        }

        builder.CloseComponent();
    }

    private sealed class BandLayout
    {
        public List<BandDefinition> Bands { get; set; } = new();
        public List<string> ColumnOrder { get; set; } = new();
        public Dictionary<string, string?> ColumnWidths { get; set; } = new(StringComparer.OrdinalIgnoreCase);
        public GridPersistentLayout? GridLayout { get; set; }
    }

    private sealed class BandDefinition
    {
        public string Id { get; set; } = string.Empty;
        public string Caption { get; set; } = string.Empty;
        public List<string> Columns { get; set; } = new();
    }

    private sealed class BandOption
    {
        public string Id { get; set; } = string.Empty;
        public string Caption { get; set; } = string.Empty;
    }

    private sealed class ColumnDefinition
    {
        public string FieldName { get; init; } = string.Empty;
        public string Caption { get; init; } = string.Empty;
        public string? Width { get; set; }
        public string? DisplayFormat { get; init; }
        public bool ReadOnly { get; init; }
        public ColumnFilterType FilterType { get; init; }
    }

    private enum ColumnFilterType
    {
        Text,
        Date
    }

    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;
        public bool IsNew { get; set; }
    }

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

    private async Task ResetBandLayoutAsync()
    {
        if (string.IsNullOrWhiteSpace(layoutUser))
        {
            return;
        }

        await LayoutApi.DeleteAsync(LayoutType, LayoutKey, layoutUser);
        bandLayout = new BandLayout();
        columnBandAssignments.Clear();
        UpdateBandOptions();
        infoMessage = "Band-Layout zurückgesetzt.";
    }

    private void ApplyColumnLayoutFromStorage()
    {
        foreach (var column in columnDefinitions)
        {
            if (bandLayout.ColumnWidths.TryGetValue(column.FieldName, out var width) && !string.IsNullOrWhiteSpace(width))
            {
                column.Width = width;
            }
        }

        columnLookup = columnDefinitions.ToDictionary(column => column.FieldName, StringComparer.OrdinalIgnoreCase);
    }

    private bool gridLayoutApplied;

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (!gridLayoutApplied && gridRef != null && bandLayout.GridLayout != null)
        {
            gridRef.LoadLayout(bandLayout.GridLayout);
            gridLayoutApplied = true;
            await InvokeAsync(StateHasChanged);
        }
    }
}