NgPivotGrid — Pivot grid

<div class="toolbar">
<NgButton OnClick="()=>rowTotals=!rowTotals">Toggle row totals</NgButton>
<NgButton OnClick="()=>columnTotals=!columnTotals">Toggle column totals</NgButton>
<NgButton OnClick="()=>locked=!locked">Toggle selection lock</NgButton>
<NgButton OnClick="()=>average=!average">Toggle average</NgButton>
<NgButton OnClick="()=>empty=!empty">Toggle empty data</NgButton>
<NgButton OnClick="()=>records=Data(2)">Update values</NgButton>
</div>
<p>Row totals @(rowTotals?"shown":"hidden") · Column totals @(columnTotals?"shown":"hidden") · Selection @(locked?"locked":"enabled")</p>
<NgPivotGrid Items="@(empty?[]:records)" Aggregate="@(average?NgAggregate.Average:NgAggregate.Sum)" ShowRowTotals="rowTotals" ShowColumnTotals="columnTotals" SelectionReadOnly="locked" ValueFormatter="Format" RowLabel="RowText" ColumnLabel="ColumnText" TotalText="All" EmptyText="No matching deliveries" OnCellSelected="Selected"/>
<p role="status">Last drilldown: @message</p>
@code {
 private bool rowTotals=true,columnTotals=true,locked,average,empty;
 private string message="none";
 private NgPivotRecord[] records=Data(1);
 private string Format(double? v)=>v.HasValue?v.Value.ToString("F1",System.Globalization.CultureInfo.InvariantCulture)+" credits":"No value";
 private string RowText(string v)=>v==""?"Unassigned":"Team "+v;
 private string ColumnText(string v)=>"Period "+v;
 private void Selected(NgPivotSelection p)=>message=$"{p.Row??"(total)"} / {p.Column??"(total)"} · {p.Records.Count} records · IDs: {string.Join(",",p.Records.Select(r=>r.Id))}";
 private static NgPivotRecord[] Data(int factor)=>[new("a",new Dictionary<string,string>{{"Team","A"},{"Quarter","Q1"}},10*factor),new("b",new Dictionary<string,string>{{"Team","A"},{"Quarter","Q1"}},30*factor),new("c",new Dictionary<string,string>{{"Team","B"},{"Quarter","Q2"}},90*factor),new("d",new Dictionary<string,string>{{"Team",""},{"Quarter","Q1"}},null)];
}

bool rowTotals=true,columnTotals=true,locked=false,average=false,empty=false;
String message='none';
List<NgPivotRecord> records=data(1);
static List<NgPivotRecord> data(int factor)=>[NgPivotRecord('a',{'Team':'A','Quarter':'Q1'},10.0*factor),NgPivotRecord('b',{'Team':'A','Quarter':'Q1'},30.0*factor),NgPivotRecord('c',{'Team':'B','Quarter':'Q2'},90.0*factor),NgPivotRecord('d',{'Team':'','Quarter':'Q1'},null)];
Widget build(BuildContext context)=>Column(crossAxisAlignment:CrossAxisAlignment.stretch,children:[
 Wrap(spacing:8,runSpacing:8,children:[
  NgButton(onPressed:()=>setState(()=>rowTotals=!rowTotals),child:const Text('Toggle row totals')),
  NgButton(onPressed:()=>setState(()=>columnTotals=!columnTotals),child:const Text('Toggle column totals')),
  NgButton(onPressed:()=>setState(()=>locked=!locked),child:const Text('Toggle selection lock')),
  NgButton(onPressed:()=>setState(()=>average=!average),child:const Text('Toggle average')),
  NgButton(onPressed:()=>setState(()=>empty=!empty),child:const Text('Toggle empty data')),
  NgButton(onPressed:()=>setState(()=>records=data(2)),child:const Text('Update values')),
 ]),
 Text('Row totals ${rowTotals?"shown":"hidden"} · Column totals ${columnTotals?"shown":"hidden"} · Selection ${locked?"locked":"enabled"}'),
 NgPivotGrid(items:empty?const []:records,aggregate:average?NgAggregate.average:NgAggregate.sum,showRowTotals:rowTotals,showColumnTotals:columnTotals,selectionReadOnly:locked,
  valueFormatter:(v)=>v==null?'No value':'${v.toStringAsFixed(1)} credits',rowLabel:(v)=>v.isEmpty?'Unassigned':'Team $v',columnLabel:(v)=>'Period $v',totalText:'All',emptyText:'No matching deliveries',
  onCellSelected:(p)=>setState(()=>message='${p.row??"(total)"} / ${p.column??"(total)"} · ${p.records.length} records · IDs: ${p.records.map((r)=>r.id).join(",")}')),
 Text('Last drilldown: $message'),
]);

const NgPivotGrid({
    super.key,
    this.label = 'Pivot table',
    required this.items,
    this.rowField = 'Team',
    this.columnField = 'Quarter',
    this.aggregate = NgAggregate.sum,
    this.onCellSelected,
    this.showRowTotals = true,
    this.showColumnTotals = true,
    this.selectionReadOnly = false,
    this.totalText = 'Total',
    this.emptyText = 'No pivot data.',
    this.valueFormatter,
    this.rowLabel,
    this.columnLabel,
  });