import { analytics } from './analytics_engine'; // Import your analytics engine

export interface PivotOptions {
  index: string[];
  columns: string[];
  values: string;
  aggFunc?: (items: number[]) => number; // Aggregation function (e.g., analytics.mean)
}

export function pivotTable(
  data: Record<string, any>[],
  options: PivotOptions
): Record<string, Record<string, number>> {
  const { index, columns, values, aggFunc = arr => arr.reduce((a, b) => a + b, 0) } = options;
  const cellMap: Record<string, Record<string, number[]>> = {};

  data.forEach(row => {
    const rowKey = index.map(k => row[k]).join('|');
    const colKey = columns.map(k => row[k]).join('|');

    if (!cellMap[rowKey]) cellMap[rowKey] = {};
    if (!cellMap[rowKey][colKey]) cellMap[rowKey][colKey] = [];
    cellMap[rowKey][colKey].push(row[values]);
  });

  // Apply aggregation function to each cell
  const result: Record<string, Record<string, number>> = {};
  Object.entries(cellMap).forEach(([rowKey, cols]) => {
    result[rowKey] = {};
    Object.entries(cols).forEach(([colKey, valuesArr]) => {
      result[rowKey][colKey] = aggFunc(valuesArr);
    });
  });

  return result;
}