function isNumericArray(data: unknown[]): data is number[] {
  return data.every(i => !Number.isNaN(i)) ? true : false;
}

import { ISummaryBuiltIns } from './p-table-types';

export const builtInSummaryFns: Record<ISummaryBuiltIns, (data: unknown[]) => any> = {
  avg: data => {
    if (isNumericArray(data)) {
      return data.length > 0 ? data.reduce((acc, item) => acc + item, 0) / data.length : undefined;
    } else {
      console.warn(`Attempt to average a non-numeric column`, data);
    }
  },
  mean: data => {
    if (isNumericArray(data)) {
      const length = data.length;
      if (length === 0) return undefined;

      const mid = Math.floor(length / 2);

      return data.length % 2 ? data[mid] : builtInSummaryFns.avg([data[mid], data[mid - 1]]);
    } else {
      console.warn(`Attempt to get the "mean" of a non-numeric column`, data);
    }
  },
  min: data => {
    if (isNumericArray(data)) {
      return data.length > 0 ? Math.min(...data) : undefined;
    } else {
      console.warn(`Attempt to find a "max" of a non-numeric column`, data);
    }
  },
  max: data => {
    if (isNumericArray(data)) {
      return data.length > 0 ? Math.max(...data) : undefined;
    } else {
      console.warn(`Attempt to find a "max" of a non-numeric column`, data);
    }
  },
};