import { Pipe, PipeTransform } from "@angular/core";

@Pipe({
  name: "groupBy",
})
export class GroupByPipe implements PipeTransform {
  transform(collection: any, property: string): any {
    if (!collection) {
      return null;
    }
    const groupedCollection = collection.reduce((previous, current) => {
      if (!previous[current[property]]) {
        previous[current[property]] = [current];
      } else {
        previous[current[property]].push(current);
      }
      return previous;
    }, {});
    return Object.keys(groupedCollection).map((key) => ({
      key,
      value: groupedCollection[key],
    }));
  }
}