bulk.ts

export enum BulkTypes {
  SEQUENCE = 'SEQUENCE',
  NOT_SEQUENCE = 'NOT_SEQUENCE',
}

interface NotSequenceValue {
  numbers: number[];
  type: BulkTypes.NOT_SEQUENCE;
}

interface SequenceValue {
  numbers: [number, number];
  type: BulkTypes.SEQUENCE;
}

type Value = SequenceValue | NotSequenceValue;

export const createBulk = <A, V>(
  data: A[],
  getNumber: (data: A) => number,
  getValue: (data: Value) => V,
): V[] => {
  const values: V[] = [];

  let i = 0;
  while (i < data.length) {
    const value = getNumber(data[i]);
    const nextValue = getNumber(data[i + 1]);

    if (nextValue === value + 1) {
      let count = 1;
      while (
        data[i + count + 1] &&
        getNumber(data[i + count + 1]) === getNumber(data[i + count]) + 1
      ) {
        count++;
      }

      values.push(
        getValue({
          numbers: [value, getNumber(data[i + count])],
          type: BulkTypes.SEQUENCE,
        }),
      );

      i += count + 1;
    } else {
      let count = 1;
      const diffNumbers: number[] = [value];
      while (
        data[i + count + 1] &&
        getNumber(data[i + count + 1]) !== getNumber(data[i + count]) + 1
      ) {
        diffNumbers.push(getNumber(data[i + count]));
        count++;
      }

      values.push(
        getValue({
          numbers: diffNumbers,
          type: BulkTypes.NOT_SEQUENCE,
        }),
      );

      i += count;
    }
  }

  return values;
};


const numbers = [1, 2, 3, 4, 6, 7, 8, 56, 66, 67, 34, 356, 4657, 745, 746, 747];
console.log(createBulk(numbers, (v) => v);
// output:
// [{
//   "numbers": [
//     1,
//     4
//   ],
//   "type": "BULK"
// }, {
//   "numbers": [
//     6,
//     8
//   ],
//   "type": "BULK"
// }, {
//   "numbers": [
//     56,
//     66,
//     67,
//     34,
//     356,
//     4657
//   ],
//   "type": "SEQUENCE"
// }, {
//   "numbers": [
//     745,
//     747
//   ],
//   "type": "BULK"
// }]