import { describe, it, expect } from 'vitest';
import { packEmptiesOntoWagons, wagonsNeeded, type EmptyLoadPick } from './emptyContainerLoad.util';

const pick = (id: string, containerSize: '20' | '40'): EmptyLoadPick => ({ id, containerSize });

describe('emptyContainerLoad.util', () => {
  it('gives each 40ft its own wagon', () => {
    const { assignments, unplaced } = packEmptiesOntoWagons(
      [pick('a', '40'), pick('b', '40')],
      [1, 2, 3],
    );
    expect(unplaced).toEqual([]);
    expect(assignments.map((a) => a.wagonSequenceNo)).toEqual([1, 2]);
  });

  it('pairs 20ft two to a wagon, last odd one alone', () => {
    const { assignments } = packEmptiesOntoWagons(
      [pick('a', '20'), pick('b', '20'), pick('c', '20')],
      [4, 5],
    );
    expect(assignments.map((a) => [a.id, a.wagonSequenceNo])).toEqual([
      ['a', 4],
      ['b', 4],
      ['c', 5],
    ]);
  });

  it('never mixes a 40ft and a 20ft on one wagon', () => {
    const { assignments } = packEmptiesOntoWagons(
      [pick('a', '20'), pick('b', '40'), pick('c', '20')],
      [1, 2],
    );
    const bySizeOnWagon = new Map<number, string[]>();
    for (const a of assignments) {
      bySizeOnWagon.set(a.wagonSequenceNo, [
        ...(bySizeOnWagon.get(a.wagonSequenceNo) ?? []),
        a.containerSize,
      ]);
    }
    for (const sizes of bySizeOnWagon.values()) {
      expect(sizes.includes('40') ? sizes.length : 0).toBeLessThan(2);
      expect(sizes.length).toBeLessThanOrEqual(2);
    }
  });

  it('reports picks that ran out of wagons instead of dropping them', () => {
    const { assignments, unplaced } = packEmptiesOntoWagons(
      [pick('a', '40'), pick('b', '40'), pick('c', '20'), pick('d', '20')],
      [7],
    );
    expect(assignments).toHaveLength(1);
    expect(unplaced.map((p) => p.id)).toEqual(['b', 'c', 'd']);
  });

  it('counts wagons needed', () => {
    expect(wagonsNeeded([])).toBe(0);
    expect(wagonsNeeded([pick('a', '40'), pick('b', '20'), pick('c', '20')])).toBe(2);
    expect(wagonsNeeded([pick('a', '20')])).toBe(1);
  });
});