import {
  canAggregate, aggregateCells,
  canRenderBar, toBarSegments, CARD_GROUPS,
  type DestinationCell, type DestinationGroup, type DestinationCategory,
} from '@/lib/destinations';

const pub = (category: DestinationCategory, pupils: number, cohort: number): DestinationCell => ({
  category, pupils, percentage: (pupils / cohort) * 100, status: 'published',
});
const sup = (category: DestinationCategory): DestinationCell => ({
  category, pupils: null, percentage: null, status: 'suppressed',
});

const fullGroup = (): DestinationGroup => ({
  cohort: 180,
  cells: [
    pub('school_sixth_form', 75, 180), pub('sixth_form_college', 21, 180),
    pub('further_education', 55, 180), pub('other_education', 6, 180),
    pub('apprenticeship', 8, 180), pub('employment', 6, 180),
    pub('not_sustained', 5, 180), pub('not_captured', 4, 180),
  ],
});

describe('canAggregate — R2, computing from components', () => {
  it('allows a sum when every component is published', () => {
    expect(canAggregate([pub('apprenticeship', 8, 180), pub('employment', 6, 180)])).toBe(true);
  });

  it('refuses a sum when any component is suppressed', () => {
    expect(canAggregate([pub('apprenticeship', 8, 180), sup('employment')])).toBe(false);
  });

  it('refuses a sum when every component is suppressed', () => {
    expect(canAggregate([sup('apprenticeship'), sup('employment')])).toBe(false);
  });
});

describe('aggregateCells', () => {
  it('sums published cells and derives a percentage from the cohort', () => {
    expect(aggregateCells([pub('apprenticeship', 8, 180), pub('employment', 6, 180)], 180))
      .toEqual({ pupils: 14, percentage: (14 / 180) * 100 });
  });

  it('returns null rather than a partial sum when a component is suppressed', () => {
    expect(aggregateCells([pub('apprenticeship', 8, 180), sup('employment')], 180)).toBeNull();
  });
});

describe('canRenderBar — R1', () => {
  it('allows a bar when the whole group is published', () => {
    expect(canRenderBar(fullGroup())).toBe(true);
  });

  it('refuses a bar when a single category is suppressed', () => {
    const g = fullGroup();
    g.cells[1] = sup('sixth_form_college');
    expect(canRenderBar(g)).toBe(false);
  });
});

describe('toBarSegments', () => {
  it('derives widths from counts, not from rounded percentages', () => {
    const segs = toBarSegments(fullGroup());
    expect(segs).toHaveLength(8);
    expect(segs[0].widthPct).toBeCloseTo((75 / 180) * 100, 10);
    expect(segs.reduce((a, s) => a + s.widthPct, 0)).toBeCloseTo(100, 6);
  });

  it('throws rather than silently leaving a gap when the group is suppressed', () => {
    const g = fullGroup();
    g.cells[1] = sup('sixth_form_college');
    expect(() => toBarSegments(g)).toThrow(/suppressed/i);
  });
});

describe('CARD_GROUPS', () => {
  it('partitions every destination category exactly once, plus the absence', () => {
    const grouped = Object.values(CARD_GROUPS).flat();
    expect(new Set(grouped).size).toBe(grouped.length);
    expect(grouped).toEqual(expect.arrayContaining([
      'school_sixth_form', 'sixth_form_college', 'further_education',
      'other_education', 'apprenticeship', 'employment',
    ]));
    expect(grouped).not.toContain('not_sustained');
    expect(grouped).not.toContain('not_captured');
  });
});