import { describe, it } from 'node:test';
import assert from 'node:assert/strict';

import { computeHhi, buildPeriodParam, parseRecords } from '../scripts/seed-recovery-import-hhi.mjs';

describe('seed-recovery-import-hhi', () => {
  it('computes HHI=1 for single-partner imports', () => {
    const records = [{ partnerCode: '156', primaryValue: 1000 }];
    const result = computeHhi(records);
    assert.equal(result.hhi, 1);
    assert.equal(result.partnerCount, 1);
  });

  it('computes HHI for two equal partners', () => {
    const records = [
      { partnerCode: '156', primaryValue: 500 },
      { partnerCode: '842', primaryValue: 500 },
    ];
    const result = computeHhi(records);
    assert.equal(result.hhi, 0.5);
    assert.equal(result.partnerCount, 2);
  });

  it('computes HHI for diversified imports (4 equal partners)', () => {
    const records = [
      { partnerCode: '156', primaryValue: 250 },
      { partnerCode: '842', primaryValue: 250 },
      { partnerCode: '276', primaryValue: 250 },
      { partnerCode: '392', primaryValue: 250 },
    ];
    const result = computeHhi(records);
    assert.equal(result.hhi, 0.25);
    assert.equal(result.partnerCount, 4);
  });

  it('HHI > 0.25 flags concentrated', () => {
    const records = [
      { partnerCode: '156', primaryValue: 900 },
      { partnerCode: '842', primaryValue: 100 },
    ];
    const result = computeHhi(records);
    assert.ok(result.hhi > 0.25, `HHI ${result.hhi} should exceed 0.25 concentration threshold`);
  });

  it('HHI with asymmetric partners matches manual calculation', () => {
    const records = [
      { partnerCode: '156', primaryValue: 600 },
      { partnerCode: '842', primaryValue: 300 },
      { partnerCode: '276', primaryValue: 100 },
    ];
    const result = computeHhi(records);
    const expected = (0.6 ** 2) + (0.3 ** 2) + (0.1 ** 2);
    assert.ok(Math.abs(result.hhi - Math.round(expected * 10000) / 10000) < 0.001);
    assert.equal(result.partnerCount, 3);
  });

  it('excludes world aggregate partner codes (0 and 000)', () => {
    const records = [
      { partnerCode: '0', primaryValue: 5000 },
      { partnerCode: '000', primaryValue: 5000 },
      { partnerCode: '156', primaryValue: 500 },
      { partnerCode: '842', primaryValue: 500 },
    ];
    const result = computeHhi(records);
    assert.equal(result.hhi, 0.5);
    assert.equal(result.partnerCount, 2);
  });

  it('returns null for empty records', () => {
    assert.equal(computeHhi([]), null);
  });

  it('returns null when all records are world aggregates', () => {
    const records = [
      { partnerCode: '0', primaryValue: 1000 },
      { partnerCode: '000', primaryValue: 2000 },
    ];
    assert.equal(computeHhi(records), null);
  });

  // P1 fix: multi-row per partner must aggregate before computing shares
  it('aggregates multiple rows for the same partner before computing shares', () => {
    // Simulates Comtrade returning multiple commodity rows for partner 156
    const records = [
      { partnerCode: '156', primaryValue: 300 },
      { partnerCode: '156', primaryValue: 200 },  // same partner, different commodity
      { partnerCode: '842', primaryValue: 500 },
    ];
    const result = computeHhi(records);
    // After aggregation: 156=500, 842=500 → HHI = 0.5^2 + 0.5^2 = 0.5
    assert.equal(result.hhi, 0.5);
    assert.equal(result.partnerCount, 2, 'partnerCount must count unique partners, not rows');
  });

  it('handles multi-year duplicate rows correctly', () => {
    // Simulates Comtrade returning the same partner across 2 years
    const records = [
      { partnerCode: '156', primaryValue: 400 },  // year 1
      { partnerCode: '156', primaryValue: 600 },  // year 2
      { partnerCode: '842', primaryValue: 200 },  // year 1
      { partnerCode: '842', primaryValue: 300 },  // year 2
    ];
    const result = computeHhi(records);
    // Aggregated: 156=1000, 842=500 → shares: 0.667, 0.333
    // HHI = 0.667^2 + 0.333^2 ≈ 0.5556
    assert.ok(Math.abs(result.hhi - 0.5556) < 0.01, `HHI ${result.hhi} should be ~0.5556`);
    assert.equal(result.partnerCount, 2);
  });
});

// PR 1 of plan 2026-04-24-002: 4-year period window + pick-latest-per-reporter
// to unblock late-reporters (UAE, OM, BH) who publish Comtrade 1-2y behind.
describe('seed-recovery-import-hhi — period window + pick-latest', () => {
  describe('buildPeriodParam', () => {
    it('emits a 4-year window descending from Y-1 to Y-4', () => {
      assert.equal(buildPeriodParam(2026), '2025,2024,2023,2022');
    });

    it('defaults to the current system year when no arg passed', () => {
      const nowYear = new Date().getFullYear();
      const produced = buildPeriodParam();
      const parts = produced.split(',').map(Number);
      assert.equal(parts.length, 4, 'must always produce exactly 4 years');
      assert.equal(parts[0], nowYear - 1, 'first year is Y-1 relative to system clock');
      assert.equal(parts[3], nowYear - 4, 'last year is Y-4');
    });

    it('never emits the current year (Comtrade is always behind by at least 1y)', () => {
      const produced = buildPeriodParam(2026).split(',').map(Number);
      assert.ok(!produced.includes(2026), `${produced} must not include the current year`);
    });
  });

  describe('parseRecords — picks year with most partners', () => {
    it('picks the year with the most partner rows (completeness tiebreak)', () => {
      const data = { data: [
        // 2023 has 3 partners → fewer than 2024
        { period: 2023, partnerCode: '156', primaryValue: 100 },
        { period: 2023, partnerCode: '842', primaryValue: 100 },
        { period: 2023, partnerCode: '276', primaryValue: 100 },
        // 2024 has 5 partners → winner on completeness
        { period: 2024, partnerCode: '156', primaryValue: 100 },
        { period: 2024, partnerCode: '842', primaryValue: 100 },
        { period: 2024, partnerCode: '276', primaryValue: 100 },
        { period: 2024, partnerCode: '392', primaryValue: 100 },
        { period: 2024, partnerCode: '410', primaryValue: 100 },
      ]};
      const { rows, year } = parseRecords(data);
      assert.equal(year, 2024, 'should pick 2024 (more partners)');
      assert.equal(rows.length, 5, 'should return the 2024 rows only');
    });

    it('picks the most recent year when partner counts tie', () => {
      const data = { data: [
        { period: 2022, partnerCode: '156', primaryValue: 100 },
        { period: 2022, partnerCode: '842', primaryValue: 100 },
        { period: 2023, partnerCode: '156', primaryValue: 100 },
        { period: 2023, partnerCode: '842', primaryValue: 100 },
      ]};
      const { rows, year } = parseRecords(data);
      assert.equal(year, 2023, 'should pick the newer year on ties');
      assert.equal(rows.length, 2);
    });

    it('picks the only populated year for late-reporters (the UAE/OM/BH scenario)', () => {
      // UAE pattern: Comtrade has 2023 data but 2024/2025 rows are empty.
      const data = { data: [
        { period: 2023, partnerCode: '156', primaryValue: 500 },
        { period: 2023, partnerCode: '842', primaryValue: 500 },
        { period: 2023, partnerCode: '276', primaryValue: 500 },
        // No 2024/2025 rows — this is what the API returns for a late reporter.
      ]};
      const { rows, year } = parseRecords(data);
      assert.equal(year, 2023, 'must surface 2023 as the latest non-empty year');
      assert.equal(rows.length, 3, 'must return all 2023 rows intact');
    });

    it('returns { rows: [], year: null } on empty input (no IMPUTE surface)', () => {
      assert.deepEqual(parseRecords({ data: [] }), { rows: [], year: null });
      assert.deepEqual(parseRecords({}), { rows: [], year: null });
      assert.deepEqual(parseRecords(null), { rows: [], year: null });
    });

    it('ignores rows with primaryValue <= 0', () => {
      const data = { data: [
        { period: 2024, partnerCode: '156', primaryValue: 0 },
        { period: 2024, partnerCode: '842', primaryValue: -100 },
        { period: 2023, partnerCode: '156', primaryValue: 500 },
      ]};
      const { rows, year } = parseRecords(data);
      assert.equal(year, 2023, 'only 2023 has a positive-value row');
      assert.equal(rows.length, 1);
    });

    it('ignores world-aggregate partner codes (0, 000) in the completeness count', () => {
      // 2024 has one real partner + two world-aggregate rows (4 total rows,
      // but only 1 "usable"); 2023 has two real partners (2 usable). 2023 wins.
      const data = { data: [
        { period: 2024, partnerCode: '0',   primaryValue: 1000 },
        { period: 2024, partnerCode: '000', primaryValue: 1000 },
        { period: 2024, partnerCode: '156', primaryValue: 500 },
        { period: 2023, partnerCode: '156', primaryValue: 500 },
        { period: 2023, partnerCode: '842', primaryValue: 500 },
      ]};
      const { year } = parseRecords(data);
      assert.equal(year, 2023, 'completeness count must exclude world-aggregates');
    });
  });
});