import { describe, it, expect } from 'vitest';

const { matchPlural, PLURALS } = require('../plurals');

describe('matchPlural', () => {
  it('returns null for empty/null input', () => {
    expect(matchPlural('')).toBeNull();
    expect(matchPlural(null)).toBeNull();
    expect(matchPlural(undefined)).toBeNull();
  });

  it('returns null for unknown nouns', () => {
    expect(matchPlural('dragon fruit ')).toBeNull();
    expect(matchPlural('toaster ')).toBeNull();
  });

  it('matches singular noun at end of text', () => {
    const result = matchPlural('onion ');
    expect(result).not.toBeNull();
    expect(result.singular).toBe('onion');
    expect(result.plural).toBe('onions');
  });

  it('matches plural noun at end of text', () => {
    const result = matchPlural('eggs ');
    expect(result).not.toBeNull();
    expect(result.singular).toBe('egg');
    expect(result.plural).toBe('eggs');
  });

  it('is case-insensitive', () => {
    expect(matchPlural('Onion ')).not.toBeNull();
    expect(matchPlural('EGGS ')).not.toBeNull();
    expect(matchPlural('Tomatoes ')).not.toBeNull();
  });

  it('trims trailing whitespace', () => {
    const result = matchPlural('onion   ');
    expect(result).not.toBeNull();
    expect(result.singular).toBe('onion');
  });

  it('respects word boundaries', () => {
    // "megg" should not match "egg"
    expect(matchPlural('megg ')).toBeNull();
    // "button" should not match as containing a known noun
    expect(matchPlural('button ')).toBeNull();
  });

  it('matches multi-word nouns (longest first)', () => {
    const result = matchPlural('garlic clove ');
    expect(result).not.toBeNull();
    expect(result.singular).toBe('garlic clove');
    expect(result.plural).toBe('garlic cloves');
  });

  it('matches "clove" when not preceded by "garlic"', () => {
    const result = matchPlural('clove ');
    expect(result).not.toBeNull();
    expect(result.singular).toBe('clove');
    expect(result.plural).toBe('cloves');
  });

  it('matches "bell pepper" before "pepper"', () => {
    const result = matchPlural('bell pepper ');
    expect(result).not.toBeNull();
    expect(result.singular).toBe('bell pepper');
    expect(result.plural).toBe('bell peppers');
  });

  it('matches "pepper" standalone', () => {
    const result = matchPlural('pepper ');
    expect(result).not.toBeNull();
    expect(result.singular).toBe('pepper');
    expect(result.plural).toBe('peppers');
  });

  it('provides correct matchStart and matchLength', () => {
    const result = matchPlural('white onion ');
    expect(result).not.toBeNull();
    expect(result.matchStart).toBe(6); // "white " is 6 chars
    expect(result.matchLength).toBe(5); // "onion" is 5 chars
  });

  it('handles text with prefix before noun', () => {
    const result = matchPlural('- [ ] eggs ');
    expect(result).not.toBeNull();
    expect(result.singular).toBe('egg');
    expect(result.plural).toBe('eggs');
  });

  it('matches egg yolk and egg white', () => {
    expect(matchPlural('egg yolk ')).not.toBeNull();
    expect(matchPlural('egg yolk ').singular).toBe('egg yolk');
    expect(matchPlural('egg white ')).not.toBeNull();
    expect(matchPlural('egg white ').singular).toBe('egg white');
  });

  it('dictionary is sorted longest-first', () => {
    for (let i = 0; i < PLURALS.length - 1; i++) {
      const currentLen = Math.max(PLURALS[i].singular.length, PLURALS[i].plural.length);
      const nextLen = Math.max(PLURALS[i + 1].singular.length, PLURALS[i + 1].plural.length);
      expect(currentLen).toBeGreaterThanOrEqual(nextLen);
    }
  });
});