import { describe, expect, test } from 'bun:test';

import { mergeStreamingText } from '@shared/utils/streamingText';

describe('streaming text merge', () => {
  test('appends plain deltas', () => {
    expect(mergeStreamingText('I am', ' going')).toBe('I am going');
  });

  test('replaces with a growing snapshot when the incoming text already contains the current text', () => {
    expect(mergeStreamingText('I am', 'I am going')).toBe('I am going');
  });

  test('preserves the current text when the incoming update is a duplicate subset', () => {
    expect(mergeStreamingText('I am going', 'going')).toBe('I am going');
  });

  test('uses overlap matching to avoid duplicated joins', () => {
    expect(mergeStreamingText('Hello wor', 'world')).toBe('Hello world');
  });

  test('replaces with a revised snapshot when the updates share most of the same tokens', () => {
    const current = 'I mirror the existing button pattern and add brief toggle docs.';
    const incoming = 'I found the standalone component pattern and I am updating toggle docs next.';

    expect(mergeStreamingText(current, incoming)).toBe(incoming);
  });

  test.each([
    ['requires all wr', 'itable fields', 'requires all writable fields'],
    ['becomes frag', 'ile for clients', 'becomes fragile for clients'],
    ['Endpoint (domain) uniqu', 'eness across tenants', 'Endpoint (domain) uniqueness across tenants'],
    ['The doc says "wildc', 'ards are allowed"', 'The doc says "wildcards are allowed"'],
    [
      'What wildcard syntax supported (*.cont',
      'oso.com? contoso.* ?)',
      'What wildcard syntax supported (*.contoso.com? contoso.* ?)',
    ],
    ['How does Pur', 'view match traffic', 'How does Purview match traffic'],
    ['more M', 'DA properties', 'more MDA properties'],
    ['does UA', 'G normalize them?', 'does UAG normalize them?'],
  ])('does not inject spaces into split words: %s + %s', (current, incoming, expected) => {
    expect(mergeStreamingText(current, incoming)).toBe(expected);
  });

  test('preserves whitespace already present in delta', () => {
    expect(mergeStreamingText('How about', ' The **Ashen Crown** feels')).toBe(
      'How about The **Ashen Crown** feels',
    );
    expect(mergeStreamingText('The **Ashen Crown** feels', ' classic and timeless.')).toBe(
      'The **Ashen Crown** feels classic and timeless.',
    );
  });

  test('preserves newline already present in delta', () => {
    expect(mergeStreamingText('If you want, I can also give you', '\n- darker titles')).toBe(
      'If you want, I can also give you\n- darker titles',
    );
  });
});