import { describe, it, expect, vi } from 'vitest';
import {
  PromptSummaryService,
  extractFirstSentence,
  extractHeadings,
  type LlmSummaryGenerator,
} from '../../src/services/prompt-summary.service.js';

describe('extractFirstSentence', () => {
  it('extracts first sentence from plain text', () => {
    const result = extractFirstSentence('This is the first sentence. And this is the second.', 20);
    expect(result).toBe('This is the first sentence.');
  });

  it('truncates to maxWords', () => {
    const long = 'word '.repeat(30).trim();
    const result = extractFirstSentence(long, 5);
    expect(result).toBe('word word word word word...');
  });

  it('skips markdown headings to find content', () => {
    const content = '# Title\n\n## Subtitle\n\nActual content here. More text.';
    expect(extractFirstSentence(content, 20)).toBe('Actual content here.');
  });

  it('falls back to first heading if no content lines', () => {
    const content = '# Only Headings\n## Nothing Else';
    expect(extractFirstSentence(content, 20)).toBe('Only Headings');
  });

  it('strips markdown formatting', () => {
    const content = 'This has **bold** and *italic* and `code` and [link](http://example.com).';
    expect(extractFirstSentence(content, 20)).toBe('This has bold and italic and code and link.');
  });

  it('handles empty content', () => {
    expect(extractFirstSentence('', 20)).toBe('');
    expect(extractFirstSentence('   ', 20)).toBe('');
  });

  it('handles content with no sentence boundary', () => {
    const content = 'No period at the end';
    expect(extractFirstSentence(content, 20)).toBe('No period at the end');
  });

  it('handles exclamation and question marks', () => {
    expect(extractFirstSentence('Is this a question? Yes it is.', 20)).toBe('Is this a question?');
    expect(extractFirstSentence('Watch out! Be careful.', 20)).toBe('Watch out!');
  });
});

describe('extractHeadings', () => {
  it('extracts all levels of markdown headings', () => {
    const content = '# H1\n## H2\n### H3\nSome text\n#### H4';
    expect(extractHeadings(content)).toEqual(['H1', 'H2', 'H3', 'H4']);
  });

  it('returns empty array for content without headings', () => {
    expect(extractHeadings('Just plain text\nMore text')).toEqual([]);
  });

  it('handles empty content', () => {
    expect(extractHeadings('')).toEqual([]);
  });

  it('trims heading text', () => {
    const content = '#  Spaced Heading  \n##  Another  ';
    expect(extractHeadings(content)).toEqual(['Spaced Heading', 'Another']);
  });
});

describe('PromptSummaryService', () => {
  it('uses regex fallback when no LLM', async () => {
    const service = new PromptSummaryService(null);
    const result = await service.generateSummary('# Overview\n\nThis is a test document. It has content.\n\n## Section One\n\n## Section Two');
    expect(result.summary).toBe('This is a test document.');
    expect(result.chapters).toEqual(['Overview', 'Section One', 'Section Two']);
  });

  it('uses LLM when available', async () => {
    const mockLlm: LlmSummaryGenerator = {
      generate: vi.fn(async () => ({
        summary: 'LLM-generated summary',
        chapters: ['LLM Chapter 1'],
      })),
    };
    const service = new PromptSummaryService(mockLlm);
    const result = await service.generateSummary('Some content');
    expect(result.summary).toBe('LLM-generated summary');
    expect(result.chapters).toEqual(['LLM Chapter 1']);
    expect(mockLlm.generate).toHaveBeenCalledWith('Some content');
  });

  it('falls back to regex on LLM failure', async () => {
    const mockLlm: LlmSummaryGenerator = {
      generate: vi.fn(async () => { throw new Error('LLM unavailable'); }),
    };
    const service = new PromptSummaryService(mockLlm);
    const result = await service.generateSummary('Fallback content here. Second sentence.');
    expect(result.summary).toBe('Fallback content here.');
    expect(mockLlm.generate).toHaveBeenCalled();
  });

  it('generateWithRegex works directly', () => {
    const service = new PromptSummaryService(null);
    const result = service.generateWithRegex('# Title\n\nContent line. More.\n\n## Chapter A\n\n## Chapter B');
    expect(result.summary).toBe('Content line.');
    expect(result.chapters).toEqual(['Title', 'Chapter A', 'Chapter B']);
  });
});
