import { describe, it, expect, vi } from 'vitest';
import { execSync } from 'child_process';
import { getChangedFiles, getCommitMessage, getPrDescription } from '../src/git';

vi.mock('child_process', () => ({
  execSync: vi.fn(),
}));

describe('git', () => {
  beforeEach(() => {
    vi.resetAllMocks();
  });

  it('returns changed files from git diff', () => {
    vi.mocked(execSync).mockReturnValue('src/a.ts\nsrc/b.ts\n');
    const files = getChangedFiles();
    expect(files).toEqual(['src/a.ts', 'src/b.ts']);
  });

  it('returns empty array when no changes', () => {
    vi.mocked(execSync).mockReturnValue('');
    const files = getChangedFiles();
    expect(files).toEqual([]);
  });

  it('uses fromRef and toRef when provided', () => {
    vi.mocked(execSync).mockReturnValue('file.ts');
    getChangedFiles('main', 'HEAD');
    expect(vi.mocked(execSync)).toHaveBeenCalledWith(
      'git diff --name-only --diff-filter=ACM main...HEAD',
      expect.any(Object)
    );
  });

  it('throws on invalid git ref', () => {
    vi.mocked(execSync).mockImplementation(() => {
      const err = new Error('fatal: bad revision');
      throw err;
    });
    expect(() => getChangedFiles('bad-ref')).toThrow('Invalid git ref');
  });

  it('throws when not a git repo', () => {
    vi.mocked(execSync).mockImplementation(() => {
      const err = new Error('fatal: not a git repository');
      throw err;
    });
    expect(() => getChangedFiles()).toThrow('Not a git repository');
  });

  it('returns commit message', () => {
    vi.mocked(execSync).mockReturnValue('feat: add thing\n');
    expect(getCommitMessage()).toBe('feat: add thing');
  });

  it('returns empty string when commit message fails', () => {
    vi.mocked(execSync).mockImplementation(() => {
      throw new Error('fail');
    });
    expect(getCommitMessage()).toBe('');
  });

  it('reads PR description from env', () => {
    process.env.GITHUB_EVENT_PATH = 'pr-desc';
    expect(getPrDescription()).toBe('pr-desc');
    delete process.env.GITHUB_EVENT_PATH;
  });

  it('returns empty string when no PR env', () => {
    delete process.env.GITHUB_EVENT_PATH;
    delete process.env.CI_MERGE_REQUEST_DESCRIPTION;
    delete process.env.BITBUCKET_PR_DESCRIPTION;
    expect(getPrDescription()).toBe('');
  });
});