/**
 * Git Tracker — discover changed files via git.
 */
import { execSync } from 'node:child_process';

export function getGitRoot(cwd: string): string | null {
  try {
    return execSync('git rev-parse --show-toplevel', { cwd, encoding: 'utf-8' }).trim();
  } catch {
    return null;
  }
}

export function getChangedFiles(cwd: string, sinceRef?: string): string[] {
  try {
    const cmd = sinceRef
      ? `git diff --name-only ${sinceRef} --`
      : 'git diff --name-only HEAD~1 --';
    const out = execSync(cmd, { cwd, encoding: 'utf-8' }).trim();
    if (!out) return [];
    return out.split('\n').filter(Boolean);
  } catch {
    return [];
  }
}

export function getAllTrackedFiles(cwd: string): string[] {
  try {
    const out = execSync('git ls-files', { cwd, encoding: 'utf-8' }).trim();
    if (!out) return [];
    return out.split('\n').filter(Boolean);
  } catch {
    return [];
  }
}

export function getLastCommitDate(cwd: string): string | null {
  try {
    return execSync('git log -1 --format=%cI', { cwd, encoding: 'utf-8' }).trim();
  } catch {
    return null;
  }
}