const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const { execFileSync } = require('child_process');
const {
  resolveCloneUrlForGit,
  stripGitCredentials,
  buildGitHttpAuthConfigArgs,
  shouldApplyDefaultGitAuth,
} = require('./gitCloneUrl.cjs');

function gitEnv() {
  return {
    ...process.env,
    GIT_TERMINAL_PROMPT: '0',
  };
}

function sha16(s) {
  return crypto.createHash('sha256').update(String(s)).digest('hex').slice(0, 16);
}

/**
 * 浅克隆学员仓库到 .cache/student-repos/<hash>/ ，已存在则 git pull。
 * @param {string} gitUrl 完整 https 地址（私有库可在 URL 中带 token）
 * @param {string} rootDir 项目根
 * @returns {string} 本地克隆目录绝对路径
 */
function ensureStudentRepo(gitUrl, rootDir) {
  const publicUrl = String(gitUrl).trim();
  const authCfg = buildGitHttpAuthConfigArgs(publicUrl);
  /** 使用 extraHeader 时不要用带密码的 origin URL（避免被凭证助手改写后仍无法拉取） */
  const originUrlForRemote = shouldApplyDefaultGitAuth(publicUrl)
    ? stripGitCredentials(publicUrl)
    : resolveCloneUrlForGit(publicUrl);
  const cacheRoot = path.join(rootDir, '.cache', 'student-repos');
  fs.mkdirSync(cacheRoot, { recursive: true });
  const dir = path.join(cacheRoot, sha16(stripGitCredentials(publicUrl)));
  if (fs.existsSync(path.join(dir, '.git'))) {
    try {
      execFileSync('git', ['-C', dir, 'remote', 'set-url', 'origin', originUrlForRemote], {
        stdio: 'pipe',
        env: gitEnv(),
      });
      execFileSync(
        'git',
        [...authCfg, '-C', dir, 'pull', '--ff-only'],
        { stdio: 'pipe', timeout: 300000, env: gitEnv() },
      );
    } catch {
      fs.rmSync(dir, { recursive: true, force: true });
      execFileSync(
        'git',
        [...authCfg, 'clone', '--depth', '1', originUrlForRemote, dir],
        { stdio: 'pipe', timeout: 300000, env: gitEnv() },
      );
    }
  } else {
    execFileSync(
      'git',
      [...authCfg, 'clone', '--depth', '1', originUrlForRemote, dir],
      { stdio: 'pipe', timeout: 300000, env: gitEnv() },
    );
  }
  if (!fs.existsSync(path.join(dir, '.git'))) {
    throw new Error('git clone 后仍未发现 .git，请检查仓库地址与网络');
  }
  return dir;
}

module.exports = { ensureStudentRepo, sha16 };