const { URL } = require('url');

const FALLBACK_DEFAULT_STUDENT_GIT =
  'https://git.educoder.net/pu428f3pz/rnsuwx89z320260422155438.git';

/** 与 server 默认学员库一致（可被 DEFAULT_STUDENT_GIT_URL 覆盖） */
function getDefaultPublicStudentGitUrl() {
  const v = process.env.DEFAULT_STUDENT_GIT_URL;
  return (v && String(v).trim()) || FALLBACK_DEFAULT_STUDENT_GIT;
}

function stripGitCredentials(href) {
  try {
    const u = new URL(String(href).trim());
    u.username = '';
    u.password = '';
    return u.href;
  } catch {
    return String(href).trim();
  }
}

/** 用于判断「是否为同一远程」：忽略凭据、主机小写、去掉末尾 /、可选去掉 .git */
function normalizeComparableGitRemote(href) {
  try {
    const u = new URL(String(href).trim());
    u.username = '';
    u.password = '';
    u.hostname = u.hostname.toLowerCase();
    let p = u.pathname.replace(/\/+$/, '') || '/';
    if (p.toLowerCase().endsWith('.git')) p = p.slice(0, -4);
    u.pathname = p || '/';
    return `${u.protocol}//${u.hostname}${u.pathname === '/' ? '' : u.pathname}`;
  } catch {
    return stripGitCredentials(href);
  }
}

function sameGitRemoteIgnoringAuth(a, b) {
  return normalizeComparableGitRemote(a) === normalizeComparableGitRemote(b);
}

function hasDefaultGitPasswordAuth() {
  const user = String(process.env.DEFAULT_STUDENT_GIT_USER || '').trim();
  const pass = String(process.env.DEFAULT_STUDENT_GIT_PASSWORD || '').trim();
  return Boolean(user && pass);
}

function shouldApplyDefaultGitAuth(publicGitUrl) {
  if (!hasDefaultGitPasswordAuth()) return false;
  const pub = String(publicGitUrl || '').trim();
  if (!pub) return false;
  const canonicalDefault = getDefaultPublicStudentGitUrl();
  if (!sameGitRemoteIgnoringAuth(pub, canonicalDefault)) return false;
  try {
    const u = new URL(pub);
    if (u.protocol !== 'https:' && u.protocol !== 'http:') return false;
    if (u.username || u.password) return false;
    return true;
  } catch {
    return false;
  }
}

/**
 * 供 git clone/pull 使用：当目标与默认学员库为同一远程、且配置了
 * DEFAULT_STUDENT_GIT_USER + DEFAULT_STUDENT_GIT_PASSWORD 时，生成带 userinfo 的 URL。
 * 注意：部分 Git/Credential Manager 会忽略 URL 内嵌密码，此时应配合 buildGitHttpAuthConfigArgs 使用。
 */
function resolveCloneUrlForGit(publicGitUrl) {
  const pub = String(publicGitUrl || '').trim();
  if (!pub) return pub;
  if (!shouldApplyDefaultGitAuth(pub)) return pub;
  try {
    const u = new URL(pub);
    const user = String(process.env.DEFAULT_STUDENT_GIT_USER || '').trim();
    const pass = String(process.env.DEFAULT_STUDENT_GIT_PASSWORD || '').trim();
    u.username = user;
    u.password = pass;
    return u.href;
  } catch {
    return pub;
  }
}

/**
 * 通过 git -c http.<scheme>//<host>/.extraHeader=Authorization: Basic … 传 HTTPS 凭据，
 * 避免新版 Git / 凭证管理器丢弃 URL 中的 user:password。
 * @returns {string[]} 形如 ['-c', 'http.https://host/.extraHeader=Authorization: Basic xxx']
 */
function buildGitHttpAuthConfigArgs(publicGitUrl) {
  if (!shouldApplyDefaultGitAuth(publicGitUrl)) return [];
  try {
    const u = new URL(String(publicGitUrl).trim());
    const user = String(process.env.DEFAULT_STUDENT_GIT_USER || '').trim();
    const pass = String(process.env.DEFAULT_STUDENT_GIT_PASSWORD || '').trim();
    const schemeHost = `${u.protocol}//${u.hostname}`;
    const token = Buffer.from(`${user}:${pass}`, 'utf8').toString('base64');
    const headerVal = `Authorization: Basic ${token}`;
    const configKey = `http.${schemeHost}/.extraHeader`;
    return ['-c', `${configKey}=${headerVal}`];
  } catch {
    return [];
  }
}

module.exports = {
  getDefaultPublicStudentGitUrl,
  stripGitCredentials,
  normalizeComparableGitRemote,
  sameGitRemoteIgnoringAuth,
  resolveCloneUrlForGit,
  buildGitHttpAuthConfigArgs,
  shouldApplyDefaultGitAuth,
  hasDefaultGitPasswordAuth,
};