'use strict';

const express = require('express');
const { getAuthConfig } = require('../services/authConfig');
const {
  SUPPORTED_SCOPES,
  TOKEN_ISSUER,
  ThirdPartySsoError,
  buildUserInfo,
  exchangeAuthorizationCode,
  getThirdPartySsoCallbackBaseUrl,
  revokeAccessToken,
  validateAuthorizationRequest,
  verifyThirdPartyAccessToken,
} = require('../services/thirdPartySsoService');
const {
  buildCallbackUrl,
  createOAuthState,
  getStateCookieName,
} = require('../services/socialAuth');
const {
  beginDirectLogin,
  createDirectLoginSession,
  pollDirectLoginSession,
} = require('../services/thirdPartySsoDirectService');

const router = express.Router();
router.use(express.urlencoded({ extended: false, limit: '32kb' }));

function requestContext(req) {
  return {
    ipAddress: req.ip || req.socket?.remoteAddress || '',
    userAgent: req.get('user-agent') || '',
  };
}

function setOauthStateCookie(res, state) {
  res.cookie(getStateCookieName('dingtalk'), state, {
    httpOnly: true,
    sameSite: 'lax',
    secure: process.env.NODE_ENV === 'production',
    maxAge: 15 * 60 * 1000,
    path: '/',
  });
}

function parseClientCredentials(req) {
  const authorization = String(req.get('authorization') || '');
  const match = authorization.match(/^Basic\s+(.+)$/iu);
  if (match) {
    try {
      const decoded = Buffer.from(match[1], 'base64').toString('utf8');
      const separator = decoded.indexOf(':');
      if (separator >= 0) {
        return {
          clientId: decodeURIComponent(decoded.slice(0, separator)),
          clientSecret: decodeURIComponent(decoded.slice(separator + 1)),
        };
      }
    } catch (_error) {
      // The service returns a standard invalid_client response below.
    }
  }
  return {
    clientId: req.body?.client_id || req.body?.clientId,
    clientSecret: req.body?.client_secret || req.body?.clientSecret || '',
  };
}

function extractBearerToken(req) {
  const match = String(req.get('authorization') || '').match(/^Bearer\s+([^\s]+)$/iu);
  return match?.[1] || '';
}

function extractApiKey(req) {
  return String(req.get('x-api-key') || '').trim();
}

function sendOauthError(res, error) {
  const status = error instanceof ThirdPartySsoError ? error.status : 500;
  const code = error instanceof ThirdPartySsoError ? error.code : 'server_error';
  return res.status(status).json({
    error: code,
    error_description: error.message || '统一认证服务异常',
  });
}

router.get('/authorize', async (req, res) => {
  try {
    const validated = await validateAuthorizationRequest(req.query);
    const authConfig = await getAuthConfig();
    if (!authConfig.dingtalkEnabled || !authConfig.dingtalkAppKey || !authConfig.dingtalkAppSecret) {
      throw new ThirdPartySsoError('钉钉登录未配置或未启用', 503, 'temporarily_unavailable');
    }

    const callbackUrl = buildCallbackUrl(getThirdPartySsoCallbackBaseUrl(), 'dingtalk');
    const oauthState = createOAuthState('dingtalk', validated.stateClaims);
    setOauthStateCookie(res, oauthState);

    const authorizeUrl = new URL('https://login.dingtalk.com/oauth2/auth');
    authorizeUrl.searchParams.set('redirect_uri', callbackUrl);
    authorizeUrl.searchParams.set('response_type', 'code');
    authorizeUrl.searchParams.set('client_id', authConfig.dingtalkAppKey);
    authorizeUrl.searchParams.set('scope', 'openid');
    authorizeUrl.searchParams.set('state', oauthState);
    return res.redirect(authorizeUrl.toString());
  } catch (error) {
    return sendOauthError(res, error);
  }
});

router.post('/direct/sessions', async (req, res) => {
  try {
    res.set('Cache-Control', 'no-store');
    return res.status(201).json(await createDirectLoginSession(
      req.body || {},
      extractApiKey(req),
      { requestContext: requestContext(req) }
    ));
  } catch (error) {
    return sendOauthError(res, error);
  }
});

router.get('/direct/sessions/:requestId', async (req, res) => {
  try {
    res.set('Cache-Control', 'no-store');
    return res.json(await pollDirectLoginSession(
      req.params.requestId,
      extractApiKey(req),
      { requestContext: requestContext(req) }
    ));
  } catch (error) {
    return sendOauthError(res, error);
  }
});

router.get('/direct/login', async (req, res) => {
  try {
    const directLogin = await beginDirectLogin(req.query.request_id);
    const authConfig = await getAuthConfig();
    if (!authConfig.dingtalkEnabled || !authConfig.dingtalkAppKey || !authConfig.dingtalkAppSecret) {
      throw new ThirdPartySsoError('钉钉登录未配置或未启用', 503, 'temporarily_unavailable');
    }

    const callbackUrl = buildCallbackUrl(getThirdPartySsoCallbackBaseUrl(), 'dingtalk');
    const oauthState = createOAuthState('dingtalk', directLogin.stateClaims);
    setOauthStateCookie(res, oauthState);

    const authorizeUrl = new URL('https://login.dingtalk.com/oauth2/auth');
    authorizeUrl.searchParams.set('redirect_uri', callbackUrl);
    authorizeUrl.searchParams.set('response_type', 'code');
    authorizeUrl.searchParams.set('client_id', authConfig.dingtalkAppKey);
    authorizeUrl.searchParams.set('scope', 'openid');
    authorizeUrl.searchParams.set('state', oauthState);
    return res.redirect(authorizeUrl.toString());
  } catch (error) {
    return sendOauthError(res, error);
  }
});

router.post('/token', async (req, res) => {
  try {
    const result = await exchangeAuthorizationCode(req.body || {}, parseClientCredentials(req), {
      requestContext: requestContext(req),
    });
    res.set('Cache-Control', 'no-store');
    res.set('Pragma', 'no-cache');
    return res.json(result);
  } catch (error) {
    if (error?.code === 'invalid_client') {
      res.set('WWW-Authenticate', 'Basic realm="third-party-sso"');
    }
    return sendOauthError(res, error);
  }
});

router.get('/userinfo', async (req, res) => {
  try {
    const verified = await verifyThirdPartyAccessToken(extractBearerToken(req));
    res.set('Cache-Control', 'no-store');
    return res.json(buildUserInfo(verified));
  } catch (error) {
    res.set('WWW-Authenticate', 'Bearer realm="third-party-sso", error="invalid_token"');
    return sendOauthError(res, error);
  }
});

router.post('/revoke', async (req, res) => {
  try {
    await revokeAccessToken(req.body?.token, parseClientCredentials(req), {
      requestContext: requestContext(req),
    });
    return res.status(200).json({ revoked: true });
  } catch (error) {
    return sendOauthError(res, error);
  }
});

router.get('/.well-known/oauth-authorization-server', (_req, res) => {
  const issuer = TOKEN_ISSUER.replace(/\/$/u, '');
  return res.json({
    issuer,
    authorization_endpoint: `${issuer}/authorize`,
    token_endpoint: `${issuer}/token`,
    revocation_endpoint: `${issuer}/revoke`,
    userinfo_endpoint: `${issuer}/userinfo`,
    response_types_supported: ['code'],
    grant_types_supported: ['authorization_code'],
    code_challenge_methods_supported: ['S256'],
    token_endpoint_auth_methods_supported: ['client_secret_basic', 'client_secret_post', 'none'],
    scopes_supported: SUPPORTED_SCOPES,
  });
});

module.exports = router;