// POST /api/student/login, /activate, /change-password, /request-password-reset,
// /reset-password, GET /api/student/profile — Phase 5A §2/§5/§6/§9/§10. Logout reuses the
// existing POST /api/logout (session-mechanism-agnostic already, no change needed there).
//
// A pilot student (password_hash IS NULL) keeps using the original POST /api/login
// (bare student_id, unchanged) until an instructor converts them — see
// docs/PHASE5A_STUDENT_IDENTITY_REMOTE_CLASSROOM.md §7. This file is exclusively the NEW
// credentialed path.

const {
  verifyPassword, hashPassword, publicStudent, getStudentByIdentifier, getActiveStudent,
  issueCredentialToken, findStudentByCredentialToken, consumeCredentialToken,
} = require('./students-auth');
const { recordAudit } = require('./audit');
const { makeCsrfToken, tooManyAttempts, parseCookies, checkCsrf } = require('./security');
const { buildCookie, clearCookie } = require('./cookies');
const { recordStudentLoginSuccess, recordStudentLoginFailure, recordStudentActivation } = require('./metrics'); // Phase 5A §34, Phase 5C
const notifications = require('./notifications');

const STUDENT_COOKIE = 'rn_session';
const STUDENT_CSRF_COOKIE = 'rn_csrf_s';
const LOGIN_MAX_ATTEMPTS = 8;
const LOGIN_WINDOW_MS = 5 * 60 * 1000;
const SESSION_MAX_AGE_SEC = 8 * 3600;

module.exports = function registerStudentAuthRoutes(app, { pool, sessions, studentSession, curriculum, loadProgress, isProduction }) {
  app.post('/api/student/login', async (req, res) => {
    const { identifier, password } = req.body || {};
    const rateKey = `student:${req.ip}:${String(identifier || '').toLowerCase()}`;
    if (await tooManyAttempts(pool, rateKey, LOGIN_MAX_ATTEMPTS, LOGIN_WINDOW_MS)) {
      return res.status(429).json({ error: 'too_many_attempts', message: 'Too many login attempts. Try again in a few minutes.' });
    }
    if (!identifier || !password) return res.status(400).json({ error: 'identifier and password are required' });

    const student = await getStudentByIdentifier(pool, identifier);
    // Same generic response whether the identifier doesn't exist, has no credentials yet
    // (pilot/unconverted), or the password is wrong — no account enumeration either way.
    const passwordOk = student && student.password_hash && verifyPassword(password, student.password_hash);
    if (!passwordOk) {
      recordStudentLoginFailure();
      await recordAudit(pool, {
        actorType: 'student', actorId: student?.student_id, action: 'login', result: 'failure', sourceIp: req.ip,
      });
      return res.status(401).json({ error: 'invalid_credentials', message: 'Invalid login or password.' });
    }
    if (student.status !== 'active') {
      recordStudentLoginFailure();
      await recordAudit(pool, { actorType: 'student', actorId: student.student_id, action: 'login', result: 'failure', sourceIp: req.ip, metadata: { reason: 'inactive' } });
      return res.status(403).json({ error: 'account_inactive', message: 'This account has been deactivated.' });
    }

    const token = await sessions.createStudentSession(pool, student.student_id);
    const csrf = makeCsrfToken();
    await pool.query(`UPDATE students SET last_login_at = now() WHERE student_id = $1`, [student.student_id]);
    recordStudentLoginSuccess();
    await recordAudit(pool, { actorType: 'student', actorId: student.student_id, action: 'login', result: 'success', sourceIp: req.ip });

    res.append('Set-Cookie', buildCookie(STUDENT_COOKIE, token, { maxAgeSec: SESSION_MAX_AGE_SEC }));
    res.append('Set-Cookie', buildCookie(STUDENT_CSRF_COOKIE, csrf, { maxAgeSec: SESSION_MAX_AGE_SEC, httpOnly: false }));
    res.json({ student: publicStudent({ ...student, last_login_at: new Date() }) });
  });

  // Consumes an activation token issued by GET/POST /api/admin/students (creation) or
  // /api/admin/students/:id/convert — sets the student's first password and logs them straight
  // in, same as any other login (§5's "temporary credential becomes invalid" is the token being
  // single-use — consumeCredentialToken clears it atomically with setting the password).
  app.post('/api/student/activate', async (req, res) => {
    const { token, password } = req.body || {};
    if (!token || !password || password.length < 10) {
      return res.status(400).json({ error: 'invalid_request', message: 'A valid token and a password of at least 10 characters are required.' });
    }
    const student = await consumeCredentialToken(pool, token, 'activation', password);
    if (!student) {
      recordStudentActivation('invalid_or_expired_token');
      return res.status(400).json({ error: 'invalid_or_expired_token', message: 'This activation link is invalid or has expired. Ask your instructor for a new one.' });
    }
    recordStudentActivation('success');

    const sessionToken = await sessions.createStudentSession(pool, student.student_id);
    const csrf = makeCsrfToken();
    await pool.query(`UPDATE students SET last_login_at = now() WHERE student_id = $1`, [student.student_id]);
    await recordAudit(pool, { actorType: 'student', actorId: student.student_id, action: 'account_activated', result: 'success', sourceIp: req.ip });

    res.append('Set-Cookie', buildCookie(STUDENT_COOKIE, sessionToken, { maxAgeSec: SESSION_MAX_AGE_SEC }));
    res.append('Set-Cookie', buildCookie(STUDENT_CSRF_COOKIE, csrf, { maxAgeSec: SESSION_MAX_AGE_SEC, httpOnly: false }));
    res.json({ student: publicStudent(student) });
  });

  // Lets a not-yet-logged-in student preview whose activation/reset link this is before they
  // submit a new password (e.g. "Activating account for Alice") — never reveals anything if
  // the token is invalid/expired/wrong-purpose, same shape either way.
  app.get('/api/student/credential-token/:purpose', async (req, res) => {
    const { purpose } = req.params;
    if (!['activation', 'reset'].includes(purpose)) return res.status(400).json({ error: 'invalid_purpose' });
    const student = await findStudentByCredentialToken(pool, req.query.token, purpose);
    if (!student) return res.status(404).json({ error: 'invalid_or_expired_token' });
    res.json({ display_name: student.display_name });
  });

  app.post('/api/student/change-password', studentSession, async (req, res) => {
    const { old_password, new_password } = req.body || {};
    if (!old_password || !new_password || new_password.length < 10) {
      return res.status(400).json({ error: 'invalid_request', message: 'new_password must be at least 10 characters' });
    }
    const student = await getActiveStudent(pool, req.studentId);
    if (!student || !student.password_hash || !verifyPassword(old_password, student.password_hash)) {
      await recordAudit(pool, { actorType: 'student', actorId: req.studentId, action: 'password_change', result: 'failure', sourceIp: req.ip });
      return res.status(401).json({ error: 'invalid_credentials', message: 'Current password is incorrect.' });
    }
    const newHash = hashPassword(new_password);
    await pool.query(`UPDATE students SET password_hash = $1, updated_at = now() WHERE student_id = $2`, [newHash, student.student_id]);
    await sessions.revokeAllStudentSessions(pool, student.student_id, req.sessionToken);
    // Phase 5C §5D — a security-notice email, no token, purely informational.
    await notifications.enqueue(pool, { studentId: student.student_id, notificationType: 'password_changed', metadata: { display_name: student.display_name } });
    await recordAudit(pool, { actorType: 'student', actorId: student.student_id, action: 'password_change', result: 'success', sourceIp: req.ip });
    res.json({ ok: true });
  });

  // §9/§6/Phase 5C §8 — self-service "forgot password." Anti-enumeration is unchanged: the
  // SAME generic response returns regardless of whether the identifier exists, is inactive, or
  // is a genuine hit — the only difference a caller can ever observe is whether an email
  // eventually arrives, never anything in this response. Production NEVER returns the token
  // (isProduction, same COOKIE_SECURE-derived signal Phase 5A already established — see
  // server.js); the dev-only echo exists purely so a local/CI run can complete the loop without
  // a real inbox, exactly as before. What Phase 5C actually closes: the token is now also
  // handed to notifications.enqueue() so a real email goes out — see
  // docs/PHASE5C_ENROLLMENT_COMMUNICATIONS.md §8 for why the token is minted here
  // (synchronously, as before) rather than by the worker.
  app.post('/api/student/request-password-reset', async (req, res) => {
    const { identifier } = req.body || {};
    const generic = { ok: true, message: 'If that account exists, a password reset has been prepared.' };
    if (!identifier) return res.json(generic);
    const student = await getStudentByIdentifier(pool, identifier);
    if (!student || student.status !== 'active' || !student.password_hash) return res.json(generic);
    const { token } = await issueCredentialToken(pool, student.student_id, 'reset');
    await notifications.enqueue(pool, { studentId: student.student_id, notificationType: 'password_reset', plaintextToken: token, metadata: { display_name: student.display_name } });
    await recordAudit(pool, { actorType: 'student', actorId: student.student_id, action: 'password_reset_requested', result: 'success', sourceIp: req.ip });
    if (!isProduction) return res.json({ ...generic, dev_reset_token: token });
    res.json(generic);
  });

  app.post('/api/student/reset-password', async (req, res) => {
    const { token, password } = req.body || {};
    if (!token || !password || password.length < 10) {
      return res.status(400).json({ error: 'invalid_request', message: 'A valid token and a password of at least 10 characters are required.' });
    }
    const student = await consumeCredentialToken(pool, token, 'reset', password);
    if (!student) return res.status(400).json({ error: 'invalid_or_expired_token', message: 'This reset link is invalid or has expired.' });
    await sessions.revokeAllStudentSessions(pool, student.student_id, null); // a reset revokes EVERY existing session — the whole point is "someone other than me might have access"
    await notifications.enqueue(pool, { studentId: student.student_id, notificationType: 'password_changed', metadata: { display_name: student.display_name } });
    await recordAudit(pool, { actorType: 'student', actorId: student.student_id, action: 'password_reset_completed', result: 'success', sourceIp: req.ip });
    res.json({ ok: true });
  });

  // §10 — minimal profile page data: identity, cohort(s), progress summary, achievements,
  // active session count. Reuses the same loadProgress/curriculum modules the existing
  // /api/progress and /api/curriculum/path routes use — no parallel progress-reading logic.
  app.get('/api/student/profile', studentSession, async (req, res) => {
    const student = await getActiveStudent(pool, req.studentId);
    if (!student) return res.status(401).json({ error: 'no_session' });
    const [{ rows: cohorts }, progress, { rows: achievements }, sessionsList] = await Promise.all([
      pool.query(
        `SELECT c.cohort_id, c.name FROM cohort_enrollments e JOIN cohorts c ON c.cohort_id = e.cohort_id
         WHERE e.student_id = $1 AND e.enrollment_status = 'enrolled'`,
        [student.student_id]
      ),
      loadProgress(pool, student.student_id),
      pool.query(
        `SELECT achievement_type, stage_id, achieved_at FROM achievements WHERE student_id = $1 ORDER BY achieved_at DESC`,
        [student.student_id]
      ),
      sessions.listStudentSessions(pool, student.student_id),
    ]);
    const scenarios = curriculum.loadScenarios();
    const completed = Object.values(progress).filter((p) => p.status === 'completed').length;
    res.json({
      student: publicStudent(student),
      cohorts,
      progress_summary: { completed, total: scenarios.length },
      achievements,
      active_sessions: sessionsList.filter((s) => !s.revoked_at && new Date(s.expires_at) > new Date()).length,
    });
  });
};

module.exports.STUDENT_COOKIE = STUDENT_COOKIE;
module.exports.STUDENT_CSRF_COOKIE = STUDENT_CSRF_COOKIE;