// Phase 5B §12 — the website/commerce integration boundary. POST /api/integrations/enrollments
// is the ONLY thing an external system (the public website, a future payment provider) ever
// calls. It is completely separate from both student and instructor session auth — no
// rn_session/rn_instructor cookie is ever read here, and this route accepts none — so a
// browser cannot reach it just by having a logged-in student or admin tab open. See
// docs/WEBSITE_ENROLLMENT_INTEGRATION.md for the full contract the website team should build
// against.
//
// Auth follows the exact same pattern as platform/provisioner/src/server.js's
// X-Provisioner-Key (a pre-shared secret in an env var, checked via a custom header, fatal at
// startup if unset) — the same internal server-to-server trust boundary this codebase already
// established for Gateway<->Provisioner, not a new scheme. The header value must be held by
// the website's OWN backend only; it is never sent to or readable by browser JS.

const enrollment = require('./enrollment');
const studentsAuth = require('./students-auth');
const metrics = require('./metrics');

const INTEGRATION_SHARED_SECRET = process.env.INTEGRATION_SHARED_SECRET;

if (!INTEGRATION_SHARED_SECRET) {
  console.error('WARNING: INTEGRATION_SHARED_SECRET is not set — POST /api/integrations/enrollments will refuse every request until it is. This is fine for a dev stack that never exercises the integration boundary, fatal for anything that needs to.');
}

// Small, deliberately provider-neutral vocabulary — NOT Stripe's (or anyone else's) object
// model. The website's backend translates whatever its payment provider says into one of these
// two values before calling this endpoint.
const STATUS_MAP = { paid: 'active', active: 'active', confirmed: 'active', pending: 'pending', awaiting_payment: 'pending' };

function enrollmentErrorStatus(code) {
  if (code === 'PROGRAM_NOT_FOUND') return 404;
  if (code === 'PROGRAM_INACTIVE') return 409;
  if (code === 'EVENT_ID_REQUIRED' || code === 'STUDENT_IDENTIFIER_REQUIRED') return 400;
  return 500;
}

module.exports = function registerIntegrationRoutes(app, deps) {
  const { getPool, recordAudit, wrap } = deps;

  app.post('/api/integrations/enrollments', wrap(async (req, res) => {
    const key = req.get('X-RootNode-Integration-Key');
    if (!INTEGRATION_SHARED_SECRET || !key || key !== INTEGRATION_SHARED_SECRET) {
      metrics.recordEnrollmentEvent('rejected');
      return res.status(401).json({ error: 'unauthorized' });
    }

    const { event_id, source, student, program_slug, status } = req.body || {};
    const email = student?.email ? String(student.email).trim() : null;
    const loginIdentifier = student?.login_identifier ? String(student.login_identifier).trim() : null;
    const mappedStatus = STATUS_MAP[status];

    if (!event_id || typeof event_id !== 'string') {
      metrics.recordEnrollmentEvent('rejected');
      return res.status(400).json({ error: 'event_id is required' });
    }
    if (!program_slug) {
      metrics.recordEnrollmentEvent('rejected');
      return res.status(400).json({ error: 'program_slug is required' });
    }
    if (!mappedStatus) {
      metrics.recordEnrollmentEvent('rejected');
      return res.status(400).json({ error: 'status must be one of: ' + Object.keys(STATUS_MAP).join(', ') });
    }
    if (!email && !loginIdentifier) {
      metrics.recordEnrollmentEvent('rejected');
      return res.status(400).json({ error: 'student.email or student.login_identifier is required' });
    }

    let result;
    try {
      result = await enrollment.createFromIntegrationEvent(getPool(), studentsAuth, {
        eventId: event_id, source: source || 'integration', studentEmail: email, studentLoginIdentifier: loginIdentifier,
        studentDisplayName: student?.display_name, programId: program_slug, status: mappedStatus,
      });
    } catch (e) {
      metrics.recordEnrollmentEvent('rejected');
      if (e.code) return res.status(enrollmentErrorStatus(e.code)).json({ error: e.code, message: e.message });
      throw e;
    }

    metrics.recordEnrollmentEvent(result.created ? 'created' : 'duplicate');
    // Audited regardless of created/duplicate — a replay is still a real, worth-recording
    // event, just not a new enrollment. No payment/card data ever reaches this far (the
    // payload never carries it — see docs/WEBSITE_ENROLLMENT_INTEGRATION.md "what NOT to send").
    await recordAudit(getPool(), {
      actorType: 'integration', actorId: source || 'integration', action: result.created ? 'enrollment_integration_created' : 'enrollment_integration_duplicate',
      resourceType: 'enrollment', resourceId: result.enrollment.enrollment_id, result: 'success', sourceIp: req.ip,
      metadata: { event_id, program_slug, student_id: result.enrollment.student_id },
    });

    res.status(result.created ? 201 : 200).json({
      enrollment_id: result.enrollment.enrollment_id,
      student_id: result.enrollment.student_id,
      program_id: result.enrollment.program_id,
      status: result.enrollment.status,
      created: result.created,
    });
  }));
};