// Phase 7 — the business/product architecture's core library: organizations, locations,
// guardians, curriculum packages, offerings, registrations, and agreement acceptances. Same
// error convention as enrollment.js/classroom.js: throw `Error` with a `.code` the route layer
// maps to an HTTP status. See docs/OFFERING_AND_REGISTRATION_MODEL.md for the full lifecycle
// diagrams this file implements, and docs/STUDENT_GUARDIAN_DATA_MODEL.md for the guardian
// model's own reasoning.

const enrollmentLib = require('./enrollment');
const notificationsLib = require('./notifications');

function err(code, message) {
  return Object.assign(new Error(message || code), { code });
}

// ── Organizations / Locations ──────────────────────────────────────────────────────────────
async function createOrganization(pool, { organizationId, name, type, contactName, contactEmail, contactPhone, notes }) {
  if (!organizationId || !name) throw err('VALIDATION', 'organizationId and name are required.');
  const { rows } = await pool.query(
    `INSERT INTO organizations (organization_id, name, type, contact_name, contact_email, contact_phone, notes)
     VALUES ($1, $2, COALESCE($3, 'other'), $4, $5, $6, $7) RETURNING *`,
    [organizationId, name, type || null, contactName || null, contactEmail || null, contactPhone || null, notes || null]
  );
  return rows[0];
}
async function listOrganizations(pool) {
  const { rows } = await pool.query(`SELECT * FROM organizations ORDER BY name`);
  return rows;
}

async function createLocation(pool, { locationId, organizationId, name, type, addressLine1, addressLine2, city, region, postalCode, country, timezone, capacity, accessNotes }) {
  if (!locationId || !name) throw err('VALIDATION', 'locationId and name are required.');
  const { rows } = await pool.query(
    `INSERT INTO locations (location_id, organization_id, name, type, address_line1, address_line2, city, region, postal_code, country, timezone, capacity, access_notes)
     VALUES ($1, $2, $3, COALESCE($4, 'online'), $5, $6, $7, $8, $9, $10, $11, $12, $13) RETURNING *`,
    [locationId, organizationId || null, name, type || null, addressLine1 || null, addressLine2 || null, city || null, region || null, postalCode || null, country || null, timezone || null, capacity || null, accessNotes || null]
  );
  return rows[0];
}
// `forInstructor` gates access_notes exactly like course-progress.js gates instructor_notes —
// internal operational detail (building access codes, parking) never leaves the instructor
// surface. See Step 8's explicit "protect private/internal operational notes."
async function listLocations(pool, { forInstructor = false } = {}) {
  const { rows } = await pool.query(`SELECT * FROM locations ORDER BY name`);
  if (forInstructor) return rows;
  return rows.map(({ access_notes, ...rest }) => rest);
}

// ── Guardians ───────────────────────────────────────────────────────────────────────────────
async function createGuardian(pool, { guardianId, displayName, email, phone, notes }) {
  if (!guardianId || !displayName) throw err('VALIDATION', 'guardianId and displayName are required.');
  const { rows } = await pool.query(
    `INSERT INTO guardians (guardian_id, display_name, email, phone, notes) VALUES ($1, $2, $3, $4, $5) RETURNING *`,
    [guardianId, displayName, email ? String(email).toLowerCase().trim() : null, phone || null, notes || null]
  );
  return rows[0];
}
async function linkStudentGuardian(pool, { studentId, guardianId, relationship, isPrimaryContact, canReceiveCommunications }) {
  if (!studentId || !guardianId) throw err('VALIDATION', 'studentId and guardianId are required.');
  const { rows } = await pool.query(
    `INSERT INTO student_guardians (student_id, guardian_id, relationship, is_primary_contact, can_receive_communications)
     VALUES ($1, $2, COALESCE($3, 'guardian'), COALESCE($4, false), COALESCE($5, true))
     ON CONFLICT (student_id, guardian_id) DO UPDATE SET relationship = EXCLUDED.relationship, is_primary_contact = EXCLUDED.is_primary_contact, can_receive_communications = EXCLUDED.can_receive_communications
     RETURNING *`,
    [studentId, guardianId, relationship || null, isPrimaryContact ?? null, canReceiveCommunications ?? null]
  );
  return rows[0];
}
// A plain instructor sees which students they have real cohort access to (via the caller's own
// RBAC check on the route) — this function itself just returns the linked guardians for one
// student, RBAC is the route layer's job, same separation of concerns as everywhere else.
async function listGuardiansForStudent(pool, studentId) {
  const { rows } = await pool.query(
    `SELECT g.*, sg.relationship, sg.is_primary_contact, sg.can_receive_communications
     FROM student_guardians sg JOIN guardians g ON g.guardian_id = sg.guardian_id
     WHERE sg.student_id = $1 ORDER BY sg.is_primary_contact DESC, g.display_name`,
    [studentId]
  );
  return rows;
}

// ── Curriculum packages (a reference list into EXISTING courses, never a clone) ─────────────
async function createCurriculumPackage(pool, { curriculumPackageId, name, programId, description }) {
  if (!curriculumPackageId || !name || !programId) throw err('VALIDATION', 'curriculumPackageId, name, and programId are required.');
  const { rows: programRows } = await pool.query(`SELECT 1 FROM programs WHERE program_id = $1`, [programId]);
  if (!programRows[0]) throw err('PROGRAM_NOT_FOUND', 'No such program.');
  const { rows } = await pool.query(
    `INSERT INTO curriculum_packages (curriculum_package_id, name, program_id, description) VALUES ($1, $2, $3, $4) RETURNING *`,
    [curriculumPackageId, name, programId, description || null]
  );
  return rows[0];
}
async function addCurriculumPackageItem(pool, { curriculumPackageId, courseId, sequence }) {
  const { rows: courseRows } = await pool.query(`SELECT 1 FROM courses WHERE course_id = $1`, [courseId]);
  if (!courseRows[0]) throw err('COURSE_NOT_FOUND', 'No such course — a package only ever REFERENCES an existing course, never clones one.');
  const { rows } = await pool.query(
    `INSERT INTO curriculum_package_items (curriculum_package_id, course_id, sequence) VALUES ($1, $2, $3)
     ON CONFLICT (curriculum_package_id, course_id) DO UPDATE SET sequence = EXCLUDED.sequence RETURNING *`,
    [curriculumPackageId, courseId, sequence]
  );
  return rows[0];
}
async function getCurriculumPackage(pool, curriculumPackageId) {
  const { rows: pkgRows } = await pool.query(`SELECT * FROM curriculum_packages WHERE curriculum_package_id = $1`, [curriculumPackageId]);
  if (!pkgRows[0]) return null;
  const { rows: items } = await pool.query(
    `SELECT cpi.course_id, cpi.sequence, c.title, c.status FROM curriculum_package_items cpi
     JOIN courses c ON c.course_id = cpi.course_id WHERE cpi.curriculum_package_id = $1 ORDER BY cpi.sequence`,
    [curriculumPackageId]
  );
  return { ...pkgRows[0], items };
}

// ── Offerings — server-defined status transitions only (Step 3's explicit requirement) ──────
const OFFERING_TRANSITIONS = {
  draft: ['published', 'cancelled'],
  published: ['enrollment_open', 'cancelled'],
  enrollment_open: ['full', 'in_progress', 'cancelled'],
  full: ['enrollment_open', 'in_progress', 'cancelled'],
  in_progress: ['completed', 'cancelled'],
  completed: [],
  cancelled: [],
};

async function createOffering(pool, { offeringId, slug, name, programId, curriculumPackageId, deliveryMode, startsAt, endsAt, enrollmentOpensAt, enrollmentClosesAt, capacity, locationId, organizationId, cohortId, recommendedMinAge, recommendedMaxAge, description, createdBy, priceAmount, priceCurrency }) {
  if (!offeringId || !slug || !name || !programId || !deliveryMode) throw err('VALIDATION', 'offeringId, slug, name, programId, and deliveryMode are required.');
  const { rows: programRows } = await pool.query(`SELECT 1 FROM programs WHERE program_id = $1`, [programId]);
  if (!programRows[0]) throw err('PROGRAM_NOT_FOUND', 'No such program.');
  try {
    const { rows } = await pool.query(
      `INSERT INTO offerings (offering_id, slug, name, program_id, curriculum_package_id, delivery_mode, starts_at, ends_at, enrollment_opens_at, enrollment_closes_at, capacity, location_id, organization_id, cohort_id, recommended_min_age, recommended_max_age, description, created_by, price_amount, price_currency)
       VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,$18,$19,COALESCE($20,'usd')) RETURNING *`,
      [offeringId, slug, name, programId, curriculumPackageId || null, deliveryMode, startsAt || null, endsAt || null, enrollmentOpensAt || null, enrollmentClosesAt || null, capacity ?? null, locationId || null, organizationId || null, cohortId || null, recommendedMinAge ?? null, recommendedMaxAge ?? null, description || null, createdBy || null, priceAmount ?? null, priceCurrency || null]
    );
    return rows[0];
  } catch (e) {
    if (e.code === '23505') throw err('DUPLICATE_SLUG', 'An offering with this slug already exists.');
    throw e;
  }
}
async function getOffering(pool, offeringId) {
  const { rows } = await pool.query(`SELECT * FROM offerings WHERE offering_id = $1`, [offeringId]);
  return rows[0] || null;
}
// Phase 9 §28 — a draft offering is created with the bare minimum, then completed over time as
// real business decisions (dates, venue, capacity, price) land — this is the one place those
// get filled in later without recreating the row. Only ever touches columns explicitly present
// in `fields`, so calling it with just `{ priceAmount, priceCurrency }` never disturbs anything
// else. Never allows changing `status` (transitionOffering is the only path for that, with its
// own server-defined transition table) or `slug`/`program_id` (identity fields).
const OFFERING_EDITABLE_FIELDS = {
  name: 'name', description: 'description', startsAt: 'starts_at', endsAt: 'ends_at',
  enrollmentOpensAt: 'enrollment_opens_at', enrollmentClosesAt: 'enrollment_closes_at', capacity: 'capacity',
  locationId: 'location_id', organizationId: 'organization_id', cohortId: 'cohort_id',
  recommendedMinAge: 'recommended_min_age', recommendedMaxAge: 'recommended_max_age',
  curriculumPackageId: 'curriculum_package_id', priceAmount: 'price_amount', priceCurrency: 'price_currency',
};
async function updateOffering(pool, offeringId, fields) {
  const sets = [];
  const values = [offeringId];
  for (const [key, column] of Object.entries(OFFERING_EDITABLE_FIELDS)) {
    if (!(key in fields)) continue;
    values.push(fields[key]);
    sets.push(`${column} = $${values.length}`);
  }
  if (!sets.length) throw err('VALIDATION', 'No editable fields provided.');
  const { rows } = await pool.query(
    `UPDATE offerings SET ${sets.join(', ')}, version = version + 1, updated_at = now() WHERE offering_id = $1 RETURNING *`,
    values
  );
  if (!rows[0]) throw err('NOT_FOUND', 'No such offering.');
  return rows[0];
}
async function listOfferings(pool, { status } = {}) {
  const { rows } = await pool.query(
    status ? `SELECT * FROM offerings WHERE status = $1 ORDER BY created_at DESC` : `SELECT * FROM offerings ORDER BY created_at DESC`,
    status ? [status] : []
  );
  return rows;
}
async function transitionOffering(pool, offeringId, toStatus) {
  const offering = await getOffering(pool, offeringId);
  if (!offering) throw err('NOT_FOUND', 'No such offering.');
  const allowed = OFFERING_TRANSITIONS[offering.status] || [];
  if (!allowed.includes(toStatus)) throw err('INVALID_TRANSITION', `Cannot move an offering from '${offering.status}' to '${toStatus}'.`);
  const { rows } = await pool.query(`UPDATE offerings SET status = $2, version = version + 1, updated_at = now() WHERE offering_id = $1 RETURNING *`, [offeringId, toStatus]);
  return rows[0];
}
async function assignInstructorToOffering(pool, offeringId, instructorId, role) {
  const { rows } = await pool.query(
    `INSERT INTO instructor_offerings (offering_id, instructor_id, role) VALUES ($1, $2, COALESCE($3, 'teacher'))
     ON CONFLICT (offering_id, instructor_id) DO UPDATE SET role = EXCLUDED.role RETURNING *`,
    [offeringId, instructorId, role || null]
  );
  return rows[0];
}

// Single atomic UPDATE, not SELECT-count-then-INSERT — see 034_phase7_....sql's own header
// comment for why this specific shape avoids the race the authorization explicitly warned
// against. A NULL capacity offering (typical for self_paced) never needs reservation at all.
async function reserveSeat(pool, offeringId) {
  const offering = await getOffering(pool, offeringId);
  if (!offering) throw err('NOT_FOUND', 'No such offering.');
  if (offering.capacity === null) return offering; // unlimited — nothing to reserve
  const { rows } = await pool.query(
    `UPDATE offerings SET reserved_seats = reserved_seats + 1, updated_at = now()
     WHERE offering_id = $1 AND reserved_seats < capacity RETURNING *`,
    [offeringId]
  );
  if (!rows[0]) throw err('OFFERING_FULL', 'This offering has no remaining capacity.');
  return rows[0];
}
async function releaseSeat(pool, offeringId) {
  const { rows } = await pool.query(
    `UPDATE offerings SET reserved_seats = GREATEST(reserved_seats - 1, 0), updated_at = now() WHERE offering_id = $1 RETURNING *`,
    [offeringId]
  );
  return rows[0];
}

// ── Registrations ────────────────────────────────────────────────────────────────────────────
const REGISTRATION_TRANSITIONS = {
  started: ['submitted', 'cancelled'],
  submitted: ['reviewed', 'agreements_pending', 'payment_pending', 'confirmed', 'cancelled'],
  reviewed: ['agreements_pending', 'payment_pending', 'confirmed', 'cancelled'],
  agreements_pending: ['payment_pending', 'confirmed', 'cancelled'],
  payment_pending: ['confirmed', 'cancelled'],
  confirmed: ['enrollment_activated', 'cancelled'],
  enrollment_activated: [],
  cancelled: [],
};

// Phase 8 §21 — registration availability is server-authoritative, checked here (the one place
// a registration row is actually created), not left to a website's own hidden-button logic.
// Distinct error codes per reason so a caller (website or admin UI) can show something more
// useful than a generic failure.
function assertRegistrationOpen(offering) {
  if (offering.status === 'draft') throw err('OFFERING_NOT_OPEN', 'This offering is not yet open for registration.');
  if (offering.status === 'cancelled') throw err('OFFERING_CANCELLED', 'This offering has been cancelled.');
  if (offering.status === 'completed') throw err('OFFERING_COMPLETED', 'This offering has already completed.');
  if (offering.status === 'full') throw err('OFFERING_FULL', 'This offering has no remaining capacity.');
  if (!['published', 'enrollment_open'].includes(offering.status)) throw err('OFFERING_NOT_OPEN', 'This offering is not currently open for registration.');
  const now = new Date();
  if (offering.enrollment_opens_at && now < new Date(offering.enrollment_opens_at)) throw err('REGISTRATION_NOT_YET_OPEN', 'Registration for this offering has not opened yet.');
  if (offering.enrollment_closes_at && now > new Date(offering.enrollment_closes_at)) throw err('REGISTRATION_CLOSED', 'Registration for this offering has closed.');
}

// Field validation -> seat reservation -> insert -> notification, strictly in that order. A
// notification is only ever enqueued for a registration that is FULLY, durably committed —
// enqueueing one earlier (e.g. before capacity is confirmed) created a real bug found during
// this phase's own regression testing: a rolled-back registration whose row got deleted after a
// failed seat reservation left behind a notification_events row still pointing at it, and the
// DELETE itself then failed on the very foreign key that row created. Reserving the seat FIRST
// (rolling it back if the insert itself somehow fails) means nothing is ever created that later
// needs to be un-created out from under a row something else already references.
// Phase 9 §26/§27 — a registration against a PAID offering carries a reservation_expires_at,
// giving the registrant a real but bounded window to complete checkout before the seat releases
// automatically (server.js's reservation reaper). A free offering never sets this — nothing new
// to expire, identical to Phase 7/8 behavior.
const RESERVATION_TIMEOUT_MINUTES = Number(process.env.REGISTRATION_RESERVATION_TIMEOUT_MINUTES) || 30;
function computeReservationExpiry(offering) {
  return offering.price_amount === null ? null : new Date(Date.now() + RESERVATION_TIMEOUT_MINUTES * 60 * 1000);
}

async function createRegistration(pool, { offeringId, guardianId, registrantDisplayName, registrantEmail, isMinor, readinessNotes, accessibilityNotes, emergencyContactName, emergencyContactPhone, source, externalReference }) {
  if (!offeringId || !registrantDisplayName) throw err('VALIDATION', 'offeringId and registrantDisplayName are required.');
  if (isMinor && !guardianId) throw err('GUARDIAN_REQUIRED', 'A minor registration must include a guardianId.');
  const offering = await getOffering(pool, offeringId);
  if (!offering) throw err('OFFERING_NOT_FOUND', 'No such offering.');
  assertRegistrationOpen(offering);

  await reserveSeat(pool, offeringId); // throws OFFERING_FULL if genuinely exhausted; nothing created yet if so

  let reg;
  try {
    const { rows } = await pool.query(
      `INSERT INTO offering_registrations (offering_id, guardian_id, registrant_display_name, registrant_email, is_minor, readiness_notes, accessibility_notes, emergency_contact_name, emergency_contact_phone, source, external_reference, reservation_expires_at)
       VALUES ($1,$2,$3,$4,COALESCE($5,false),$6,$7,$8,$9,COALESCE($10,'admin'),$11,$12) RETURNING *`,
      [offeringId, guardianId || null, registrantDisplayName, registrantEmail || null, isMinor ?? null, readinessNotes || null, accessibilityNotes || null, emergencyContactName || null, emergencyContactPhone || null, source || null, externalReference || null, computeReservationExpiry(offering)]
    );
    reg = rows[0];
  } catch (e) {
    await releaseSeat(pool, offeringId).catch(() => {});
    if (e.code === '23505') throw err('DUPLICATE_REGISTRATION', 'A registration with this external_reference already exists for this offering.');
    throw e;
  }
  // Best-effort — a notification failure must never fail the registration itself (matches
  // enrollment.js's own precedent of never letting notification concerns block the academic
  // action they're merely announcing). Safe to fire now: reg is fully, durably committed.
  await notificationsLib.enqueueForRegistration(pool, {
    registration: reg, notificationType: 'registration_received',
    metadata: { display_name: reg.registrant_display_name, offering_name: offering.name },
  }).catch((e) => console.error("[offerings] registration_received notification failed:", e.message));
  return reg;
}
async function getRegistration(pool, registrationId) {
  const { rows } = await pool.query(`SELECT * FROM offering_registrations WHERE registration_id = $1`, [registrationId]);
  return rows[0] || null;
}
async function listRegistrationsForOffering(pool, offeringId) {
  const { rows } = await pool.query(`SELECT * FROM offering_registrations WHERE offering_id = $1 ORDER BY created_at`, [offeringId]);
  return rows;
}
async function transitionRegistration(pool, registrationId, toStatus) {
  const reg = await getRegistration(pool, registrationId);
  if (!reg) throw err('NOT_FOUND', 'No such registration.');
  const allowed = REGISTRATION_TRANSITIONS[reg.status] || [];
  if (!allowed.includes(toStatus)) throw err('INVALID_TRANSITION', `Cannot move a registration from '${reg.status}' to '${toStatus}'.`);
  if (toStatus === 'cancelled' && !['enrollment_activated', 'cancelled'].includes(reg.status)) await releaseSeat(pool, reg.offering_id);
  const { rows } = await pool.query(`UPDATE offering_registrations SET status = $2, updated_at = now() WHERE registration_id = $1 RETURNING *`, [registrationId, toStatus]);
  const updated = rows[0];

  // Best-effort lifecycle notifications — see createRegistration's own comment on why a
  // notification failure never blocks the real state change it's merely announcing.
  const offering = await getOffering(pool, reg.offering_id);
  if (toStatus === 'confirmed') {
    await notificationsLib.enqueueForRegistration(pool, {
      registration: updated, notificationType: 'registration_confirmed',
      metadata: { display_name: updated.registrant_display_name, offering_name: offering?.name },
    }).catch((e) => console.error("[offerings] registration lifecycle notification failed:", e.message));
  }
  if (toStatus === 'agreements_pending') {
    const status = await getRegistrationAgreementStatus(pool, registrationId);
    for (const missing of status.missing) {
      await notificationsLib.enqueueForRegistration(pool, {
        registration: updated, notificationType: 'agreement_required',
        metadata: { display_name: updated.registrant_display_name, offering_name: offering?.name, agreement_title: missing.title },
      }).catch((e) => console.error("[offerings] agreement_required notification failed:", e.message));
    }
  }
  return updated;
}

// ── Offering agreement requirements (Step 18) ────────────────────────────────────────────────
async function addAgreementRequirement(pool, offeringId, agreementId) {
  const { rows: agreementRows } = await pool.query(`SELECT 1 FROM agreement_definitions WHERE agreement_id = $1`, [agreementId]);
  if (!agreementRows[0]) throw err('AGREEMENT_NOT_FOUND', 'No such agreement.');
  const { rows } = await pool.query(
    `INSERT INTO offering_agreement_requirements (offering_id, agreement_id) VALUES ($1, $2) ON CONFLICT DO NOTHING RETURNING *`,
    [offeringId, agreementId]
  );
  return rows[0] || { offering_id: offeringId, agreement_id: agreementId };
}
async function listAgreementRequirementsForOffering(pool, offeringId) {
  const { rows } = await pool.query(
    `SELECT ad.* FROM offering_agreement_requirements oar JOIN agreement_definitions ad ON ad.agreement_id = oar.agreement_id
     WHERE oar.offering_id = $1 ORDER BY ad.title`,
    [offeringId]
  );
  return rows;
}
// Required vs. accepted vs. missing, for one registration — the exact shape both the
// agreements_pending notification loop above and the admin/registration-detail UI need.
async function getRegistrationAgreementStatus(pool, registrationId) {
  const reg = await getRegistration(pool, registrationId);
  if (!reg) throw err('NOT_FOUND', 'No such registration.');
  const required = await listAgreementRequirementsForOffering(pool, reg.offering_id);
  const accepted = await listAcceptancesForRegistration(pool, registrationId);
  const acceptedIds = new Set(accepted.map((a) => a.agreement_id));
  const missing = required.filter((r) => !acceptedIds.has(r.agreement_id));
  return { required, accepted, missing };
}

// The one place a registration becomes a real academic enrollment. Reuses
// enrollment.js's resolveOrCreateStudent/createManualEnrollment/activateEnrollment rather than
// duplicating student-matching or enrollment-creation logic — see that file's own comment on
// why resolveOrCreateStudent is now exported. Cohort membership (if the offering has a cohort)
// is created here too, using the existing cohort_enrollments table unchanged.
async function convertRegistrationToEnrollment(pool, studentsAuth, registrationId, { activate = true } = {}) {
  const reg = await getRegistration(pool, registrationId);
  if (!reg) throw err('NOT_FOUND', 'No such registration.');
  if (reg.status !== 'confirmed') throw err('INVALID_STATE', 'A registration must be confirmed before it can become an enrollment.');
  const offering = await getOffering(pool, reg.offering_id);
  if (!offering) throw err('OFFERING_NOT_FOUND', 'No such offering.');
  // Step 18 — a required agreement with no matching acceptance blocks conversion, always (this
  // offering's own configured requirements, not a global policy toggle this phase invents).
  const agreementStatus = await getRegistrationAgreementStatus(pool, registrationId);
  if (agreementStatus.missing.length) {
    throw err('AGREEMENTS_INCOMPLETE', `Missing required agreement(s): ${agreementStatus.missing.map((m) => m.title).join(', ')}`);
  }

  const student = reg.student_id
    ? (await pool.query(`SELECT * FROM students WHERE student_id = $1`, [reg.student_id])).rows[0]
    : await enrollmentLib.resolveOrCreateStudent(pool, studentsAuth, {
        studentEmail: reg.is_minor ? null : reg.registrant_email,
        studentLoginIdentifier: reg.is_minor ? `reg-${reg.registration_id}` : null,
        studentDisplayName: reg.registrant_display_name,
      }); // no returnToken here — notifyForEnrollment below issues the ONE real token that
          // actually gets used; pre-issuing a second one here would just have it silently
          // overwritten (found while wiring Phase 9's activation-notification call — see that
          // call's own comment).

  const enrollment = await enrollmentLib.createManualEnrollment(pool, {
    studentId: student.student_id, programId: offering.program_id,
    status: activate ? 'active' : 'pending', deliveryMode: offering.delivery_mode,
    externalReference: reg.external_reference,
    metadata: reg.is_minor && reg.registrant_email ? { contact_email: reg.registrant_email } : null,
  });

  if (offering.cohort_id) {
    await pool.query(
      `INSERT INTO cohort_enrollments (cohort_id, student_id) VALUES ($1, $2) ON CONFLICT DO NOTHING`,
      [offering.cohort_id, student.student_id]
    );
  }

  // Phase 9 — the registration's own guardian (set at registration time when a guardian object
  // was submitted) never used to survive conversion into the relational student_guardians model,
  // which is what resolveRecipient's guardian fallback (and any future guardian-facing feature)
  // actually reads. Without this, a brand-new minor student converts with no guardian link at
  // all, and the activation email below has no recipient to resolve to.
  if (reg.is_minor && reg.guardian_id) {
    await linkStudentGuardian(pool, {
      studentId: student.student_id, guardianId: reg.guardian_id,
      relationship: 'guardian', isPrimaryContact: true, canReceiveCommunications: true,
    });
  }

  await pool.query(
    `UPDATE offering_registrations SET student_id = $2, enrollment_id = $3, status = 'enrollment_activated', updated_at = now() WHERE registration_id = $1`,
    [registrationId, student.student_id, enrollment.enrollment_id]
  );

  // Phase 9 §9/§20 — the same activation-or-confirmation email every OTHER enrollment path
  // (the admin manual-enroll route, the website's /api/integrations/enrollments) already
  // triggers automatically. A registration-converted enrollment was the one path that never
  // called this — closed here so a new camp student's real path to logging in doesn't depend
  // on an admin manually relaying `student._activationToken` by hand.
  const programsLib = require('./programs');
  const program = await programsLib.getProgram(pool, offering.program_id);
  let activationToken = null;
  try {
    const notification = await notificationsLib.notifyForEnrollment(pool, studentsAuth, {
      studentId: student.student_id, enrollmentId: enrollment.enrollment_id, programName: program?.name || offering.name,
    });
    activationToken = notification?._activationToken || null;
  } catch (e) {
    console.error('[offerings] enrollment-activation notification failed:', e.message);
  }

  return { student: activationToken ? { ...student, _activationToken: activationToken } : student, enrollment };
}

// ── Agreements ────────────────────────────────────────────────────────────────────────────────
async function createAgreementDefinition(pool, { agreementId, title, bodySummary, requiresGuardianForMinor }) {
  if (!agreementId || !title) throw err('VALIDATION', 'agreementId and title are required.');
  const { rows } = await pool.query(
    `INSERT INTO agreement_definitions (agreement_id, title, body_summary, requires_guardian_for_minor) VALUES ($1, $2, $3, COALESCE($4, true)) RETURNING *`,
    [agreementId, title, bodySummary || null, requiresGuardianForMinor ?? null]
  );
  return rows[0];
}
async function listAgreementDefinitions(pool) {
  const { rows } = await pool.query(`SELECT * FROM agreement_definitions ORDER BY title`);
  return rows;
}
// accepted_by_type: 'student' | 'guardian' | 'instructor_on_behalf' | 'registrant'. 'registrant'
// (Step 7's fix) is the one case allowed with neither a student nor a guardian id — an adult
// self-accepting AT REGISTRATION TIME, before their eventual student_id exists, tied only to
// registrationId. Every other type still requires a real student or guardian id — enforced here
// AND by the DB CHECK constraint (035_phase8_...sql), so this can never be bypassed by a future
// caller that skips this function.
async function recordAgreementAcceptance(pool, { agreementId, acceptedByType, acceptedByStudentId, acceptedByGuardianId, registrationId, enrollmentId, ipAddress }) {
  const { rows: defRows } = await pool.query(`SELECT * FROM agreement_definitions WHERE agreement_id = $1`, [agreementId]);
  const def = defRows[0];
  if (!def) throw err('AGREEMENT_NOT_FOUND', 'No such agreement.');
  if (!['student', 'guardian', 'instructor_on_behalf', 'registrant'].includes(acceptedByType)) {
    throw err('VALIDATION', "accepted_by_type must be one of: student, guardian, instructor_on_behalf, registrant.");
  }
  if (acceptedByType === 'registrant') {
    if (!registrationId) throw err('VALIDATION', 'A registrant acceptance must be tied to a registrationId.');
  } else if (!acceptedByStudentId && !acceptedByGuardianId) {
    throw err('VALIDATION', 'An acceptance must be tied to a student or a guardian.');
  }
  const { rows } = await pool.query(
    `INSERT INTO agreement_acceptances (agreement_id, accepted_version, accepted_by_type, accepted_by_student_id, accepted_by_guardian_id, registration_id, enrollment_id, ip_address)
     VALUES ($1,$2,$3,$4,$5,$6,$7,$8) RETURNING *`,
    [agreementId, def.version, acceptedByType, acceptedByStudentId || null, acceptedByGuardianId || null, registrationId || null, enrollmentId || null, ipAddress || null]
  );
  return rows[0];
}
async function listAcceptancesForRegistration(pool, registrationId) {
  const { rows } = await pool.query(`SELECT * FROM agreement_acceptances WHERE registration_id = $1 ORDER BY accepted_at`, [registrationId]);
  return rows;
}

// ── Website integration — idempotent registration submission (Step 13/14) ──────────────────
// Mirrors enrollment.js's createFromIntegrationEvent exactly: a real DB-level unique index
// (external_reference, 035_phase8_...sql) is what makes concurrent duplicate submissions safe,
// not a SELECT-then-INSERT check. A replay of the same event_id returns the ORIGINAL
// registration, created:false, never a duplicate — same contract shape as the existing
// /api/integrations/enrollments endpoint website code already knows how to handle.
async function createRegistrationFromIntegrationEvent(pool, { eventId, offeringSlug, registrantDisplayName, registrantEmail, isMinor, guardianDisplayName, guardianEmail, guardianPhone, readinessNotes, source }) {
  if (!eventId) throw err('EVENT_ID_REQUIRED', 'event_id is required for idempotent registration events.');
  if (!offeringSlug) throw err('OFFERING_SLUG_REQUIRED', 'offering_slug is required.');
  if (!registrantDisplayName) throw err('VALIDATION', 'registrant display name is required.');
  if (isMinor && !guardianEmail) throw err('GUARDIAN_REQUIRED', 'A minor registration requires a guardian email.');

  const existing = await pool.query(`SELECT * FROM offering_registrations WHERE external_reference = $1`, [eventId]);
  if (existing.rows[0]) return { registration: existing.rows[0], created: false };

  const { rows: offeringRows } = await pool.query(`SELECT * FROM offerings WHERE slug = $1`, [offeringSlug]);
  const offering = offeringRows[0];
  if (!offering) throw err('OFFERING_NOT_FOUND', 'Unknown offering_slug.');
  assertRegistrationOpen(offering);

  let guardianId = null;
  if (isMinor) {
    // Match an existing guardian by email first (a returning family shouldn't get a duplicate
    // guardian row per sibling/per camp) — same "match before create" principle
    // enrollment.js's resolveOrCreateStudent already established for students.
    const existingGuardian = await pool.query(`SELECT guardian_id FROM guardians WHERE email = $1`, [String(guardianEmail).toLowerCase().trim()]);
    if (existingGuardian.rows[0]) {
      guardianId = existingGuardian.rows[0].guardian_id;
    } else {
      guardianId = `guardian-${eventId}`;
      await createGuardian(pool, { guardianId, displayName: guardianDisplayName || guardianEmail, email: guardianEmail, phone: guardianPhone });
    }
  }

  try {
    await reserveSeat(pool, offering.offering_id);
  } catch (e) {
    if (e.code === 'OFFERING_FULL') throw e;
    throw e;
  }
  try {
    const { rows } = await pool.query(
      `INSERT INTO offering_registrations (offering_id, guardian_id, registrant_display_name, registrant_email, is_minor, readiness_notes, source, external_reference, reservation_expires_at)
       VALUES ($1,$2,$3,$4,COALESCE($5,false),$6,$7,$8,$9)
       ON CONFLICT (external_reference) WHERE external_reference IS NOT NULL DO NOTHING
       RETURNING *`,
      [offering.offering_id, guardianId, registrantDisplayName, registrantEmail || null, isMinor ?? null, readinessNotes || null, source || 'website', eventId, computeReservationExpiry(offering)]
    );
    if (rows[0]) {
      await notificationsLib.enqueueForRegistration(pool, {
        registration: rows[0], notificationType: 'registration_received',
        metadata: { display_name: rows[0].registrant_display_name, offering_name: offering.name },
      }).catch((e) => console.error("[offerings] website registration_received notification failed:", e.message));
      return { registration: rows[0], created: true };
    }
    // Lost the ON CONFLICT race (concurrent identical replay) — release the seat we just
    // reserved (the winner already holds theirs) and return the winner's row.
    await releaseSeat(pool, offering.offering_id);
    const { rows: won } = await pool.query(`SELECT * FROM offering_registrations WHERE external_reference = $1`, [eventId]);
    return { registration: won[0], created: false };
  } catch (e) {
    await releaseSeat(pool, offering.offering_id).catch(() => {});
    throw e;
  }
}

// ── Launch readiness (Step 20) — server-derived, never left to frontend logic alone ─────────
async function computeOfferingReadiness(pool, offeringId) {
  const offering = await getOffering(pool, offeringId);
  if (!offering) throw err('NOT_FOUND', 'No such offering.');
  const checks = [];
  checks.push({ key: 'curriculum', label: 'Curriculum', ready: !!offering.program_id });
  const needsInstructor = offering.delivery_mode !== 'self_paced';
  if (needsInstructor) {
    const { rows } = await pool.query(`SELECT count(*)::int AS n FROM instructor_offerings WHERE offering_id = $1`, [offeringId]);
    checks.push({ key: 'instructor', label: 'Instructor assigned', ready: rows[0].n > 0 });
  }
  const needsSchedule = !['self_paced'].includes(offering.delivery_mode);
  if (needsSchedule) checks.push({ key: 'schedule', label: 'Dates', ready: !!(offering.starts_at && offering.ends_at) });
  const needsLocation = !['self_paced'].includes(offering.delivery_mode);
  if (needsLocation) checks.push({ key: 'location', label: 'Location', ready: !!offering.location_id || offering.delivery_mode === 'community' });
  checks.push({ key: 'capacity', label: 'Capacity', ready: offering.capacity !== null || offering.delivery_mode === 'self_paced' });
  checks.push({ key: 'registration_window', label: 'Registration window', ready: !!(offering.enrollment_opens_at && offering.enrollment_closes_at) });
  const requirements = await listAgreementRequirementsForOffering(pool, offeringId);
  checks.push({ key: 'agreements', label: 'Agreements configured', ready: requirements.length > 0 });
  if (offering.curriculum_package_id) {
    const pkg = await getCurriculumPackage(pool, offering.curriculum_package_id);
    checks.push({ key: 'curriculum_package', label: 'Curriculum package valid', ready: !!pkg && pkg.items.length > 0 });
  }
  // Phase 9 §29 — a PAID offering (price_amount set) additionally needs a real price and a
  // configured payment provider before it's genuinely launch-ready; a free offering never
  // needs either, unchanged from Phase 8.
  if (offering.price_amount !== null) {
    checks.push({ key: 'price', label: 'Price configured', ready: offering.price_amount > 0 && !!offering.price_currency });
    const { getPaymentProvider } = require('./payment-provider');
    let providerConfigured = false;
    try { const p = getPaymentProvider(); providerConfigured = p.name === 'test' || !!(process.env.STRIPE_SECRET_KEY && process.env.STRIPE_WEBHOOK_SECRET); } catch { providerConfigured = false; }
    checks.push({ key: 'payment_provider', label: 'Payment provider configured', ready: providerConfigured });
  }
  const allReady = checks.every((c) => c.ready);
  return { offering_id: offeringId, ready_to_open_registration: allReady, checks };
}

module.exports = {
  createOrganization, listOrganizations,
  createLocation, listLocations,
  createGuardian, linkStudentGuardian, listGuardiansForStudent,
  createCurriculumPackage, addCurriculumPackageItem, getCurriculumPackage,
  createOffering, getOffering, updateOffering, listOfferings, transitionOffering, assignInstructorToOffering, reserveSeat, releaseSeat,
  createRegistration, getRegistration, listRegistrationsForOffering, transitionRegistration, convertRegistrationToEnrollment,
  createAgreementDefinition, listAgreementDefinitions, recordAgreementAcceptance, listAcceptancesForRegistration,
  addAgreementRequirement, listAgreementRequirementsForOffering, getRegistrationAgreementStatus,
  createRegistrationFromIntegrationEvent, computeOfferingReadiness, assertRegistrationOpen,
};