/***********************************************************************************************************************************************************************
 * File Name: certificate.controller.js  (client)
 * Type of Program: Controller
 * Description: Issues a PDF certificate for a completed course.
 *              A certificate is available only when the user has passed the course assessment.
 *              Certificate records are persisted (findOrCreate) so the same cert_no/ref_no is
 *              returned on every subsequent download.
 *
 * Author: Kenneth Obsequio (@lash0000)
 * Date Created: Jun. 18, 2026
 ***********************************************************************************************************************************************************************/
'use strict';

const R                       = require('../../utils/response.util');
const mdl_Users               = require('../../models/users/users.mdl');
const { generateCertificate } = require('../../services/certificate.service');
const { ensureCertificateRecord, formatInstructors } = require('../../services/certificate-record.service');
const { fmtDate }             = require('../../utils/datetime.util');

const {
  Course,
  CourseAssessment,
  CourseInstructor,
} = require('../../models/courses/courses.associations');

const notDeleted = { deletedAt: null };

// ─── GET /api/client/certificates/:courseUuid ──────────────────────────────────

exports.getCertificate = async (req, res) => {
  try {
    const { courseUuid } = req.params;
    const user_id        = req.user.user_id;

    // ── 1. Resolve course ──────────────────────────────────────────────────────
    const course = await Course.findOne({
      where:      { uuid: courseUuid, ...notDeleted },
      attributes: ['course_id', 'title', 'course_code', 'duration_seconds'],
      include: [
        {
          model:      CourseAssessment,
          as:         'assessment',
          attributes: ['assessment_id'],
          required:   false,
        },
        {
          model:      CourseInstructor,
          as:         'instructors',
          attributes: ['display_name', 'order_index'],
          required:   false,
          order:      [['order_index', 'ASC']],
        },
      ],
    });

    if (!course) return R.error(res, 'Course not found.', 404);

    if (!course.assessment) {
      return R.error(res, 'This course does not have an assessment — no certificate available.', 404);
    }

    // ── 2. Get user's name ──────────────────────────────────────────────────────
    const user     = await mdl_Users.findByPk(user_id, { attributes: ['personal_info'] });
    const fullName = user?.personal_info?.name?.full_name?.trim() || 'Participant';

    // ── 3. Resolve or create the certificate record ─────────────────────────────
    // Shared with the hourly issuance cron (cron/jobs/issue_certificates.cron.js)
    // so both write through the same cert_no/ref_no sequence.
    const cert = await ensureCertificateRecord({ userId: user_id, courseId: course.course_id });
    if (!cert) {
      return R.error(res, 'Certificate not available — course assessment not passed yet.', 403);
    }

    // Always use live instructors from course_instructors table for the PDF,
    // in case they changed since the certificate row was created.
    const liveInstructors = formatInstructors(course.instructors ?? []);

    // ── 4. Format issued date as MM/DD/YY HH:MM AM/PM ───────────────────────────
    const issuedDate = new Date(cert.issued_at);
    const dateStr    = fmtDate(issuedDate);

    // ── 5. Generate PDF ────────────────────────────────────────────────────────
    const pdf = await generateCertificate({
      name:        fullName,
      course:      course.title,
      date:        dateStr,
      cert_no:     cert.cert_no,
      ref_no:      cert.ref_no,
      instructors: liveInstructors,
      length:      cert.length_str  ?? '',
    });

    // ── 6. Stream response ─────────────────────────────────────────────────────
    const nameParts  = fullName.trim().split(/\s+/);
    const lastName   = nameParts.length > 1 ? nameParts[nameParts.length - 1] : nameParts[0];
    const firstName  = nameParts.length > 1 ? nameParts.slice(0, -1).join(' ') : '';
    const safeTitle  = course.title.replace(/[/\\:*?"<>|]/g, '').trim();
    const filename   = `${lastName},${firstName}_${safeTitle}_${cert.cert_no}.pdf`;
    const asciiName  = filename.replace(/[^\x20-\x7E]/g, '_').replace(/"/g, '_');
    const encodedName = encodeURIComponent(filename);

    res.set({
      'Content-Type':        'application/pdf',
      'Content-Disposition': `attachment; filename="${asciiName}"; filename*=UTF-8''${encodedName}`,
      'Content-Length':      pdf.length,
    });

    return res.send(pdf);
  } catch (err) {
    console.error('[CLIENT][CERTIFICATE]', err);
    return R.error(res, 'Could not generate certificate.', 500);
  }
};