upskill-event-manager/wordpress-dev/wordpress/wp-content/plugins/hvac-community-events/docs/certificate-generation-plan.md

Certificate Generation Implementation Plan

Overview

This document outlines the development plan for implementing the certificate generation feature for the HVAC Community Events plugin. This feature is part of Phase 3 and will enable trainers to create, manage, and distribute certificates to event attendees.

1. Feature Architecture

1.1 Database Schema

We will create a new table in the WordPress database called {prefix}_hvac_certificates with the following structure:

CREATE TABLE {prefix}_hvac_certificates (
    certificate_id BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
    event_id BIGINT(20) UNSIGNED NOT NULL,
    attendee_id BIGINT(20) UNSIGNED NOT NULL,
    user_id BIGINT(20) UNSIGNED NOT NULL,
    certificate_number VARCHAR(50) NOT NULL,
    file_path VARCHAR(255) NOT NULL,
    date_generated DATETIME NOT NULL,
    generated_by BIGINT(20) UNSIGNED NOT NULL,
    revoked TINYINT(1) NOT NULL DEFAULT 0,
    revoked_date DATETIME DEFAULT NULL,
    revoked_by BIGINT(20) UNSIGNED DEFAULT NULL,
    revoked_reason TEXT DEFAULT NULL,
    email_sent TINYINT(1) NOT NULL DEFAULT 0,
    email_sent_date DATETIME DEFAULT NULL,
    PRIMARY KEY (certificate_id),
    UNIQUE KEY event_attendee (event_id, attendee_id),
    KEY event_id (event_id),
    KEY attendee_id (attendee_id),
    KEY user_id (user_id),
    KEY certificate_number (certificate_number),
    KEY revoked (revoked)
) {charset_collate};

We will also need options to store certificate generation settings:

// Certificate options
update_option('hvac_certificate_counter', 0); // For generating sequential certificate numbers
update_option('hvac_certificate_prefix', 'HVAC-'); // Prefix for certificate numbers
update_option('hvac_certificate_storage_path', 'certificates'); // Relative to wp-content/uploads/

1.2 File Structure

hvac-community-events/
├── assets/
│   ├── css/
│   │   ├── hvac-certificates-report.css
│   │   └── hvac-generate-certificates.css
│   ├── js/
│   │   ├── hvac-certificates-report.js
│   │   └── hvac-generate-certificates.js
│   └── templates/
│       └── certificate-template.pdf
├── includes/
│   ├── certificates/
│   │   ├── class-certificate-manager.php
│   │   ├── class-certificate-generator.php
│   │   ├── class-certificates-report.php
│   │   └── class-certificates-settings.php
│   └── community/
│       ├── class-certificates-report-page.php
│       └── class-generate-certificates-page.php
├── templates/
│   ├── template-certificates-report.php
│   └── template-generate-certificates.php

1.3 Class Structure

HVAC_Certificate_Manager

• Main controller class for certificate operations
• Manages database interactions
• Handles certificate status updates

HVAC_Certificate_Generator

• Handles PDF generation
• Manages certificate templates
• Creates individualized certificates

HVAC_Certificates_Report

• Data handler for the Certificates Report page
• Retrieves statistics and certificate data

HVAC_Certificates_Settings

• Manages certificate settings
• Handles template customization options

HVAC_Certificates_Report_Page

• Controller for the Certificates Report page
• Registers shortcode and handles rendering

HVAC_Generate_Certificates_Page

• Controller for the Generate Certificates page
• Manages multi-step workflow

2. Implementation Steps

2.1 Setup Phase

1. Add PDF Library

   • Add TCPDF or mPDF library to composer.json
   • Update composer dependencies
   • Create base certificate template

2. Create Database Tables

   • Implement activation hook for table creation
   • Create upgrade routine for existing installations

3. Create Certificate Management Classes

   • Implement Certificate_Manager class
   • Implement Certificate_Generator class
   • Add certificate settings management

2.2 UI Development Phase

4. Develop Certificate Report Page

   • Create page template with statistics section
   • Implement certificates table with filtering
   • Add navigation and action buttons

5. Develop Generate Certificates Page

   • Implement multi-step form UI
   • Create event selection interface
   • Create attendee selection interface
   • Add certificate preview functionality
   • Implement distribution options

6. Integrate with Existing Pages

   • Add certificate actions to Event Summary page
   • Add certificate indicators to Dashboard

2.3 Functionality Development Phase

7. Implement Certificate Generation

   • Create PDF generation functionality
   • Implement certificate numbering system
   • Add storage and retrieval mechanisms

8. Implement Email Distribution

   • Create email template for certificates
   • Add batch email functionality
   • Implement email tracking

9. Add Revocation Functionality

   • Create certificate revocation UI
   • Implement revocation status tracking
   • Add revocation reason documentation

2.4 Testing and Finalization Phase

10. Create Automated Tests

    • Add unit tests for certificate classes
    • Implement E2E tests for certificate workflow
    • Test cross-browser compatibility

11. Finalize Documentation

    • Update user documentation
    • Create admin documentation
    • Add code comments and docblocks

12. Security and Performance Optimization

    • Add proper capability checks
    • Implement file access security
    • Optimize database queries
    • Add caching where appropriate

3. PDF Library Selection

After reviewing available PHP PDF libraries, we recommend using TCPDF for the following reasons:

1. WordPress Compatibility: TCPDF works well with WordPress environments
2. Feature Set: Supports all required features for certificates (text, images, signatures)
3. Active Maintenance: Regular updates and security patches
4. License: Compatible with GPL-2.0+
5. Performance: Efficient for generating certificate PDFs

Alternatives considered:

• FPDF: Simpler but fewer features
• mPDF: HTML to PDF conversion (more complex but more flexible)
• Dompdf: HTML to PDF conversion (good for complex layouts)

4. Certificate Design

The certificate template will include:

1. Header: HVAC Community Events logo and title

2. Main Content:

   • "Certificate of Completion" title
   • Attendee name (large, prominent font)
   • Course completion statement
   • Event name and date
   • Training organization name
   • Venue location

3. Footer:

   • Instructor name and signature
   • Certificate number
   • Date of issuance
   • QR code linking to verification page (future enhancement)

5. Integration Points

5.1 The Events Calendar Integration

• Pull event details (name, date, venue)
• Access organizer information

5.2 Event Tickets Integration

• Access attendee data
• Check attendance status from check-in feature

5.3 WordPress Integration

• User authentication and capabilities
• File storage in wp-content/uploads

6. Timeline and Dependencies

Task	Dependencies	Estimated Time
Database Setup	None	1 day
PDF Library Integration	None	1 day
Certificate Template Design	PDF Library	2 days
Certificate Manager Class	Database Setup	2 days
Certificates Report Page	Certificate Manager	3 days
Generate Certificates Page	Certificate Manager, Template	4 days
Email Integration	Generate Certificates Page	2 days
Event Summary Integration	Certificate Manager	1 day
Testing and Bug Fixes	All Above	3 days
Documentation	All Above	1 day

Total estimated time: 20 days

7. Potential Challenges and Solutions

7.1 PDF Generation Performance

Challenge: Generating multiple PDFs could be resource-intensive Solution:

• Implement batch processing
• Add progress indicators
• Use asynchronous processing for large batches

7.2 File Storage and Security

Challenge: Certificate PDFs need secure storage but must be accessible Solution:

• Store in protected directory with .htaccess rules
• Implement secure download mechanism
• Use WordPress nonces for download links

7.3 Email Deliverability

Challenge: Bulk sending certificates could trigger spam filters Solution:

• Use WordPress mail with proper headers
• Implement rate limiting
• Add configurable batch sizes

8. Future Enhancements

1. Certificate Verification System

   • Public verification page using certificate number
   • QR codes on certificates linking to verification

2. Advanced Certificate Templates

   • Multiple template options
   • Custom branding for trainers

3. Integration with My Training Page

   • Allow trainees to access their certificates from profile

4. Certificate Analytics

   • Track certificate views and downloads
   • Generate reports on certificate usage

9. Conclusion

This implementation plan provides a comprehensive approach to developing the certificate generation feature for the HVAC Community Events plugin. By following this structured approach, we can deliver a robust, secure, and user-friendly certificate system that enhances the value of the training platform for both trainers and attendees.