• Plugin development - PHP 8 OOP design patterns - full-stack architecture, data modeling, and API integrations.

🧠 Architecture Overview

• Advanced Form Engine is designed as a modular, event-driven WordPress plugin, intentionally structured to resemble larger PHP applications rather than traditional monolithic WordPress plugins.

• The goal of this architecture is to keep business logic decoupled, features extensible, and integrations replaceable, while remaining fully compatible with WordPress core APIs.

🧩 High-Level Design

• The plugin is organized into clear, responsibility-driven layers:

src/
├── Admin/          → WordPress admin UI (forms list, editor, settings)
├── Frontend/       → Shortcodes, rendering, submission handling
├── Forms/          → Form entities and repositories
├── Submissions/    → Submission persistence
├── Notifications/  → Slack, Email, Webhook strategies
├── Events/         → Domain events
├── Core/           → Plugin bootstrap, service container, event dispatcher
└── Settings/       → Plugin configuration storage

• Each layer has a single responsibility and communicates with others through interfaces and events, not direct dependencies.

🔧 Dependency Injection & Service Container

• All core services are registered during plugin bootstrap using a lightweight service container.

• Examples of container-managed services include:

  • Form repositories

  • Submission repositories

  • Event dispatcher

  • Notification manager

  • Settings handler

  • Frontend shortcode handler

• This avoids:

  • Global state

  • Hard-coded dependencies

  • Tight coupling between unrelated components

  • It also improves maintainability, testability, and long-term extensibility.

🔁 Event-Driven Submissions (Observer Pattern)

• When a form submission is successfully saved, the plugin emits a domain-level event:

  • afe.submission.created

• This event contains:

  • The form ID

  • The submission ID

  • Sanitized submission data

• The submission logic does not know which integrations will react to this event.

• Instead, listeners subscribe via an internal EventDispatcher, implementing the Observer pattern.

• This allows new behaviors (notifications, logging, integrations) to be added without modifying the submission workflow.

🔌 Notifications via Strategy Pattern

• All notification integrations implement a shared interface:

  • NotifierInterface

• Current notifier strategies include:

  • Slack Incoming Webhook

  • Email notifications (via wp_mail)

  • Custom JSON Webhook (HTTP POST)

• Each notifier:

  • Determines internally whether it is enabled

  • Reacts independently to submission events

  • Can be added or removed without impacting other integrations

🌉 WordPress ↔ Domain Bridge

• WordPress hooks are used only as entry points, not as the core architectural layer.

• For example:

  • A WordPress action (do_action('afe/submission_created')) is triggered after saving a submission.

• This action is translated into a domain event.

• Internal observers respond to the event independently.

• This keeps WordPress-specific concerns isolated and prevents framework lock-in inside business logic.

🔐 Security & Data Handling

• The plugin follows WordPress security best practices throughout:

  • Nonce verification for all form submissions.

  • Capability checks for admin actions.

  • Field-level sanitization and validation.

  • JSON-based storage for flexible submission schemas.

  • Integration secrets (webhook URLs, notification emails) are stored centrally through the Settings layer.

🚀 Why This Architecture?

• This architecture was chosen to demonstrate:

  • Scalable plugin design beyond procedural hooks.

  • Clean separation of concerns.

  • OPP patterns (Repository, Strategy, Observer)

  • Long-term maintainability and extensibility