Best practices for organizing a custom calculator plugin in PhpStorm?

Hi everyone,

I'm currently building a custom calculator plugin for a WordPress website. The calculator itself is fairly straightforward—it takes a few user inputs, performs the necessary calculations, and displays the result instantly using JavaScript. I decided to build it from scratch instead of relying on a third-party plugin because I wanted something lightweight and easier to customize.

I'm using PhpStorm for development, and so far the experience has been great. Features like code completion, navigation, and inspections have definitely made development faster. However, as the project grows, I'm starting to think more about code organization and long-term maintainability.

At the moment, my plugin is organized like this:

calculator-plugin/
├── calculator.php
├── assets/
│   ├── css/
│   └── js/
├── includes/
├── templates/
└── README.md

The next features I plan to add include:

• Better input validation
• AJAX support
• Admin settings
• Reusable helper functions
• Unit conversion options
• Improved error handling

Before I continue, I'd like to know how other developers structure similar WordPress projects.

A few questions I have:

1. At what point do you switch from procedural code to an object-oriented structure?
2. Do you use Composer and namespaces even for relatively small WordPress plugins?
3. Are there any PhpStorm inspections or plugins that you consider essential for WordPress development?
4. How do you organize reusable utility functions without making the project difficult to maintain?
5. Do you follow any specific project structure that has worked well for medium-sized plugins?

I'm trying to keep the project clean, readable, and easy to maintain as new features are added. I'd appreciate any suggestions or examples from developers who have built custom WordPress plugins using PhpStorm.

Thanks in advance!