How to enable WordPress Extensions in your Plugin | https://www.ibenic.com/wordpress-extensions-plugin

abstract.php

<?php

/**
 * Abstract Extension Class from which all others should be done
 */

if( ! defined( 'ABSPATH' ) ) {
    return;
}

abstract class My_Plugin_Extension {
    
    /**
    * Extension ID
    * @var string
    */
    public $id = '';
    
    /**
     * Active Indicator
     * @var boolean
     */
    public $active = false;

    /**
     * Integration Image
     * @var string
     */
    public $image = '';

    /**
     * Integration Title
     * @var string
     */
    public $title = '';

    /**
     * Integration Description
     * @var string
     */
    public $desc = '';
    
    /**
    * Load method used to create hooks to extend or apply new features
    * This method will be called only on active extensions
    */
    public function load() {}

    /**
     * Buttons to be shown on the Extensions screen
     *
     * @param  array $integrations Array of active integrations.
     * @return void 
     */
    public function buttons( $integrations ) {

        if( ! isset( $integrations[ $this->id ] ) ) {
                ?>
                    <button type="button" data-integration="<?php echo $this->id; ?>" class="button button-primary button-extension-activate"><?php _e( 'Activate', 'givasap' ); ?></button>
                <?php
            } else {
                ?>
                    <button type="button" data-integration="<?php echo $this->id; ?>" class="button button-default button-extension-deactivate"><?php _e( 'Deactivate', 'givasap' ); ?></button>
                <?php
            }
        ?>
        <?php
    }
}

activate_ajax.php

<?php

add_action( 'wp_ajax_myplugin_activate_extension', 'myplugin_activate_extension_ajax' );

/**
 * Activating the Extension through AJAX
 * @return void 
 */
function myplugin_activate_extension_ajax() {
    // Check if there is a nonce and if it is, verify it. Otherwise throw an error
    if( ! isset( $_POST['nonce'] ) 
        || ! wp_verify_nonce( $_POST['nonce'], 'myplugin-nonce' ) ) {
        
        wp_send_json_error( array( 'message' => __( 'Something went wrong!', 'mytextdomain' ) ) );
        die();
    }
    // If we don't have an extension id, don't process any further.
    if( ! isset( $_POST['extension'] ) ) {
        wp_send_json_error( array( 'message' => __( 'No Integration Sent', 'mytextdomain' ) ) );
        die();
    }
    // The extension to activate
    $extension = $_POST['extension'];

    $active_extensions = get_active_extensions();
    // If that extension is already active, don't process it further.
    // If the extension is not active yet, let's try to activate it.
    if( ! isset( $active_extensions[ $extension ] ) ) {
        // Let's get all the registered extensions.
        $extensions = get_extensions(); 
        // Check if we have that extensions registered.
        if( isset( $extensions[ $extension ] ) ) {
            // Put it in the active extensions array
            $active_extensions[ $extension ] = $extensions[ $extension ];
            // Trigger an action so some plugins can also process some data here.
            do_action( 'my_plugin' . $extension . '_extension_activated' );
            // Update the active extensions.
            update_option( 'my_plugin_active_extensions', $active_extensions );
            wp_send_json_success( array( 'message' => __( 'Activated', 'mytextdomain' ) ) );
            die();
        }
        
    } else {
        // Our extension is already active.
        wp_send_json_success( array( 'message' => __( 'Already Activated', 'mytextdomain' ) ) );
        die();
    }

    // Extension might not be registered.
    wp_send_json_error( array( 'message' => __( 'Nothing Happened', 'mytextdomain' ) ) );
    die();
}

admin_enqueue.php

<?php

add_action( 'admin_enqueue_scripts', 'my_plugin_admin_enqueue_scripts' );

/**
* Enqueue Admin Scripts
*/
function my_plugin_admin_enqueue_scripts( $hook_suffix ) {
		 
 $hook_scripts = false;
		
 // var_dump the hook suffix so you find your own hook suffix here
 // Uncomment below to find the suffix
 // var_dump( $hook_suffix ); die(); 
 if( 'page_page_myplugin_extensions' == $hook_suffix ) {
  $hook_scripts = true;
 }

 if ( $hook_scripts ) {
  // Be sure to change the URL to the script where you will have it.
  wp_register_script( 'myplugin-admin-js', YOUR_PLUGIN_URL_TO_JS . '/myplugin-admin.js', array( 'jquery' ) );
  // Localizing our script so we have a global 
  // Javascript variable myplugin to access the values such as nonce.
  wp_localize_script( 
   'myplugin-admin-js',
   'myplugin', 
   array(
    'ajax_url' => admin_url( 'admin-ajax.php' ),
    'nonce'    => wp_create_nonce( 'myplugin-nonce' ),
    'text'     => array(
     'activate' => __( 'Activate', 'mytextdomain' ),
     'deactivate' => __( 'Deactivate', 'mytextdomain' ),
    )
   ));
   wp_enqueue_script( 'myplugin-admin-js' );
  }
}

deactivate_ajax.php

<?php

add_action( 'wp_ajax_myplugin_deactivate_extension', 'myplugin_deactivate_extension_ajax' );

/**
 * Deactivating the Integration through AJAX
 * @return void 
 */
function myplugin_deactivate_extension_ajax() {
    // Check if there is a nonce and if it is, verify it. Otherwise throw an error
    if( ! isset( $_POST['nonce'] ) 
        || ! wp_verify_nonce( $_POST['nonce'], 'myplugin-nonce' ) ) {
        
        wp_send_json_error( array( 'message' => __( 'Something went wrong!', 'mytextdomain' ) ) );
        die();
    }
    // If we don't have an extension id, don't process any further.
    if( ! isset( $_POST['extension'] ) ) {
        wp_send_json_error( array( 'message' => __( 'No Integration Sent', 'mytextdomain' ) ) );
        die();
    }
    // The extension to activate
    $extension = $_POST['extension'];

    $active_extensions = get_active_extensions();
    // If that extension is already deactived, don't process it further.
    // If the extension is active, let's try to deactivate it.
    if( isset( $active_extensions[ $extension ] ) ) {
        // Remove the extension from the active extensions.
        unset( $active_extensions[ $extension ] );
        do_action( 'my_plugin' . $extension . '_extension_activated' );
        // Update the active extensions.
        update_option( 'my_plugin_active_extensions', $active_extensions );
        wp_send_json_success( array( 'message' => __( 'Deactivated', 'mytextdomain' ) ) );
        die();
    } else {
        wp_send_json_error( array( 'message' => __( 'Not Activated', 'mytextdomain' ) ) );
        die();
    }

    wp_send_json_error( array( 'message' => __( 'Nothing Happened', 'mytextdomain' ) ) );
    die();
}

example.php

<?php

/**
 * Plugin Name: Example Extension
 * Descriptipn: This can be passed as a plugin or inside the main plugin itself.
 */

if( ! defined( 'ABSPATH' ) ) {
    return;
}

// Check if the abstract class exists. If not, don't do anything. 
// You can define this class after a hook such as plugins_loaded to be sure.
if( ! class_exists( 'My_Plugin_Extension' ) ) { return; }

class My_Plugin_MailChimp extends My_Plugin_Extension {
  
    public function __construct() {
     $this->id = 'mailchimp';
     $this->image = URL_TO_THE_IMAGE;
     $this->title = __( 'MailChimp', 'mytextdomain' );
     $this->desc  = __( 'MailChimp Integration for My Plugin', 'mytextdomain' );
    }
   
    /**
    * Load method used to create hooks to extend or apply new features
    * This method will be called only on active extensions
    */
    public function load() {
      add_action( 'user_register', array( $this, 'add_user_to_mailchimp' ) );
    }
  
    public function add_user_to_mailchimp( $user_id ) {
      // Code to get the user email and subscribe it to Mailchimp.
    }
}

add_filter( 'my_plugin_extensions', 'add_mailchimp_extension' );

/**
* Add mailchimp extension by passing the id and the name of the class.
*
* @param  array $extensions
* @return array
*/
function add_mailchimp_extension( $extensions ) {
  $extensions['mailchimp'] = 'My_Plugin_MailChimp';
  return $extensions;
}

get_active_integrations.php

<?php

/**
* Get all activated extensions
*/
function get_active_extensions() {
  return get_option( 'my_plugin_active_extensions', array() );
}

get_integrations.php

<?php

/**
* Get all the registered extensions through a filter
*/
function get_extensions() {
  return apply_filters( 'my_plugin_extensions', array() );
}

loading_extensions.php

<?php

/**
* This hook can be on 'init' also all if you have a custom one like this
*/
add_action( 'my_plugin_loaded', 'my_plugin_loading_extensions' );

function my_plugin_loading_extensions() {
 $active_extensions = get_active_extensions();
 if( $active_extensions ) {
  foreach( $active_extensions as $slug => $extension ) {
    if( ! class_exists( $extension ) ) {
     continue;
    }
    $extension = new $extension();
    $extension->load();
  }
 }
}

myplugin-admin.js

(function($){

    $( document ).on( 'click', '.button-extension-activate', function( e ){
      e.preventDefault();
      // Get the current extension ID
      var extension = $(this).attr('data-integration'),
          $this = $(this);
      
      if( extension ) {
        // Process AJAX
        $.ajax({
          url: myplugin.ajax_url,
          dataType: 'json',
          type: 'POST',
          data: { action: 'myplugin_activate_extension', extension: extension, nonce: myplugin.nonce },
          success: function(resp) {
            if( resp.success ) {
              // On success, add the deactivate class and remove the activate class. 
              // Also remove the primary class so we have a gray button and not a blue one.
              $this.addClass('button-integration-deactivate')
                .addClass('button-default')
                .removeClass('button-integration-activate')
                .removeClass('button-primary')
                .html( myplugin.text.deactivate );
            } 
          }
        });
      }

    });


})(jQuery);

myplugin-admin2.js

(function($){
  
   // ...
  
   $( document ).on( 'click', '.button-extension-deactivate', function( e ){
      e.preventDefault();

      var extension = $(this).attr('data-integration'),
          $this = $(this);
      if( extension ) {
        $.ajax({
          url: myplugin.ajax_url,
          dataType: 'json',
          type: 'POST',
          data: { action: 'myplugin_deactivate_extension', extension: extension, nonce: myplugin.nonce },
          success: function(resp) {
            if( resp.success ) {
              $this.removeClass('button-integration-deactivate')
                .removeClass('button-default')
                .addClass('button-integration-activate')
                .addClass('button-primary')
                .html( myplugin.text.activate );
            } 
          }
        });
      }

    });
})(jQuery);

submenu.php

<?php

add_action( 'admin_menu', 'my_plugin_add_extensions_submenu' );

/**
* Add a submenu
* Assuming we have a parent menu such as a custom post type
* Otherwise add it as a menu or under some other parent menu
*/
function my_plugin_add_extensions_submenu() {
  add_submenu_page( 
    'edit.php?post_type=page', // Put your cpt slug if you have one
    __( 'Extensions', 'mytextdomain' ),
    __( 'Extensions', 'mytextdomain' ),
    'manage_options',
    'myplugin_extensions',
    'my_plugin_extensions_html' );
}

submenu_html.php

<?php

/**
* Admin Screen for extensions
*/
function my_plugin_extensions_html() {
  // Get all extensions
  $all_extensions    = get_extensions();
  // Get active extensions
 $active_extensions = get_active_extensions();
 ?>
 <div class="wrap">
  <h1><?php echo get_admin_page_title(); ?></h1>
  <p><?php _e( 'All My Plugin Extensions. Choose which to use and activate them.', 'mytextdomain' ); ?></p>
		 
  <div class="wp-list-table widefat plugin-install">
   <div id="the-list">
   <?php 
   if( $all_extensions ) {
    foreach ( $all_extensions as $slug => $class ) {
     if( ! class_exists( $class ) ) {
      continue;
     }
     // Instantiate each extension
     $extension_object = new $class();
     // We will use this object to get the title, description and image of the extension.
     ?>
     <div class="plugin-card plugin-card-<?php echo $slug; ?>">
      <div class="plugin-card-top">
       <div class="name column-name">
        <h3>
         <?php echo $extension_object->title; ?>					
         <img src="<?php echo $extension_object->image; ?>" class="plugin-icon" alt="">
        </h3>
       </div>
       <div class="desc column-description">
        <p><?php echo $extension_object->desc; ?></p>
       </div>
      </div>
      <div class="plugin-card-bottom">
       <?php 
	    // Use the buttons from our Abstract class to create the buttons
	    // Can be overwritten by each integration if needed.
	    $extension_object->buttons( $active_extensions ); 
        ?>
      </div>
     </div>
    <?php
    }
   }
   ?>
   </div>
  </div>
 </div>	 
<?php
}