commerce_simple_stock.module

<?php

use Drupal\Core\Form\FormStateInterface;
use \Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function commerce_simple_stock_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the commerce_simple_stock module.
    case 'help.page.commerce_simple_stock':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Allows commerce_simple_stock.') . '</p>';
      // Here should be details about setting up and using
      return $output;

    default:
  }
}

function commerce_simple_stock_theme($existing, $type, $theme, $path) {
  return [
    'commerce_simple_stock_inventory_control_form' => [
      'render element' => 'form',
    ],
  ];
}

function commerce_simple_stock_form_commerce_order_item_add_to_cart_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  $form_data = $form_state->getStorage();
  if (empty($form_data['product'])) {
    return;
  }

	$selectedVariationId = $form_state->get('selected_variation');
	if ($selectedVariationId != null) {
		$variation = \Drupal\commerce_product\Entity\ProductVariation::load($selectedVariationId);
	} else {
		$product = $form_data['product'];
		$variation = $product->getDefaultVariation();
	}
	
	if ($variation->hasField('field_stock') && $variation->field_stock->value != null) {
		
		$stock = (integer) $variation->field_stock->value;
		
		if ($stock <= 0) {
			$form['quantity'] = null;
			$form['actions'] = null;
			$form['outofstock'] = [
			  '#type' => 'textfield',
			  '#value' => t('Out of Stock'),
			  '#weight' => 0,
			  '#disabled' => true,
			];
		}
		
	}
	
}