Allow $maximum magic number in https://wordpress.org/support/plugin/woo-min-max-quantity-limit

change.patch

diff --git a/woo-min-max-quantity.php b/woo-min-max-quantity.php
index f9614ef..c35e2b9 100644
--- a/woo-min-max-quantity.php
+++ b/woo-min-max-quantity.php
@@ -86,7 +86,7 @@ function _wcmmax_options_page()
   
   <table>
   <tr valign="top">
-  <th scope="row"><label for="_wcmmax_options_option_name">Custom alert message for maximum Quantity limit </label></th>
+  <th scope="row"><label for="_wcmmax_options_option_name">Custom alert message for maximum Quantity limit. Use $maximum to have the maximum in the text.</label></th>
   </tr>
   <tr>
       <td><textarea cols="60" rows="5" id="_wcmmax_options_option_name" name="_wcmmax_options_option_name" ><?php echo get_option('_wcmmax_options_option_name'); ?> </textarea></td>
@@ -135,7 +135,7 @@ function wc_mmax_custom_add_to_cart($args,$product)
 $cartQty =  wc_mmax_woo_in_cart($product);
 if(get_option('_wcmmax_options_option_name') != NULL && get_option('_wcmmax_options_option_name') !='')
 {
-$maxQTYMsg = get_option('_wcmmax_options_option_name');
+    $maxQTYMsg = str_replace('$maximum', strval($maxQty), get_option('_wcmmax_options_option_name'));
 }
 else {
     $maxQTYMsg = 'You have already added the maximum Quantity for the product for the current purchase';

woo-min-max-quantity-modified.php

<?php
/*
Plugin Name: Woocommerce Minimum and Maximum Quantity
Plugin URI:  http://ashokg.in/
Description: Allow the site admin to enable the feature of minimum and maximum purchase of a particular product in each product.
Version: 2.1.5
Author: Ashok G
Text Domain: wcmmax
Author URI: https://ashokg.in
WC tested up to: 5.1.0
Copyright: © 2020 Ashok G.
License: GNU General Public License v3.0
License URI: http://www.gnu.org/licenses/gpl-3.0.html
*/


add_action('add_meta_boxes', 'wc_mmax_meta_box_create');
add_action('save_post', 'wc_mmax_save_meta_box');
function wc_mmax_meta_box_create()
{
    add_meta_box('wc_mmax_enable', __('Min Max Quantity', 'wcmmax'), 'wc_mmax_meta_box', 'product', 'side');
}

function wc_mmax_meta_box($post)
{
    wp_nonce_field('wc_mmax_cst_prd_nonce', 'wc_mmax_cst_prd_nonce');
    
    echo '<table>';
    echo '<tr><td><label for="_wc_mmax_prd_opt_enable">' . __('Enable', 'wcmmax') . '</label>';
    echo '<input type="hidden" name="_wc_mmax_prd_opt_enable" value="0" /></td>';
    echo '<td><input type="checkbox" id="_wc_mmax_prd_opt_enable" class="checkbox" name="_wc_mmax_prd_opt_enable" value="1" ' . checked(get_post_meta($post->ID, '_wc_mmax_prd_opt_enable', true), 1, false) . ' /></td>';
    echo '</tr>';
    echo '<tr>';
    $wc_mmax_max = get_post_meta($post->ID, '_wc_mmax_max', true) ? get_post_meta($post->ID, '_wc_mmax_max', true) : 1;
    $wc_mmax_min = get_post_meta($post->ID, '_wc_mmax_min', true) ? get_post_meta($post->ID, '_wc_mmax_min', true) : 1;
    $wc_mmax_increment = get_post_meta($post->ID, '_wc_mmax_increment', true) ? get_post_meta($post->ID, '_wc_mmax_increment', true) : 1;
    echo '<td><label for="_wc_mmax_min">' . __('Min Quantity', 'wcmmax') . '</label></td>';
    echo '<td><input type="number" id="_wc_mmax_min" class="short" name="_wc_mmax_min" value="' . $wc_mmax_min . '" /></td>';
    echo '</tr>';
    echo '<tr>';
    echo '<td><label for="_wc_mmax_max">' . __('Max Quantity', 'wcmmax') . '</label></td>';
    echo '<td><input type="number" id="_wc_mmax_max" class="short" name="_wc_mmax_max" value="' . $wc_mmax_max . '" /></td>';
    echo '</tr>';
    echo '<tr>';
    echo '<td><label for="_wc_mmax_increment">' . __('Increment', 'wcmmax') . '</label></td>';
    echo '<td><input type="number" id="_wc_mmax_increment" class="short" name="_wc_mmax_increment" value="' . $wc_mmax_increment . '" /></td>';
    echo '</tr></table>';
    
}

function wc_mmax_save_meta_box($post_id)
{
    if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE)
        return;
    if (!isset($_POST['_wc_mmax_prd_opt_enable']) || !wp_verify_nonce($_POST['wc_mmax_cst_prd_nonce'], 'wc_mmax_cst_prd_nonce'))
        return;
    update_post_meta($post_id, '_wc_mmax_prd_opt_enable', (int) $_POST['_wc_mmax_prd_opt_enable']);
    update_post_meta($post_id, '_wc_mmax_max',(int) $_POST['_wc_mmax_max']);
    update_post_meta($post_id, '_wc_mmax_min', (int) $_POST['_wc_mmax_min']);
    update_post_meta($post_id, '_wc_mmax_increment', (int) $_POST['_wc_mmax_increment']);
}



  
/** Functions For Custom Option Page for Plugin **/ 
function _wcmmax_options_register_settings() {
   add_option( '_wcmmax_options_option_name', 'Settings.');
   register_setting( '_wcmmax_options_group', '_wcmmax_options_option_name', '_wcmmax_options_callback' );
}
add_action( 'admin_init', '_wcmmax_options_register_settings' );

function _wcmmax_register_options_page() {
  add_options_page('WooCommerce Minimum & Maximum Quantity Limit Settings', 'WooCommerce Minimum & Maximum Quantity Limit', 'manage_options', '_wcmmax_', '_wcmmax_options_page');
}
add_action('admin_menu', '_wcmmax_register_options_page');

function _wcmmax_options_page()
{
?>
  <div>
  
  <h2>WooCommerce Minimum & Maximum Quantity Limit Settings</h2>
  <form method="post" action="options.php">
  <?php settings_fields( '_wcmmax_options_group' ); ?>
  
  <table>
  <tr valign="top">
  <th scope="row"><label for="_wcmmax_options_option_name">Custom alert message for maximum Quantity limit. Use $maximum to have the maximum in the text.</label></th>
  </tr>
  <tr>
      <td><textarea cols="60" rows="5" id="_wcmmax_options_option_name" name="_wcmmax_options_option_name" ><?php echo get_option('_wcmmax_options_option_name'); ?> </textarea></td>
  </tr>
  </table>
  <?php  submit_button(); ?>
  </form>
  </div>
<?php
}

  /** Functions For Custom Option Page for Plugin **/

/*Function to manipulate custom minimum and maximum purchase*/
add_filter('woocommerce_quantity_input_args', 'wc_mmax_quantity_input_args', 10, 2);
function wc_mmax_quantity_input_args($args, $product)
{
if(function_exists('icl_object_id')) {
	$default_language = wpml_get_default_language();
	$prodid = icl_object_id($product->get_id(), 'product', true, $default_language);
} else {
    $prodid = $product->get_id();
}
    $mmaxEnable = get_post_meta($prodid, '_wc_mmax_prd_opt_enable', true);
    $minQty     = get_post_meta($prodid, '_wc_mmax_min', true);
    $maxQty     = get_post_meta($prodid, '_wc_mmax_max', true);
    $incrementbyQty     = get_post_meta($prodid, '_wc_mmax_increment', true);
    if ($minQty > 0 && $maxQty > 0 && $mmaxEnable == 1) {
        $args['min_value'] = $minQty; // Starting value
        $args['max_value'] = $maxQty; // Ending value
        $args['step'] = $incrementbyQty; // Increase by value
    }
 return $args;
   
}
/*Function to check weather the maximum quantity is already existing in the cart*/

add_action('woocommerce_add_to_cart', 'wc_mmax_custom_add_to_cart',10,2);

function wc_mmax_custom_add_to_cart($args,$product)
{
	$orderQTY = $_POST['quantity'];
    $mmaxEnable = get_post_meta($product, '_wc_mmax_prd_opt_enable', true);
    $minQty     = get_post_meta($product, '_wc_mmax_min', true);
    $maxQty     = get_post_meta($product, '_wc_mmax_max', true);
$cartQty =  wc_mmax_woo_in_cart($product);
if(get_option('_wcmmax_options_option_name') != NULL && get_option('_wcmmax_options_option_name') !='')
{
    $maxQTYMsg = str_replace('$maximum', strval($maxQty), get_option('_wcmmax_options_option_name'));
}
else {
    $maxQTYMsg = 'You have already added the maximum Quantity for the product for the current purchase';
}
if($maxQty < $cartQty && $mmaxEnable == 1)
{

wc_add_notice($maxQTYMsg,'error');
exit(wp_redirect( get_permalink($product) ));

}

if(($orderQTY + $cartQty)  < $minQty && $mmaxEnable == 1)
{

wc_add_notice(__('You have ordered '.$orderQTY.'  which is less than the allowed Minimum Quantity '.$minQty.'','wcmax'),'error');
exit(wp_redirect( get_permalink($product) ));
}

}

function wc_mmax_woo_in_cart($product_id) {
    global $woocommerce;
    foreach($woocommerce->cart->get_cart() as $key => $val ) {
	
        $_product = $val['data'];
        if($product_id == $_product->get_id()) {

		
 	    return  $val['quantity'];
	
        }
    }
 
    return 0;
}


#filter hook to remove extra add to cart button in the shop and category pages
add_filter( 'woocommerce_loop_add_to_cart_link','_wcmmax_add2cart' );
function _wcmmax_add2cart( $link ) {
	global $product;
	$product_id = $product->get_id();
	$product_sku = $product->get_sku();
	$product_type = $product->get_type();
	$qtylink = '';
        $ajax_class = '';
	$mmaxEnable = get_post_meta( $product_id, '_wc_mmax_prd_opt_enable', true );
	$minQty     = get_post_meta( $product_id, '_wc_mmax_min', true );

	if ( $product_type != 'simple' || $mmaxEnable != 1 ){
		return $link;
	}
	$qtylink = '&quantity='.$minQty;
	$ajax_cart_en = 'yes' === get_option( 'woocommerce_enable_ajax_add_to_cart' );
	if ( $ajax_cart_en && $mmaxEnable == 0  && $product_type !='variable' ) { //solution by @tigerrockmartialarts https://wordpress.org/support/topic/add-to-cart-on-variable-products/
		$ajax_class = 'ajax_add_to_cart';
	}
	$link = sprintf( '<a href="%s" rel="nofollow" data-product_id="%s" data-product_sku="%s" data-quantity="%s" class="button %s product_type_%s %s">%s</a>',
		esc_url( $product->add_to_cart_url().$qtylink ),
		esc_attr( $product_id ),
		esc_attr( $product->get_sku() ),
		esc_attr( isset( $minQty ) ? $minQty : 1 ),
		$product->is_purchasable() && $product->is_in_stock() ? 'add_to_cart_button' : '',
		esc_attr( $product->product_type ),
		esc_attr( $ajax_class ),
		esc_html( $product->add_to_cart_text() )
	);
	return $link;
}