Woocommerce variation dropdown with stock qty.

functions_wc_dropdown.php

function wc_dropdown_variation_attribute_options( $args = array() ) {
	global $product;
	$variations = $product->get_available_variations();

		$args = wp_parse_args( apply_filters( 'woocommerce_dropdown_variation_attribute_options_args', $args ), array(
			'options'          => false,
			'attribute'        => false,
			'product'          => false,
			'selected' 	       => false,
			'name'             => '',
			'id'               => '',
			'class'            => '',
			'show_option_none' => __( 'Choose an option', 'woocommerce' ),
		) );
		$options   = $args['options'];
		$product   = $args['product'];
		$attribute = $args['attribute'];
		$name      = $args['name'] ? $args['name'] : 'attribute_' . sanitize_title( $attribute );
		$id        = $args['id'] ? $args['id'] : sanitize_title( $attribute );
		$class     = $args['class'];
		if ( empty( $options ) && ! empty( $product ) && ! empty( $attribute ) ) {
			$attributes = $product->get_variation_attributes();
			$options    = $attributes[ $attribute ];
			
		}
		$html = '<select id="' . esc_attr( $id ) . '" class="' . esc_attr( $class ) . '" name="' . esc_attr( $name ) . '" data-attribute_name="attribute_' . esc_attr( sanitize_title( $attribute ) ) . '">';
		if ( $args['show_option_none'] ) {
			$html .= '<option value="">' . esc_html( $args['show_option_none'] ) . '</option>';
		}
		if ( ! empty( $options ) ) {
			if ( $product && taxonomy_exists( $attribute ) ) {
				// Get terms if this is a taxonomy - ordered. We need the names too.
				$terms = wc_get_product_terms( $product->id, $attribute, array( 'fields' => 'all' ) );
				foreach ( $terms as $term ) {
					if ( in_array( $term->slug, $options ) ) {
						$html .= '<option value="' . esc_attr( $term->slug ) . '" ' . selected( sanitize_title( $args['selected'] ), $term->slug, false ) . '>' . esc_html( apply_filters( 'woocommerce_variation_option_name', $term->name ) ) . '</option>';
					}
				}
			} else {
				foreach ( $options as $option ) {

					foreach ($variations as $variation) {
						if($variation['attributes'][$name] == $option) {
							$stock = esc_html($variation['max_qty']);
						}
					}
					if( $stock == 0) {
						$stock_text = ' - (Out of Stock)';
						$class = 'option-out-of-stock';
						$disabled = 'disabled';
					} elseif ($stock < 5 ) {
						$stock_text = ' - Only ' . $stock . ' left!';
						$class= 'option-hurry';
						$disabled = '';
					} elseif ($stock < 6) {
						$stock_text = ' - Only a few left!';
						$class = 'option-few';
						$disabled = '';
					} else {
						$stock_text = ' - (In Stock)';
						$class = '';
						$disabled = '';
					}
					// This handles < 2.4.0 bw compatibility where text attributes were not sanitized.
					$selected = sanitize_title( $args['selected'] ) === $args['selected'] ? selected( $args['selected'], sanitize_title( $option ), false ) : selected( $args['selected'], $option, false );
					$html .= '<option value="' . esc_attr( $option ) . '" ' . $selected . ' class="'.$class.'" '.$disabled.'>' . $option  .  $stock_text .'</option>';
				}
			}
		}
		$html .= '</select>';
		
		echo apply_filters( 'woocommerce_dropdown_variation_attribute_options_html', $html, $args );
	}