wc-tier-and-package-prices/includes/class-wc-tpp-cart.php

<?php
/**
 * Cart price calculation for tier and package pricing
 */

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

class WC_TPP_Cart {

    public function __construct() {
        add_action('woocommerce_before_calculate_totals', array($this, 'apply_tier_package_pricing'), 10, 1);
        add_filter('woocommerce_cart_item_price', array($this, 'display_cart_item_price'), 10, 3);
        add_filter('woocommerce_cart_item_subtotal', array($this, 'display_cart_item_subtotal'), 10, 3);
        add_filter('woocommerce_add_to_cart_validation', array($this, 'validate_package_quantity'), 10, 3);
        add_filter('woocommerce_cart_item_quantity', array($this, 'maybe_hide_cart_quantity_input'), 10, 3);
    }

    public function apply_tier_package_pricing($cart) {
        if (is_admin() && !defined('DOING_AJAX')) {
            return;
        }

        // Prevent infinite loops
        if (did_action('woocommerce_before_calculate_totals') >= 2) {
            return;
        }

        // Check if cart object is valid
        if (!$cart || !is_a($cart, 'WC_Cart')) {
            return;
        }

        foreach ($cart->get_cart() as $cart_item_key => $cart_item) {
            $product_id = $cart_item['product_id'];
            $quantity = $cart_item['quantity'];
            $product = $cart_item['data'];

            // Validate product object
            if (!$product || !is_a($product, 'WC_Product')) {
                continue;
            }

            // Check for exact package match first
            $package_price = null;
            if (get_option('wc_tpp_enable_package_pricing') === 'yes') {
                $package_price = WC_TPP_Frontend::get_package_price($product_id, $quantity);
            }

            if ($package_price !== null) {
                // Apply package pricing (total price divided by quantity)
                $unit_price = $package_price / $quantity;
                $product->set_price($unit_price);
                // Store pricing information in cart item for display
                WC()->cart->cart_contents[$cart_item_key]['wc_tpp_pricing_type'] = 'package';
                WC()->cart->cart_contents[$cart_item_key]['wc_tpp_total_price'] = $package_price;
            } else {
                // Apply tier pricing if no package match
                if (get_option('wc_tpp_enable_tier_pricing') === 'yes') {
                    $tier_price = WC_TPP_Frontend::get_tier_price($product_id, $quantity);
                    if ($tier_price !== null) {
                        $product->set_price($tier_price);
                        // Store pricing information in cart item for display
                        WC()->cart->cart_contents[$cart_item_key]['wc_tpp_pricing_type'] = 'tier';
                        WC()->cart->cart_contents[$cart_item_key]['wc_tpp_unit_price'] = $tier_price;
                    }
                }
            }
        }
    }

    public function display_cart_item_price($price, $cart_item, $cart_item_key) {
        if (isset($cart_item['wc_tpp_pricing_type'])) {
            if ($cart_item['wc_tpp_pricing_type'] === 'package') {
                $total_price = isset($cart_item['wc_tpp_total_price']) ? $cart_item['wc_tpp_total_price'] : $cart_item['line_total'];
                $unit_price = $total_price / $cart_item['quantity'];
                return wc_price($unit_price) . ' <small class="wc-tpp-notice">(' . __('Package price', 'wc-tier-package-prices') . ')</small>';
            } elseif ($cart_item['wc_tpp_pricing_type'] === 'tier') {
                $unit_price = isset($cart_item['wc_tpp_unit_price']) ? $cart_item['wc_tpp_unit_price'] : $cart_item['data']->get_price();
                return wc_price($unit_price) . ' <small class="wc-tpp-notice">(' . __('Volume discount', 'wc-tier-package-prices') . ')</small>';
            }
        }
        return $price;
    }

    public function display_cart_item_subtotal($subtotal, $cart_item, $cart_item_key) {
        if (isset($cart_item['wc_tpp_pricing_type']) && $cart_item['wc_tpp_pricing_type'] === 'package') {
            $total_price = isset($cart_item['wc_tpp_total_price']) ? $cart_item['wc_tpp_total_price'] : $cart_item['line_total'];
            return wc_price($total_price);
        }
        return $subtotal;
    }

    public function validate_package_quantity($passed, $product_id, $quantity) {
        // Check if restriction is enabled globally or for this product
        $global_restrict = get_option('wc_tpp_restrict_package_quantities', 'no') === 'yes';
        $product_restrict = get_post_meta($product_id, '_wc_tpp_restrict_to_packages', true) === 'yes';

        if (!$global_restrict && !$product_restrict) {
            return $passed;
        }

        // Get packages for this product
        $packages = get_post_meta($product_id, '_wc_tpp_packages', true);

        if (empty($packages) || !is_array($packages)) {
            return $passed;
        }

        // Check if the quantity matches any package
        $valid_quantity = false;
        $available_quantities = array();

        foreach ($packages as $package) {
            $available_quantities[] = $package['qty'];
            if ($quantity == $package['qty']) {
                $valid_quantity = true;
                break;
            }
        }

        if (!$valid_quantity) {
            $product = wc_get_product($product_id);
            $product_name = $product ? $product->get_name() : __('this product', 'wc-tier-package-prices');

            wc_add_notice(
                sprintf(
                    __('The quantity %1$d is not available for %2$s. Please choose from the available package sizes: %3$s', 'wc-tier-package-prices'),
                    $quantity,
                    $product_name,
                    implode(', ', $available_quantities)
                ),
                'error'
            );
            return false;
        }

        return $passed;
    }

    public function maybe_hide_cart_quantity_input($product_quantity, $cart_item_key, $cart_item) {
        $product_id = $cart_item['product_id'];

        // Check if restriction is enabled globally or for this product
        $global_restrict = get_option('wc_tpp_restrict_package_quantities', 'no') === 'yes';
        $product_restrict = get_post_meta($product_id, '_wc_tpp_restrict_to_packages', true) === 'yes';

        // Get packages for this product
        $packages = get_post_meta($product_id, '_wc_tpp_packages', true);

        // If restriction is enabled and packages exist, show quantity as text only
        if (($global_restrict || $product_restrict) && !empty($packages)) {
            return sprintf('<span class="wc-tpp-cart-quantity">%s</span>', $cart_item['quantity']);
        }

        return $product_quantity;
    }
}

new WC_TPP_Cart();