add_action('rest_api_init', function () {
    register_rest_route('wc/store/v1', '/get-cart', [
        'methods'  => 'GET',
        'callback' => 'get_cart_data_with_metadata',
        'permission_callback' => '__return_true',
    ]);
});

function _safe_get($src, $key, $default = '') {
    if (is_array($src) && array_key_exists($key, $src)) return $src[$key];
    if (is_object($src) && isset($src->$key)) return $src->$key;
    return $default;
}

/**
 * Normalize any mixed array/object structure to associative array
 */
function _to_array($value) {
    return json_decode(json_encode($value), true);
}

function get_cart_data_with_metadata(WP_REST_Request $request) {
    try {
        // -------- Cart token --------
        $cart_token = $request->get_header('cart-token') ?: $request->get_param('cart-token');

        // -------- Shipping address (request headers/params fallback to store base) --------
        $base_loc = wc_get_base_location();
        $shipping_address = [
            'country'   => strtoupper(sanitize_text_field($request->get_param('shipping_country') ?: $request->get_header('shipping-country') ?: ($base_loc['country'] ?? ''))),
            'state'     => strtoupper(sanitize_text_field($request->get_param('shipping_state') ?: $request->get_header('shipping-state') ?: ($base_loc['state'] ?? ''))),
            'postcode'  => sanitize_text_field($request->get_param('shipping_postcode') ?: $request->get_header('shipping-postcode') ?: ''),
            'city'      => sanitize_text_field($request->get_param('shipping_city') ?: $request->get_header('shipping-city') ?: ''),
            'address_1' => sanitize_text_field($request->get_param('shipping_address_1') ?: $request->get_header('shipping-address-1') ?: ''),
            'address_2' => sanitize_text_field($request->get_param('shipping_address_2') ?: $request->get_header('shipping-address-2') ?: ''),
        ];
        $requested_rate_id = sanitize_text_field($request->get_param('shipping_rate_id') ?: $request->get_header('shipping-rate-id'));

        // -------- Load current cart from Store API internally --------
        $store_request = new WP_REST_Request('GET', '/wc/store/v1/cart');
        if ($cart_token) {
            $store_request->set_header('Cart-Token', sanitize_text_field($cart_token));
        }
        $response = rest_do_request($store_request);
        if (is_wp_error($response)) {
            return rest_respond(false, 'Failed to load cart from Store API.', $response->get_error_message());
        }

        // Normalize response data to associative arrays
        $server = rest_get_server();
        $data_raw = $server->response_to_data($response, false);
        $data = _to_array($data_raw);

        if (empty($data['items']) || !is_array($data['items'])) {
            return new WP_REST_Response(['success' => false, 'message' => 'Cart is empty.'], 200);
        }

        // -------- Discount calculation (existing logic) --------
        $rules = get_option('yaydp_product_pricing_rules', []);
        $discount_results = [];
        $total_discount = 0.0;

        foreach ($rules as $rule) {
            if (empty($rule['is_enabled'])) continue;
            $rule_discount = calculate_rule_discount($rule, $data['items']);
            if (!empty($rule_discount['applicable'])) {
                $discount_results[] = $rule_discount;
                $total_discount += (float) $rule_discount['discount_amount'];
            }
        }

        // Apply discounts (keeps items as arrays, augment them)
        $cart_items_with_discounts = apply_discounts_to_items($data['items'], $discount_results);

        // Inject per-item tax fields if present from Store API items
        foreach ($cart_items_with_discounts as &$item) {
            // item may contain 'line_total_tax' or totals array -> normalize
            $item_tax = 0.0;
            if (isset($item['line_total_tax'])) {
                $item_tax = (float) $item['line_total_tax'];
            } elseif (isset($item['totals']) && is_array($item['totals']) && isset($item['totals']['line_total_tax'])) {
                $item_tax = (float) $item['totals']['line_total_tax'];
            } elseif (isset($item['taxes']) && is_array($item['taxes'])) {
                // fallback: sum taxes array
                $item_tax = array_sum(array_map('floatval', $item['taxes']));
            }
            $item['tax_total'] = round($item_tax, 2);

            // ensure numeric fields
            $qty = (int) ($item['quantity'] ?? 1);
            $orig_price = (float) ($item['prices']['regular_price'] ?? ($item['prices']['price'] ?? 0));
            $line_total = round($orig_price * $qty, 2);
            $item['line_total'] = $line_total;
            $item['total_with_tax'] = round($line_total + $item['tax_total'], 2);
        }
        unset($item); // break reference

        // -------- Subtotals --------
        $cart_subtotal = 0.0;
        foreach ($cart_items_with_discounts as $it) {
            $cart_subtotal += (float) ($it['line_total'] ?? 0);
        }
        $discount_total = min((float)$total_discount, (float)$cart_subtotal);
        $subtotal_after_discount = max(0.0, $cart_subtotal - $discount_total);

        // --- Build shipping_rates formatted data ---
        $shipping_rates_output = [];

        if (WC()->shipping()) {
            $shipping = WC()->shipping;
            $shipping->load_shipping_methods();

            // Build a single package
            $package = [
                'contents'       => [],
                'contents_cost'  => 0,
                'destination'    => [
                    'address_1' => $shipping_address['address_1'] ?? '',
                    'address_2' => $shipping_address['address_2'] ?? '',
                    'city'      => $shipping_address['city'] ?? '',
                    'state'     => $shipping_address['state'] ?? '',
                    'postcode'  => $shipping_address['postcode'] ?? '',
                    'country'   => $shipping_address['country'] ?? 'GB',
                ],
            ];

            // Add cart items to the shipping package
            foreach ($cart_items_with_discounts as $key => $it) {
                $product = wc_get_product((int)($it['product_id'] ?? 0));
                if ($product && is_a($product, 'WC_Product')) {
                    $qty        = (int)($it['quantity'] ?? 1);
                    $line_total = (float)$it['line_total'] ?? 0;

                    $package['contents'][$key] = [
                        'data'          => $product,
                        'quantity'      => $qty,
                        'line_total'    => $line_total,
                        'line_subtotal' => $line_total,
                    ];

                    $package['contents_cost'] += $line_total;
                }
            }

            $packages = [$package];
            $shipping->calculate_shipping($packages);
            $packages_with_rates = $shipping->get_packages();

            if (!empty($packages_with_rates)) {
                foreach ($packages_with_rates as $pkg_index => $pkg) {
                    $destination = $pkg['destination'] ?? [];
                    $items_list  = [];
                    $items_label = [];

                    foreach ($pkg['contents'] as $key => $item) {
                        $product_name = $item['data']->get_name();
                        $qty = $item['quantity'];
                        $items_list[] = [
                            'key'      => $key,
                            'name'     => $product_name,
                            'quantity' => $qty,
                        ];
                        $items_label[] = sprintf('%s × %d', $product_name, $qty);
                    }

                    $rates_list = [];
                    $rates = $pkg['rates'] ?? [];

                    foreach ($rates as $rate_id => $rate_obj) {
                        if (!is_a($rate_obj, 'WC_Shipping_Rate')) continue;

                        $taxes = (array)$rate_obj->get_taxes();
                        $tax_total = array_sum($taxes);

                        $rates_list[] = [
                            'rate_id'                     => $rate_id,
                            'name'                        => $rate_obj->get_label(),
                            'description'                 => '',
                            'delivery_time'               => '',
                            'price'                       => (string)round($rate_obj->get_cost(), 2),
                            'taxes'                       => (string)round($tax_total, 2),
                            'instance_id'                 => (int)$rate_obj->get_instance_id(),
                            'method_id'                   => $rate_obj->get_method_id(),
                            'meta_data'                   => [
                                [
                                    'key'   => 'Items',
                                    'value' => implode(', ', $items_label),
                                ]
                            ],
                            'selected'                    => true, // choose default for now
                            'currency_code'               => get_woocommerce_currency(),
                            'currency_symbol'             => get_woocommerce_currency_symbol(),
                            'currency_minor_unit'         => wc_get_price_decimals(),
                            'currency_decimal_separator'  => wc_get_price_decimal_separator(),
                            'currency_thousand_separator' => wc_get_price_thousand_separator(),
                            'currency_prefix'             => get_woocommerce_currency_symbol(),
                            'currency_suffix'             => '',
                        ];
                    }

                    $shipping_rates_output[] = [
                        'package_id'   => $pkg_index,
                        'name'         => 'Shipment ' . ($pkg_index + 1),
                        'destination'  => $destination,
                        'items'        => $items_list,
                        'shipping_rates' => $rates_list,
                    ];
                }
            }
        }

       
        // --- Calculate tax lines ---
        $tax_lines = [];
        $tax_total = 0;
        $total_tax = 0.0;

        if (WC()->cart && !WC()->cart->is_empty()) {
            // Ensure taxes are recalculated
            WC()->cart->calculate_totals();

            // Get tax totals from WooCommerce
            $tax_totals = WC()->cart->get_tax_totals(); // array of WC_Tax_Rate objects

            foreach ($tax_totals as $rate_code => $tax_obj) {
                $rate_label = $tax_obj->label;
                $rate_percent = $tax_obj->formatted_rate; // e.g. "20%"
                $tax_amount = wc_format_decimal($tax_obj->amount, wc_get_price_decimals());
                $tax_total += floatval($tax_amount);

                $tax_lines[] = [
                    'name'  => $rate_label ?: $rate_percent,
                    'price' => (string)$tax_amount,
                    'rate'  => $rate_percent ?: $rate_label,
                ];
            }

            // If no tax lines were found, still include one with 0
            if (empty($tax_lines)) {
                $tax_lines[] = [
                    'name'  => '0%',
                    'price' => '0',
                    'rate'  => '0%',
                ];
            }
        }


        // Fallback: sum item line_total_tax values
        if ($total_tax <= 0) {
            foreach ($data['items'] as $it) {
                $it_arr = _to_array($it);
                if (isset($it_arr['line_total_tax'])) {
                    $total_tax += (float)$it_arr['line_total_tax'];
                } elseif (isset($it_arr['totals']['line_total_tax'])) {
                    $total_tax += (float)$it_arr['totals']['line_total_tax'];
                } elseif (!empty($it_arr['taxes']) && is_array($it_arr['taxes'])) {
                    $total_tax += array_sum(array_map('floatval', $it_arr['taxes']));
                }
            }
        }

        // Add shipping tax (calculated from chosen rate)
        $total_tax += $shipping_tax_total;

        // If no breakdown_by_rate was assembled, provide a generic single-entry bucket
        if (empty($tax_breakdown_by_rate)) {
            $tax_breakdown_by_rate = ['1' => round($total_tax, 2)];
        } else {
            // Round each
            foreach ($tax_breakdown_by_rate as $k => $v) {
                $tax_breakdown_by_rate[$k] = round((float)$v, 2);
            }
        }

        $tax_info = [
            'prices_include_tax' => (bool) $prices_include_tax,
            'breakdown_by_rate'  => $tax_breakdown_by_rate,
            'total_tax'          => round($total_tax, 2),
        ];

        // -------- Totals --------
        $shipping_total = $shipping_cost_ex_tax + $shipping_tax_total;
        $grand_total = round($subtotal_after_discount, 2) + round($shipping_total, 2) + round($total_tax, 2);

        // -------- RESPONSE --------
        return new WP_REST_Response([
            'success' => true,
            'cart_items' => $cart_items_with_discounts,
            'discounts' => [
                'total_discount' => round($discount_total, 2),
                'applied_rules'  => $discount_results,
            ],
            'shipping_rates' => $shipping_rates_output,
            'tax_lines'  => $tax_lines,
            'totals' => [
                'subtotal' => round($cart_subtotal, 2),
                'subtotal_after_discount' => round($subtotal_after_discount, 2),
                'shipping_total' => $shipping_total,
                'tax_total' => round($total_tax, 2),
                'grand_total' => round($grand_total, 2),
            ],
        ], 200);

    } catch (Throwable $e) {
        return new WP_REST_Response([
            'success' => false,
            'message' => 'Calculation failed.',
            'error' => $e->getMessage(),
            'trace' => WP_DEBUG ? $e->getTraceAsString() : null,
        ], 200);
    }
}

/* -------------------------
   Your existing discount helpers (kept mostly unchanged)
   ------------------------- */

function calculate_rule_discount($rule, $cart_items) {
    $rule_type = $rule['type'] ?? '';
    switch ($rule_type) {
        case 'buy_x_get_y':
            return calculate_buy_x_get_y_discount($rule, $cart_items);
        case 'bulk_pricing':
            return function_exists('calculate_bulk_pricing_discount') ? calculate_bulk_pricing_discount($rule, $cart_items) : array('applicable' => false, 'discount_amount' => 0);
        case 'simple_adjustment':
            return function_exists('calculate_simple_adjustment_discount') ? calculate_simple_adjustment_discount($rule, $cart_items) : array('applicable' => false, 'discount_amount' => 0);
        default:
            return array('applicable' => false, 'discount_amount' => 0);
    }
}

function calculate_buy_x_get_y_discount($rule, $cart_items) {
    $buy_products = $rule['buy_products']['filters'][0]['value'] ?? array();
    $get_products = $rule['get_products']['filters'][0]['value'] ?? array();
    $pricing = $rule['pricing'] ?? array();
    $required_quantity = $rule['buy_products']['filters'][0]['quantity'] ?? 1;
    $get_quantity = $rule['get_products']['filters'][0]['quantity'] ?? 1;
    $discount_value = $pricing['value'] ?? 100;
    $discount_type = $pricing['type'] ?? 'percentage_discount';
    $repeat = $pricing['repeat'] ?? 1;
    $effect_type = $pricing['affected_items']['effect_type'] ?? 'lowest_price';
    $affected_items_type = $pricing['affected_items']['type'] ?? 'whole_bundle';

    $buy_product_ids = array_map(function($item) {
        return (int)(is_array($item) && isset($item['value']) ? $item['value'] : $item);
    }, $buy_products);

    $qualifying_quantity = 0;
    foreach ($cart_items as $item) {
        if (in_array($item['product_id'], $buy_product_ids)) {
            $qualifying_quantity += $item['quantity'];
        }
    }

    if ($qualifying_quantity < $required_quantity) {
        return array('applicable' => false, 'discount_amount' => 0);
    }

    $free_sets = floor($qualifying_quantity / $required_quantity);
    $total_free_items = $free_sets * $get_quantity;
    $discount_amount = 0;

    $discountable_items = [];
    foreach ($cart_items as $item) {
        $product = wc_get_product($item['product_id']);
        if ($product) {
            $discountable_items[] = [
                'product_id' => $item['product_id'],
                'price' => (float)$product->get_price(),
                'quantity' => (int)$item['quantity']
            ];
        }
    }

    usort($discountable_items, function($a, $b) {
        return $a['price'] <=> $b['price'];
    });

    $items_to_discount = min($total_free_items, array_sum(array_column($discountable_items, 'quantity')));
    foreach ($discountable_items as $item) {
        if ($items_to_discount <= 0) break;
        $discount_qty = min($items_to_discount, $item['quantity']);
        $discount_amount += $item['price'] * $discount_qty * ($discount_value / 100);
        $items_to_discount -= $discount_qty;
    }

    return [
        'applicable' => true,
        'rule_id' => $rule['rule_id'] ?? null,
        'rule_name' => $rule['name'] ?? null,
        'discount_amount' => $discount_amount,
        'free_items' => $total_free_items,
        'qualifying_quantity' => $qualifying_quantity,
        'pricing_details' => [
            'buy_quantity' => $required_quantity,
            'get_quantity' => $get_quantity,
            'discount_type' => $discount_type,
            'discount_value' => $discount_value,
            'effect_type' => $effect_type,
            'repeat' => $repeat,
        ],
    ];
}

function apply_discounts_to_items($cart_items, $discount_results) {
    foreach ($cart_items as &$item) {
        $product = function_exists('wc_get_product') ? wc_get_product($item['product_id']) : null;
        $item['original_price'] = $product ? (float) $product->get_price() : (float) ($item['price'] ?? 0);
        $item['discounted_price'] = $item['original_price'];
        $item['discount_amount'] = 0;
        $item['applied_rules'] = [];

        foreach ($discount_results as $rule_result) {
            if (!empty($rule_result['applicable'])) {
                $item['applied_rules'][] = $rule_result['rule_name'] ?? '';
            }
        }
    }
    unset($item);
    return $cart_items;
}

/* ------- small helper - respond uniform error format ------- */
function rest_respond($success, $message = '', $error = null) {
    $payload = ['success' => $success, 'message' => $message];
    if ($error) $payload['error'] = $error;
    return new WP_REST_Response($payload, 200);
}