<?php
/**
 * @package AKSRT
 */

namespace AKSRT\Shop;

defined('ABSPATH') || exit;

class CheckoutService {

    private Shop $shop;

    public function __construct(Shop $shop) {
        $this->shop = $shop;
    }

    public function preview_checkout(int $user_id, array $payload): array {
        if ($user_id <= 0) {
            return ['success' => false, 'message' => __('请先登录后再结算。', 'aksrt')];
        }

        $items = $this->normalize_checkout_items($payload['items'] ?? []);
        if (empty($items)) {
            return ['success' => false, 'message' => __('请选择至少一个商品。', 'aksrt')];
        }

        $product_views = [];
        $subtotal = 0.0;
        foreach ($items as $item) {
            $product = $this->shop->get_product_detail_view((int) $item['product_id']);
            if (empty($product) || empty($product['purchase_enabled'])) {
                return ['success' => false, 'message' => __('存在不可购买商品，请刷新后重试。', 'aksrt')];
            }

            if ((int) $product['stock'] < (int) $item['quantity']) {
                return ['success' => false, 'message' => sprintf(__('商品 %s 库存不足。', 'aksrt'), $product['title'])];
            }

            $line_total = round(((float) $product['price']) * (int) $item['quantity'], 2);

            // R69: Apply discount engine (shop_discount taxonomy campaigns)
            $discount_result = ['discount_amount' => 0, 'gifts' => [], 'applied' => []];
            if (class_exists('\AKSRT\Payment\Discount')) {
                $discount_result = \AKSRT\Payment\Discount::get_instance()->calculate(
                    (float) $product['price'],
                    (int) $item['quantity'],
                    (int) $product['id'],
                    $user_id
                );
                $line_total = $discount_result['final_price'];
            }

            $subtotal += $line_total;
            $product_views[] = [
                'product_id' => (int) $product['id'],
                'title' => $product['title'],
                'price' => (float) $product['price'],
                'quantity' => (int) $item['quantity'],
                'line_total' => $line_total,
                'image' => $product['image'],
                'shipping' => $product['shipping'],
                'discount_amount' => (float) ($discount_result['discount_amount'] ?? 0),
                'gifts' => (array) ($discount_result['gifts'] ?? []),
                'applied_discounts' => (array) ($discount_result['applied'] ?? []),
            ];
        }

        $shipping_method = sanitize_key((string) ($payload['shipping_method'] ?? 'express'));
        $shipping_profile = $this->resolve_shipping_quote($product_views, $shipping_method);

        $coupon_code = sanitize_text_field((string) ($payload['coupon_code'] ?? ''));
        $product_ids = array_values(array_unique(array_map(static function ($row) {
            return (int) ($row['product_id'] ?? $row['id'] ?? 0);
        }, $product_views)));
        $coupon_result = $this->resolve_coupon_discount($coupon_code, $subtotal + $shipping_profile['fee'], $product_ids);
        if (!$coupon_result['success']) {
            return $coupon_result;
        }

        $total = max(0, round($subtotal + $shipping_profile['fee'] - $coupon_result['discount'], 2));
        $address = $this->resolve_checkout_address($user_id, (int) ($payload['address_id'] ?? 0));
        $payment_method = $this->resolve_payment_method((string) ($payload['payment_method'] ?? 'balance'));

        return [
            'success' => true,
            'data' => [
                'items' => $product_views,
                'subtotal' => round($subtotal, 2),
                'shipping_fee' => $shipping_profile['fee'],
                'shipping_method' => $shipping_profile['method'],
                'discount' => $coupon_result['discount'],
                'coupon' => $coupon_result['coupon'],
                'address' => $address,
                'payment_method' => $payment_method,
                'total' => $total,
            ],
        ];
    }

    public function create_checkout_order(int $user_id, array $payload): array {
        $preview = $this->preview_checkout($user_id, $payload);
        if (empty($preview['success'])) {
            return $preview;
        }

        $data = $preview['data'];
        $primary_item = $data['items'][0] ?? null;
        if (!$primary_item || !class_exists('\AKSRT\Payment\OrderRepository')) {
            return ['success' => false, 'message' => __('订单创建失败。', 'aksrt')];
        }

        $payment_method = sanitize_key((string) ($data['payment_method']['value'] ?? 'balance'));
        $meta_payload = [
            'customer_note' => sanitize_textarea_field((string) ($payload['customer_note'] ?? '')),
            'items' => $data['items'],
            'coupon' => $data['coupon'],
            'shipping_fee' => $data['shipping_fee'],
            'shipping_method' => $data['shipping_method'],
            'address' => $data['address'],
            'payment_method' => $data['payment_method'],
            'discount' => $data['discount'],
        ];

        $expiry_minutes = 30;
        if (class_exists('\AKSRT\Settings\Settings')) {
            $order_settings = \AKSRT\Settings\Settings::get_order_settings();
            $expiry_minutes = max(5, min(1440, (int) ($order_settings['expiry'] ?? 30)));
        }

        $order_number = \AKSRT\Payment\OrderRepository::get_instance()->create([
            'user_id' => $user_id,
            'product_type' => 'shop_product',
            'product_id' => (int) $primary_item['product_id'],
            'amount' => (float) $data['total'],
            'currency' => 'CNY',
            'status' => \AKSRT\Payment\Order::STATUS_PENDING,
            'payment_method' => $payment_method,
            'expires_at' => date('Y-m-d H:i:s', strtotime('+' . $expiry_minutes . ' minutes')),
            'note' => wp_json_encode($meta_payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES),
        ]);

        if ($order_number === '') {
            return ['success' => false, 'message' => __('订单创建失败。', 'aksrt')];
        }

        $this->shop->save_order_items($order_number, $data['items']);

        if (!empty($data['coupon']['code']) && class_exists('\AKSRT\Payment\Coupon')) {
            $coupon_instance = \AKSRT\Payment\Coupon::get_instance();
            $coupon_instance->use_coupon($data['coupon']['code']);
            // R69: Log coupon usage for per-user tracking
            $coupon_row = $coupon_instance->validate($data['coupon']['code']);
            $coupon_id = (int) ($coupon_row['coupon']['id'] ?? 0);
            if ($coupon_id > 0) {
                $coupon_instance->log_usage(
                    $coupon_id,
                    $user_id,
                    $order_number,
                    (float) ($data['discount'] ?? 0)
                );
            }
        }

        $detail = $this->shop->get_order_detail_view($user_id, $order_number);

        return [
            'success' => true,
            'data' => [
                'order_number' => $order_number,
                'order' => $detail,
            ],
        ];
    }

    public function pay_order(int $user_id, string $order_number, string $payment_method): array {
        if ($user_id <= 0 || $order_number === '' || !class_exists('\AKSRT\Payment\OrderRepository')) {
            return ['success' => false, 'message' => __('订单不存在。', 'aksrt')];
        }

        $repo = \AKSRT\Payment\OrderRepository::get_instance();
        $order = $repo->get_user_order($user_id, $order_number);
        if (!$order) {
            return ['success' => false, 'message' => __('订单不存在。', 'aksrt')];
        }

        $status = (string) ($order['status'] ?? '');
        if (!in_array($status, [
            \AKSRT\Payment\Order::STATUS_CREATED,
            \AKSRT\Payment\Order::STATUS_PENDING,
        ], true)) {
            return ['success' => false, 'message' => __('当前订单状态不可支付。', 'aksrt')];
        }

        // Payment attempts are bound to the method selected when the order was created.
        $stored_method = sanitize_key((string) ($order['payment_method'] ?? ''));
        $payment_method = sanitize_key($payment_method ?: ($stored_method ?: 'balance'));
        if ($stored_method !== '' && $payment_method !== $stored_method) {
            return ['success' => false, 'message' => __('支付方式与订单不一致，请重新下单。', 'aksrt')];
        }

        $gateway_manager = class_exists('\AKSRT\Payment\Gateway') ? \AKSRT\Payment\Gateway::get_instance() : null;
        $gateway = $gateway_manager ? $gateway_manager->get_gateway($payment_method) : null;

        if (!$gateway) {
            return ['success' => false, 'message' => __('当前支付方式不可用。', 'aksrt')];
        }

        if (method_exists($gateway, 'is_configured') && !$gateway->is_configured()) {
            return ['success' => false, 'message' => __('该支付方式尚未配置，请联系站长。', 'aksrt')];
        }

        // Points payment is a purely internal settlement (no provider attempt),
        // but still needs the attempt lock against double-click double deduction.
        if ($payment_method === 'points') {
            $lock = class_exists('\AKSRT\Payment\PaymentAttemptLock')
                ? \AKSRT\Payment\PaymentAttemptLock::acquire($order_number)
                : false;
            if ($lock === false) {
                return ['success' => false, 'message' => __('该订单正在发起支付，请稍后重试。', 'aksrt')];
            }
            try {
                return $this->pay_with_points($user_id, $order_number, $order);
            } finally {
                \AKSRT\Payment\PaymentAttemptLock::release($order_number, $lock);
            }
        }

        // 携带订单号与摘要，供网关生成支付单。
        // PaymentOrchestrator 内部持有 attempt 锁并分配 provider out_trade_no。
        $order['subject'] = $order['subject'] ?? sprintf(__('订单 %s', 'aksrt'), $order_number);
        $order['payment_method'] = $payment_method;

        $payment_result = \AKSRT\Payment\PaymentOrchestrator::pay($gateway, $order, [
            'paid_note' => __('用户在前台完成支付。', 'aksrt'),
        ]);
        if (empty($payment_result['success'])) {
            return ['success' => false, 'message' => $payment_result['message']];
        }

        // 跳转/扫码型网关（支付宝/微信/PayPal/Stripe）：返回支付凭据，订单保持待支付，
        // 由 /payment/{gateway}/notify|return 回调确认到账；此处绝不预先标记已支付。
        if (!empty($payment_result['redirect'])) {
            return [
                'success' => true,
                'data' => [
                    'redirect'     => true,
                    'payment_url'  => (string) ($payment_result['payment_url'] ?? ''),
                    'qr_content'   => (string) ($payment_result['qr_content'] ?? ''),
                    'order_number' => $order_number,
                    'message'      => $payment_result['message'],
                ],
            ];
        }

        return [
            'success' => true,
            'data' => [
                'order' => $this->shop->get_order_detail_view($user_id, $order_number),
                'message' => $payment_result['message'],
            ],
        ];
    }

    private function pay_with_points(int $user_id, string $order_number, array $order): array {
        if (!class_exists('\AKSRT\Credits\Credits')) {
            return ['success' => false, 'message' => __('积分系统不可用。', 'aksrt')];
        }

        $amount = (int) round((float) ($order['amount'] ?? 0));
        if ($amount <= 0) {
            return ['success' => false, 'message' => __('订单金额无效。', 'aksrt')];
        }

        $balance = \AKSRT\Credits\Credits::balance($user_id);
        if ($balance < $amount) {
            return ['success' => false, 'message' => sprintf(__('积分不足，需要 %d 积分，当前余额 %d。', 'aksrt'), $amount, $balance)];
        }

        $deducted = \AKSRT\Credits\Credits::deduct(
            $user_id,
            $amount,
            'shop_points_pay',
            ['order' => $order_number],
            sprintf(__('积分购买订单 %s', 'aksrt'), $order_number)
        );
        if (is_wp_error($deducted)) {
            return ['success' => false, 'message' => $deducted->get_error_message() ?: __('积分扣除失败。', 'aksrt')];
        }

        $repo = \AKSRT\Payment\OrderRepository::get_instance();
        $paid = $repo->update_status($order_number, \AKSRT\Payment\Order::STATUS_PAID, [
            'payment_method' => 'points',
            'payment_transaction_id' => 'points_' . $order_number,
            'note' => sprintf(__('积分支付 %d 积分。', 'aksrt'), $amount),
            'require_transition' => true,
        ]);
        if (!$paid) {
            $compensation = \AKSRT\Credits\Credits::add(
                $user_id,
                $amount,
                'shop_points_pay_rollback',
                ['order' => $order_number],
                sprintf(__('订单 %s 支付失败退回积分', 'aksrt'), $order_number)
            );
            if (is_wp_error($compensation)) {
                error_log(sprintf(
                    '[AKSRT Payment] points rollback failed order=%s: %s',
                    $order_number,
                    $compensation->get_error_message()
                ));
                return ['success' => false, 'message' => __('订单状态已变化，积分补偿失败，请联系管理员处理。', 'aksrt')];
            }
            return ['success' => false, 'message' => __('订单状态已变化，积分已退回。', 'aksrt')];
        }

        return [
            'success' => true,
            'data' => [
                'order' => $this->shop->get_order_detail_view($user_id, $order_number),
                'message' => __('积分支付成功。', 'aksrt'),
            ],
        ];
    }

    private function normalize_checkout_items($items): array {
        if (!is_array($items)) {
            return [];
        }

        $normalized = [];
        foreach ($items as $item) {
            $product_id = (int) ($item['product_id'] ?? 0);
            $quantity = max(1, (int) ($item['quantity'] ?? 1));
            if ($product_id <= 0) {
                continue;
            }

            $normalized[] = [
                'product_id' => $product_id,
                'quantity' => $quantity,
            ];
        }

        return $normalized;
    }

    private function resolve_coupon_discount(string $coupon_code, float $order_amount, array $product_ids = []): array {
        if ($coupon_code === '') {
            return ['success' => true, 'discount' => 0.0, 'coupon' => []];
        }

        if (!class_exists('\AKSRT\Payment\Coupon')) {
            return ['success' => false, 'message' => __('优惠券系统不可用。', 'aksrt')];
        }

        $result = \AKSRT\Payment\Coupon::get_instance()->validate($coupon_code, $order_amount, [
            'user_id'     => get_current_user_id(),
            'product_ids' => array_values(array_filter(array_map('intval', $product_ids))),
            'context'     => 'shop',
        ]);
        if (empty($result['valid'])) {
            return ['success' => false, 'message' => $result['message'] ?? __('优惠券不可用。', 'aksrt')];
        }

        return [
            'success' => true,
            'discount' => (float) ($result['discount'] ?? 0),
            'coupon' => [
                'code' => (string) ($result['coupon']['code'] ?? $coupon_code),
                'type' => (string) ($result['coupon']['type'] ?? ''),
                'value' => (float) ($result['coupon']['value'] ?? 0),
            ],
        ];
    }

    private function resolve_shipping_quote(array $items, string $shipping_method): array {
        $methods = $this->shop->get_shipping_method_options();
        $method = $methods[$shipping_method] ?? $methods['express'];

        $base_fee = (float) ($method['fee'] ?? 0);
        foreach ($items as $item) {
            $base_fee += (float) ($item['shipping']['fee'] ?? 0);
        }

        return [
            'method' => $method,
            'fee' => round($base_fee, 2),
        ];
    }

    private function resolve_checkout_address(int $user_id, int $address_id): array {
        $addresses = $this->shop->get_address_book($user_id);
        foreach ($addresses as $address) {
            if ((int) ($address['id'] ?? 0) === $address_id) {
                return $address;
            }
        }

        return $addresses[0] ?? [];
    }

    private function resolve_payment_method(string $value): array {
        $methods = $this->shop->get_payment_method_options();
        return $methods[$value] ?? reset($methods);
    }

    public function get_checkout_hint(array $product): array {
        return [
            'delivery' => $product['shipping']['delivery_note'] ?: __('付款后自动进入订单中心，可继续查看物流和售后进度。', 'aksrt'),
            'service' => $product['after_sale']['policy'] ?: __('支持在订单中心发起售后申请。', 'aksrt'),
        ];
    }
}