<?php
namespace Sodino\Services;

use Sodino\Repositories\EventRepository;
use Sodino\Repositories\RuleRepository;

class AnalyticsService {
    private $eventRepository;
    private $ruleRepository;

    public function __construct(EventRepository $eventRepository, RuleRepository $ruleRepository) {
        $this->eventRepository = $eventRepository;
        $this->ruleRepository = $ruleRepository;
    }

    public function primeCache() {
        $cache_keys = [
            'sodino_dashboard_summary',
            'sodino_dashboard_sales_chart',
            'sodino_dashboard_rule_performance',
            'sodino_dashboard_user_behavior',
        ];

        foreach ($cache_keys as $key) {
            delete_transient($key);
        }
    }

    public function getDashboardData(array $filters = []) {
        $cache_key = 'sodino_dashboard_' . md5(wp_json_encode($filters));
        $cached = get_transient($cache_key);
        if ($cached !== false) {
            return $cached;
        }

        $range = $this->getDateRange($filters['range'] ?? '7d', $filters['start_date'] ?? '', $filters['end_date'] ?? '');
        $filters['from'] = $range['start'];
        $filters['to'] = $range['end'];

        if (!empty($filters['category_id'])) {
            $filters['product_ids'] = $this->getProductIdsByCategory($filters['category_id']);
        }

        $summary = $this->getSummary($filters);
        $salesChart = $this->getSalesChart($filters);
        $rulePerformance = $this->getRulePerformance($filters);
        $userBehavior = $this->getUserBehavior($filters);
        $insights = $this->getInsights($summary, $filters);

        $result = [
            'summary' => $summary,
            'sales_chart' => $salesChart,
            'rule_performance' => $rulePerformance,
            'user_behavior' => $userBehavior,
            'insights' => $insights,
        ];

        set_transient($cache_key, $result, 10 * MINUTE_IN_SECONDS);
        return $result;
    }

    public function getSummary(array $filters = []) {
        $purchaseFilters = array_merge($filters, ['event_type' => 'purchase']);
        $discountFilters = array_merge($filters, ['event_type' => 'discount_applied']);

        $purchaseCount = $this->eventRepository->getCount($purchaseFilters);
        $totalRevenue = $this->eventRepository->getSum('value', $purchaseFilters);
        $totalDiscount = $this->eventRepository->getSum('discount_value', $discountFilters);

        $productViewCount = $this->eventRepository->getCount(array_merge($filters, ['event_type' => 'product_view']));
        $addToCartCount = $this->eventRepository->getCount(array_merge($filters, ['event_type' => 'add_to_cart']));
        $checkoutStartCount = $this->eventRepository->getCount(array_merge($filters, ['event_type' => 'checkout_start']));

        $conversionRate = 0;
        if ($checkoutStartCount > 0) {
            $conversionRate = round(($purchaseCount / $checkoutStartCount) * 100, 2);
        } elseif ($addToCartCount > 0) {
            $conversionRate = round(($purchaseCount / $addToCartCount) * 100, 2);
        }

        $addToCartRate = 0;
        if ($productViewCount > 0) {
            $addToCartRate = round(($addToCartCount / $productViewCount) * 100, 2);
        }

        $bestRule = $this->getBestRule($filters);

        return [
            'total_revenue' => $totalRevenue,
            'total_discount' => $totalDiscount,
            'purchase_count' => $purchaseCount,
            'conversion_rate' => $conversionRate,
            'add_to_cart_rate' => $addToCartRate,
            'best_rule' => $bestRule,
        ];
    }

    public function getSalesChart(array $filters = []) {
        $filters = array_merge($filters, $this->getDateRange($filters['range'] ?? '7d', $filters['start_date'] ?? '', $filters['end_date'] ?? ''));

        if (!empty($filters['category_id'])) {
            $filters['product_ids'] = $this->getProductIdsByCategory($filters['category_id']);
        }

        $start = new \DateTime($filters['start']);
        $end = new \DateTime($filters['end']);
        $days = [];
        $series = [ 'before' => [], 'after' => [], 'labels' => [] ];

        while ($start <= $end) {
            $date = $start->format('Y-m-d');
            $series['labels'][] = $date;
            $dayFilters = array_merge($filters, ['from' => $date . ' 00:00:00', 'to' => $date . ' 23:59:59']);
            $purchases = $this->eventRepository->getEvents(array_merge($dayFilters, ['event_type' => 'purchase']));
            $dayRevenue = 0;
            $dayDiscount = 0;
            foreach ($purchases as $purchase) {
                $dayRevenue += floatval($purchase['value']);
            }
            $discountEvents = $this->eventRepository->getEvents(array_merge($dayFilters, ['event_type' => 'discount_applied']));
            foreach ($discountEvents as $discount) {
                $dayDiscount += floatval($discount['discount_value']);
            }
            $series['after'][] = round($dayRevenue, 2);
            $series['before'][] = round($dayRevenue + $dayDiscount, 2);
            $start->modify('+1 day');
        }

        return $series;
    }

    public function getRulePerformance(array $filters = []) {
        $rules = $this->ruleRepository->getAll();
        $result = [];

        foreach ($rules as $rule) {
            $ruleFilters = array_merge($filters, ['event_type' => 'discount_applied', 'rule_id' => $rule->id]);
            $count = $this->eventRepository->getCount($ruleFilters);
            $revenue = $this->eventRepository->getSum('value', $ruleFilters);
            $totalDiscount = $this->eventRepository->getSum('discount_value', $ruleFilters);

            if ($count > 0) {
                $result[] = [
                    'name' => $rule->name,
                    'count' => $count,
                    'revenue' => round($revenue, 2),
                    'discount' => round($totalDiscount, 2),
                ];
            }
        }

        return $result;
    }

    public function getUserBehavior(array $filters = []) {
        $productViewCount = $this->eventRepository->getCount(array_merge($filters, ['event_type' => 'product_view']));
        $addToCartCount = $this->eventRepository->getCount(array_merge($filters, ['event_type' => 'add_to_cart']));
        $checkoutStartCount = $this->eventRepository->getCount(array_merge($filters, ['event_type' => 'checkout_start']));
        $purchaseCount = $this->eventRepository->getCount(array_merge($filters, ['event_type' => 'purchase']));

        return [
            'product_views' => $productViewCount,
            'add_to_cart' => $addToCartCount,
            'checkout_start' => $checkoutStartCount,
            'purchases' => $purchaseCount,
        ];
    }

    private function getBestRule(array $filters = []) {
        $performance = $this->getRulePerformance($filters);
        if (empty($performance)) {
            return null;
        }

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

        return $performance[0]['name'] ?? null;
    }

    private function getInsights(array $summary, array $filters = []) {
        $insights = [];

        if (!empty($summary['best_rule'])) {
            $insights[] = sprintf('%s %s', __('قانون برتر:', 'sodino'), esc_html($summary['best_rule']));
        }

        if ($summary['total_discount'] > 0 && $summary['total_revenue'] > 0) {
            $discountShare = round(($summary['total_discount'] / ($summary['total_revenue'] + $summary['total_discount'])) * 100, 2);
            $insights[] = sprintf(
                '%s %s%% %s',
                __('تخفیف‌ها باعث ایجاد', 'sodino'),
                esc_html($discountShare),
                __('درصد از درآمد شده‌اند.', 'sodino')
            );
        }

        if ($summary['conversion_rate'] > 0) {
            $insights[] = sprintf('%s %s%% %s', __('نرخ تبدیل تقریبی', 'sodino'), esc_html($summary['conversion_rate']), __('است.', 'sodino'));
        }

        if (empty($insights)) {
            $insights[] = __('هیچ دادهٔ قابل تحلیلی هنوز ثبت نشده است.', 'sodino');
        }

        return $insights;
    }

    private function getDateRange($range, $start, $end) {
        $result = [
            'start' => date('Y-m-d', strtotime('-6 days')),
            'end' => date('Y-m-d'),
        ];

        if ($range === '30d') {
            $result['start'] = date('Y-m-d', strtotime('-29 days'));
            $result['end'] = date('Y-m-d');
        }

        if ($range === 'custom' && !empty($start) && !empty($end)) {
            $result['start'] = date('Y-m-d', strtotime($start));
            $result['end'] = date('Y-m-d', strtotime($end));
        }

        return $result;
    }

    public function getProductIdsByCategory($category_id) {
        $products = get_posts([
            'post_type' => 'product',
            'numberposts' => -1,
            'fields' => 'ids',
            'tax_query' => [
                [
                    'taxonomy' => 'product_cat',
                    'field' => 'term_id',
                    'terms' => intval($category_id),
                ],
            ],
        ]);

        return $products ?: [];
    }

    public function getProductOptions() {
        $products = get_posts([
            'post_type' => 'product',
            'numberposts' => -1,
            'fields' => 'ids',
            'orderby' => 'title',
            'order' => 'ASC',
        ]);

        $options = [];
        foreach ($products as $product_id) {
            $options[] = [
                'id' => $product_id,
                'name' => get_the_title($product_id),
            ];
        }

        return $options;
    }

    public function getCategoryOptions() {
        $categories = get_terms(['taxonomy' => 'product_cat', 'hide_empty' => false]);
        $options = [];

        if (!is_wp_error($categories)) {
            foreach ($categories as $category) {
                $options[] = [
                    'id' => $category->term_id,
                    'name' => $category->name,
                ];
            }
        }

        return $options;
    }
}