<?php

namespace WPZaraz\Telemetry;

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

/**
 * Order delivery statistics for the dashboard: daily buckets for the last 30 days
 * and the 20 most recent orders, kept in a single option.
 */
class TelemetryAggregator {

    public const OPTION_KEY = 'wp_zaraz_telemetry_30d';
    public const PERIOD_DAYS = 30;

    /**
     * Records an order conversion event.
     *
     * @param int|string $orderId
     * @param float $amount
     * @param bool $isRescued
     * @param string $currency
     * @param string $eventName
     * @param array $meta
     */
    public function recordOrder($orderId, float $amount, bool $isRescued = false, string $currency = 'USD', string $eventName = 'order_completed', array $meta = []): void {
        $data = $this->load();
        $today = gmdate('Y-m-d');

        $data['summary']['currency'] = $currency ?: ($data['summary']['currency'] ?? 'USD');

        // Recent live events ring buffer
        if (!isset($data['events']) || !is_array($data['events'])) {
            $data['events'] = [];
        }

        $reason = !empty($meta['reason']) ? (string) $meta['reason'] : ($isRescued ? 'Sent by server' : 'Delivered by browser');

        array_unshift($data['events'], [
            'event'     => $eventName,
            'id'        => '#' . ltrim((string) $orderId, '#'),
            'amount'    => (float) $amount,
            'currency'  => $currency,
            'rescued'   => (bool) $isRescued,
            'reason'    => $reason,
            'timestamp' => gmdate('Y-m-d H:i:s'),
        ]);

        if (count($data['events']) > 20) {
            $data['events'] = array_slice($data['events'], 0, 20);
        }

        $this->ensureBucket($data, $today);
        $data['daily'][$today]['orders']++;
        $data['daily'][$today]['revenue'] += (float) $amount;
        if ($isRescued) {
            $data['daily'][$today]['rescued']++;
            $data['daily'][$today]['rescued_revenue'] += (float) $amount;
        }

        $this->pruneOldEntries($data);
        $this->save($data);
    }

    /**
     * Records a refund deduction against net revenue.
     *
     * @param float $amount
     */
    public function recordRefund(float $amount): void {
        $data = $this->load();
        $today = gmdate('Y-m-d');
        $this->ensureBucket($data, $today);
        $data['daily'][$today]['refunds'] = (float) ($data['daily'][$today]['refunds'] ?? 0.0) + $amount;
        $this->pruneOldEntries($data);
        $this->save($data);
    }

    /**
     * Returns the recent live server-side dispatched events.
     *
     * @return array
     */
    public function getRecentEvents(): array {
        $data = $this->load();
        if (!empty($data['events']) && is_array($data['events'])) {
            return $data['events'];
        }

        return [];
    }

    /**
     * Totals for the last 30 days.
     *
     * @return array
     */
    public function getSummary(): array {
        $data = $this->load();
        $cutoff = gmdate('Y-m-d', strtotime('-' . (self::PERIOD_DAYS - 1) . ' days'));
        $summary = [
            'total_orders'    => 0,
            'rescued_orders'  => 0,
            'total_revenue'   => 0.0,
            'rescued_revenue' => 0.0,
            'refund_revenue'  => 0.0,
        ];
        foreach ((array) ($data['daily'] ?? []) as $date => $bucket) {
            if ((string) $date < $cutoff) {
                continue;
            }
            $summary['total_orders']    += (int) ($bucket['orders'] ?? 0);
            $summary['rescued_orders']  += (int) ($bucket['rescued'] ?? 0);
            $summary['total_revenue']   += (float) ($bucket['revenue'] ?? 0.0);
            $summary['rescued_revenue'] += (float) ($bucket['rescued_revenue'] ?? 0.0);
            $summary['refund_revenue']  += (float) ($bucket['refunds'] ?? 0.0);
        }

        $total = $summary['total_orders'];
        $summary['rescue_rate_percent'] = ($total > 0) ? round(($summary['rescued_orders'] / $total) * 100, 1) : 0.0;
        $summary['net_revenue'] = max(0.0, $summary['total_revenue'] - $summary['refund_revenue']);
        $summary['currency'] = (string) ($data['summary']['currency'] ?? 'USD');
        $summary['period_days'] = self::PERIOD_DAYS;

        return $summary;
    }

    /**
     * Creates today's daily bucket if missing.
     *
     * @param array &$data
     * @param string $date
     */
    private function ensureBucket(array &$data, string $date): void {
        if (!isset($data['daily'][$date])) {
            $data['daily'][$date] = [
                'orders'          => 0,
                'rescued'         => 0,
                'revenue'         => 0.0,
                'rescued_revenue' => 0.0,
                'refunds'         => 0.0,
            ];
        }
    }

    /**
     * Returns daily statistics buckets.
     *
     * @return array
     */
    public function getDailyStats(): array {
        $data = $this->load();
        return $data['daily'] ?? [];
    }

    /**
     * Prunes daily buckets older than 30 days.
     *
     * @param array &$data
     * @param int $daysToKeep
     */
    public function pruneOldEntries(array &$data, int $daysToKeep = 30): void {
        if (empty($data['daily']) || !is_array($data['daily'])) {
            return;
        }

        $cutoff = strtotime("-{$daysToKeep} days");
        foreach (array_keys($data['daily']) as $dateStr) {
            $ts = strtotime($dateStr);
            if ($ts !== false && $ts < $cutoff) {
                unset($data['daily'][$dateStr]);
            }
        }
    }

    /**
     * Resets telemetry metrics.
     */
    public function reset(): void {
        delete_option(self::OPTION_KEY);
    }

    /**
     * Loads telemetry data with defaults.
     *
     * @return array
     */
    private function load(): array {
        $data = get_option(self::OPTION_KEY, []);
        if (!is_array($data) || empty($data)) {
            $data = [
                'summary' => [
                    'currency' => 'USD',
                ],
                'daily' => [],
            ];
        }
        return $data;
    }

    /**
     * Persists telemetry data.
     *
     * @param array $data
     */
    private function save(array $data): void {
        update_option(self::OPTION_KEY, $data, false);
    }
}