<?php
/** Identity-free daily aggregates. Writes participate in the caller's session transaction. */
namespace EmbodiedAssistant;
if (!defined('ABSPATH')) { exit; }

class UsageStore {
    public function table() { global $wpdb; return $wpdb->prefix . 'ea_usage_daily'; }

    public function retention_days() {
        $days = defined('EMBODIED_ASSISTANT_USAGE_RETENTION_DAYS') ? EMBODIED_ASSISTANT_USAGE_RETENTION_DAYS : 365;
        return max(1, min(365, (int) $days));
    }

    public function cutoff($now = null) {
        return gmdate('Y-m-d', ($now ?? time()) - ($this->retention_days() - 1) * DAY_IN_SECONDS);
    }

    public function install() {
        global $wpdb;
        require_once ABSPATH . 'wp-admin/includes/upgrade.php';
        dbDelta('CREATE TABLE ' . $this->table() . " (
 usage_day date NOT NULL,
 sessions bigint unsigned NOT NULL DEFAULT 0,
 seconds bigint unsigned NOT NULL DEFAULT 0,
 PRIMARY KEY  (usage_day)
) ENGINE=InnoDB " . $wpdb->get_charset_collate() . ';');
        $this->cleanup();
    }

    private function query($sql) {
        global $wpdb;
        // Private callers prepare all values and identifiers. Writes share the session transaction;
        // current usage totals must not come from an independently cached snapshot.
        // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching,PluginCheck.Security.DirectDB.UnescapedDBParameter -- Prepared by every private caller; transactional accounting requires direct access.
        if (false === $wpdb->query($sql)) { throw new \RuntimeException('usage_storage_unavailable'); }
    }

    /** No event rows, session IDs, visitors, URLs, provider payloads or transcripts. */
    public function add($day, $sessions, $seconds) {
        global $wpdb;
        if ($day < $this->cutoff() || $day > gmdate('Y-m-d')) { return; }
        $this->query($wpdb->prepare('INSERT INTO %i (usage_day,sessions,seconds) VALUES (%s,%d,%d) ON DUPLICATE KEY UPDATE sessions=sessions+VALUES(sessions),seconds=seconds+VALUES(seconds)', $this->table(), $day, max(0, (int) $sessions), max(0, (int) $seconds)));
    }

    /** Split elapsed time at UTC midnight; a session is counted only on its start day. */
    public function add_duration($start, $end) {
        $start = max((int) $start, strtotime($this->cutoff() . ' UTC'));
        $end = min((int) $end, time());
        while ($start < $end) {
            $next = min($end, (intdiv($start, DAY_IN_SECONDS) + 1) * DAY_IN_SECONDS);
            $this->add(gmdate('Y-m-d', $start), 0, $next - $start);
            $start = $next;
        }
    }

    public function cleanup() {
        global $wpdb;
        $this->query($wpdb->prepare('DELETE FROM %i WHERE usage_day<%s', $this->table(), $this->cutoff()));
    }

    public function daily() {
        global $wpdb;
        $this->cleanup();
        $this->query($wpdb->prepare('SELECT usage_day,sessions,seconds FROM %i WHERE usage_day>=%s AND usage_day<=%s ORDER BY usage_day', $this->table(), $this->cutoff(), gmdate('Y-m-d')));
        return array_map(static function ($row) { return (array) $row; }, $wpdb->last_result);
    }

    public function purge() { global $wpdb; $this->query($wpdb->prepare('DROP TABLE IF EXISTS %i', $this->table())); }
}