<?php
/** Bounded encrypted native handles and durable at-most-one-send receipts. */
if (!defined('ABSPATH')) { exit; }
final class Chat4U_Commerce_Storage {
    public static function table(): string { global $wpdb; return $wpdb->prefix . 'chat4u_commerce'; }
    public static function activate(): void {
        global $wpdb; require_once ABSPATH . 'wp-admin/includes/upgrade.php'; $table=self::table();
        dbDelta("CREATE TABLE {$table} (
            record_key varchar(80) NOT NULL,
            kind varchar(24) NOT NULL,
            subject_hash char(64) NOT NULL DEFAULT '',
            cart_identity char(64) NOT NULL DEFAULT '',
            parameter_hash char(64) NOT NULL DEFAULT '',
            state varchar(24) NOT NULL DEFAULT '',
            payload longtext NULL,
            expires_at bigint unsigned NOT NULL,
            updated_at bigint unsigned NOT NULL,
            PRIMARY KEY  (record_key),
            KEY expires_at (expires_at),
            KEY kind_state (kind,state),
            KEY cart_state (cart_identity,state),
            KEY subject_hash (subject_hash)
        ) " . $wpdb->get_charset_collate() . ';');
    }
    public static function ensure(): void {
        if (Chat4U_Commerce::available() && get_option("chat4u_commerce_schema") !== "4") {
            self::activate();global $wpdb;
            $columns=$wpdb->get_col($wpdb->prepare("SHOW COLUMNS FROM %i",self::table()));
            if (!array_diff(["record_key","kind","subject_hash","cart_identity","parameter_hash","state","payload","expires_at","updated_at"],$columns)) { update_option("chat4u_commerce_schema","4",false); }
        }
    }
    private static function key(string $module): string {
        $name='chat4u_commerce_key_' . $module; $key=get_option($name);
        if (!$key) { add_option($name,bin2hex(random_bytes(32)),'',false); $key=get_option($name); }
        return hex2bin($key);
    }
    public static function encode(array $value,string $module): string {
        $nonce=random_bytes(12);$tag='';
        $body=openssl_encrypt(wp_json_encode($value),'aes-256-gcm',self::key($module),OPENSSL_RAW_DATA,$nonce,$tag);
        if ($body===false) { throw new RuntimeException('Commerce encryption unavailable'); }
        return base64_encode($nonce.$tag.$body);
    }
    public static function decode(?string $value,string $module): array {
        $raw=base64_decode($value ?: '',true);
        if ($raw===false || strlen($raw)<28) { return []; }
        $body=openssl_decrypt(substr($raw,28),'aes-256-gcm',self::key($module),OPENSSL_RAW_DATA,substr($raw,0,12),substr($raw,12,16));
        return $body===false ? [] : (array) json_decode($body,true);
    }
    public static function put(string $key,string $kind,array $value,int $seconds,string $module='cart'): void {
        global $wpdb;
        $ok=$wpdb->replace(self::table(),['record_key'=>$key,'kind'=>$kind,'subject_hash'=>$value['email_hash'] ?? $value['grant']['email_hash'] ?? '', 'payload'=>self::encode($value,$module),
            'expires_at'=>time()+$seconds,'updated_at'=>time()]);
        if ($ok===false) { throw new RuntimeException('Commerce receipt unavailable'); }
    }
    public static function get(string $key,string $module='cart'): array {
        global $wpdb;
        $row=$wpdb->get_row($wpdb->prepare('SELECT payload,expires_at FROM %i WHERE record_key=%s',self::table(),$key),ARRAY_A);
        return $row && (int)$row['expires_at']>time() ? self::decode($row['payload'],$module) : [];
    }
    public static function cleanup(): array {
        if (get_option("chat4u_commerce_schema") !== "4") { return []; }
        Chat4U_Commerce_Privacy::cleanup();
        global $wpdb;
        $wpdb->query($wpdb->prepare("DELETE FROM %i WHERE option_name LIKE %s AND CAST(option_value AS UNSIGNED)<=%d LIMIT 100",$wpdb->options,$wpdb->esc_like("chat4u_woo_nonce_")."%",time()));
        // Preserve unresolved action identity; scrub its sensitive payload separately.
        $wpdb->query($wpdb->prepare("UPDATE %i SET payload=NULL WHERE expires_at<=%d AND payload IS NOT NULL AND kind='action' AND state IN ('sending','unknown') LIMIT 100",self::table(),time()));
        $wpdb->query($wpdb->prepare("DELETE FROM %i WHERE expires_at<=%d AND kind<>'order_cleanup' AND NOT(kind='action' AND state IN ('sending','unknown')) LIMIT 100",self::table(),time()));
        return ['oldest_expired'=>(int)$wpdb->get_var($wpdb->prepare("SELECT MIN(expires_at) FROM %i WHERE expires_at<=%d AND (payload IS NOT NULL OR NOT(kind='action' AND state IN ('sending','unknown')))",self::table(),time()))];
    }
    public static function revoke($prior=null,$next=null): void {
        if ($next===null || (!empty($prior["cart_assistance"]) && empty($next["cart_assistance"]))) { delete_option("chat4u_commerce_key_cart"); }
        if ($next===null || (!empty($prior["order_status"]) && empty($next["order_status"]))) { delete_option("chat4u_commerce_key_order"); }
        if ($next===null || (!empty($prior["purchase_evidence"]) && empty($next["purchase_evidence"]))) { delete_option("chat4u_commerce_key_measurement"); }
        self::cleanup();
    }
}