<?php
declare(strict_types=1);

/**
 * Server-side validation and sanitization of the Plan Your Visit payload.
 * Mirrors src/lib/schema.ts. The server is authoritative.
 */
final class Validator
{
    public const CHILD_AGE_RANGES = ['0-2', '3-5', '6-10', '11-13', '14-18'];
    private const ATTR_KEYS = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_content', 'utm_term', 'gclid', 'gbraid', 'wbraid', 'fbclid', 'ttclid', 'twclid', 'variant', 'landing_url', 'referrer', 'first_seen_at'];

    /**
     * @param array<string,mixed> $in
     * @return array{data:array<string,mixed>, errors:array<string,string>}
     */
    public static function planVisit(array $in): array
    {
        $errors = [];
        $d = [];

        $d['submission_id'] = self::str($in, 'submissionId', 36);
        if (!preg_match('/^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i', $d['submission_id'])) {
            $errors['submissionId'] = 'Invalid submission id.';
        }

        $d['first_name'] = self::str($in, 'firstName', 60);
        if ($d['first_name'] === '') {
            $errors['firstName'] = 'Please tell us your first name.';
        }
        $d['last_name'] = self::str($in, 'lastName', 60) ?: null;

        $email = strtolower(self::str($in, 'email', 254));
        if (!filter_var($email, FILTER_VALIDATE_EMAIL) || !str_contains($email, '.')) {
            $errors['email'] = "That email doesn't look right.";
        }
        $d['email'] = $email;

        $d['email_consent'] = (bool)($in['emailConsent'] ?? false);
        $d['sms_consent'] = (bool)($in['smsConsent'] ?? false);

        $phoneRaw = self::str($in, 'phone', 30);
        $d['phone_e164'] = null;
        if ($phoneRaw !== '') {
            $e164 = Phone::normalizeNanp($phoneRaw);
            if ($e164 === null) {
                $errors['phone'] = "That phone number doesn't look right.";
            } else {
                $d['phone_e164'] = $e164;
            }
        }
        if ($d['sms_consent'] && $d['phone_e164'] === null && !isset($errors['phone'])) {
            $errors['phone'] = 'Add a mobile number so we can text you, or uncheck texting.';
        }

        $d['campus_id'] = self::str($in, 'campusId', 40);
        if (!in_array($d['campus_id'], Campuses::openIds(), true)) {
            $errors['campusId'] = 'Please choose a campus.';
        }

        $visitDate = self::str($in, 'visitDate', 10);
        $d['visit_date'] = null;
        if ($visitDate !== '') {
            if (!preg_match('/^\d{4}-\d{2}-\d{2}$/', $visitDate) || !strtotime($visitDate)) {
                $errors['visitDate'] = 'Use the date picker.';
            } elseif ($visitDate < gmdate('Y-m-d', time() - 86400)) { // allow one day of timezone slack
                $errors['visitDate'] = 'Pick today or a future date.';
            } else {
                $d['visit_date'] = $visitDate;
            }
        }

        $d['service_time'] = self::str($in, 'serviceTime', 80) ?: null;

        $d['adults'] = self::intOrNull($in, 'adults', 1, 20);
        $d['children'] = self::intOrNull($in, 'children', 0, 10);

        $ranges = $in['childAgeRanges'] ?? [];
        $clean = [];
        if (is_array($ranges)) {
            foreach ($ranges as $r) {
                if (is_string($r) && in_array($r, self::CHILD_AGE_RANGES, true) && !in_array($r, $clean, true)) {
                    $clean[] = $r;
                }
            }
        }
        $d['child_age_ranges'] = $clean ? implode(',', $clean) : null;

        $d['questions'] = self::str($in, 'questions', 1000) ?: null;

        $d['consent_version'] = self::str($in, 'consentVersion', 40);
        if ($d['consent_version'] === '') {
            $errors['consentVersion'] = 'Missing consent version.';
        }

        // Anti-spam: honeypot + minimum time on form
        $d['honeypot'] = self::str($in, 'website', 200);
        $startedAt = (int)($in['startedAt'] ?? 0);
        $d['elapsed_ms'] = $startedAt > 0 ? max(0, (int)(microtime(true) * 1000) - $startedAt) : 0;

        // Attribution: whitelist keys, cap lengths, strip control chars
        $attr = [];
        if (isset($in['attribution']) && is_array($in['attribution'])) {
            foreach ($in['attribution'] as $k => $v) {
                if (is_string($k) && is_string($v) && in_array($k, self::ATTR_KEYS, true)) {
                    $max = in_array($k, ['landing_url', 'referrer'], true) ? 2000 : 200;
                    $attr[$k] = self::clean($v, $max);
                }
            }
        }
        $d['attribution'] = $attr;
        $d['turnstile_token'] = is_string($in['turnstileToken'] ?? null) ? substr($in['turnstileToken'], 0, 4000) : null;

        return ['data' => $d, 'errors' => $errors];
    }

    /** @param array<string,mixed> $in */
    private static function str(array $in, string $key, int $max): string
    {
        $v = $in[$key] ?? '';
        if (!is_string($v)) {
            return '';
        }
        return self::clean($v, $max);
    }

    public static function clean(string $v, int $max): string
    {
        $v = preg_replace('/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/u', '', $v) ?? '';
        $v = trim($v);
        if (!mb_check_encoding($v, 'UTF-8')) {
            $v = mb_convert_encoding($v, 'UTF-8', 'UTF-8');
        }
        return mb_substr($v, 0, $max);
    }

    /** @param array<string,mixed> $in */
    private static function intOrNull(array $in, string $key, int $min, int $max): ?int
    {
        if (!isset($in[$key]) || $in[$key] === '' || $in[$key] === null) {
            return null;
        }
        if (!is_numeric($in[$key])) {
            return null;
        }
        $n = (int)$in[$key];
        return ($n < $min || $n > $max) ? null : $n;
    }
}