<?php

namespace LDC\WebAdminSecureLaravel;

use Dxw\CIDR\IPAddress;
use Dxw\CIDR\IPv4Address;
use Dxw\CIDR\IPv4Range;
use Dxw\CIDR\IPv6Address;
use Dxw\CIDR\IPv6Range;
use Illuminate\Http\Client\Response;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;
use LDC\WebAdminSecureLaravel\Exceptions\AdminSecureException;
use LDC\WebAdminSecureLaravel\Exceptions\AdminSecureInvalidAdressException;

abstract class AdminSecure
{
    /**
     * The cache key where to store ip list.
     *
     * @var string
     */
    private static string $cache_key = 'ldcweb_ip_list';

    /**
     * The cache key where to store config cidr list.
     *
     * @var string
     */
    private static string $cache_config_key = 'ldcweb_ip_cidr_config_list';

    /**
     * Private ipV4 CIDR list
     *
     * @var array
     */
    private static array $private_ip_v4_cidr_list = [
        '10.0.0.0/8', '172.16.0.0/12', '192.168.0.0/16'
    ];

    /**
     * Private ipV4 CIDR loopback
     *
     * @var string
     */
    private static string $private_ip_v4_loopback_cidr = '127.0.0.0/8';

    /**
     * Private ipV6 CIDR list
     *
     * @var array
     */
    private static array $private_ip_v6_cidr_list = [
        'fd00::/8'
    ];

    /**
     * Private ipV6 CIDR loopback
     *
     * @var string
     */
    private static string $private_ip_v6_loopback_cidr = '::1/128';

    /**
     * Check if ip is private
     *
     * @param \Dxw\CIDR\IPv4Address|\Dxw\CIDR\IPv6Address $ip_address
     * @return boolean
     */
    public static function ipIsPrivate(IPv4Address|IPv6Address $ip_address): bool
    {
        return \get_class($ip_address) === IPv4Address::class ?
            self::ipV4IsPrivate($ip_address) : self::ipV6IsPrivate($ip_address);
    }

    /**
     * Fetch client IP
     *
     * @return \Dxw\CIDR\IPv4Address|\Dxw\CIDR\IPv6Address
     * @throws \LDC\WebAdminSecureLaravel\AdminSecureException If the ip is invalid.
     */
    public static function fetchClientIp(): IPv4Address|IPv6Address
    {
        // ! HA PROXY HACK.
        $ip = request()->server('HTTP_X_FORWARDED_FOR') ?? request()->getClientIp();
        $ip = IPAddress::Make($ip);

        if ($ip->isErr()) {
            throw new AdminSecureException(\trans('Client IP not valid ') . $ip->getErr());
        }
        return $ip->unwrap();
    }

    /**
     * Fetch Ip Adress list from LDC Web
     *
     * @return array<\Dxw\CIDR\IPv4Address|\Dxw\CIDR\IPv6Address>
     * @throws \LDC\WebAdminSecureLaravel\AdminSecureException If Wrong env value.
     * @throws \Illuminate\Http\Client\RequestException        If calling admin secure fails.
     * @phpcs:disable Squiz.Commenting.FunctionCommentThrowTag.WrongNumber
     */
    public static function fetchIpList(): array
    {
        // phpcs:enable
        $endpoint = config('admin-secure.endpoint');
        $key      = config('admin-secure.apiKey');
        if (!$endpoint or !\filter_var($endpoint, \FILTER_VALIDATE_URL)) {
            throw new AdminSecureException('LDC_WEB_API_ENDPOINT is required in .env to ba a valid url.');
        }
        if (!$key) {
            throw new AdminSecureException('LDC_WEB_API_KEY is required in .env .');
        }

        $response = Http::get($endpoint, ['token' => $key])->throw();
        $adresses = self::parseAdresses($response);

        Log::info(\sprintf('ADMINSECURE : Fetched %d ip(s) from LDC WEB', \count($adresses)));

        return $adresses;
    }

    /**
     * Fetch Ip Adress list from LDC Web
     *
     * @return array<\Dxw\CIDR\IPv4Range|\Dxw\CIDR\IPv6Range>
     * @throws \LDC\WebAdminSecureLaravel\AdminSecureException If Wrong env value.
     * @phpcs:disable Squiz.Commenting.FunctionCommentThrowTag.WrongNumber
     */
    public static function fetchConfigAllowedCidrList(): array
    {
        $allowed_cidr_config_list      = \collect(config('admin-secure.cidrManualAllowedList'))->filter();
        $allowed_cidr_config_list_hash = \md5($allowed_cidr_config_list->implode(','));
        $allowed_cidr_list             = $allowed_cidr_config_list
            ->map(function (string $cidr) {
                $ip_range = !IPv4Range::Make($cidr)->isErr() ? IPv4Range::Make($cidr) : IPv6Range::Make($cidr);
                if ($ip_range->isErr()) {
                    throw new AdminSecureException(\trans(
                        'LDC_WEB_CIDR_MANUAL_ALLOWED_LIST not valid (ipv4 or ipv6 cidr) :cidr',
                        [
                            'cidr' => $cidr
                        ]
                    ));
                }
                return $ip_range->unwrap();
            })->all();

        // * Flush cache if hash config hash changed
        if ($allowed_cidr_config_list_hash !== \collect(Cache::get(self::$cache_config_key))->get('hash')) {
            Cache::flush(self::$cache_config_key);
        }

        /** @var array<\Dxw\CIDR\IPv4Range|\Dxw\CIDR\IPv6Range> $allowed_cidr_list */
        return \collect(Cache::rememberForever(self::$cache_config_key, fn () => [
            'list' => $allowed_cidr_list,
            'hash' => $allowed_cidr_config_list_hash
        ]))->get('list');
    }

    /**
     * Get ip list from cache
     *
     * @return array<\Dxw\CIDR\IPv4Address|\Dxw\CIDR\IPv6Address>
     */
    public static function getCacheList(): array
    {
        try {
            $ip_list = Cache::get(self::$cache_key, self::fetchIpList());
            self::validateIpList($ip_list);
            /** @var array<\Dxw\CIDR\IPv4Address|\Dxw\CIDR\IPv6Address> $ip_list */
            return $ip_list;
        } catch (AdminSecureInvalidAdressException) {
            $ip_list = self::fetchIpList();
            self::validateIpList($ip_list);
            self::setCacheList($ip_list);
            return $ip_list;
        }
    }

    /**
     * Set ip list to cache
     *
     * @param array<\Dxw\CIDR\IPv4Address|\Dxw\CIDR\IPv6Address> $ip_list
     * @return void
     */
    public static function setCacheList(array $ip_list): void
    {
        self::validateIpList($ip_list);
        Cache::put(self::$cache_key, $ip_list);
    }

    /**
     * Check if ipV4 is private
     *
     * @param \Dxw\CIDR\IPv4Address $ipv4_address
     * @return boolean
     */
    private static function ipV4IsPrivate(IPv4Address $ipv4_address): bool
    {
        return \collect(self::$private_ip_v4_cidr_list)
            ->concat([self::$private_ip_v4_loopback_cidr])
            ->map(fn (string $ipv4_cidr) => IPv4Range::Make($ipv4_cidr)->unwrap())
            ->reduce(fn (bool|null $initial, IPv4Range $ipv4_range) =>
            $initial || $ipv4_range->containsAddress($ipv4_address));
    }

    /**
     * Check if ipV6 is private
     *
     * @param \Dxw\CIDR\IPv6Address $ipv6_address
     * @return boolean
     */
    private static function ipV6IsPrivate(IPv6Address $ipv6_address): bool
    {
        return \collect(self::$private_ip_v6_cidr_list)
            ->concat([self::$private_ip_v6_loopback_cidr])
            ->map(fn (string $ipv6_cidr) => IPv6Range::Make($ipv6_cidr)->unwrap())
            ->reduce(fn (bool|null $initial, IPv6Range $ipv6_range) =>
            $initial || $ipv6_range->containsAddress($ipv6_address));
    }

    /**
     * Validate ip list
     *
     * @param array $ip_list
     * @return void
     * @throws \LDC\WebAdminSecureLaravel\Exceptions\AdminSecureInvalidAdressException If an IP is invalid.
     */
    private static function validateIpList(array $ip_list): void
    {
        \collect($ip_list)->each(function ($ip) {
            if (!\is_object($ip) or !\in_array(\get_class($ip), [IPv4Address::class, IPv6Address::class])) {
                throw new AdminSecureInvalidAdressException('Invalid adresse ' . \strval(\json_encode($ip)));
            }
        });
    }

    /**
     * Parse adresses
     *
     * @param \Illuminate\Http\Client\Response $response
     * @return array<\Dxw\CIDR\IPAddress>
     */
    private static function parseAdresses(Response $response): array
    {
        return \collect($response->json())
            ->map(fn (string $ip) => IPAddress::Make($ip)->unwrap())->all();
    }
}