<?php

namespace MingTsay\Akanyan;

use Exception;
use MingTsay\Akanyan\Discord\Me;
use MingTsay\Akanyan\Discord\Token;

require_once __DIR__ . '/../env.php';

class Auth
{
    private const DISCORD_REDIRECT_URI = 'https://akanyan.oho.tw/auth.php?source=discord';

    public static function encrypt(Token $payload): ?string
    {
        $key = file_get_contents(__DIR__ . '/../sodium_key');
        try {
            $nonce = random_bytes(SODIUM_CRYPTO_AEAD_XCHACHA20POLY1305_IETF_NPUBBYTES);
            $cipher = sodium_crypto_aead_xchacha20poly1305_ietf_encrypt(json_encode($payload), '', $nonce, $key);

            return implode(';', array_map('base64_encode', [$nonce, $cipher]));
        } catch (Exception) {
            return null;
        }
    }

    public static function decrypt(string $u): ?Token
    {
        $key = file_get_contents(__DIR__ . '/../sodium_key');
        try {
            list($nonce, $cipher) = array_map('base64_decode', explode(';', $u));
            $payload = json_decode(sodium_crypto_aead_xchacha20poly1305_ietf_decrypt($cipher, '', $nonce, $key));
            if ($payload === null) return null;
            return new Token($payload);
        } catch (Exception) {
            return null;
        }
    }

    public static function authorize(): string
    {
        $query_string = http_build_query([
            'client_id' => $_ENV['DISCORD_CLIENT_ID'],
            'redirect_uri' => static::DISCORD_REDIRECT_URI,
            'response_type' => 'code',
            'scope' => 'identify',
        ]);
        return "https://discord.com/api/oauth2/authorize?$query_string";
    }

    public static function getTokenByCode(string $code): ?Token
    {
        $payload = json_decode(file_get_contents('https://discord.com/api/oauth2/token', false, stream_context_create([
            'http' => [
                'method' => 'POST',
                'header' => 'Content-Type: application/x-www-form-urlencoded',
                'content' => http_build_query([
                    'client_id' => $_ENV['DISCORD_CLIENT_ID'],
                    'client_secret' => $_ENV['DISCORD_CLIENT_SECRET'],
                    'grant_type' => 'authorization_code',
                    'code' => $code,
                    'redirect_uri' => static::DISCORD_REDIRECT_URI,
                ]),
            ],
        ])));
        if ($payload === null) return null;
        return new Token($payload);
    }

    public static function getMe(Token $getU): ?Me
    {
        return new Me(json_decode(file_get_contents('https://discord.com/api/oauth2/@me', false, stream_context_create([
            'http' => [
                'method' => 'GET',
                'header' => "Authorization: Bearer $getU->access_token",
            ],
        ]))));
    }
}