<?php

declare (strict_types=1);
namespace GDAVSCOPE\Amp\Socket;

final class ServerTlsContext
{
    public const TLSv1_0 = \STREAM_CRYPTO_METHOD_TLSv1_0_SERVER;
    public const TLSv1_1 = \STREAM_CRYPTO_METHOD_TLSv1_1_SERVER;
    public const TLSv1_2 = \STREAM_CRYPTO_METHOD_TLSv1_2_SERVER;
    public const TLSv1_3 = \STREAM_CRYPTO_METHOD_TLSv1_3_SERVER;
    private const TLS_VERSIONS = ['TLSv1.0' => self::TLSv1_0, 'TLSv1.1' => self::TLSv1_1, 'TLSv1.2' => self::TLSv1_2, 'TLSv1.3' => self::TLSv1_3];
    /**
     * @param resource $socket
     */
    public static function fromServerResource($socket): ?self
    {
        $tls = \stream_context_get_options($socket)['ssl'] ?? [];
        if (!$tls) {
            return null;
        }
        $context = (new self())->withPeerName($tls['peer_name'])->withVerificationDepth($tls['verify_depth'])->withCiphers($tls['ciphers'])->withSecurityLevel($tls['security_level'])->withDefaultCertificate(new Certificate($tls['local_cert'], $tls['local_pk'] ?? null));
        if ($tls['verify_peer'] || $tls['verify_peer_name']) {
            $context = $context->withPeerVerification();
        }
        if ($tls['capture_peer_cert'] || $tls['capture_peer_chain']) {
            $context = $context->withPeerCapturing();
        }
        $minVersion = self::TLSv1_3;
        foreach ([self::TLSv1_2, self::TLSv1_1, self::TLSv1_0] as $tlsVersion) {
            if ($tls['crypto_method'] & $tlsVersion) {
                $minVersion = $tlsVersion;
            }
        }
        return $context->withMinimumVersion($minVersion);
    }
    private int $minVersion = self::TLSv1_2;
    private ?string $peerName = null;
    private bool $verifyPeer = \false;
    private int $verifyDepth = 10;
    private ?string $ciphers = null;
    private ?string $caFile = null;
    private ?string $caPath = null;
    private bool $capturePeer = \false;
    private ?Certificate $defaultCertificate = null;
    /** @var Certificate[] */
    private array $certificates = [];
    private int $securityLevel = 2;
    /** @var string[] */
    private array $alpnProtocols = [];
    /**
     * Minimum TLS version to negotiate.
     *
     * Defaults to TLS 1.2.
     *
     * @param int $version One of the `ServerTlsContext::TLSv*` constants.
     *
     * @return self Cloned, modified instance.
     * @throws \Error If an invalid minimum version is given.
     */
    public function withMinimumVersion(int $version): self
    {
        if (!\in_array($version, self::TLS_VERSIONS, \true)) {
            throw new \Error(\sprintf('Invalid minimum version, only %s allowed', \implode(', ', \array_keys(self::TLS_VERSIONS))));
        }
        $clone = clone $this;
        $clone->minVersion = $version;
        return $clone;
    }
    /**
     * Returns the minimum TLS version to negotiate.
     */
    public function getMinimumVersion(): int
    {
        return $this->minVersion;
    }
    /**
     * Expected name of the peer.
     *
     * @return self Cloned, modified instance.
     */
    public function withPeerName(?string $peerName = null): self
    {
        $clone = clone $this;
        $clone->peerName = $peerName;
        return $clone;
    }
    /**
     * @return null|string Expected name of the peer or `null` if such an expectation doesn't exist.
     */
    public function getPeerName(): ?string
    {
        return $this->peerName;
    }
    /**
     * Enable peer verification.
     *
     * @return self Cloned, modified instance.
     */
    public function withPeerVerification(): self
    {
        $clone = clone $this;
        $clone->verifyPeer = \true;
        return $clone;
    }
    /**
     * Disable peer verification, this is the default for servers.
     *
     * @return self Cloned, modified instance.
     */
    public function withoutPeerVerification(): self
    {
        $clone = clone $this;
        $clone->verifyPeer = \false;
        return $clone;
    }
    /**
     * @return bool Whether peer verification is enabled.
     */
    public function hasPeerVerification(): bool
    {
        return $this->verifyPeer;
    }
    /**
     * Maximum chain length the peer might present including the certificates in the local trust store.
     *
     * @param int $verifyDepth Maximum length of the certificate chain.
     *
     * @return self Cloned, modified instance.
     */
    public function withVerificationDepth(int $verifyDepth): self
    {
        if ($verifyDepth < 0) {
            throw new \Error("Invalid verification depth ({$verifyDepth}), must be greater than or equal to 0");
        }
        $clone = clone $this;
        $clone->verifyDepth = $verifyDepth;
        return $clone;
    }
    /**
     * @return int Maximum length of the certificate chain.
     */
    public function getVerificationDepth(): int
    {
        return $this->verifyDepth;
    }
    /**
     * List of ciphers to negotiate, the server's order is always preferred.
     *
     * @param string|null $ciphers List of ciphers in OpenSSL's format (colon separated).
     *
     * @return self Cloned, modified instance.
     */
    public function withCiphers(?string $ciphers = null): self
    {
        $clone = clone $this;
        $clone->ciphers = $ciphers;
        return $clone;
    }
    /**
     * @return string List of ciphers in OpenSSL's format (colon separated).
     */
    public function getCiphers(): string
    {
        return $this->ciphers ?? \OPENSSL_DEFAULT_STREAM_CIPHERS;
    }
    /**
     * CAFile to check for trusted certificates.
     *
     * @param string|null $cafile Path to the file or `null` to unset.
     *
     * @return self Cloned, modified instance.
     */
    public function withCaFile(?string $cafile = null): self
    {
        $clone = clone $this;
        $clone->caFile = $cafile;
        return $clone;
    }
    /**
     * @return null|string Path to the trusted certificates file if one is set, otherwise `null`.
     */
    public function getCaFile(): ?string
    {
        return $this->caFile;
    }
    /**
     * CAPath to check for trusted certificates.
     *
     * @param string|null $capath Path to the directory or `null` to unset.
     *
     * @return self Cloned, modified instance.
     */
    public function withCaPath(?string $capath = null): self
    {
        $clone = clone $this;
        $clone->caPath = $capath;
        return $clone;
    }
    /**
     * @return null|string Path to the trusted certificate directory if one is set, otherwise `null`.
     */
    public function getCaPath(): ?string
    {
        return $this->caPath;
    }
    /**
     * Capture the certificates sent by the peer.
     *
     * Note: This is the chain as sent by the peer, NOT the verified chain.
     *
     * @return self Cloned, modified instance.
     */
    public function withPeerCapturing(): self
    {
        $clone = clone $this;
        $clone->capturePeer = \true;
        return $clone;
    }
    /**
     * Don't capture the certificates sent by the peer.
     *
     * @return self Cloned, modified instance.
     */
    public function withoutPeerCapturing(): self
    {
        $clone = clone $this;
        $clone->capturePeer = \false;
        return $clone;
    }
    /**
     * @return bool Whether to capture the certificates sent by the peer.
     */
    public function hasPeerCapturing(): bool
    {
        return $this->capturePeer;
    }
    /**
     * Default certificate to use in case no SNI certificate matches.
     *
     * @return self Cloned, modified instance.
     */
    public function withDefaultCertificate(?Certificate $defaultCertificate = null): self
    {
        $clone = clone $this;
        $clone->defaultCertificate = $defaultCertificate;
        return $clone;
    }
    /**
     * @return Certificate|null Default certificate to use in case no SNI certificate matches, or `null` if unset.
     */
    public function getDefaultCertificate(): ?Certificate
    {
        return $this->defaultCertificate;
    }
    /**
     * Certificates to use for the given host names.
     *
     * @param array $certificates Must be a associative array mapping hostnames to certificate instances.
     *
     * @return self Cloned, modified instance.
     */
    public function withCertificates(array $certificates): self
    {
        foreach ($certificates as $key => $certificate) {
            if (!\is_string($key)) {
                throw new \TypeError('Expected an array mapping domain names to Certificate instances');
            }
            if (!$certificate instanceof Certificate) {
                throw new \TypeError('Expected an array of Certificate instances');
            }
        }
        $clone = clone $this;
        $clone->certificates = $certificates;
        return $clone;
    }
    /**
     * @return array Associative array mapping hostnames to certificate instances.
     */
    public function getCertificates(): array
    {
        return $this->certificates;
    }
    /**
     * Security level to use.
     *
     * Requires OpenSSL 1.1.0 or higher.
     *
     * @param int $level Must be between 0 and 5.
     *
     * @return self Cloned, modified instance.
     */
    public function withSecurityLevel(int $level): self
    {
        // See https://www.openssl.org/docs/manmaster/man3/SSL_CTX_set_security_level.html
        // Level 2 is not recommended, because of SHA-1 by that document,
        // but SHA-1 should be phased out now on general internet use.
        // We therefore default to level 2.
        if ($level < 0 || $level > 5) {
            throw new \Error("Invalid security level ({$level}), must be between 0 and 5.");
        }
        if (!hasTlsSecurityLevelSupport()) {
            throw new \Error("Can't set a security level, as PHP is compiled with OpenSSL < 1.1.0.");
        }
        $clone = clone $this;
        $clone->securityLevel = $level;
        return $clone;
    }
    /**
     * @return int Security level between 0 and 5. Always 0 for OpenSSL < 1.1.0.
     */
    public function getSecurityLevel(): int
    {
        // 0 is equivalent to previous versions of OpenSSL and just does nothing
        if (!hasTlsSecurityLevelSupport()) {
            return 0;
        }
        return $this->securityLevel;
    }
    /**
     * @param string[] $protocols
     *
     * @return self Cloned, modified instance.
     */
    public function withApplicationLayerProtocols(array $protocols): self
    {
        if (!hasTlsAlpnSupport()) {
            throw new \Error("Can't set an application layer protocol list, as PHP is compiled with OpenSSL < 1.0.2.");
        }
        foreach ($protocols as $protocol) {
            if (!\is_string($protocol)) {
                throw new \TypeError("Protocol names must be strings");
            }
        }
        $clone = clone $this;
        $clone->alpnProtocols = $protocols;
        return $clone;
    }
    /**
     * @return string[]
     */
    public function getApplicationLayerProtocols(): array
    {
        return $this->alpnProtocols;
    }
    /**
     * Converts this TLS context into PHP's equivalent stream context array.
     *
     * @return array Stream context array compatible with PHP's streams.
     */
    public function toStreamContextArray(): array
    {
        $options = ['crypto_method' => $this->toStreamCryptoMethod(), 'peer_name' => $this->peerName, 'verify_peer' => $this->verifyPeer, 'verify_peer_name' => $this->verifyPeer, 'verify_depth' => $this->verifyDepth, 'ciphers' => $this->ciphers ?? \OPENSSL_DEFAULT_STREAM_CIPHERS, 'honor_cipher_order' => \true, 'single_dh_use' => \true, 'no_ticket' => \true, 'capture_peer_cert' => $this->capturePeer, 'capture_peer_chain' => $this->capturePeer];
        if (!empty($this->alpnProtocols)) {
            $options['alpn_protocols'] = \implode(',', $this->alpnProtocols);
        }
        if ($this->defaultCertificate !== null) {
            $options['local_cert'] = $this->defaultCertificate->getCertFile();
            if ($this->defaultCertificate->getCertFile() !== $this->defaultCertificate->getKeyFile()) {
                $options['local_pk'] = $this->defaultCertificate->getKeyFile();
            }
        }
        if ($this->certificates) {
            $options['SNI_server_certs'] = \array_map(static function (Certificate $certificate) {
                $options = ['local_cert' => $certificate->getCertFile(), 'local_pk' => $certificate->getKeyFile()];
                if ($certificate->getPassphrase() !== null) {
                    $options['passphrase'] = $certificate->getPassphrase();
                }
                return $options;
            }, $this->certificates);
        }
        if ($this->caFile !== null) {
            $options['cafile'] = $this->caFile;
        }
        if ($this->caPath !== null) {
            $options['capath'] = $this->caPath;
        }
        if (hasTlsSecurityLevelSupport()) {
            $options['security_level'] = $this->securityLevel;
        }
        return ['ssl' => $options];
    }
    /**
     * @return int Crypto method compatible with PHP's streams.
     */
    public function toStreamCryptoMethod(): int
    {
        return match ($this->minVersion) {
            self::TLSv1_0 => self::TLSv1_0 | self::TLSv1_1 | self::TLSv1_2 | self::TLSv1_3,
            self::TLSv1_1 => self::TLSv1_1 | self::TLSv1_2 | self::TLSv1_3,
            self::TLSv1_2 => self::TLSv1_2 | self::TLSv1_3,
            self::TLSv1_3 => self::TLSv1_3,
            default => throw new \Error('Unknown minimum TLS version: ' . $this->minVersion),
        };
    }
}
