//SPDX-License-Identifier: LGPL-3.0-only
//SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

// Mutual TLS on the HTTP/1.1 listener, plus the raw :TLS stream API on its
// own. A server that asks for a client certificate is only useful if it also
// refuses the peers that do not have one, so both directions are asserted.
//
// The certificate authority and client certificate are minted with the openssl
// CLI: a client certificate needs the clientAuth extended key usage, which the
// library's built-in development certificate (serverAuth, for listeners) does
// not carry. Without openssl the mTLS half is skipped.

import Crafter.Network;
import std;
using namespace Crafter;

namespace {
    int failures = 0;

    void Check(bool condition, std::string_view what) {
        if (!condition) {
            std::println("FAIL: {}", what);
            ++failures;
        }
    }

    bool HaveCommand(std::string_view name) {
        const std::string probe = "command -v " + std::string(name) + " >/dev/null 2>&1";
        return std::system(probe.c_str()) == 0;
    }

    std::unordered_map<std::string, std::function<HTTPResponse(const HTTPRequest&)>> Routes() {
        std::unordered_map<std::string, std::function<HTTPResponse(const HTTPRequest&)>> routes;
        routes["/"] = [](const HTTPRequest&) {
            return CreateResponseHTTP("200", "authenticated");
        };
        return routes;
    }

    // A throwaway CA and a client certificate signed by it.
    struct ClientIdentity {
        std::filesystem::path directory;
        std::filesystem::path authority;
        std::filesystem::path certificate;
        std::filesystem::path privateKey;
        bool ok = false;

        ClientIdentity() {
            directory = std::filesystem::temp_directory_path() / "crafter-network-mtls";
            std::error_code error;
            std::filesystem::remove_all(directory, error);
            std::filesystem::create_directories(directory);
            authority = directory / "ca.pem";
            certificate = directory / "client.pem";
            privateKey = directory / "client-key.pem";

            const std::string extensions = (directory / "client.ext").string();
            std::ofstream(extensions, std::ios::binary)
                << "basicConstraints=critical,CA:FALSE\n"
                << "keyUsage=critical,digitalSignature\n"
                << "extendedKeyUsage=clientAuth\n";

            const std::string command = std::format(
                "set -e\n"
                "openssl req -x509 -newkey ec -pkeyopt ec_paramgen_curve:P-256 -nodes"
                " -keyout '{0}/ca-key.pem' -out '{1}' -days 5 -subj '/CN=Crafter Test CA'"
                " -addext 'basicConstraints=critical,CA:TRUE'"
                " -addext 'keyUsage=critical,keyCertSign'\n"
                "openssl req -newkey ec -pkeyopt ec_paramgen_curve:P-256 -nodes"
                " -keyout '{2}' -out '{0}/client.csr' -subj '/CN=crafter-test-client'\n"
                "openssl x509 -req -in '{0}/client.csr' -CA '{1}' -CAkey '{0}/ca-key.pem'"
                " -set_serial 2 -days 5 -extfile '{0}/client.ext' -out '{3}'\n",
                directory.string(), authority.string(), privateKey.string(),
                certificate.string());
            ok = std::system((command + " >/dev/null 2>&1").c_str()) == 0;
        }
        ~ClientIdentity() {
            std::error_code error;
            std::filesystem::remove_all(directory, error);
        }
        ClientIdentity(const ClientIdentity&) = delete;
    };

    // The :TLS layer without any HTTP on top — the case for anything else that
    // owns a connected socket and wants a record layer over it.
    void RawStreamAgainstListener() {
        ListenerAsyncHTTP1 listener(8099, Routes(), TLSServerCredentials{ .selfSigned = true });

        TLSClientCredentials credentials;
        credentials.caPem = GetSelfSignedCertificatePem().certificate;
        auto context = TLSContext::Client(credentials);

        ClientTCP socket("localhost", 8099);
        std::unique_ptr<TLSStream> stream =
            TLSStream::Connect(socket.socketid, context, "localhost",
                               std::chrono::seconds(5));

        Check(stream->Secure(), "a TLSStream reports itself as secure");
        Check(stream->Protocol() == "http/1.1", "the raw stream negotiated ALPN");
        Check(stream->Version().starts_with("TLS"), "a TLS version was negotiated");
        // The listener presents the development certificate, whose subject is
        // CN=localhost.
        Check(stream->PeerCertificateSubject().find("localhost") != std::string::npos,
              "the server certificate subject is readable");

        // Hand-written HTTP/1.1 straight down the stream, to prove the record
        // layer is usable on its own.
        const std::string request = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";
        stream->Write(request.data(), request.size(), std::chrono::seconds(5));

        HTTP1::MessageParser parser(HTTP1::MessageKind::Response);
        std::vector<char> chunk(4096);
        while (!parser.Complete()) {
            std::size_t read = 0;
            const StreamStatus status =
                stream->ReadSome(chunk.data(), chunk.size(), std::chrono::seconds(5), read);
            if (status != StreamStatus::Data) break;
            parser.Feed(chunk.data(), read);
        }
        Check(parser.Complete(), "a response arrived over the raw TLS stream");
        if (parser.Complete()) {
            HTTPResponse response = parser.TakeResponse();
            Check(response.status == "200", "raw TLS stream response status");
            Check(response.body == "authenticated", "raw TLS stream response body");
        }

        stream.reset();
        listener.Stop();
    }

    void MutualTLS() {
        if (!HaveCommand("openssl")) {
            std::println("skipping the mTLS half: openssl is not installed");
            return;
        }
        ClientIdentity identity;
        if (!identity.ok) {
            std::println("skipping the mTLS half: could not mint a client certificate");
            return;
        }

        TLSServerCredentials server;
        server.selfSigned = true;
        server.requireClientCertificate = true;
        server.clientCaPath = identity.authority.string();
        ListenerAsyncHTTP1 listener(8100, Routes(), server);

        // A client with a certificate the listener's CA vouches for.
        {
            TLSClientCredentials credentials;
            credentials.caPem = GetSelfSignedCertificatePem().certificate;
            credentials.certPath = identity.certificate.string();
            credentials.keyPath = identity.privateKey.string();
            ClientHTTP1 client("localhost", 8100, credentials);

            HTTPResponse response = client.Send(CreateRequestHTTP("GET", "/", "localhost"));
            Check(response.status == "200", "a client with a trusted certificate is served");
            Check(response.body == "authenticated", "mTLS response body");
        }
        Check(listener.listener.HandshakeFailureCount() == 0,
              "a valid client certificate is not a handshake failure");

        // The same client, with no certificate at all. Under TLS 1.3 the
        // server's rejection arrives after the client believes the handshake
        // finished, so the failure can surface at connect *or* on the first
        // exchange — either is a refusal, and neither may be a success.
        {
            TLSClientCredentials credentials;
            credentials.caPem = GetSelfSignedCertificatePem().certificate;
            ClientHTTP1 anonymous("localhost", 8100, credentials);
            bool refused = false;
            try {
                anonymous.Send(CreateRequestHTTP("GET", "/", "localhost"));
            } catch (const std::exception&) {
                refused = true;
            }
            Check(refused, "a client with no certificate is refused");
        }
        for (int wait = 0; wait < 100; ++wait) {
            if (listener.listener.HandshakeFailureCount() > 0) break;
            std::this_thread::sleep_for(std::chrono::milliseconds(20));
        }
        Check(listener.listener.HandshakeFailureCount() == 1,
              "the refused client is counted as a handshake failure");

        listener.Stop();
    }
}

int main() {
    try {
        RawStreamAgainstListener();
        MutualTLS();
    } catch (const std::exception& error) {
        std::println("threw: {}", error.what());
        return 1;
    }

    if (failures != 0) {
        std::println("{} check(s) failed", failures);
        return 1;
    }
    return 0;
}