#pragma once
#include "bmcweb_config.h"

#include "async_resp.hpp"
#include "authentication.hpp"
#include "complete_response_fields.hpp"
#include "http2_connection.hpp"
#include "http_response.hpp"
#include "http_utility.hpp"
#include "logging.hpp"
#include "mutual_tls.hpp"
#include "ssl_key_handler.hpp"
#include "str_utility.hpp"
#include "utility.hpp"

#include <boost/asio/io_context.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/ssl/stream.hpp>
#include <boost/asio/steady_timer.hpp>
#include <boost/beast/_experimental/test/stream.hpp>
#include <boost/beast/core/buffers_generator.hpp>
#include <boost/beast/core/flat_static_buffer.hpp>
#include <boost/beast/http/error.hpp>
#include <boost/beast/http/parser.hpp>
#include <boost/beast/http/read.hpp>
#include <boost/beast/http/write.hpp>
#include <boost/beast/ssl/ssl_stream.hpp>
#include <boost/beast/websocket.hpp>

#include <atomic>
#include <chrono>
#include <vector>

namespace crow
{

// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
static int connectionCount = 0;

// request body limit size set by the bmcwebHttpReqBodyLimitMb option
constexpr uint64_t httpReqBodyLimit = 1024UL * 1024UL *
                                      bmcwebHttpReqBodyLimitMb;

constexpr uint64_t loggedOutPostBodyLimit = 4096;

constexpr uint32_t httpHeaderLimit = 8192;

template <typename>
struct IsTls : std::false_type
{};

template <typename T>
struct IsTls<boost::beast::ssl_stream<T>> : std::true_type
{};

template <typename Adaptor, typename Handler>
class Connection :
    public std::enable_shared_from_this<Connection<Adaptor, Handler>>
{
    using self_type = Connection<Adaptor, Handler>;

  public:
    Connection(Handler* handlerIn, boost::asio::steady_timer&& timerIn,
               std::function<std::string()>& getCachedDateStrF,
               Adaptor adaptorIn) :
        adaptor(std::move(adaptorIn)),
        handler(handlerIn), timer(std::move(timerIn)),
        getCachedDateStr(getCachedDateStrF)
    {
        parser.emplace(std::piecewise_construct, std::make_tuple());
        parser->body_limit(httpReqBodyLimit);
        parser->header_limit(httpHeaderLimit);

#ifdef BMCWEB_ENABLE_MUTUAL_TLS_AUTHENTICATION
        prepareMutualTls();
#endif // BMCWEB_ENABLE_MUTUAL_TLS_AUTHENTICATION

        connectionCount++;

        BMCWEB_LOG_DEBUG("{} Connection open, total {}", logPtr(this),
                         connectionCount);
    }

    ~Connection()
    {
        res.setCompleteRequestHandler(nullptr);
        cancelDeadlineTimer();

        connectionCount--;
        BMCWEB_LOG_DEBUG("{} Connection closed, total {}", logPtr(this),
                         connectionCount);
    }

    Connection(const Connection&) = delete;
    Connection(Connection&&) = delete;
    Connection& operator=(const Connection&) = delete;
    Connection& operator=(Connection&&) = delete;

    bool tlsVerifyCallback(bool preverified,
                           boost::asio::ssl::verify_context& ctx)
    {
        // We always return true to allow full auth flow for resources that
        // don't require auth
        if (preverified)
        {
            boost::asio::ip::address ipAddress;
            if (getClientIp(ipAddress))
            {
                return true;
            }

            mtlsSession = verifyMtlsUser(ipAddress, ctx);
            if (mtlsSession)
            {
                BMCWEB_LOG_DEBUG("{} Generating TLS session: {}", logPtr(this),
                                 mtlsSession->uniqueId);
            }
        }
        return true;
    }

    void prepareMutualTls()
    {
        if constexpr (IsTls<Adaptor>::value)
        {
            std::error_code error;
            std::filesystem::path caPath(ensuressl::trustStorePath);
            auto caAvailable = !std::filesystem::is_empty(caPath, error);
            caAvailable = caAvailable && !error;
            if (caAvailable && persistent_data::SessionStore::getInstance()
                                   .getAuthMethodsConfig()
                                   .tls)
            {
                adaptor.set_verify_mode(boost::asio::ssl::verify_peer);
                std::string id = "bmcweb";

                const char* cStr = id.c_str();
                // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
                const auto* idC = reinterpret_cast<const unsigned char*>(cStr);
                int ret = SSL_set_session_id_context(
                    adaptor.native_handle(), idC,
                    static_cast<unsigned int>(id.length()));
                if (ret == 0)
                {
                    BMCWEB_LOG_ERROR("{} failed to set SSL id", logPtr(this));
                }
            }

            adaptor.set_verify_callback(
                std::bind_front(&self_type::tlsVerifyCallback, this));
        }
    }

    Adaptor& socket()
    {
        return adaptor;
    }

    void start()
    {
        if (connectionCount >= 100)
        {
            BMCWEB_LOG_CRITICAL("{}Max connection count exceeded.",
                                logPtr(this));
            return;
        }

        startDeadline();

        // TODO(ed) Abstract this to a more clever class with the idea of an
        // asynchronous "start"
        if constexpr (IsTls<Adaptor>::value)
        {
            adaptor.async_handshake(boost::asio::ssl::stream_base::server,
                                    [this, self(shared_from_this())](
                                        const boost::system::error_code& ec) {
                if (ec)
                {
                    return;
                }
                afterSslHandshake();
            });
        }
        else
        {
            doReadHeaders();
        }
    }

    void afterSslHandshake()
    {
        // If http2 is enabled, negotiate the protocol
        if constexpr (bmcwebEnableHTTP2)
        {
            const unsigned char* alpn = nullptr;
            unsigned int alpnlen = 0;
            SSL_get0_alpn_selected(adaptor.native_handle(), &alpn, &alpnlen);
            if (alpn != nullptr)
            {
                std::string_view selectedProtocol(
                    std::bit_cast<const char*>(alpn), alpnlen);
                BMCWEB_LOG_DEBUG("ALPN selected protocol \"{}\" len: {}",
                                 selectedProtocol, alpnlen);
                if (selectedProtocol == "h2")
                {
                    auto http2 =
                        std::make_shared<HTTP2Connection<Adaptor, Handler>>(
                            std::move(adaptor), handler, getCachedDateStr);
                    http2->start();
                    return;
                }
            }
        }

        doReadHeaders();
    }

    void handle()
    {
        std::error_code reqEc;
        if (!parser)
        {
            return;
        }
        crow::Request& thisReq = req.emplace(parser->release(), reqEc);
        if (reqEc)
        {
            BMCWEB_LOG_DEBUG("Request failed to construct{}", reqEc.message());
            res.result(boost::beast::http::status::bad_request);
            completeRequest(res);
            return;
        }
        thisReq.session = userSession;

        // Fetch the client IP address
        readClientIp();

        // Check for HTTP version 1.1.
        if (thisReq.version() == 11)
        {
            if (thisReq.getHeaderValue(boost::beast::http::field::host).empty())
            {
                res.result(boost::beast::http::status::bad_request);
                completeRequest(res);
                return;
            }
        }

        BMCWEB_LOG_INFO("Request:  {} HTTP/{}.{} {} {} {}", logPtr(this),
                        thisReq.version() / 10, thisReq.version() % 10,
                        thisReq.methodString(), thisReq.target(),
                        thisReq.ipAddress.to_string());

        res.isAliveHelper = [this]() -> bool { return isAlive(); };

        thisReq.ioService = static_cast<decltype(thisReq.ioService)>(
            &adaptor.get_executor().context());

        if (res.completed)
        {
            completeRequest(res);
            return;
        }
        keepAlive = thisReq.keepAlive();
        if constexpr (!std::is_same_v<Adaptor, boost::beast::test::stream>)
        {
#ifndef BMCWEB_INSECURE_DISABLE_AUTHX
            if (!crow::authentication::isOnAllowlist(req->url().path(),
                                                     req->method()) &&
                thisReq.session == nullptr)
            {
                BMCWEB_LOG_WARNING("Authentication failed");
                forward_unauthorized::sendUnauthorized(
                    req->url().encoded_path(),
                    req->getHeaderValue("X-Requested-With"),
                    req->getHeaderValue("Accept"), res);
                completeRequest(res);
                return;
            }
#endif // BMCWEB_INSECURE_DISABLE_AUTHX
        }
        auto asyncResp = std::make_shared<bmcweb::AsyncResp>();
        BMCWEB_LOG_DEBUG("Setting completion handler");
        asyncResp->res.setCompleteRequestHandler(
            [self(shared_from_this())](crow::Response& thisRes) {
            self->completeRequest(thisRes);
        });
        bool isSse =
            isContentTypeAllowed(req->getHeaderValue("Accept"),
                                 http_helpers::ContentType::EventStream, false);
        std::string_view upgradeType(
            thisReq.getHeaderValue(boost::beast::http::field::upgrade));
        if ((thisReq.isUpgrade() &&
             bmcweb::asciiIEquals(upgradeType, "websocket")) ||
            isSse)
        {
            asyncResp->res.setCompleteRequestHandler(
                [self(shared_from_this())](crow::Response& thisRes) {
                if (thisRes.result() != boost::beast::http::status::ok)
                {
                    // When any error occurs before handle upgradation,
                    // the result in response will be set to respective
                    // error. By default the Result will be OK (200),
                    // which implies successful handle upgrade. Response
                    // needs to be sent over this connection only on
                    // failure.
                    self->completeRequest(thisRes);
                    return;
                }
            });
            handler->handleUpgrade(thisReq, asyncResp, std::move(adaptor));
            return;
        }
        std::string_view expected =
            req->getHeaderValue(boost::beast::http::field::if_none_match);
        if (!expected.empty())
        {
            res.setExpectedHash(expected);
        }
        handler->handle(thisReq, asyncResp);
    }

    bool isAlive()
    {
        if constexpr (IsTls<Adaptor>::value)
        {
            return adaptor.next_layer().is_open();
        }
        else if constexpr (std::is_same_v<Adaptor, boost::beast::test::stream>)
        {
            return true;
        }
        else
        {
            return adaptor.is_open();
        }
    }
    void close()
    {
        if constexpr (IsTls<Adaptor>::value)
        {
            adaptor.next_layer().close();
            if (mtlsSession != nullptr)
            {
                BMCWEB_LOG_DEBUG("{} Removing TLS session: {}", logPtr(this),
                                 mtlsSession->uniqueId);
                persistent_data::SessionStore::getInstance().removeSession(
                    mtlsSession);
            }
        }
        else
        {
            adaptor.close();
        }
    }

    void completeRequest(crow::Response& thisRes)
    {
        if (!req)
        {
            return;
        }
        res = std::move(thisRes);
        res.keepAlive(keepAlive);

        completeResponseFields(*req, res);
        res.addHeader(boost::beast::http::field::date, getCachedDateStr());
        if (!isAlive())
        {
            res.setCompleteRequestHandler(nullptr);
            return;
        }

        doWrite(res);

        // delete lambda with self shared_ptr
        // to enable connection destruction
        res.setCompleteRequestHandler(nullptr);
    }

    void readClientIp()
    {
        boost::asio::ip::address ip;
        boost::system::error_code ec = getClientIp(ip);
        if (ec)
        {
            return;
        }
        if (!req)
        {
            return;
        }
        req->ipAddress = ip;
    }

    boost::system::error_code getClientIp(boost::asio::ip::address& ip)
    {
        boost::system::error_code ec;
        BMCWEB_LOG_DEBUG("Fetch the client IP address");

        if constexpr (!std::is_same_v<Adaptor, boost::beast::test::stream>)
        {
            boost::asio::ip::tcp::endpoint endpoint =
                boost::beast::get_lowest_layer(adaptor).remote_endpoint(ec);

            if (ec)
            {
                // If remote endpoint fails keep going. "ClientOriginIPAddress"
                // will be empty.
                BMCWEB_LOG_ERROR(
                    "Failed to get the client's IP Address. ec : {}", ec);
                return ec;
            }
            ip = endpoint.address();
        }
        return ec;
    }

  private:
    void doReadHeaders()
    {
        BMCWEB_LOG_DEBUG("{} doReadHeaders", logPtr(this));
        if (!parser)
        {
            return;
        }
        // Clean up any previous Connection.
        boost::beast::http::async_read_header(
            adaptor, buffer, *parser,
            [this,
             self(shared_from_this())](const boost::system::error_code& ec,
                                       std::size_t bytesTransferred) {
            BMCWEB_LOG_DEBUG("{} async_read_header {} Bytes", logPtr(this),
                             bytesTransferred);
            bool errorWhileReading = false;
            if (ec)
            {
                errorWhileReading = true;
                if (ec == boost::beast::http::error::end_of_stream)
                {
                    BMCWEB_LOG_WARNING("{} Error while reading: {}",
                                       logPtr(this), ec.message());
                }
                else
                {
                    BMCWEB_LOG_ERROR("{} Error while reading: {}", logPtr(this),
                                     ec.message());
                }
            }
            else
            {
                // if the adaptor isn't open anymore, and wasn't handed to a
                // websocket, treat as an error
                if (!isAlive() &&
                    !boost::beast::websocket::is_upgrade(parser->get()))
                {
                    errorWhileReading = true;
                }
            }

            cancelDeadlineTimer();

            if (errorWhileReading)
            {
                close();
                BMCWEB_LOG_DEBUG("{} from read(1)", logPtr(this));
                return;
            }

            readClientIp();

            boost::asio::ip::address ip;
            if (getClientIp(ip))
            {
                BMCWEB_LOG_DEBUG("Unable to get client IP");
            }
            if constexpr (!std::is_same_v<Adaptor, boost::beast::test::stream>)
            {
#ifndef BMCWEB_INSECURE_DISABLE_AUTHX
                boost::beast::http::verb method = parser->get().method();
                userSession = crow::authentication::authenticate(
                    ip, res, method, parser->get().base(), mtlsSession);

                bool loggedIn = userSession != nullptr;
                if (!loggedIn)
                {
                    const boost::optional<uint64_t> contentLength =
                        parser->content_length();
                    if (contentLength &&
                        *contentLength > loggedOutPostBodyLimit)
                    {
                        BMCWEB_LOG_DEBUG("Content length greater than limit {}",
                                         *contentLength);
                        close();
                        return;
                    }

                    BMCWEB_LOG_DEBUG("Starting quick deadline");
                }
#endif // BMCWEB_INSECURE_DISABLE_AUTHX
            }

            if (parser->is_done())
            {
                handle();
                return;
            }

            doRead();
        });
    }

    void doRead()
    {
        BMCWEB_LOG_DEBUG("{} doRead", logPtr(this));
        if (!parser)
        {
            return;
        }
        startDeadline();
        boost::beast::http::async_read_some(
            adaptor, buffer, *parser,
            [this,
             self(shared_from_this())](const boost::system::error_code& ec,
                                       std::size_t bytesTransferred) {
            BMCWEB_LOG_DEBUG("{} async_read_some {} Bytes", logPtr(this),
                             bytesTransferred);

            if (ec)
            {
                BMCWEB_LOG_ERROR("{} Error while reading: {}", logPtr(this),
                                 ec.message());
                close();
                BMCWEB_LOG_DEBUG("{} from read(1)", logPtr(this));
                return;
            }

            // If the user is logged in, allow them to send files incrementally
            // one piece at a time. If authentication is disabled then there is
            // no user session hence always allow to send one piece at a time.
            if (userSession != nullptr)
            {
                cancelDeadlineTimer();
            }
            if (!parser->is_done())
            {
                doRead();
                return;
            }

            cancelDeadlineTimer();
            handle();
        });
    }

    void afterDoWrite(const std::shared_ptr<self_type>& /*self*/,
                      const boost::system::error_code& ec,
                      std::size_t bytesTransferred)
    {
        BMCWEB_LOG_DEBUG("{} async_write {} bytes", logPtr(this),
                         bytesTransferred);

        cancelDeadlineTimer();

        if (ec)
        {
            BMCWEB_LOG_DEBUG("{} from write(2)", logPtr(this));
            return;
        }
        if (!keepAlive)
        {
            close();
            BMCWEB_LOG_DEBUG("{} from write(1)", logPtr(this));
            return;
        }

        BMCWEB_LOG_DEBUG("{} Clearing response", logPtr(this));
        res.clear();
        parser.emplace(std::piecewise_construct, std::make_tuple());
        parser->body_limit(httpReqBodyLimit); // reset body limit for
                                              // newly created parser
        buffer.consume(buffer.size());

        userSession = nullptr;

        // Destroy the Request via the std::optional
        req.reset();
        doReadHeaders();
    }

    void doWrite(crow::Response& thisRes)
    {
        BMCWEB_LOG_DEBUG("{} doWrite", logPtr(this));
        thisRes.preparePayload();

        startDeadline();
        boost::beast::async_write(adaptor, thisRes.generator(),
                                  std::bind_front(&self_type::afterDoWrite,
                                                  this, shared_from_this()));
    }

    void cancelDeadlineTimer()
    {
        timer.cancel();
    }

    void startDeadline()
    {
        // Timer is already started so no further action is required.
        if (timerStarted)
        {
            return;
        }

        std::chrono::seconds timeout(15);

        std::weak_ptr<Connection<Adaptor, Handler>> weakSelf = weak_from_this();
        timer.expires_after(timeout);
        timer.async_wait([weakSelf](const boost::system::error_code& ec) {
            // Note, we are ignoring other types of errors here;  If the timer
            // failed for any reason, we should still close the connection
            std::shared_ptr<Connection<Adaptor, Handler>> self =
                weakSelf.lock();
            if (!self)
            {
                BMCWEB_LOG_CRITICAL("{} Failed to capture connection",
                                    logPtr(self.get()));
                return;
            }

            self->timerStarted = false;

            if (ec == boost::asio::error::operation_aborted)
            {
                // Canceled wait means the path succeeded.
                return;
            }
            if (ec)
            {
                BMCWEB_LOG_CRITICAL("{} timer failed {}", logPtr(self.get()),
                                    ec);
            }

            BMCWEB_LOG_WARNING("{}Connection timed out, closing",
                               logPtr(self.get()));

            self->close();
        });

        timerStarted = true;
        BMCWEB_LOG_DEBUG("{} timer started", logPtr(this));
    }

    Adaptor adaptor;
    Handler* handler;
    // Making this a std::optional allows it to be efficiently destroyed and
    // re-created on Connection reset
    std::optional<
        boost::beast::http::request_parser<boost::beast::http::string_body>>
        parser;

    boost::beast::flat_static_buffer<8192> buffer;

    std::optional<crow::Request> req;
    crow::Response res;

    std::shared_ptr<persistent_data::UserSession> userSession;
    std::shared_ptr<persistent_data::UserSession> mtlsSession;

    boost::asio::steady_timer timer;

    bool keepAlive = true;

    bool timerStarted = false;

    std::function<std::string()>& getCachedDateStr;

    using std::enable_shared_from_this<
        Connection<Adaptor, Handler>>::shared_from_this;

    using std::enable_shared_from_this<
        Connection<Adaptor, Handler>>::weak_from_this;
};
} // namespace crow