Crow/include/crow/routing.h

#pragma once

#include <cstdint>
#include <utility>
#include <tuple>
#include <unordered_map>
#include <memory>
#include <vector>
#include <algorithm>
#include <type_traits>

#include "crow/common.h"
#include "crow/http_response.h"
#include "crow/http_request.h"
#include "crow/utility.h"
#include "crow/logging.h"
#include "crow/websocket.h"
#include "crow/mustache.h"
#include "crow/middleware.h"

namespace crow
{

    constexpr const uint16_t INVALID_BP_ID{((uint16_t)-1)};

    namespace detail
    {
        /// Typesafe wrapper for storing lists of middleware as their indices in the App
        struct middleware_indices
        {
            template<typename App>
            void push()
            {}

            template<typename App, typename MW, typename... Middlewares>
            void push()
            {
                using MwContainer = typename App::mw_container_t;
                static_assert(black_magic::has_type<MW, MwContainer>::value, "Middleware must be present in app");
                static_assert(std::is_base_of<crow::ILocalMiddleware, MW>::value, "Middleware must extend ILocalMiddleware");
                int idx = black_magic::tuple_index<MW, MwContainer>::value;
                indices_.push_back(idx);
                push<App, Middlewares...>();
            }

            void merge_front(const detail::middleware_indices& other)
            {
                indices_.insert(indices_.begin(), other.indices_.cbegin(), other.indices_.cend());
            }

            void merge_back(const detail::middleware_indices& other)
            {
                indices_.insert(indices_.end(), other.indices_.cbegin(), other.indices_.cend());
            }

            void pop_back(const detail::middleware_indices& other)
            {
                indices_.resize(indices_.size() - other.indices_.size());
            }

            bool empty() const
            {
                return indices_.empty();
            }

            // Sorts indices and filters out duplicates to allow fast lookups with traversal
            void pack()
            {
                std::sort(indices_.begin(), indices_.end());
                indices_.erase(std::unique(indices_.begin(), indices_.end()), indices_.end());
            }

            const std::vector<int>& indices()
            {
                return indices_;
            }

        private:
            std::vector<int> indices_;
        };
    } // namespace detail

    /// A base class for all rules.

    ///
    /// Used to provide a common interface for code dealing with different types of rules.<br>
    /// A Rule provides a URL, allowed HTTP methods, and handlers.
    class BaseRule
    {
    public:
        BaseRule(std::string rule):
          rule_(std::move(rule))
        {}

        virtual ~BaseRule()
        {}

        virtual void validate() = 0;
        
        void set_added() {
            added_ = true;
        }

        bool is_added() {
            return added_;
        }

        std::unique_ptr<BaseRule> upgrade()
        {
            if (rule_to_upgrade_)
                return std::move(rule_to_upgrade_);
            return {};
        }

        virtual void handle(request&, response&, const routing_params&) = 0;
        virtual void handle_upgrade(const request&, response& res, SocketAdaptor&&)
        {
            res = response(404);
            res.end();
        }
#ifdef CROW_ENABLE_SSL
        virtual void handle_upgrade(const request&, response& res, SSLAdaptor&&)
        {
            res = response(404);
            res.end();
        }
#endif

        uint32_t get_methods()
        {
            return methods_;
        }

        template<typename F>
        void foreach_method(F f)
        {
            for (uint32_t method = 0, method_bit = 1; method < static_cast<uint32_t>(HTTPMethod::InternalMethodCount); method++, method_bit <<= 1)
            {
                if (methods_ & method_bit)
                    f(method);
            }
        }

        std::string custom_templates_base;

        const std::string& rule() { return rule_; }

    protected:
        uint32_t methods_{1 << static_cast<int>(HTTPMethod::Get)};

        std::string rule_;
        std::string name_;
        bool added_{false};

        std::unique_ptr<BaseRule> rule_to_upgrade_;

        detail::middleware_indices mw_indices_;

        friend class Router;
        friend class Blueprint;
        template<typename T>
        friend struct RuleParameterTraits;
    };


    namespace detail
    {
        namespace routing_handler_call_helper
        {
            template<typename T, int Pos>
            struct call_pair
            {
                using type = T;
                static const int pos = Pos;
            };

            template<typename H1>
            struct call_params
            {
                H1& handler;
                const routing_params& params;
                request& req;
                response& res;
            };

            template<typename F, int NInt, int NUint, int NDouble, int NString, typename S1, typename S2>
            struct call
            {};

            template<typename F, int NInt, int NUint, int NDouble, int NString, typename... Args1, typename... Args2>
            struct call<F, NInt, NUint, NDouble, NString, black_magic::S<int64_t, Args1...>, black_magic::S<Args2...>>
            {
                void operator()(F cparams)
                {
                    using pushed = typename black_magic::S<Args2...>::template push_back<call_pair<int64_t, NInt>>;
                    call<F, NInt + 1, NUint, NDouble, NString, black_magic::S<Args1...>, pushed>()(cparams);
                }
            };

            template<typename F, int NInt, int NUint, int NDouble, int NString, typename... Args1, typename... Args2>
            struct call<F, NInt, NUint, NDouble, NString, black_magic::S<uint64_t, Args1...>, black_magic::S<Args2...>>
            {
                void operator()(F cparams)
                {
                    using pushed = typename black_magic::S<Args2...>::template push_back<call_pair<uint64_t, NUint>>;
                    call<F, NInt, NUint + 1, NDouble, NString, black_magic::S<Args1...>, pushed>()(cparams);
                }
            };

            template<typename F, int NInt, int NUint, int NDouble, int NString, typename... Args1, typename... Args2>
            struct call<F, NInt, NUint, NDouble, NString, black_magic::S<double, Args1...>, black_magic::S<Args2...>>
            {
                void operator()(F cparams)
                {
                    using pushed = typename black_magic::S<Args2...>::template push_back<call_pair<double, NDouble>>;
                    call<F, NInt, NUint, NDouble + 1, NString, black_magic::S<Args1...>, pushed>()(cparams);
                }
            };

            template<typename F, int NInt, int NUint, int NDouble, int NString, typename... Args1, typename... Args2>
            struct call<F, NInt, NUint, NDouble, NString, black_magic::S<std::string, Args1...>, black_magic::S<Args2...>>
            {
                void operator()(F cparams)
                {
                    using pushed = typename black_magic::S<Args2...>::template push_back<call_pair<std::string, NString>>;
                    call<F, NInt, NUint, NDouble, NString + 1, black_magic::S<Args1...>, pushed>()(cparams);
                }
            };

            template<typename F, int NInt, int NUint, int NDouble, int NString, typename... Args1>
            struct call<F, NInt, NUint, NDouble, NString, black_magic::S<>, black_magic::S<Args1...>>
            {
                void operator()(F cparams)
                {
                    cparams.handler(
                      cparams.req,
                      cparams.res,
                      cparams.params.template get<typename Args1::type>(Args1::pos)...);
                }
            };

            template<typename Func, typename... ArgsWrapped>
            struct Wrapped
            {
                template<typename... Args>
                void set_(Func f, typename std::enable_if<!std::is_same<typename std::tuple_element<0, std::tuple<Args..., void>>::type, const request&>::value, int>::type = 0)
                {
                    handler_ = (
#ifdef CROW_CAN_USE_CPP14
                      [f = std::move(f)]
#else
                      [f]
#endif
                      (const request&, response& res, Args... args) {
                          res = response(f(args...));
                          res.end();
                      });
                }

                template<typename Req, typename... Args>
                struct req_handler_wrapper
                {
                    req_handler_wrapper(Func f):
                      f(std::move(f))
                    {
                    }

                    void operator()(const request& req, response& res, Args... args)
                    {
                        res = response(f(req, args...));
                        res.end();
                    }

                    Func f;
                };

                template<typename... Args>
                void set_(Func f, typename std::enable_if<
                                    std::is_same<typename std::tuple_element<0, std::tuple<Args..., void>>::type, const request&>::value &&
                                      !std::is_same<typename std::tuple_element<1, std::tuple<Args..., void, void>>::type, response&>::value,
                                    int>::type = 0)
                {
                    handler_ = req_handler_wrapper<Args...>(std::move(f));
                    /*handler_ = (
                        [f = std::move(f)]
                        (const request& req, response& res, Args... args){
                             res = response(f(req, args...));
                             res.end();
                        });*/
                }

                template<typename... Args>
                void set_(Func f, typename std::enable_if<
                                    std::is_same<typename std::tuple_element<0, std::tuple<Args..., void>>::type, const request&>::value &&
                                      std::is_same<typename std::tuple_element<1, std::tuple<Args..., void, void>>::type, response&>::value,
                                    int>::type = 0)
                {
                    handler_ = std::move(f);
                }

                template<typename... Args>
                struct handler_type_helper
                {
                    using type = std::function<void(const crow::request&, crow::response&, Args...)>;
                    using args_type = black_magic::S<typename black_magic::promote_t<Args>...>;
                };

                template<typename... Args>
                struct handler_type_helper<const request&, Args...>
                {
                    using type = std::function<void(const crow::request&, crow::response&, Args...)>;
                    using args_type = black_magic::S<typename black_magic::promote_t<Args>...>;
                };

                template<typename... Args>
                struct handler_type_helper<const request&, response&, Args...>
                {
                    using type = std::function<void(const crow::request&, crow::response&, Args...)>;
                    using args_type = black_magic::S<typename black_magic::promote_t<Args>...>;
                };

                typename handler_type_helper<ArgsWrapped...>::type handler_;

                void operator()(request& req, response& res, const routing_params& params)
                {
                    detail::routing_handler_call_helper::call<
                      detail::routing_handler_call_helper::call_params<
                        decltype(handler_)>,
                      0, 0, 0, 0,
                      typename handler_type_helper<ArgsWrapped...>::args_type,
                      black_magic::S<>>()(
                      detail::routing_handler_call_helper::call_params<
                        decltype(handler_)>{handler_, params, req, res});
                }
            };

        } // namespace routing_handler_call_helper
    }     // namespace detail


    class CatchallRule
    {
    public:
        /// @cond SKIP
        CatchallRule() {}

        template<typename Func>
        typename std::enable_if<black_magic::CallHelper<Func, black_magic::S<>>::value, void>::type
          operator()(Func&& f)
        {
            static_assert(!std::is_same<void, decltype(f())>::value,
                          "Handler function cannot have void return type; valid return types: string, int, crow::response, crow::returnable");

            handler_ = (
#ifdef CROW_CAN_USE_CPP14
              [f = std::move(f)]
#else
              [f]
#endif
              (const request&, response& res) {
                  res = response(f());
                  res.end();
              });
        }

        template<typename Func>
        typename std::enable_if<
          !black_magic::CallHelper<Func, black_magic::S<>>::value &&
            black_magic::CallHelper<Func, black_magic::S<crow::request>>::value,
          void>::type
          operator()(Func&& f)
        {
            static_assert(!std::is_same<void, decltype(f(std::declval<crow::request>()))>::value,
                          "Handler function cannot have void return type; valid return types: string, int, crow::response, crow::returnable");

            handler_ = (
#ifdef CROW_CAN_USE_CPP14
              [f = std::move(f)]
#else
              [f]
#endif
              (const crow::request& req, crow::response& res) {
                  res = response(f(req));
                  res.end();
              });
        }

        template<typename Func>
        typename std::enable_if<
          !black_magic::CallHelper<Func, black_magic::S<>>::value &&
            !black_magic::CallHelper<Func, black_magic::S<crow::request>>::value &&
            black_magic::CallHelper<Func, black_magic::S<crow::response&>>::value,
          void>::type
          operator()(Func&& f)
        {
            static_assert(std::is_same<void, decltype(f(std::declval<crow::response&>()))>::value,
                          "Handler function with response argument should have void return type");
            handler_ = (
#ifdef CROW_CAN_USE_CPP14
              [f = std::move(f)]
#else
              [f]
#endif
              (const crow::request&, crow::response& res) {
                  f(res);
              });
        }

        template<typename Func>
        typename std::enable_if<
          !black_magic::CallHelper<Func, black_magic::S<>>::value &&
            !black_magic::CallHelper<Func, black_magic::S<crow::request>>::value &&
            !black_magic::CallHelper<Func, black_magic::S<crow::response&>>::value,
          void>::type
          operator()(Func&& f)
        {
            static_assert(std::is_same<void, decltype(f(std::declval<crow::request>(), std::declval<crow::response&>()))>::value,
                          "Handler function with response argument should have void return type");

            handler_ = std::move(f);
        }
        /// @endcond
        bool has_handler()
        {
            return (handler_ != nullptr);
        }

    protected:
        friend class Router;

    private:
        std::function<void(const crow::request&, crow::response&)> handler_;
    };


    /// A rule dealing with websockets.

    ///
    /// Provides the interface for the user to put in the necessary handlers for a websocket to work.
    template<typename App>
    class WebSocketRule : public BaseRule
    {
        using self_t = WebSocketRule;

    public:
        WebSocketRule(std::string rule, App* app):
          BaseRule(std::move(rule)),
          app_(app),
          max_payload_(UINT64_MAX)
        {}

        void validate() override
        {}

        void handle(request&, response& res, const routing_params&) override
        {
            res = response(404);
            res.end();
        }

        void handle_upgrade(const request& req, response&, SocketAdaptor&& adaptor) override
        {
            max_payload_ = max_payload_override_ ? max_payload_ : app_->websocket_max_payload();
            new crow::websocket::Connection<SocketAdaptor, App>(req, std::move(adaptor), app_, max_payload_, open_handler_, message_handler_, close_handler_, error_handler_, accept_handler_);
        }
#ifdef CROW_ENABLE_SSL
        void handle_upgrade(const request& req, response&, SSLAdaptor&& adaptor) override
        {
            new crow::websocket::Connection<SSLAdaptor, App>(req, std::move(adaptor), app_, max_payload_, open_handler_, message_handler_, close_handler_, error_handler_, accept_handler_);
        }
#endif

        /// Override the global payload limit for this single WebSocket rule
        self_t& max_payload(uint64_t max_payload)
        {
            max_payload_ = max_payload;
            max_payload_override_ = true;
            return *this;
        }

        template<typename Func>
        self_t& onopen(Func f)
        {
            open_handler_ = f;
            return *this;
        }

        template<typename Func>
        self_t& onmessage(Func f)
        {
            message_handler_ = f;
            return *this;
        }

        template<typename Func>
        self_t& onclose(Func f)
        {
            close_handler_ = f;
            return *this;
        }

        template<typename Func>
        self_t& onerror(Func f)
        {
            error_handler_ = f;
            return *this;
        }

        template<typename Func>
        self_t& onaccept(Func f)
        {
            accept_handler_ = f;
            return *this;
        }

    protected:
        App* app_;
        std::function<void(crow::websocket::connection&)> open_handler_;
        std::function<void(crow::websocket::connection&, const std::string&, bool)> message_handler_;
        std::function<void(crow::websocket::connection&, const std::string&)> close_handler_;
        std::function<void(crow::websocket::connection&, const std::string&)> error_handler_;
        std::function<bool(const crow::request&, void**)> accept_handler_;
        uint64_t max_payload_;
        bool max_payload_override_ = false;
    };

    /// Allows the user to assign parameters using functions.

    ///
    /// `rule.name("name").methods(HTTPMethod::POST)`
    template<typename T>
    struct RuleParameterTraits
    {
        using self_t = T;

        template<typename App>
        WebSocketRule<App>& websocket(App* app)
        {
            auto p = new WebSocketRule<App>(static_cast<self_t*>(this)->rule_, app);
            static_cast<self_t*>(this)->rule_to_upgrade_.reset(p);
            return *p;
        }

        self_t& name(std::string name) noexcept
        {
            static_cast<self_t*>(this)->name_ = std::move(name);
            return static_cast<self_t&>(*this);
        }

        self_t& methods(HTTPMethod method)
        {
            static_cast<self_t*>(this)->methods_ = 1 << static_cast<int>(method);
            return static_cast<self_t&>(*this);
        }

        template<typename... MethodArgs>
        self_t& methods(HTTPMethod method, MethodArgs... args_method)
        {
            methods(args_method...);
            static_cast<self_t*>(this)->methods_ |= 1 << static_cast<int>(method);
            return static_cast<self_t&>(*this);
        }

        /// Enable local middleware for this handler
        template<typename App, typename... Middlewares>
        self_t& middlewares()
        {
            static_cast<self_t*>(this)->mw_indices_.template push<App, Middlewares...>();
            return static_cast<self_t&>(*this);
        }
    };

    /// A rule that can change its parameters during runtime.
    class DynamicRule : public BaseRule, public RuleParameterTraits<DynamicRule>
    {
    public:
        DynamicRule(std::string rule):
          BaseRule(std::move(rule))
        {}

        void validate() override
        {
            if (!erased_handler_)
            {
                throw std::runtime_error(name_ + (!name_.empty() ? ": " : "") + "no handler for url " + rule_);
            }
        }

        void handle(request& req, response& res, const routing_params& params) override
        {
            if (!custom_templates_base.empty())
                mustache::set_base(custom_templates_base);
            else if (mustache::detail::get_template_base_directory_ref() != "templates")
                mustache::set_base("templates");
            erased_handler_(req, res, params);
        }

        template<typename Func>
        void operator()(Func f)
        {
#ifdef CROW_MSVC_WORKAROUND
            using function_t = utility::function_traits<decltype(&Func::operator())>;
#else
            using function_t = utility::function_traits<Func>;
#endif
            erased_handler_ = wrap(std::move(f), black_magic::gen_seq<function_t::arity>());
        }

        // enable_if Arg1 == request && Arg2 == response
        // enable_if Arg1 == request && Arg2 != resposne
        // enable_if Arg1 != request
#ifdef CROW_MSVC_WORKAROUND
        template<typename Func, size_t... Indices>
#else
        template<typename Func, unsigned... Indices>
#endif
        std::function<void(request&, response&, const routing_params&)>
          wrap(Func f, black_magic::seq<Indices...>)
        {
#ifdef CROW_MSVC_WORKAROUND
            using function_t = utility::function_traits<decltype(&Func::operator())>;
#else
            using function_t = utility::function_traits<Func>;
#endif
            if (!black_magic::is_parameter_tag_compatible(
                  black_magic::get_parameter_tag_runtime(rule_.c_str()),
                  black_magic::compute_parameter_tag_from_args_list<
                    typename function_t::template arg<Indices>...>::value))
            {
                throw std::runtime_error("route_dynamic: Handler type is mismatched with URL parameters: " + rule_);
            }
            auto ret = detail::routing_handler_call_helper::Wrapped<Func, typename function_t::template arg<Indices>...>();
            ret.template set_<
              typename function_t::template arg<Indices>...>(std::move(f));
            return ret;
        }

        template<typename Func>
        void operator()(std::string name, Func&& f)
        {
            name_ = std::move(name);
            (*this).template operator()<Func>(std::forward(f));
        }

    private:
        std::function<void(request&, response&, const routing_params&)> erased_handler_;
    };

    /// Default rule created when CROW_ROUTE is called.
    template<typename... Args>
    class TaggedRule : public BaseRule, public RuleParameterTraits<TaggedRule<Args...>>
    {
    public:
        using self_t = TaggedRule<Args...>;

        TaggedRule(std::string rule):
          BaseRule(std::move(rule))
        {}

        void validate() override
        {
            if (rule_.at(0) != '/')
                throw std::runtime_error("Internal error: Routes must start with a '/'");

            if (!handler_)
            {
                throw std::runtime_error(name_ + (!name_.empty() ? ": " : "") + "no handler for url " + rule_);
            }
        }

        template<typename Func>
        void operator()(Func&& f)
        {
            handler_ = (
#ifdef CROW_CAN_USE_CPP14
              [f = std::move(f)]
#else
              [f]
#endif
              (crow::request& req, crow::response& res, Args... args) {
                  detail::wrapped_handler_call(req, res, f, std::forward<Args>(args)...);
              });
        }

        template<typename Func>
        void operator()(std::string name, Func&& f)
        {
            name_ = std::move(name);
            (*this).template operator()<Func>(std::forward(f));
        }

        void handle(request& req, response& res, const routing_params& params) override
        {
            if (!custom_templates_base.empty())
                mustache::set_base(custom_templates_base);
            else if (mustache::detail::get_template_base_directory_ref() != mustache::detail::get_global_template_base_directory_ref())
                mustache::set_base(mustache::detail::get_global_template_base_directory_ref());

            detail::routing_handler_call_helper::call<
              detail::routing_handler_call_helper::call_params<decltype(handler_)>,
              0, 0, 0, 0,
              black_magic::S<Args...>,
              black_magic::S<>>()(
              detail::routing_handler_call_helper::call_params<decltype(handler_)>{handler_, params, req, res});
        }

    private:
        std::function<void(crow::request&, crow::response&, Args...)> handler_;
    };

    const int RULE_SPECIAL_REDIRECT_SLASH = 1;


    /// A search tree.
    class Trie
    {
    public:
        struct Node
        {
            uint16_t rule_index{};
            // Assign the index to the maximum 32 unsigned integer value by default so that any other number (specifically 0) is a valid BP id.
            uint16_t blueprint_index{INVALID_BP_ID};
            std::string key;
            ParamType param = ParamType::MAX; // MAX = No param.
            std::vector<Node> children;

            bool IsSimpleNode() const
            {
                return !rule_index &&
                       blueprint_index == INVALID_BP_ID &&
                       children.size() < 2 &&
                       param == ParamType::MAX &&
                       std::all_of(std::begin(children), std::end(children), [](const Node& x) {
                           return x.param == ParamType::MAX;
                       });
            }

            Node& add_child_node()
            {
                children.emplace_back();
                return children.back();
            }
        };


        Trie()
        {}

        /// Check whether or not the trie is empty.
        bool is_empty()
        {
            return head_.children.empty();
        }

        void optimize()
        {
            for (auto& child : head_.children)
            {
                optimizeNode(child);
            }
        }


    private:
        void optimizeNode(Node& node)
        {
            if (node.children.empty())
                return;
            if (node.IsSimpleNode())
            {
                auto children_temp = std::move(node.children);
                auto& child_temp = children_temp[0];
                node.key += child_temp.key;
                node.rule_index = child_temp.rule_index;
                node.blueprint_index = child_temp.blueprint_index;
                node.children = std::move(child_temp.children);
                optimizeNode(node);
            }
            else
            {
                for (auto& child : node.children)
                {
                    optimizeNode(child);
                }
            }
        }

        void debug_node_print(const Node& node, int level)
        {
            if (node.param != ParamType::MAX)
            {
                switch (node.param)
                {
                    case ParamType::INT:
                        CROW_LOG_DEBUG << std::string(3 * level, ' ') << "└➝ "
                                       << "<int>";
                        break;
                    case ParamType::UINT:
                        CROW_LOG_DEBUG << std::string(3 * level, ' ') << "└➝ "
                                       << "<uint>";
                        break;
                    case ParamType::DOUBLE:
                        CROW_LOG_DEBUG << std::string(3 * level, ' ') << "└➝ "
                                       << "<double>";
                        break;
                    case ParamType::STRING:
                        CROW_LOG_DEBUG << std::string(3 * level, ' ') << "└➝ "
                                       << "<string>";
                        break;
                    case ParamType::PATH:
                        CROW_LOG_DEBUG << std::string(3 * level, ' ') << "└➝ "
                                       << "<path>";
                        break;
                    default:
                        CROW_LOG_DEBUG << std::string(3 * level, ' ') << "└➝ "
                                       << "<ERROR>";
                        break;
                }
            }
            else
                CROW_LOG_DEBUG << std::string(3 * level, ' ') << "└➝ " << node.key;

            for (const auto& child : node.children)
            {
                debug_node_print(child, level + 1);
            }
        }

    public:
        void debug_print()
        {
            CROW_LOG_DEBUG << "└➙ ROOT";
            for (const auto& child : head_.children)
                debug_node_print(child, 1);
        }

        void validate()
        {
            if (!head_.IsSimpleNode())
                throw std::runtime_error("Internal error: Trie header should be simple!");
            optimize();
        }

        //Rule_index, Blueprint_index, routing_params
        routing_handle_result find(const std::string& req_url, const Node& node, unsigned pos = 0, routing_params* params = nullptr, std::vector<uint16_t>* blueprints = nullptr) const
        {
            //start params as an empty struct
            routing_params empty;
            if (params == nullptr)
                params = &empty;
            //same for blueprint vector
            std::vector<uint16_t> MT;
            if (blueprints == nullptr)
                blueprints = &MT;

            uint16_t found{};               //The rule index to be found
            std::vector<uint16_t> found_BP; //The Blueprint indices to be found
            routing_params match_params;    //supposedly the final matched parameters

            auto update_found = [&found, &found_BP, &match_params](routing_handle_result& ret) {
                found_BP = std::move(ret.blueprint_indices);
                if (ret.rule_index && (!found || found > ret.rule_index))
                {
                    found = ret.rule_index;
                    match_params = std::move(ret.r_params);
                }
            };

            //if the function was called on a node at the end of the string (the last recursion), return the nodes rule index, and whatever params were passed to the function
            if (pos == req_url.size())
            {
                found_BP = std::move(*blueprints);
                return routing_handle_result{node.rule_index, *blueprints, *params};
            }

            bool found_fragment = false;

            for (const auto& child : node.children)
            {
                if (child.param != ParamType::MAX)
                {
                    if (child.param == ParamType::INT)
                    {
                        char c = req_url[pos];
                        if ((c >= '0' && c <= '9') || c == '+' || c == '-')
                        {
                            char* eptr;
                            errno = 0;
                            long long int value = strtoll(req_url.data() + pos, &eptr, 10);
                            if (errno != ERANGE && eptr != req_url.data() + pos)
                            {
                                found_fragment = true;
                                params->int_params.push_back(value);
                                if (child.blueprint_index != INVALID_BP_ID) blueprints->push_back(child.blueprint_index);
                                auto ret = find(req_url, child, eptr - req_url.data(), params, blueprints);
                                update_found(ret);
                                params->int_params.pop_back();
                                if (!blueprints->empty()) blueprints->pop_back();
                            }
                        }
                    }

                    else if (child.param == ParamType::UINT)
                    {
                        char c = req_url[pos];
                        if ((c >= '0' && c <= '9') || c == '+')
                        {
                            char* eptr;
                            errno = 0;
                            unsigned long long int value = strtoull(req_url.data() + pos, &eptr, 10);
                            if (errno != ERANGE && eptr != req_url.data() + pos)
                            {
                                found_fragment = true;
                                params->uint_params.push_back(value);
                                if (child.blueprint_index != INVALID_BP_ID) blueprints->push_back(child.blueprint_index);
                                auto ret = find(req_url, child, eptr - req_url.data(), params, blueprints);
                                update_found(ret);
                                params->uint_params.pop_back();
                                if (!blueprints->empty()) blueprints->pop_back();
                            }
                        }
                    }

                    else if (child.param == ParamType::DOUBLE)
                    {
                        char c = req_url[pos];
                        if ((c >= '0' && c <= '9') || c == '+' || c == '-' || c == '.')
                        {
                            char* eptr;
                            errno = 0;
                            double value = strtod(req_url.data() + pos, &eptr);
                            if (errno != ERANGE && eptr != req_url.data() + pos)
                            {
                                found_fragment = true;
                                params->double_params.push_back(value);
                                if (child.blueprint_index != INVALID_BP_ID) blueprints->push_back(child.blueprint_index);
                                auto ret = find(req_url, child, eptr - req_url.data(), params, blueprints);
                                update_found(ret);
                                params->double_params.pop_back();
                                if (!blueprints->empty()) blueprints->pop_back();
                            }
                        }
                    }

                    else if (child.param == ParamType::STRING)
                    {
                        size_t epos = pos;
                        for (; epos < req_url.size(); epos++)
                        {
                            if (req_url[epos] == '/')
                                break;
                        }

                        if (epos != pos)
                        {
                            found_fragment = true;
                            params->string_params.push_back(req_url.substr(pos, epos - pos));
                            if (child.blueprint_index != INVALID_BP_ID) blueprints->push_back(child.blueprint_index);
                            auto ret = find(req_url, child, epos, params, blueprints);
                            update_found(ret);
                            params->string_params.pop_back();
                            if (!blueprints->empty()) blueprints->pop_back();
                        }
                    }

                    else if (child.param == ParamType::PATH)
                    {
                        size_t epos = req_url.size();

                        if (epos != pos)
                        {
                            found_fragment = true;
                            params->string_params.push_back(req_url.substr(pos, epos - pos));
                            if (child.blueprint_index != INVALID_BP_ID) blueprints->push_back(child.blueprint_index);
                            auto ret = find(req_url, child, epos, params, blueprints);
                            update_found(ret);
                            params->string_params.pop_back();
                            if (!blueprints->empty()) blueprints->pop_back();
                        }
                    }
                }

                else
                {
                    const std::string& fragment = child.key;
                    if (req_url.compare(pos, fragment.size(), fragment) == 0)
                    {
                        found_fragment = true;
                        if (child.blueprint_index != INVALID_BP_ID) blueprints->push_back(child.blueprint_index);
                        auto ret = find(req_url, child, pos + fragment.size(), params, blueprints);
                        update_found(ret);
                        if (!blueprints->empty()) blueprints->pop_back();
                    }
                }
            }

            if (!found_fragment)
                found_BP = std::move(*blueprints);

            return routing_handle_result{found, found_BP, match_params}; //Called after all the recursions have been done
        }

        routing_handle_result find(const std::string& req_url) const
        {
            return find(req_url, head_);
        }

        //This functions assumes any blueprint info passed is valid
        void add(const std::string& url, uint16_t rule_index, unsigned bp_prefix_length = 0, uint16_t blueprint_index = INVALID_BP_ID)
        {
            auto idx = &head_;

            bool has_blueprint = bp_prefix_length != 0 && blueprint_index != INVALID_BP_ID;

            for (unsigned i = 0; i < url.size(); i++)
            {
                char c = url[i];
                if (c == '<')
                {
                    static struct ParamTraits
                    {
                        ParamType type;
                        std::string name;
                    } paramTraits[] =
                      {
                        {ParamType::INT, "<int>"},
                        {ParamType::UINT, "<uint>"},
                        {ParamType::DOUBLE, "<float>"},
                        {ParamType::DOUBLE, "<double>"},
                        {ParamType::STRING, "<str>"},
                        {ParamType::STRING, "<string>"},
                        {ParamType::PATH, "<path>"},
                      };

                    for (const auto& x : paramTraits)
                    {
                        if (url.compare(i, x.name.size(), x.name) == 0)
                        {
                            bool found = false;
                            for (auto& child : idx->children)
                            {
                                if (child.param == x.type)
                                {
                                    idx = &child;
                                    i += x.name.size();
                                    found = true;
                                    break;
                                }
                            }
                            if (found)
                                break;

                            auto new_node_idx = &idx->add_child_node();
                            new_node_idx->param = x.type;
                            idx = new_node_idx;
                            i += x.name.size();
                            break;
                        }
                    }

                    i--;
                }
                else
                {
                    //This part assumes the tree is unoptimized (every node has a max 1 character key)
                    bool piece_found = false;
                    for (auto& child : idx->children)
                    {
                        if (child.key[0] == c)
                        {
                            idx = &child;
                            piece_found = true;
                            break;
                        }
                    }
                    if (!piece_found)
                    {
                        auto new_node_idx = &idx->add_child_node();
                        new_node_idx->key = c;
                        //The assumption here is that you'd only need to add a blueprint index if the tree didn't have the BP prefix.
                        if (has_blueprint && i == bp_prefix_length)
                            new_node_idx->blueprint_index = blueprint_index;
                        idx = new_node_idx;
                    }
                }
            }

            //check if the last node already has a value (exact url already in Trie)
            if (idx->rule_index)
                throw std::runtime_error("handler already exists for " + url);
            idx->rule_index = rule_index;
        }

    private:
        Node head_;
    };

    /// A blueprint can be considered a smaller section of a Crow app, specifically where the router is conecerned.

    ///
    /// You can use blueprints to assign a common prefix to rules' prefix, set custom static and template folders, and set a custom catchall route.
    /// You can also assign nest blueprints for maximum Compartmentalization.
    class Blueprint
    {
    public:
        Blueprint(const std::string& prefix):
          prefix_(prefix){};

        Blueprint(const std::string& prefix, const std::string& static_dir):
          prefix_(prefix), static_dir_(static_dir){};

        Blueprint(const std::string& prefix, const std::string& static_dir, const std::string& templates_dir):
          prefix_(prefix), static_dir_(static_dir), templates_dir_(templates_dir){};

        /*
        Blueprint(Blueprint& other)
        {
            prefix_ = std::move(other.prefix_);
            all_rules_ = std::move(other.all_rules_);
        }

        Blueprint(const Blueprint& other)
        {
            prefix_ = other.prefix_;
            all_rules_ = other.all_rules_;
        }
*/
        Blueprint(Blueprint&& value)
        {
            *this = std::move(value);
        }

        Blueprint& operator=(const Blueprint& value) = delete;

        Blueprint& operator=(Blueprint&& value) noexcept
        {
            prefix_ = std::move(value.prefix_);
            static_dir_ = std::move(value.static_dir_);
            templates_dir_ = std::move(value.templates_dir_);
            all_rules_ = std::move(value.all_rules_);
            catchall_rule_ = std::move(value.catchall_rule_);
            blueprints_ = std::move(value.blueprints_);
            mw_indices_ = std::move(value.mw_indices_);
            return *this;
        }

        bool operator==(const Blueprint& value)
        {
            return value.prefix() == prefix_;
        }

        bool operator!=(const Blueprint& value)
        {
            return value.prefix() != prefix_;
        }

        std::string prefix() const
        {
            return prefix_;
        }

        std::string static_dir() const
        {
            return static_dir_;
        }

        void set_added() {
            added_ = true;
        }

        bool is_added() {
            return added_;
        }

        DynamicRule& new_rule_dynamic(const std::string& rule)
        {
            std::string new_rule = '/' + prefix_ + rule;
            auto ruleObject = new DynamicRule(std::move(new_rule));
            ruleObject->custom_templates_base = templates_dir_;
            all_rules_.emplace_back(ruleObject);

            return *ruleObject;
        }

        template<uint64_t N>
        typename black_magic::arguments<N>::type::template rebind<TaggedRule>& new_rule_tagged(const std::string& rule)
        {
            std::string new_rule = '/' + prefix_ + rule;
            using RuleT = typename black_magic::arguments<N>::type::template rebind<TaggedRule>;

            auto ruleObject = new RuleT(std::move(new_rule));
            ruleObject->custom_templates_base = templates_dir_;
            all_rules_.emplace_back(ruleObject);

            return *ruleObject;
        }

        void register_blueprint(Blueprint& blueprint)
        {
            if (blueprints_.empty() || std::find(blueprints_.begin(), blueprints_.end(), &blueprint) == blueprints_.end())
            {
                apply_blueprint(blueprint);
                blueprints_.emplace_back(&blueprint);
            }
            else
                throw std::runtime_error("blueprint \"" + blueprint.prefix_ + "\" already exists in blueprint \"" + prefix_ + '\"');
        }


        CatchallRule& catchall_rule()
        {
            return catchall_rule_;
        }

        template<typename App, typename... Middlewares>
        void middlewares()
        {
            mw_indices_.push<App, Middlewares...>();
        }

    private:
        void apply_blueprint(Blueprint& blueprint)
        {

            blueprint.prefix_ = prefix_ + '/' + blueprint.prefix_;
            blueprint.static_dir_ = static_dir_ + '/' + blueprint.static_dir_;
            blueprint.templates_dir_ = templates_dir_ + '/' + blueprint.templates_dir_;
            for (auto& rule : blueprint.all_rules_)
            {
                std::string new_rule = '/' + prefix_ + rule->rule_;
                rule->rule_ = new_rule;
            }
            for (Blueprint* bp_child : blueprint.blueprints_)
            {
                Blueprint& bp_ref = *bp_child;
                apply_blueprint(bp_ref);
            }
        }

        std::string prefix_;
        std::string static_dir_;
        std::string templates_dir_;
        std::vector<std::unique_ptr<BaseRule>> all_rules_;
        CatchallRule catchall_rule_;
        std::vector<Blueprint*> blueprints_;
        detail::middleware_indices mw_indices_;
        bool added_{false};

        friend class Router;
    };

    /// Handles matching requests to existing rules and upgrade requests.
    class Router
    {
    public:
        Router()
        {}

        DynamicRule& new_rule_dynamic(const std::string& rule)
        {
            auto ruleObject = new DynamicRule(rule);
            all_rules_.emplace_back(ruleObject);

            return *ruleObject;
        }

        template<uint64_t N>
        typename black_magic::arguments<N>::type::template rebind<TaggedRule>& new_rule_tagged(const std::string& rule)
        {
            using RuleT = typename black_magic::arguments<N>::type::template rebind<TaggedRule>;

            auto ruleObject = new RuleT(rule);
            all_rules_.emplace_back(ruleObject);

            return *ruleObject;
        }

        CatchallRule& catchall_rule()
        {
            return catchall_rule_;
        }

        void internal_add_rule_object(const std::string& rule, BaseRule* ruleObject)
        {
            internal_add_rule_object(rule, ruleObject, INVALID_BP_ID, blueprints_);
        }

        void internal_add_rule_object(const std::string& rule, BaseRule* ruleObject, const uint16_t& BP_index, std::vector<Blueprint*>& blueprints)
        {
            bool has_trailing_slash = false;
            std::string rule_without_trailing_slash;
            if (rule.size() > 1 && rule.back() == '/')
            {
                has_trailing_slash = true;
                rule_without_trailing_slash = rule;
                rule_without_trailing_slash.pop_back();
            }

            ruleObject->mw_indices_.pack();

            ruleObject->foreach_method([&](int method) {
                per_methods_[method].rules.emplace_back(ruleObject);
                per_methods_[method].trie.add(rule, per_methods_[method].rules.size() - 1, BP_index != INVALID_BP_ID ? blueprints[BP_index]->prefix().length() : 0, BP_index);

                // directory case:
                //   request to '/about' url matches '/about/' rule
                if (has_trailing_slash)
                {
                    per_methods_[method].trie.add(rule_without_trailing_slash, RULE_SPECIAL_REDIRECT_SLASH, BP_index != INVALID_BP_ID ? blueprints[BP_index]->prefix().length() : 0, BP_index);
                }
            });

            ruleObject->set_added();
        }

        void register_blueprint(Blueprint& blueprint)
        {
            if (std::find(blueprints_.begin(), blueprints_.end(), &blueprint) == blueprints_.end())
            {
                blueprints_.emplace_back(&blueprint);
            }
            else
                throw std::runtime_error("blueprint \"" + blueprint.prefix_ + "\" already exists in router");
        }

        void get_recursive_child_methods(Blueprint* blueprint, std::vector<HTTPMethod>& methods)
        {
            //we only need to deal with children if the blueprint has absolutely no methods (meaning its index won't be added to the trie)
            if (blueprint->static_dir_.empty() && blueprint->all_rules_.empty())
            {
                for (Blueprint* bp : blueprint->blueprints_)
                {
                    get_recursive_child_methods(bp, methods);
                }
            }
            else if (!blueprint->static_dir_.empty())
                methods.emplace_back(HTTPMethod::Get);
            for (auto& rule : blueprint->all_rules_)
            {
                rule->foreach_method([&methods](unsigned method) {
                    HTTPMethod method_final = static_cast<HTTPMethod>(method);
                    if (std::find(methods.begin(), methods.end(), method_final) == methods.end())
                        methods.emplace_back(method_final);
                });
            }
        }

        void validate_bp() {
            //Take all the routes from the registered blueprints and add them to `all_rules_` to be processed.
            detail::middleware_indices blueprint_mw;
            validate_bp(blueprints_, blueprint_mw);
        }

        void validate_bp(std::vector<Blueprint*> blueprints, detail::middleware_indices& current_mw)
        {
            for (unsigned i = 0; i < blueprints.size(); i++)
            {
                Blueprint* blueprint = blueprints[i];

                if (blueprint->is_added()) continue;

                if (blueprint->static_dir_ == "" && blueprint->all_rules_.empty())
                {
                    std::vector<HTTPMethod> methods;
                    get_recursive_child_methods(blueprint, methods);
                    for (HTTPMethod x : methods)
                    {
                        int i = static_cast<int>(x);
                        per_methods_[i].trie.add(blueprint->prefix(), 0, blueprint->prefix().length(), i);
                    }
                }

                current_mw.merge_back(blueprint->mw_indices_);
                for (auto& rule : blueprint->all_rules_)
                {
                    if (rule && !rule->is_added())
                    {
                        auto upgraded = rule->upgrade();
                        if (upgraded)
                            rule = std::move(upgraded);
                        rule->validate();
                        rule->mw_indices_.merge_front(current_mw);
                        internal_add_rule_object(rule->rule(), rule.get(), i, blueprints);
                    }
                }
                validate_bp(blueprint->blueprints_, current_mw);
                current_mw.pop_back(blueprint->mw_indices_);
                blueprint->set_added();
            }
        }

        void validate()
        {
            for (auto& rule : all_rules_)
            {
                if (rule && !rule->is_added())
                {
                    auto upgraded = rule->upgrade();
                    if (upgraded)
                        rule = std::move(upgraded);
                    rule->validate();
                    internal_add_rule_object(rule->rule(), rule.get());
                }
            }
            for (auto& per_method : per_methods_)
            {
                per_method.trie.validate();
            }
        }

        // TODO maybe add actual_method
        template<typename Adaptor>
        void handle_upgrade(const request& req, response& res, Adaptor&& adaptor)
        {
            if (req.method >= HTTPMethod::InternalMethodCount)
                return;

            auto& per_method = per_methods_[static_cast<int>(req.method)];
            auto& rules = per_method.rules;
            unsigned rule_index = per_method.trie.find(req.url).rule_index;

            if (!rule_index)
            {
                for (auto& per_method : per_methods_)
                {
                    if (per_method.trie.find(req.url).rule_index)
                    {
                        CROW_LOG_DEBUG << "Cannot match method " << req.url << " " << method_name(req.method);
                        res = response(405);
                        res.end();
                        return;
                    }
                }

                CROW_LOG_INFO << "Cannot match rules " << req.url;
                res = response(404);
                res.end();
                return;
            }

            if (rule_index >= rules.size())
                throw std::runtime_error("Trie internal structure corrupted!");

            if (rule_index == RULE_SPECIAL_REDIRECT_SLASH)
            {
                CROW_LOG_INFO << "Redirecting to a url with trailing slash: " << req.url;
                res = response(301);

                // TODO(ipkn) absolute url building
                if (req.get_header_value("Host").empty())
                {
                    res.add_header("Location", req.url + "/");
                }
                else
                {
                    res.add_header("Location", "http://" + req.get_header_value("Host") + req.url + "/");
                }
                res.end();
                return;
            }

            CROW_LOG_DEBUG << "Matched rule (upgrade) '" << rules[rule_index]->rule_ << "' " << static_cast<uint32_t>(req.method) << " / " << rules[rule_index]->get_methods();

            try
            {
                rules[rule_index]->handle_upgrade(req, res, std::move(adaptor));
            }
            catch (...)
            {
                exception_handler_(res);
                res.end();
                return;
            }
        }

        void get_found_bp(std::vector<uint16_t>& bp_i, std::vector<Blueprint*>& blueprints, std::vector<Blueprint*>& found_bps, uint16_t index = 0)
        {
            // This statement makes 3 assertions:
            // 1. The index is above 0.
            // 2. The index does not lie outside the given blueprint list.
            // 3. The next blueprint we're adding has a prefix that starts the same as the already added blueprint + a slash (the rest is irrelevant).
            //
            // This is done to prevent a blueprint that has a prefix of "bp_prefix2" to be assumed as a child of one that has "bp_prefix".
            //
            // If any of the assertions is untrue, we delete the last item added, and continue using the blueprint list of the blueprint found before, the topmost being the router's list
            auto verify_prefix = [&bp_i, &index, &blueprints, &found_bps]() {
                return index > 0 &&
                       bp_i[index] < blueprints.size() &&
                       blueprints[bp_i[index]]->prefix().substr(0, found_bps[index - 1]->prefix().length() + 1).compare(std::string(found_bps[index - 1]->prefix() + '/')) == 0;
            };
            if (index < bp_i.size())
            {

                if (verify_prefix())
                {
                    found_bps.push_back(blueprints[bp_i[index]]);
                    get_found_bp(bp_i, found_bps.back()->blueprints_, found_bps, ++index);
                }
                else
                {
                    if (found_bps.size() < 2)
                    {
                        found_bps.clear();
                        found_bps.push_back(blueprints_[bp_i[index]]);
                    }
                    else
                    {
                        found_bps.pop_back();
                        Blueprint* last_element = found_bps.back();
                        found_bps.push_back(last_element->blueprints_[bp_i[index]]);
                    }
                    get_found_bp(bp_i, found_bps.back()->blueprints_, found_bps, ++index);
                }
            }
        }

        /// Is used to handle errors, you insert the error code, found route, request, and response. and it'll either call the appropriate catchall route (considering the blueprint system) and send you a status string (which is mainly used for debug messages), or just set the response code to the proper error code.
        std::string get_error(unsigned short code, routing_handle_result& found, const request& req, response& res)
        {
            res.code = code;
            std::vector<Blueprint*> bps_found;
            get_found_bp(found.blueprint_indices, blueprints_, bps_found);
            for (int i = bps_found.size() - 1; i > 0; i--)
            {
                std::vector<uint16_t> bpi = found.blueprint_indices;
                if (bps_found[i]->catchall_rule().has_handler())
                {
                    try
                    {
                        bps_found[i]->catchall_rule().handler_(req, res);
                    }
                    catch (...)
                    {
                        exception_handler_(res);
                    }
#ifdef CROW_ENABLE_DEBUG
                    return std::string("Redirected to Blueprint \"" + bps_found[i]->prefix() + "\" Catchall rule");
#else
                    return std::string();
#endif
                }
            }
            if (catchall_rule_.has_handler())
            {
                try
                {
                    catchall_rule_.handler_(req, res);
                }
                catch (...)
                {
                    exception_handler_(res);
                }
#ifdef CROW_ENABLE_DEBUG
                return std::string("Redirected to global Catchall rule");
#else
                return std::string();
#endif
            }
            return std::string();
        }

        std::unique_ptr<routing_handle_result> handle_initial(request& req, response& res)
        {
            HTTPMethod method_actual = req.method;

            std::unique_ptr<routing_handle_result> found{
              new routing_handle_result(
                0,
                std::vector<uint16_t>(),
                routing_params(),
                HTTPMethod::InternalMethodCount)}; // This is always returned to avoid a null pointer dereference.

            // NOTE(EDev): This most likely will never run since the parser should handle this situation and close the connection before it gets here.
            if (CROW_UNLIKELY(req.method >= HTTPMethod::InternalMethodCount))
                return found;
            else if (req.method == HTTPMethod::Head)
            {
                *found = per_methods_[static_cast<int>(method_actual)].trie.find(req.url);
                // support HEAD requests using GET if not defined as method for the requested URL
                if (!found->rule_index)
                {
                    method_actual = HTTPMethod::Get;
                    *found = per_methods_[static_cast<int>(method_actual)].trie.find(req.url);
                    if (!found->rule_index) // If a route is still not found, return a 404 without executing the rest of the HEAD specific code.
                    {
                        CROW_LOG_DEBUG << "Cannot match rules " << req.url;
                        res = response(404); //TODO(EDev): Should this redirect to catchall?
                        res.end();
                        return found;
                    }
                }

                res.skip_body = true;
                found->method = method_actual;
                return found;
            }
            else if (req.method == HTTPMethod::Options)
            {
                std::string allow = "OPTIONS, HEAD, ";

                if (req.url == "/*")
                {
                    for (int i = 0; i < static_cast<int>(HTTPMethod::InternalMethodCount); i++)
                    {
                        if (static_cast<int>(HTTPMethod::Head) == i)
                            continue; // HEAD is always allowed

                        if (!per_methods_[i].trie.is_empty())
                        {
                            allow += method_name(static_cast<HTTPMethod>(i)) + ", ";
                        }
                    }
                    allow = allow.substr(0, allow.size() - 2);
                    res = response(204);
                    res.set_header("Allow", allow);
                    res.end();
                    found->method = method_actual;
                    return found;
                }
                else
                {
                    bool rules_matched = false;
                    for (int i = 0; i < static_cast<int>(HTTPMethod::InternalMethodCount); i++)
                    {
                        if (per_methods_[i].trie.find(req.url).rule_index)
                        {
                            rules_matched = true;

                            if (static_cast<int>(HTTPMethod::Head) == i)
                                continue; // HEAD is always allowed

                            allow += method_name(static_cast<HTTPMethod>(i)) + ", ";
                        }
                    }
                    if (rules_matched)
                    {
                        allow = allow.substr(0, allow.size() - 2);
                        res = response(204);
                        res.set_header("Allow", allow);
                        res.end();
                        found->method = method_actual;
                        return found;
                    }
                    else
                    {
                        CROW_LOG_DEBUG << "Cannot match rules " << req.url;
                        res = response(404); //TODO(EDev): Should this redirect to catchall?
                        res.end();
                        return found;
                    }
                }
            }
            else // Every request that isn't a HEAD or OPTIONS request
            {
                *found = per_methods_[static_cast<int>(method_actual)].trie.find(req.url);
                // TODO(EDev): maybe ending the else here would allow the requests coming from above (after removing the return statement) to be checked on whether they actually point to a route
                if (!found->rule_index)
                {
                    for (auto& per_method : per_methods_)
                    {
                        if (per_method.trie.find(req.url).rule_index) //Route found, but in another method
                        {
                            const std::string error_message(get_error(405, *found, req, res));
                            CROW_LOG_DEBUG << "Cannot match method " << req.url << " " << method_name(method_actual) << ". " << error_message;
                            res.end();
                            return found;
                        }
                    }
                    //Route does not exist anywhere

                    const std::string error_message(get_error(404, *found, req, res));
                    CROW_LOG_DEBUG << "Cannot match rules " << req.url << ". " << error_message;
                    res.end();
                    return found;
                }

                found->method = method_actual;
                return found;
            }
        }

        template<typename App>
        void handle(request& req, response& res, routing_handle_result found)
        {
            HTTPMethod method_actual = found.method;
            auto& rules = per_methods_[static_cast<int>(method_actual)].rules;
            unsigned rule_index = found.rule_index;

            if (rule_index >= rules.size())
                throw std::runtime_error("Trie internal structure corrupted!");

            if (rule_index == RULE_SPECIAL_REDIRECT_SLASH)
            {
                CROW_LOG_INFO << "Redirecting to a url with trailing slash: " << req.url;
                res = response(301);

                // TODO(ipkn) absolute url building
                if (req.get_header_value("Host").empty())
                {
                    res.add_header("Location", req.url + "/");
                }
                else
                {
                    res.add_header("Location", "http://" + req.get_header_value("Host") + req.url + "/");
                }
                res.end();
                return;
            }

            CROW_LOG_DEBUG << "Matched rule '" << rules[rule_index]->rule_ << "' " << static_cast<uint32_t>(req.method) << " / " << rules[rule_index]->get_methods();

            try
            {
                auto& rule = rules[rule_index];
                handle_rule<App>(rule, req, res, found.r_params);
            }
            catch (...)
            {
                exception_handler_(res);
                res.end();
                return;
            }
        }

        template<typename App>
        typename std::enable_if<std::tuple_size<typename App::mw_container_t>::value != 0, void>::type
          handle_rule(BaseRule* rule, crow::request& req, crow::response& res, const crow::routing_params& rp)
        {
            if (!rule->mw_indices_.empty())
            {
                auto& ctx = *reinterpret_cast<typename App::context_t*>(req.middleware_context);
                auto& container = *reinterpret_cast<typename App::mw_container_t*>(req.middleware_container);
                detail::middleware_call_criteria_dynamic<false> crit_fwd(rule->mw_indices_.indices());

                auto glob_completion_handler = std::move(res.complete_request_handler_);
                res.complete_request_handler_ = [] {};

                detail::middleware_call_helper<decltype(crit_fwd),
                                               0, typename App::context_t, typename App::mw_container_t>(crit_fwd, container, req, res, ctx);

                if (res.completed_)
                {
                    glob_completion_handler();
                    return;
                }

                res.complete_request_handler_ = [&rule, &ctx, &container, &req, &res, glob_completion_handler] {
                    detail::middleware_call_criteria_dynamic<true> crit_bwd(rule->mw_indices_.indices());

                    detail::after_handlers_call_helper<
                      decltype(crit_bwd),
                      std::tuple_size<typename App::mw_container_t>::value - 1,
                      typename App::context_t,
                      typename App::mw_container_t>(crit_bwd, container, ctx, req, res);
                    glob_completion_handler();
                };
            }
            rule->handle(req, res, rp);
        }

        template<typename App>
        typename std::enable_if<std::tuple_size<typename App::mw_container_t>::value == 0, void>::type
          handle_rule(BaseRule* rule, crow::request& req, crow::response& res, const crow::routing_params& rp)
        {
            rule->handle(req, res, rp);
        }

        void debug_print()
        {
            for (int i = 0; i < static_cast<int>(HTTPMethod::InternalMethodCount); i++)
            {
                Trie& trie_ = per_methods_[i].trie;
                if (!trie_.is_empty())
                {
                    CROW_LOG_DEBUG << method_name(static_cast<HTTPMethod>(i));
                    trie_.debug_print();
                }
            }
        }

        std::vector<Blueprint*>& blueprints()
        {
            return blueprints_;
        }

        std::function<void(crow::response&)>& exception_handler()
        {
            return exception_handler_;
        }

        static void default_exception_handler(response& res)
        {
            // any uncaught exceptions become 500s
            res = response(500);

            try
            {
                throw;
            }
            catch (const std::exception& e)
            {
                CROW_LOG_ERROR << "An uncaught exception occurred: " << e.what();
            }
            catch (...)
            {
                CROW_LOG_ERROR << "An uncaught exception occurred. The type was unknown so no information was available.";
            }
        }

    private:
        CatchallRule catchall_rule_;

        struct PerMethod
        {
            std::vector<BaseRule*> rules;
            Trie trie;

            // rule index 0, 1 has special meaning; preallocate it to avoid duplication.
            PerMethod():
              rules(2) {}
        };
        std::array<PerMethod, static_cast<int>(HTTPMethod::InternalMethodCount)> per_methods_;
        std::vector<std::unique_ptr<BaseRule>> all_rules_;
        std::vector<Blueprint*> blueprints_;
        std::function<void(crow::response&)> exception_handler_ = &default_exception_handler;
    };
} // namespace crow