// SPDX-FileCopyrightText: 2024 Yury Gubich <blue@macaw.me>
// SPDX-License-Identifier: GPL-3.0-or-later

#include "router.h"

#include <string_view>

#include "module/module.h"
#include "connection/connection.h"

Router::Router(const Shared::Logger& logger):
    Shared::Loggable(logger, {"Router"}),
    modules(),
    actors(),
    defaultGroup("Stranger"),
    responses({
        {Shared::forbidden, { "Forbidden" }},
        {Shared::error, { "Command error" }},
        {Shared::unhandled, { "No such command" }},
    }),
    generator(std::random_device{}())
{}

void Router::registerModule(const std::shared_ptr<Module::Module>& module) {
    info("Registering module " + module->name + " as " + module->alias);
    modules[module->alias] = module;
}

void Router::registerActor(const std::string& key, const std::string& group) {
    if (key == "default") {
        defaultGroup = group;
        return;
    }

    Actors::iterator act = actors.find(key);
    if (act == actors.end())
        actors.emplace(key, std::make_shared<Actor>(key, group));
    else
        act->second->setGroup(group);
}

void Router::routeMessage(const std::string& sender, const std::string& body) {
    Actors::iterator aItr = actors.find(sender);
    if (aItr == actors.end())
        aItr = actors.emplace(sender, std::make_shared<Actor>(sender, defaultGroup)).first;

    std::string_view view(body);
    std::string_view aliasView = Module::Module::pop(view);
    
    if (aliasView.size() > 1000)  {
        warn("Received a message with the first word larger than 1000 symbols, " + sender + "is clearly looking for a vulnerability");
        return onMessageResult(Shared::unhandled, sender);
    }

    if (view.empty()) {
        debug("Incoming message from " + sender + " consists of only one word, modules have nothing to process");
        return onMessageResult(Shared::unhandled, sender);
    }

    std::string alias(aliasView);
    Modules::iterator mItr = modules.find(alias);
    if (mItr == modules.end()) {
        debug("could not find module \"" + alias + "\" to handle message from " + sender);
        return onMessageResult(Shared::unhandled, sender);
    }

    std::shared_ptr<Module::Module> module = mItr->second.lock();
    if (!module) {
        error("could not lock module \"" + mItr->first + "\" to handle message from " + sender);
        return onMessageResult(Shared::error, sender);
    }

    Shared::Result result;
    try {
        result = module->message(aItr->second, view);
        if (result == Shared::success)
        debug("module \"" + mItr->first + "\" successfully handled message from " + sender);
    } catch (...) {
        error("module \"" + mItr->first + "\" thew an unhandled exception handling message from " + sender);
        result = Shared::error;
    }

    onMessageResult(result, sender);
}

std::map<std::string, std::string> Router::getActors() const {
    std::map<std::string, std::string> result;

    for (const std::pair<const std::string, std::shared_ptr<Actor>>& pair : actors)
        result.emplace(pair.first, pair.second->getGroup());

    return result;
}

std::string Router::getDefaultGroup() const {
    return defaultGroup;
}

void Router::setConnection(const std::shared_ptr<Connection>& cn) {
    connection = cn;
}

void Router::setResponses(Shared::Result result, const Shared::Strings& options) {
    responses[result] = options;
}

std::string Router::getGroup(const std::string& key) const {
    Actors::const_iterator itr = actors.find(key);
    if (itr == actors.end())
        return defaultGroup;

    return itr->second->getGroup();
}

void Router::onMessageResult(Shared::Result result, const std::string& sender) {
    Responses::const_iterator rItr = responses.find(result);
    if (rItr == responses.end() || rItr->second.empty())
        return;
    
    std::shared_ptr<Connection> cn = connection.lock();
    if (!cn) {
        warn("Couldn't send a message to " + sender + ", connection is not available");
        return;
    }

    const List& options = rItr->second;
    std::uniform_int_distribution<std::size_t> dist(0, options.size() - 1);
    cn->send(sender, options[dist(generator)]);
}