/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2025                                                               *
 *                                                                                       *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this  *
 * software and associated documentation files (the "Software"), to deal in the Software *
 * without restriction, including without limitation the rights to use, copy, modify,    *
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to    *
 * permit persons to whom the Software is furnished to do so, subject to the following   *
 * conditions:                                                                           *
 *                                                                                       *
 * The above copyright notice and this permission notice shall be included in all copies *
 * or substantial portions of the Software.                                              *
 *                                                                                       *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,   *
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A         *
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT    *
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF  *
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE  *
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                                         *
 ****************************************************************************************/

#include <modules/webgui/webguimodule.h>

#include <modules/server/servermodule.h>
#include <openspace/documentation/documentation.h>
#include <openspace/documentation/verifier.h>
#include <openspace/engine/globals.h>
#include <openspace/engine/moduleengine.h>
#include <openspace/util/json_helper.h>
#include <ghoul/filesystem/filesystem.h>
#include <ghoul/format.h>
#include <ghoul/logging/logmanager.h>
#include <ghoul/misc/dictionary.h>
#include <ghoul/misc/profiling.h>
#include <filesystem>
#include <optional>

namespace {
    constexpr std::string_view _loggerCat = "WebGuiModule";

    constexpr openspace::properties::Property::PropertyInfo ServerProcessEnabledInfo = {
        "ServerProcessEnabled",
        "Enable Server Process",
        "Enable the node js based process used to serve the Web GUI.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo AddressInfo = {
        "Address",
        "Address",
        "The network address to use when connecting to OpenSpace from the Web GUI.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo PortInfo = {
        "Port",
        "Port",
        "The network port to use when serving the Web GUI over HTTP.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo WebSocketInterfaceInfo = {
        "WebSocketInterface",
        "WebSocket Interface",
        "The identifier of the websocket interface to use when communicating.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo ServerProcessEntryPointInfo =
    {
        "ServerProcessEntryPoint",
        "Server Process Entry Point",
        "The node js command to invoke.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo DirectoriesInfo = {
        "Directories",
        "Directories",
        "Directories from which to to serve static content, as a string list "
        "with entries expressed as pairs, where every odd is the endpoint name and every "
        "even is the directory.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo DefaultEndpointInfo = {
        "DefaultEndpoint",
        "Default Endpoint",
        "The 'default' endpoint. The server will redirect http requests from / to "
        "/<DefaultEndpoint>.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo ServedDirectoriesInfo = {
        "ServedDirectories",
        "ServedDirectories",
        "Directories that are currently served. This value is set by the server process, "
        "as a verification of the actually served directories. For example, an onChange "
        "callback can be registered to this, to reload browsers when the server is "
        "ready. Manual changes to this property have no effect.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    struct [[codegen::Dictionary(WebGuiModule)]] Parameters {
        // [[codegen::verbatim(PortInfo.description)]]
        std::optional<int> port [[codegen::key("HttpPort")]];

        // [[codegen::verbatim(AddressInfo.description)]]
        std::string address;

        // [[codegen::verbatim(WebSocketInterfaceInfo.description)]]
        std::optional<std::string> webSocketInterface;
    };
#include "webguimodule_codegen.cpp"
} // namespace

namespace openspace {

documentation::Documentation WebGuiModule::Documentation() {
    return codegen::doc<Parameters>("module_webgui");
}

WebGuiModule::WebGuiModule()
    : OpenSpaceModule(WebGuiModule::Name)
    , _enabled(ServerProcessEnabledInfo, true)
    , _entryPoint(ServerProcessEntryPointInfo)
    , _directories(DirectoriesInfo)
    , _servedDirectories(ServedDirectoriesInfo)
    , _defaultEndpoint(DefaultEndpointInfo)
    , _port(PortInfo, 4680)
    , _address(AddressInfo, "localhost")
    , _webSocketInterface(WebSocketInterfaceInfo)
{
    addProperty(_enabled);
    addProperty(_entryPoint);
    addProperty(_directories);
    addProperty(_servedDirectories);
    addProperty(_defaultEndpoint);
    addProperty(_address);
    addProperty(_port);
}

int WebGuiModule::port() const {
    return _port;
}

std::string  WebGuiModule::address() const {
    return _address;
}

WebGuiModule::CallbackHandle WebGuiModule::addEndpointChangeCallback(EndpointCallback cb)
{
    const CallbackHandle handle = _nextCallbackHandle++;
    _endpointChangeCallbacks.emplace_back(handle, std::move(cb));
    return handle;
}

void WebGuiModule::removeEndpointChangeCallback(CallbackHandle handle) {
    const auto it = std::find_if(
        _endpointChangeCallbacks.cbegin(),
        _endpointChangeCallbacks.cend(),
        [handle](const std::pair<CallbackHandle, EndpointCallback>& cb) {
            return cb.first == handle;
        }
    );

    ghoul_assert(it != _endpointChangeCallbacks.cend(), "Must be valid callback handle");
    _endpointChangeCallbacks.erase(it);
}

void WebGuiModule::internalInitialize(const ghoul::Dictionary& configuration) {
    const Parameters p = codegen::bake<Parameters>(configuration);

    _port = p.port.value_or(_port);
    _address = p.address;
    _webSocketInterface = p.webSocketInterface.value_or(_webSocketInterface);

    auto startOrStop = [this]() {
        if (_enabled && !_entryPoint.value().empty()) {
            startProcess();
        }
        else {
            stopProcess();
        }
    };

    auto restartIfEnabled = [this]() {
        stopProcess();
        if (_enabled) {
            startProcess();
        }
    };

    _enabled.onChange(startOrStop);
    _entryPoint.onChange(restartIfEnabled);
    _directories.onChange(restartIfEnabled);
    _defaultEndpoint.onChange(restartIfEnabled);
    _servedDirectories.onChange([this]() {
        std::unordered_map<std::string, std::string> newEndpoints;
        std::vector<std::string> list = _servedDirectories;
        if (!list.empty()) {
            for (size_t i = 0; i < list.size() - 1; i += 2) {
                newEndpoints[list[i]] = newEndpoints[list[i + 1]];
            }
        }
        for (const std::pair<const std::string, std::string>& e : _endpoints) {
            if (newEndpoints.find(e.first) == newEndpoints.end()) {
                // This endpoint existed before but does not exist anymore.
                notifyEndpointListeners(e.first, false);
            }
        }
        for (const std::pair<const std::string, std::string>& e : newEndpoints) {
            if (_endpoints.find(e.first) == _endpoints.end() ||
                newEndpoints[e.first] != e.second)
            {
                // This endpoint exists now but did not exist before,
                // or the directory has changed.
                notifyEndpointListeners(e.first, true);
            }
        }
        _endpoints = newEndpoints;
    });
    _port.onChange(restartIfEnabled);
    startOrStop();
}

void WebGuiModule::notifyEndpointListeners(const std::string& endpoint, bool exists) {
    using K = CallbackHandle;
    using V = EndpointCallback;
    for (const std::pair<K, V>& it : _endpointChangeCallbacks) {
        it.second(endpoint, exists);
    }
}

void WebGuiModule::startProcess() {
    ZoneScoped;

    _endpoints.clear();

    ServerModule* serverModule = global::moduleEngine->module<ServerModule>();
    const ServerInterface* serverInterface = serverModule->serverInterfaceByIdentifier(
        _webSocketInterface
    );
    if (!serverInterface) {
        LERROR("Missing server interface. Server process could not start");
        return;
    }
    const int webSocketPort = serverInterface->port();

#ifdef _MSC_VER
    const std::filesystem::path node = absPath("${MODULE_WEBGUI}/ext/nodejs/node.exe");
#else  // ^^^^ _MSC_VER // !_MSC_VER vvvv
    const std::filesystem::path node = absPath("${MODULE_WEBGUI}/ext/nodejs/node");
#endif // _MSC_VER

    std::string formattedDirectories = "[";

    std::vector<std::string> directories = _directories;
    for (size_t i = 0; i < directories.size(); i++) {
        std::string arg = directories[i];
        if (i % 2 == 1) {
            arg = absPath(arg).string();
        }
        formattedDirectories += "\\\"" + escapedJson(escapedJson(arg)) + "\\\"";
        if (i != directories.size() - 1) {
            formattedDirectories += ",";
        }
    }
    formattedDirectories += "]";

    std::string defaultEndpoint;
    if (!_defaultEndpoint.value().empty()) {
        defaultEndpoint = std::format("--redirect \"{}\"", _defaultEndpoint.value());
    }

    const std::string command = std::format(
        "\"{}\" \"{}\" --directories \"{}\" {} --http-port \"{}\" --ws-address \"{}\" "
        "--ws-port {} --auto-close --local",
        node.string(), absPath(_entryPoint.value()), formattedDirectories,
        defaultEndpoint, _port.value(), _address.value(), webSocketPort
    );

    _process = std::make_unique<ghoul::Process>(
        command,
        absPath("${BIN}"),
        [](const char* data, size_t n) {
            const std::string_view str = std::string_view(data, n);
            LDEBUG(std::format("Web GUI server output: {}", str));
        },
        [](const char* data, size_t n) {
            const std::string_view str = std::string_view(data, n);
            LERROR(std::format("Web GUI server error: {}", str));
        }
    );
}

void WebGuiModule::stopProcess() {
    for (const std::pair<const std::string, std::string>& e : _endpoints) {
        notifyEndpointListeners(e.first, false);
    }
    _endpoints.clear();

    if (_process) {
        _process->kill();
    }
    _process = nullptr;
}

} // namespace openspace