// Copyright (C) 2024 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0

#include "luaengine.h"

#include "luapluginspec.h"
#include "luatr.h"

#include <coreplugin/icore.h>
#include <coreplugin/messagemanager.h>

#include <utils/algorithm.h>
#include <utils/hostosinfo.h>
#include <utils/lua.h>
#include <utils/stringutils.h>
#include <utils/theme/theme.h>

#include <QJsonArray>
#include <QJsonDocument>
#include <QJsonObject>
#include <QStandardPaths>
#include <QTemporaryDir>

using namespace Utils;
using namespace std::string_view_literals;

namespace Lua {

Utils::Result<> connectHooks(
        sol::state_view lua, const sol::table &table, const QString &path, QObject *guard);

static Q_LOGGING_CATEGORY(logLuaEngine, "qtc.lua.engine", QtWarningMsg);

QString luaToString(lua_State *state, int index)
{
    size_t l;
    const char *s = luaL_tolstring(state, index, &l);
    if (s == nullptr)
        return {};

    // Remove from stack what tolstring pushed onto it.
    sol::stack::pop_n(state, 1);

    return QString::fromUtf8(s, l);
}

template<typename T>
QString refToString(const T &ref)
{
    if (ref.template is<QString>())
        return ref.template as<QString>();

    if (ref.template is<sol::table>())
        return toJsonString(ref.template as<sol::table>());

    auto pp = sol::stack::push_pop(ref);
    return luaToString(ref.lua_state(), -1);
}

class LuaInterfaceImpl final : public QObject, public LuaInterface
{
public:
    LuaInterfaceImpl(QObject *guard) : QObject(guard) { Utils::setLuaInterface(this); }
    ~LuaInterfaceImpl() final { Utils::setLuaInterface(nullptr); }

    Result<std::unique_ptr<LuaState>> runScript(
        const QString &script, const QString &name) final
    {
        return Lua::runScript(script, name);
    }

    QHash<QString, PackageProvider> m_providers;
    QList<std::function<void(sol::state_view)>> m_autoProviders;

    QMap<QString, std::function<void(sol::function, QObject *)>> m_hooks;
};

static LuaInterfaceImpl *d = nullptr;

class LuaStateImpl : public Utils::LuaState
{
public:
    sol::state lua;
    QTemporaryDir appDataDir;
};

QObject *ScriptPluginSpec::setup(
    sol::state_view lua,
    const QString &id,
    const QString &name,
    const Utils::FilePath appDataPath,
    const Utils::FilePath pluginLocation)
{
    lua.new_usertype<ScriptPluginSpec>(
        "PluginSpec",
        sol::no_constructor,
        "id",
        sol::property([](ScriptPluginSpec &self) { return self.id; }),
        "name",
        sol::property([](ScriptPluginSpec &self) { return self.name; }),
        "pluginDirectory",
        sol::property([pluginLocation]() { return pluginLocation; }),
        "appDataPath",
        sol::property([appDataPath]() { return appDataPath; }));

    auto guardObject = std::make_unique<QObject>();
    auto guardObjectPtr = guardObject.get();

    lua["PluginSpec"] = ScriptPluginSpec{id, name, appDataPath, std::move(guardObject)};

    return guardObjectPtr;
}

void prepareLuaState(
    sol::state &lua,
    const QString &name,
    const std::function<void(sol::state &)> &customizeState,
    const FilePath &appDataPath)
{
    lua.open_libraries(
        sol::lib::base,
        sol::lib::bit32,
        sol::lib::coroutine,
        sol::lib::debug,
        sol::lib::io,
        sol::lib::math,
        sol::lib::os,
        sol::lib::package,
        sol::lib::string,
        sol::lib::table,
        sol::lib::utf8);

    lua["print"] = [prefix = name, printToOutputPane = true](sol::variadic_args va) {
        const QString msg = variadicToStringList(va).join("\t");

        qDebug().noquote() << "[" << prefix << "]" << msg;
        if (printToOutputPane) {
            static const QString p
                = ansiColoredText("[" + prefix + "]", creatorColor(Theme::Token_Text_Muted));
            Core::MessageManager::writeSilently(QString("%1 %2").arg(p, msg));
        }
    };
    const Result<FilePath> tmpDir = HostOsInfo::root().tmpDir();
    QTC_ASSERT_RESULT(tmpDir, return);
    QString id = name;
    static const QRegularExpression regexp("[^a-zA-Z0-9_]");
    id = id.replace(regexp, "_").toLower();
    ScriptPluginSpec::setup(lua, id, name, appDataPath, *tmpDir);

    for (const auto &[name, func] : d->m_providers.asKeyValueRange()) {
        lua["package"]["preload"][name.toStdString()] = [func = func](const sol::this_state &s) {
            return func(s);
        };
    }

    for (const auto &func : std::as_const(d->m_autoProviders))
        func(lua);

    if (customizeState)
        customizeState(lua);
}

// Runs the gives script in a new Lua state. The returned Object manages the lifetime of the state.
std::unique_ptr<Utils::LuaState> runScript(
    const QString &script, const QString &name, std::function<void(sol::state &)> customizeState)
{
    std::unique_ptr<LuaStateImpl> opaque = std::make_unique<LuaStateImpl>();

    prepareLuaState(
        opaque->lua, name, customizeState, FilePath::fromUserInput(opaque->appDataDir.path()));

    auto result
        = opaque->lua
              .safe_script(script.toStdString(), sol::script_pass_on_error, name.toStdString());

    if (!result.valid()) {
        sol::error err = result;
        qWarning() << "Failed to run script" << name << ":" << QString::fromUtf8(err.what());
        Core::MessageManager::writeFlashing(
            Tr::tr("Failed to run script %1: %2").arg(name, QString::fromUtf8(err.what())));
    }

    return opaque;
}

sol::protected_function_result runFunction(
    sol::state &lua,
    const QString &script,
    const QString &name,
    std::function<void(sol::state &)> customizeState)
{
    prepareLuaState(lua, name, customizeState, {});
    return lua.safe_script(script.toStdString(), sol::script_pass_on_error, name.toStdString());
}

void registerProvider(const QString &packageName, const PackageProvider &provider)
{
    QTC_ASSERT(!d->m_providers.contains(packageName), return);
    d->m_providers[packageName] = provider;
}

void registerProvider(const QString &packageName, const FilePath &path)
{
    registerProvider(packageName, [path](sol::state_view lua) -> sol::object {
        auto content = path.fileContents();
        if (!content)
            throw sol::error(content.error().toStdString());

        sol::protected_function_result res
            = lua.script(content->data(), path.fileName().toStdString());
        if (!res.valid()) {
            sol::error err = res;
            throw err;
        }
        return res.get<sol::table>(0);
    });
}

void autoRegister(const std::function<void(sol::state_view)> &registerFunction)
{
    d->m_autoProviders.append(registerFunction);
}

void registerHook(QString name, const std::function<void(sol::function, QObject *guard)> &hook)
{
    d->m_hooks.insert("." + name, hook);
}

Result<> connectHooks(
    sol::state_view lua, const sol::table &table, const QString &path, QObject *guard)
{
    qCDebug(logLuaEngine) << "connectHooks called with path: " << path;

    for (const auto &[k, v] : table) {
        if (k.get_type() != sol::type::string)
            return make_unexpected(
                Tr::tr("Non-string key encountered in Lua table at path \"%1\".").arg(path));

        const auto keyName = k.as<QString>();
        const auto currentPath = QStringList{path, keyName}.join(".");
        qCDebug(logLuaEngine) << "Processing path:" << currentPath;

        switch (v.get_type()) {
        case sol::type::table: {
            auto result = connectHooks(lua, v.as<sol::table>(), currentPath, guard);
            if (!result)
                return result;
            break;
        }
        case sol::type::function: {
            qCDebug(logLuaEngine) << "Connecting function to hook:" << currentPath;

            auto it = d->m_hooks.find(currentPath);
            if (it == d->m_hooks.end()) {
                return make_unexpected(
                    Tr::tr("No hook with the name \"%1\" found.").arg(currentPath));
            }

            it.value()(v.as<sol::function>(), guard);
            break;
        }
        default: {
            return make_unexpected(Tr::tr("Unsupported value type \"%1\" at path \"%2\".")
                                       .arg(static_cast<int>(v.get_type()))
                                       .arg(currentPath));
        }
        }
    }

    return {};
}

Result<LuaPluginSpec *> loadPlugin(const FilePath &path)
{
    auto contents = path.fileContents();
    if (!contents)
        return make_unexpected(contents.error());

    sol::state lua;
    lua["tr"] = [](const QString &str) { return str; };

    sol::protected_function_result result = lua.safe_script(
        std::string_view(contents->data(), contents->size()),
        sol::script_pass_on_error,
        path.fileName().toUtf8().constData());

    if (!result.valid()) {
        sol::error err = result;
        return make_unexpected(QString(QString::fromUtf8(err.what())));
    }

    if (result.get_type() != sol::type::table)
        return make_unexpected(QString("Script did not return a table"));

    sol::table pluginInfo = result.get<sol::table>();
    if (!pluginInfo.valid())
        return make_unexpected(QString("Script did not return a table with plugin info"));
    return LuaPluginSpec::create(path, pluginInfo);
}

Result<sol::protected_function> prepareSetup(
    sol::state_view lua, const LuaPluginSpec &pluginSpec)
{
    auto contents = pluginSpec.filePath().fileContents();
    if (!contents)
        return make_unexpected(contents.error());

    // TODO: Only open libraries requested by the plugin
    lua.open_libraries(
        sol::lib::base,
        sol::lib::bit32,
        sol::lib::coroutine,
        sol::lib::debug,
        sol::lib::io,
        sol::lib::math,
        sol::lib::os,
        sol::lib::package,
        sol::lib::string,
        sol::lib::table,
        sol::lib::utf8);

    const bool printToOutputPane = pluginSpec.printToOutputPane();
    const QString prefix = pluginSpec.filePath().fileName();
    lua["print"] = [prefix, printToOutputPane](sol::variadic_args va) {
        const QString msg = variadicToStringList(va).join("\t");

        qDebug().noquote() << "[" << prefix << "]" << msg;
        if (printToOutputPane) {
            static const QString p
                = ansiColoredText("[" + prefix + "]", creatorColor(Theme::Token_Text_Muted));
            Core::MessageManager::writeSilently(QString("%1 %2").arg(p, msg));
        }
    };

    const QString searchPath = (pluginSpec.location() / "?.lua").toUserOutput();
    lua["package"]["path"] = searchPath.toStdString();

    const FilePath appDataPath = Core::ICore::userResourcePath() / "plugin-data" / "lua"
                                 / pluginSpec.location().fileName();

    QObject *guard = ScriptPluginSpec::setup(
        lua, pluginSpec.id(), pluginSpec.name(), appDataPath, pluginSpec.location());

    // TODO: only register what the plugin requested
    for (const auto &[name, func] : d->m_providers.asKeyValueRange()) {
        lua["package"]["preload"][name.toStdString()] = [func = func](const sol::this_state &s) {
            sol::state_view lua = s;
            // We need to make sure that providers work on the main_thread, otherwise they might
            // crash when trying to access the lua state on destruction.
            if (isCoroutine(lua))
                lua = sol::main_thread(lua);
            return func(lua);
        };
    }

    for (const auto &func : std::as_const(d->m_autoProviders))
        func(lua);

    sol::protected_function_result result = lua.safe_script(
        std::string_view(contents->data(), contents->size()),
        sol::script_pass_on_error,
        pluginSpec.filePath().fileName().toUtf8().constData());

    auto pluginTable = result.get<sol::optional<sol::table>>();
    if (!pluginTable)
        return make_unexpected(Tr::tr("Script did not return a table."));

    if (logLuaEngine().isDebugEnabled()) {
        qCDebug(logLuaEngine) << "Script returned table with keys:";
        for (const auto &[key, value] : *pluginTable) {
            qCDebug(logLuaEngine) << "Key:" << refToString(key);
            qCDebug(logLuaEngine) << "Value:" << refToString(value);
        }
    }

    auto hookTable = pluginTable->get<sol::optional<sol::table>>("hooks");

    qCDebug(logLuaEngine) << "Hooks table found: " << hookTable.has_value();
    if (hookTable) {
        auto connectResult = connectHooks(lua, *hookTable, {}, guard);
        if (!connectResult)
            return make_unexpected(connectResult.error());
    }

    auto setupFunction = pluginTable->get_or<sol::function>("setup"sv, {});

    if (!setupFunction)
        return make_unexpected(Tr::tr("Extension info table did not contain a setup function."));

    return setupFunction;
}

bool isCoroutine(lua_State *state)
{
    bool ismain = lua_pushthread(state) == 1;
    return !ismain;
}

template<typename KeyType>
static void setFromJson(sol::table &t, KeyType k, const QJsonValue &v)
{
    if (v.isDouble())
        t[k] = v.toDouble();
    else if (v.isBool())
        t[k] = v.toBool();
    else if (v.isString())
        t[k] = v.toString();
    else if (v.isObject())
        t[k] = toTable(t.lua_state(), v);
    else if (v.isArray())
        t[k] = toTable(t.lua_state(), v);
}

sol::table toTable(const sol::state_view &lua, const QJsonValue &v)
{
    sol::table table(lua, sol::create);

    if (v.isObject()) {
        QJsonObject o = v.toObject();
        for (auto it = o.constBegin(); it != o.constEnd(); ++it)
            setFromJson(table, it.key(), it.value());
    } else if (v.isArray()) {
        int i = 1;
        for (const auto &v : v.toArray())
            setFromJson(table, i++, v);
    }

    return table;
}

sol::table toTable(const sol::state_view &lua, const QJsonDocument &doc)
{
    if (doc.isArray())
        return toTable(lua, doc.array());
    else if (doc.isObject())
        return toTable(lua, doc.object());
    return sol::table();
}

QJsonValue toJsonValue(const sol::object &object);

QJsonValue toJsonValue(const sol::table &table)
{
    if (table.get<std::optional<sol::object>>(1)) {
        // Is Array
        QJsonArray arr;

        for (size_t i = 0; i < table.size(); ++i) {
            std::optional<sol::object> v = table.get<std::optional<sol::object>>(i + 1);
            if (!v)
                continue;
            arr.append(toJsonValue(*v));
        }

        return arr;
    }

    // Is Object
    QJsonObject obj;
    for (const auto &[k, v] : table)
        obj[k.as<QString>()] = toJsonValue(v);

    return obj;
}

QJsonValue toJsonValue(const sol::object &object)
{
    switch (object.get_type()) {
    case sol::type::lua_nil:
        return {};
    case sol::type::boolean:
        return object.as<bool>();
    case sol::type::number:
        return object.as<double>();
    case sol::type::string:
        return object.as<QString>();
    case sol::type::table:
        return toJsonValue(object.as<sol::table>());
    default:
        return {};
    }
}

QJsonValue toJson(const sol::table &table)
{
    return toJsonValue(table);
}

QString toJsonString(const sol::table &t)
{
    QJsonValue v = toJson(t);
    if (v.isArray())
        return QString::fromUtf8(QJsonDocument(v.toArray()).toJson(QJsonDocument::Compact));
    else if (v.isObject())
        return QString::fromUtf8(QJsonDocument(v.toObject()).toJson(QJsonDocument::Compact));
    return {};
}

QStringList variadicToStringList(const sol::variadic_args &vargs)
{
    QStringList strings;
    for (size_t i = 1, n = vargs.size(); i <= n; i++) {
        size_t l;
        const char *s = luaL_tolstring(vargs.lua_state(), int(i), &l);
        if (s != nullptr)
            strings.append(QString::fromUtf8(s, l).replace(QLatin1Char('\0'), "\\0"));
    }

    return strings;
}

void setupLuaEngine(QObject *guard)
{
    QTC_ASSERT(!d, return);
    d = new LuaInterfaceImpl(guard);

    autoRegister([](sol::state_view lua) {
        lua.new_usertype<Null>("NullType", sol::no_constructor);
        lua.set("Null", Null{});
    });
}

} // namespace Lua
