#include <cstdlib>
#include <iostream>
#include <string>
#include <fstream>
#include <filesystem>
#include <ciso646>

#ifdef __linux__
    #include <unistd.h>
#endif

using namespace std;

enum class System{
    WSL,
    Linux,
    Unsupported };
enum class WslDistro{
    Ubuntu,
    Debian,
    Unsupported,
    IsNotWsl };
enum class User{
    Root,
    Other };

auto GetCurrentSystemType(){
    #pragma warning(suppress : 4996)
    if (getenv("WSL_DISTRO_NAME") != nullptr){
        return System::WSL; }
    #pragma warning(suppress : 4996)
    if (getenv("WSL_INTEROP") != nullptr){
        return System::WSL; }
    if (filesystem::exists("/proc/version")) {
        ifstream version_file("/proc/version");
        string version_info = "";
        getline(version_file, version_info);
        if (version_info.find("Microsoft") != string::npos or 
        version_info.find("WSL") != string::npos) {
            return System::WSL; }
        version_file.close(); }
    if (filesystem::exists("/proc/sys/kernel/osrelease")) {
        ifstream osrelease_file("/proc/sys/kernel/osrelease");
        string osrelease_info = "";
        getline(osrelease_file, osrelease_info);
        if (osrelease_info.find("microsoft") != string::npos or
            osrelease_info.find("WSL") != string::npos) {
            return System::WSL; }
        osrelease_file.close(); }

    #ifdef __linux__
        return System::Linux;
    #else
        return System::Unsupported;
    #endif
}

auto GetCurrentWslDistro(){
    #pragma warning(suppress : 4996)
    if (getenv("WSL_DISTRO_NAME") != nullptr){
        string DistroName = getenv("WSL_DISTRO_NAME");
        if (DistroName.find("Ubuntu") != string::npos){
            return WslDistro::Ubuntu; }
        else if (DistroName.find("Debian") != string::npos){
            return WslDistro::Debian; }
        else{
            return WslDistro::Unsupported; } }
    else{
        return WslDistro::IsNotWsl; } }

auto GetCurrentUser(){
    #pragma warning(suppress : 4996)
    if (getenv("USER") != nullptr){
        string user = getenv("USER");
        if (user == "root" or geteuid() == 0){
            return User::Root; }
        else{
            return User::Other; } }
    else{
        throw runtime_error("无法获取用户信息"); } }

/// @brief  获取当前系统的发行版名称
/// @return 发行版名称，带有版本号
/// @author ChatGPT
auto GetCurrentSystem() {
    string distro_name = "";
    ifstream release_file("/etc/os-release");
    if (release_file.is_open()) {
        string line = "";
        while (getline(release_file, line)) {
            if (line.find("PRETTY_NAME=") != string::npos) {
                distro_name = line.substr(line.find("=") + 1);
                distro_name.erase(0, 1); // remove opening quote
                distro_name.erase(distro_name.size() - 1); // remove closing quote
                break;} }
        release_file.close(); }
    return distro_name; }

auto check() {
    cout << "请输入您的选项（输入y或者yes继续）";
    string userin = "";
    cin >> userin;
    if (userin == "y" or userin == "yes")
        return;
    else{
        cout << "输入不正确欸，如果想停止本程序的话请按下Ctrl+C" << endl;
        check(); } }

auto RebootIfIsWSL(){
    if (GetCurrentSystemType() == System::WSL){
        system("wsl.exe --terminate $WSL_DISTRO_NAME"); } }

auto Ubuntu(){
    cout << "即将开始安装并配置简体中文语言包，请输入y或者yes继续，或者按Ctrl+C终止本程序";
    check();
    cout << "开始更新语言配置" << endl;
    system("apt update");
    system("apt install -y language-pack-zh-hans");
    system("update-locale LANG=zh_CN.UTF-8");
    cout << "语言配置更新完成" << endl;
    cout << "即将重启以应用语言设置，请保存您未完成的工作以防数据丢失" << endl;
    cout << "输入y或者yes重启或者按Ctrl+C终止本程序" << endl;
    check();
    RebootIfIsWSL();
    system("reboot"); }

auto Debian(){
    cout << "即将开始更新语言配置，请输入y或者yes继续，或者按Ctrl+C终止本程序";
    check();
    cout << "开始更新语言配置" << endl;
    fstream locale_gen("/etc/locale.gen", ios::app);
    locale_gen << '\n' <<
        "zh_CN.UTF-8 UTF-8" << endl;
    locale_gen.close();
    system("locale-gen");
    system("update-locale LANG=zh_CN.UTF-8");
    cout << "即将重启以应用语言设置，请保存您未完成的工作以防数据丢失" << endl;
    cout << "输入y或者yes重启或者按Ctrl+C终止本程序" << endl;
    check();
    RebootIfIsWSL();
    system("reboot");}

auto OsType = GetCurrentSystemType();

int main() {
    if (OsType == System::Unsupported){
        cout << "未知操作系统，为确保数据安全将会强制退出。"
            << endl 
            << "如果是误报，请联系作者修复问题。"
            << endl;
        throw runtime_error("不支持的操作系统"); }

    auto OS = GetCurrentSystem();
    auto Distro = GetCurrentWslDistro();
    auto CurrentUser = GetCurrentUser();

    if (CurrentUser == User::Other){
        cout << "更改语言文件需要root权限，请使用sudo重新运行本程序" << endl;
        throw runtime_error("权限不足"); }

    if (OsType == System::WSL) {
        cout << "检测到您使用的系统为：" << OS << endl;
        cout << "并且该系统工作于WSL环境" << endl;
        if (Distro == WslDistro::IsNotWsl){
            throw runtime_error("无法获取WSL发行版信息"); }

        if (Distro == WslDistro::Ubuntu){ Ubuntu(); }
        else if (Distro == WslDistro::Debian){ Debian(); }
        else{
            cout << endl
                << "错误：当前仅适配了Ubuntu和Debian" << endl
                << "强行使用可能会造成不可预知的问题" << endl
                << "为避免出现故障，程序会强制退出" << endl;
            throw runtime_error("不支持的发行版"); } }

    else if (OsType == System::Linux) {
        cout << "检测到您使用的系统为：" << OS << endl;
        if (OS.find("Ubuntu") != string::npos){
            Ubuntu(); }
        if (OS.find("Debian") != string::npos or
            OS.find("Armbian") != string::npos){
            Debian(); } } }