/**
 * @file loginui.cpp
 * @author apio (cloudapio.eu)
 * @brief Graphical login prompt.
 *
 * @copyright Copyright (c) 2024, the Luna authors.
 *
 */

#include <luna/RefString.h>
#include <luna/SHA.h>
#include <os/ArgumentParser.h>
#include <os/Config.h>
#include <os/File.h>
#include <os/FileSystem.h>
#include <os/IPC.h>
#include <os/Process.h>
#include <os/Security.h>
#include <pwd.h>
#include <shadow.h>
#include <sys/stat.h>
#include <ui/App.h>
#include <ui/Button.h>
#include <ui/InputField.h>
#include <ui/Label.h>
#include <ui/Layout.h>
#include <unistd.h>

enum Stage
{
    UsernameInput,
    PasswordInput,
};

static constexpr ui::Color BACKGROUND_COLOR = ui::Color::from_rgb(89, 89, 89);

Result<String> hash_password(StringView& view)
{
    SHA256 sha;
    sha.append((const u8*)view.chars(), view.length());
    auto digest = TRY(sha.digest());
    return digest.to_string();
}

Result<int> luna_main(int argc, char** argv)
{
    os::ArgumentParser parser;
    parser.add_description("Login prompt for a graphical UI session.");
    parser.add_system_program_info("loginui"_sv);
    parser.parse(argc, argv);

    if (geteuid() != 0)
    {
        os::eprintln("error: %s can only be started as root.", argv[0]);
        return 1;
    }

    TRY(os::Security::pledge("stdio rpath wpath unix proc exec id", nullptr));

    setsid();

    bool success = os::IPC::Notifier::run_and_wait(
        [&] {
            StringView wind_command[] = { "/usr/bin/wind" };
            os::Process::spawn(wind_command[0], Slice<StringView>(wind_command, 1));
        },
        1000);

    if (!success)
    {
        os::eprintln("loginui: failed to start wind, timed out");
        return 1;
    }

    auto config = TRY(os::ConfigFile::open("/etc/loginui.conf"));

    if (config->read_boolean_or("Autologin", false))
    {
        StringView username = config->read_string_or("AutologinUser", "");

        if (!username.is_empty())
        {
            auto flag = RefString::format("--user=%s"_sv, username.chars()).release_value();

            StringView startui_command[] = { "/usr/bin/startui", flag.view() };
            os::Process::exec(startui_command[0], Slice<StringView>(startui_command, 2));
            unreachable();
        }
    }

    ui::App app;
    TRY(app.init());

    auto* window = TRY(ui::Window::create(ui::Rect { 300, 300, 400, 300 }));
    app.set_main_window(window);

    window->set_title("Log in");
    window->set_background(BACKGROUND_COLOR);

    ui::VerticalLayout main_layout;
    window->set_main_widget(main_layout);

    ui::Label label("Username:");
    main_layout.add_widget(label);

    ui::InputField input(ui::Font::default_font());
    main_layout.add_widget(input);

    ui::Label error("");
    error.set_font(ui::Font::default_bold_font());
    error.set_color(ui::RED);
    main_layout.add_widget(error);

    Stage stage = Stage::UsernameInput;
    struct passwd* pw;

    input.on_submit([&](StringView data) {
        error.set_text("");
        if (stage == Stage::UsernameInput)
        {
            struct passwd* entry = getpwnam(data.chars());
            if (!entry)
            {
                error.set_text("User not found.");
                input.clear();
                return;
            }

            pw = entry;
            stage = Stage::PasswordInput;
            label.set_text("Password:");

            RefString title = RefString::format("Log in: %s"_sv, data.chars()).release_value();
            window->set_title(title.view());

            input.clear();

            return;
        }
        else
        {
            const char* passwd = pw->pw_passwd;

            // If the user's password entry is 'x', read their password from the shadow file instead.
            if (!strcmp(pw->pw_passwd, "x"))
            {
                struct spwd* sp = getspnam(pw->pw_name);

                if (!sp)
                {
                    error.set_text("User not found in shadow file.");
                    input.clear();
                    return;
                }

                endspent();

                passwd = sp->sp_pwdp;
            }

            if (!strcmp(passwd, "!"))
            {
                error.set_text("User's password is disabled.");
                input.clear();
                return;
            }

            auto result = hash_password(data).release_value();

            if (strcmp(result.chars(), passwd))
            {
                error.set_text("Incorrect password.");
                input.clear();
                return;
            }

            auto flag = RefString::format("--user=%s"_sv, pw->pw_name).release_value();

            StringView startui_command[] = { "/usr/bin/startui", flag.view() };
            os::Process::exec(startui_command[0], Slice<StringView>(startui_command, 2));
            unreachable();
        }
    });

    return app.run();
}