/*
 * Xournal++
 *
 * Lua API, application library
 *
 * @author Xournal++ Team
 * https://github.com/xournalpp/xournalpp
 *
 * @license GNU GPLv2 or later
 */

#include <cstring>
#include <map>

#include <gtk/gtk.h>

#include "control/Control.h"
#include "control/PageBackgroundChangeController.h"
#include "control/Tool.h"
#include "control/layer/LayerController.h"
#include "control/pagetype/PageTypeHandler.h"
#include "gui/XournalView.h"
#include "gui/widgets/XournalWidget.h"
#include "model/Text.h"

#include "StringUtils.h"
#include "XojMsgBox.h"
using std::map;

/**
 * Renames file 'from' to file 'to' in the file system.
 * Overwrites 'to' if it already exists.
 *
 * Example:
 *   assert(app.glib_rename("path/to/foo", "other/bar"))
 *
 * Preferred to os.rename() because it works across
 * partitions. Uses glib's rename function.
 *
 * Returns 1 on success, and (nil, message) on failure.
 */
static int applib_glib_rename(lua_State* L) {
    GError* err = nullptr;
    GFile* to = g_file_new_for_path(lua_tostring(L, -1));
    GFile* from = g_file_new_for_path(lua_tostring(L, -2));

    g_file_move(from, to, G_FILE_COPY_OVERWRITE, nullptr, nullptr, nullptr, &err);
    g_object_unref(from);
    g_object_unref(to);
    if (err) {
        lua_pushnil(L);
        lua_pushfstring(L, "%s (error code: %d)", err->message, err->code);
        g_error_free(err);
        return 2;
    } else {
        lua_pushinteger(L, 1);
        return 1;
    }
}


/**
 * Create a 'Save As' native dialog and return as a string
 * the filepath of the location the user chose to save.
 *
 * Examples:
 *   local filename = app.saveAs() -- defaults to suggestion "Untitled"
 *   local filename = app.saveAs("foo") -- suggests "foo" as filename
 */
static int applib_saveAs(lua_State* L) {
    GtkFileChooserNative* native;
    gint res;
    int args_returned = 0;  // change to 1 if user chooses file

    const char* filename = luaL_checkstring(L, -1);

    // Create a 'Save As' native dialog
    native = gtk_file_chooser_native_new(_("Save file"), nullptr, GTK_FILE_CHOOSER_ACTION_SAVE, nullptr, nullptr);

    // If user tries to overwrite a file, ask if it's OK
    gtk_file_chooser_set_do_overwrite_confirmation(GTK_FILE_CHOOSER(native), TRUE);
    // Offer a suggestion for the filename if filename absent
    gtk_file_chooser_set_current_name(GTK_FILE_CHOOSER(native),
                                      filename ? filename : (std::string{_("Untitled")}).c_str());

    // Wait until user responds to dialog
    res = gtk_native_dialog_run(GTK_NATIVE_DIALOG(native));

    // Return the filename chosen to lua
    if (res == GTK_RESPONSE_ACCEPT) {
        char* filename = static_cast<char*>(gtk_file_chooser_get_filename(GTK_FILE_CHOOSER(native)));

        lua_pushlstring(L, filename, strlen(filename));
        g_free(static_cast<gchar*>(filename));
        args_returned = 1;
    }

    // Destroy the dialog and free memory
    g_object_unref(native);

    return args_returned;
}

/**
 * Example: local result = app.msgbox("Test123", {[1] = "Yes", [2] = "No"})
 * Pops up a message box with two buttons "Yes" and "No" and returns 1 for yes, 2 for no
 */
static int applib_msgbox(lua_State* L) {
    const char* msg = luaL_checkstring(L, 1);

    // discard any extra arguments passed in
    lua_settop(L, 2);
    luaL_checktype(L, 2, LUA_TTABLE);

    lua_pushnil(L);

    map<int, string> button;

    while (lua_next(L, 2) != 0) {
        int index = lua_tointeger(L, -2);
        const char* buttonText = luaL_checkstring(L, -1);
        lua_pop(L, 1);

        button.insert(button.begin(), std::pair<int, string>(index, buttonText));
    }

    Plugin* plugin = Plugin::getPluginFromLua(L);

    int result = XojMsgBox::showPluginMessage(plugin->getName(), msg, button);
    lua_pushinteger(L, result);
    return 1;
}


/**
 * Allow to register menupoints, this needs to be called from initUi
 *
 * Example: app.registerUi({["menu"] = "HelloWorld", callback="printMessage", accelerator="<Control>a"})
 * registers a menupoint with name "HelloWorld" executing a function named "printMessage",
 * which can be triggered via the "<Control>a" keyboard accelerator
 */
static int applib_registerUi(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    if (!plugin->isInInitUi()) {
        luaL_error(L, "registerUi needs to be called within initUi()");
    }

    // discard any extra arguments passed in
    lua_settop(L, 1);
    luaL_checktype(L, 1, LUA_TTABLE);

    // Now to get the data out of the table
    // 'unpack' the table by putting the values onto
    // the stack first. Then convert those stack values
    // into an appropriate C type.
    lua_getfield(L, 1, "accelerator");
    lua_getfield(L, 1, "menu");
    lua_getfield(L, 1, "callback");
    // stack now has following:
    //    1 = {"menu"="MenuName", callback="functionName", accelerator="<Control>a"}
    //   -3 = "<Control>a"
    //   -2 = "MenuName"
    //   -1 = "functionName"

    const char* accelerator = luaL_optstring(L, -3, nullptr);
    const char* menu = luaL_optstring(L, -2, nullptr);
    const char* callback = luaL_optstring(L, -1, nullptr);
    if (callback == nullptr) {
        luaL_error(L, "Missing callback function!");
    }
    if (menu == nullptr) {
        menu = "";
    }
    if (accelerator == nullptr) {
        accelerator = "";
    }

    int toolbarId = -1;

    int menuId = plugin->registerMenu(menu, callback, accelerator);

    // Make sure to remove all vars which are put to the stack before!
    lua_pop(L, 3);

    // Add return value to the Stack
    lua_createtable(L, 0, 2);

    lua_pushstring(L, "menuId");
    lua_pushinteger(L, menuId);
    lua_settable(L, -3); /* 3rd element from the stack top */

    lua_pushstring(L, "toolbarId");
    lua_pushinteger(L, toolbarId);
    lua_settable(L, -3);

    return 1;
}

/**
 * Execute an UI action (usually internally called from Toolbar / Menu)
 * The argument consists of a Lua table with 3 keys: "action", "group" and "enabled"
 * The key "group" is currently only used for debugging purpose and can savely be omitted.
 * The key "enabled" is true by default.
 *
 * Example 1: app.uiAction({["action"] = "ACTION_PASTE"})
 * pastes the clipboard content into the document
 *
 * Example 2: app.uiAction({["action"] = "ACTION_TOOL_DRAW_ELLIPSE", ["enabled"] = false})
 * turns off the Ellipse drawing type
 */
static int applib_uiAction(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);

    // discard any extra arguments passed in
    lua_settop(L, 1);
    luaL_checktype(L, 1, LUA_TTABLE);

    lua_getfield(L, 1, "group");
    lua_getfield(L, 1, "enabled");
    lua_getfield(L, 1, "action");
    // stack now has following:
    //    1 = {["action"] = "ACTION_GRID_SNAPPING", ["group"] = "GROUP_GRID_SNAPPING", ["enabled"] = true}
    //   -3 = GROUP_GRID_SNAPPING
    //   -2 = true
    //   -1 = "ACTION_GRID_SNAPPING"

    bool enabled = true;

    ActionGroup group = GROUP_NOGROUP;
    const char* groupStr = luaL_optstring(L, -3, nullptr);
    if (groupStr != nullptr) {
        group = ActionGroup_fromString(groupStr);
    }

    if (lua_isboolean(L, -2)) {
        enabled = lua_toboolean(L, -2);
    }

    const char* actionStr = luaL_optstring(L, -1, nullptr);
    if (actionStr == nullptr) {
        luaL_error(L, "Missing action!");
    }

    ActionType action = ActionType_fromString(actionStr);
    GdkEvent* event = nullptr;
    GtkMenuItem* menuitem = nullptr;
    GtkToolButton* toolbutton = nullptr;

    Control* ctrl = plugin->getControl();
    ctrl->actionPerformed(action, group, event, menuitem, toolbutton, enabled);

    // Make sure to remove all vars which are put to the stack before!
    lua_pop(L, 3);

    return 1;
}

/**
 * Select UI action (notifies action listeners)
 * Unless you are sure what you do, use app.uiAction instead!
 * The problem is that only notifying action listeners does not store these changes in the settings, which may create
 * confusion
 *
 * Example: app.uiActionSelected("GROUP_GRID_SNAPPING", "ACTION_GRID_SNAPPING")
 * notifies the action listeners that grid snapping is turned on; it is not recorded in the settings,
 * so better use app.uiAction({["action"] = "ACTION_GRID_SNAPPING") instead
 */
static int applib_uiActionSelected(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);

    ActionGroup group = ActionGroup_fromString(luaL_checkstring(L, 1));
    ActionType action = ActionType_fromString(luaL_checkstring(L, 2));

    Control* ctrl = plugin->getControl();
    ctrl->fireActionSelected(group, action);

    return 1;
}

/**
 * Execute action from sidebar menu
 *
 * Example: app.sidebarAction("MOVE_DOWN")
 * moves down the current page
 */
static int applib_sidebarAction(lua_State* L) {
    // Connect the context menu actions
    const std::map<std::string, SidebarActions> actionMap = {
            {"COPY", SIDEBAR_ACTION_COPY},
            {"DELETE", SIDEBAR_ACTION_DELETE},
            {"MOVE_UP", SIDEBAR_ACTION_MOVE_UP},
            {"MOVE_DOWN", SIDEBAR_ACTION_MOVE_DOWN},
            {"NEW_BEFORE", SIDEBAR_ACTION_NEW_BEFORE},
            {"NEW_AFTER", SIDEBAR_ACTION_NEW_AFTER},
    };
    const char* actionStr = luaL_checkstring(L, 1);
    if (actionStr == nullptr) {
        luaL_error(L, "Missing action!");
    }
    auto pos = actionMap.find(actionStr);
    if (pos == actionMap.end()) {
        luaL_error(L, "Unkonwn action: %s", actionStr);
    }
    Plugin* plugin = Plugin::getPluginFromLua(L);
    SidebarToolbar* toolbar = plugin->getControl()->getSidebar()->getToolbar();
    toolbar->runAction(pos->second);

    return 1;
}

/**
 * Execute action from layer controller
 *
 * Example: app.layerAction("ACTION_DELETE_LAYER")
 * deletes the current layer
 */
static int applib_layerAction(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);

    ActionType action = ActionType_fromString(luaL_checkstring(L, 1));

    Control* ctrl = plugin->getControl();
    ctrl->getLayerController()->actionPerformed(action);

    return 1;
}

/**
 * Change page background of current page
 *
 * Example: app.changeCurrentPageBackground("graph")
 * changes the page background of the current page to graph paper
 */
static int applib_changeCurrentPageBackground(lua_State* L) {
    PageType pt;
    pt.format = PageTypeHandler::getPageTypeFormatForString(luaL_checkstring(L, 1));
    pt.config = luaL_optstring(L, 2, "");

    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* ctrl = plugin->getControl();
    PageBackgroundChangeController* pageBgCtrl = ctrl->getPageBackgroundChangeController();
    pageBgCtrl->changeCurrentPageBackground(pt);

    return 1;
}

/**
 * Change color of a specified tool or of the current tool
 *
 * Example 1: app.changeToolColor({["color"] = 0xff00ff, ["tool"] = "PEN"})
 * changes the color of the pen tool to violet without applying this change to the current selection
 *
 * Example 2: app.changeToolColor({["color"] = 0xff0000, ["selection"] = true })
 * changes the color of the current tool to red and also applies it to the current selection if there is one
 */
static int applib_changeToolColor(lua_State* L) {

    // discard any extra arguments passed in
    lua_settop(L, 1);
    luaL_checktype(L, 1, LUA_TTABLE);

    lua_getfield(L, 1, "selection"); /* either true or false, for changing selection color
                                       defaults to false*/
    lua_getfield(L, 1, "tool");      /* "pen", "highlighter", "text"
                                      "select_rect", "select_object", "select_region"
                                      if omitted, current Tool is used */
    lua_getfield(L, 1, "color");     // an RGB hex code defining the color
    // stack now has following:
    //    1 = {["color"] = 0xff00ff, ["tool"] = "PEN", ["selection"] = true}
    //   -3 = true
    //   -2 = "pen"
    //   -1 = 0xff0077

    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* ctrl = plugin->getControl();
    ToolHandler* toolHandler = ctrl->getToolHandler();

    bool selection = false;
    if (lua_isboolean(L, -3)) {
        selection = lua_toboolean(L, -3);
    } else if (!lua_isnil(L, -3)) {
        g_warning(""
                  "selection"
                  " key should be a boolean value (or nil)");
    }

    ToolType toolType = toolHandler->getToolType();
    const char* toolStr = luaL_optstring(L, -2, nullptr);
    if (toolStr != nullptr) {
        toolType = toolTypeFromString(StringUtils::toLowerCase(toolStr));
    }

    if (toolType == TOOL_NONE) {
        g_warning("tool \"%s\" is not valid or no tool has been selected", toolTypeToString(toolType).c_str());
        lua_pop(L, 3);
        return 0;
    }

    int color = 0x000000;
    if (lua_isinteger(L, -1)) {
        color = lua_tointeger(L, -1);
        if (color < 0x000000 || color > 0xffffff) {
            g_warning("Color 0x%x is no valid RGB color. ", color);
            return 0;
        }
    } else if (!lua_isnil(L, -1)) {
        g_warning(" "
                  "color"
                  " key should be an RGB hex code in the form 0xRRGGBB (or nil)");
    }

    Tool& tool = toolHandler->getTool(toolType);

    if (tool.hasCapability(TOOL_CAP_COLOR)) {
        tool.setColor(color);
        ctrl->toolColorChanged();
        if (selection)
            ctrl->changeColorOfSelection();
    } else {
        g_warning("tool \"%s\" has no color capability", toolTypeToString(toolType).c_str());
    }

    // Make sure to remove all vars which are put to the stack before!
    lua_pop(L, 3);

    return 1;
}

/*
 * Select Background Pdf Page for Current Page
 * First argument is an integer (page number) and the second argument is a boolean (isRelative)
 * specifying whether the page number is relative to the current pdf page or absolute
 *
 * Example 1: app.changeBackgroundPdfPageNr(1, true)
 * changes the pdf page to the next one (relative mode)
 *
 * Example 2: app.changeBackgroundPdfPageNr(7, false)
 * changes the page background to the 7th pdf page (absolute mode)
 */
static int applib_changeBackgroundPdfPageNr(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);

    size_t nr = luaL_checkinteger(L, 1);
    bool relative = true;
    if (lua_isboolean(L, 2)) {
        relative = lua_toboolean(L, 2);
    }

    Control* control = plugin->getControl();
    Document* doc = control->getDocument();
    PageRef const& page = control->getCurrentPage();

    if (!page) {
        luaL_error(L, "No page!");
    }

    size_t selected = nr - 1;
    if (relative) {
        bool isPdf = page->getBackgroundType().isPdfPage();
        if (isPdf) {
            selected = page->getPdfPageNr() + nr;
        } else {
            luaL_error(L, "Current page has no pdf background, cannot use relative mode!");
        }
    }
    if (selected >= 0 && selected < static_cast<int>(doc->getPdfPageCount())) {
        // no need to set a type, if we set the page number the type is also set
        page->setBackgroundPdfPageNr(selected);

        XojPdfPageSPtr p = doc->getPdfPage(selected);
        page->setSize(p->getWidth(), p->getHeight());
    } else {
        luaL_error(L, "Pdf page number %d does not exist!", selected + 1);
    }

    return 1;
}

/*
 * Returns a table encoding the document structure in a Lua table of the shape
 * {
 *   "pages" = {
 *     {
 *       "pageWidth" = number,
 *       "pageHeight" = number,
 *       "isAnnoated" = bool,
 *       "pageTypeFormat" = string,
 *       "pdfBackgroundPageNo" = integer (0, if there is no pdf background page),
 *       "layers" = {
 *         [0] = {
 *           "isVisible" = bool
 *         },
 *         [1] = {
 *           "isVisible" = bool,
 *           "isAnnotated" = bool
 *         },
 *         ...
 *       },
 *       "currentLayer" = integer
 *     },
 *     ...
 *   }
 *   "currentPage" = integer,
 *   "pdfBackgroundFilename" = string (empty if there is none)
 * }
 *
 * Example: local docStructure = app.getDocumentStructure()
 */
static int applib_getDocumentStructure(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();
    Document* doc = control->getDocument();
    LayerController* lc = control->getLayerController();

    lua_newtable(L);

    lua_pushliteral(L, "pages");
    lua_newtable(L);  // beginning of pages table

    // add pages
    for (size_t p = 1; p <= doc->getPageCount(); ++p) {
        auto page = doc->getPage(p - 1);
        lua_pushinteger(L, p);
        lua_newtable(L);  // beginning of table for page p

        lua_pushliteral(L, "pageWidth");
        lua_pushnumber(L, page->getWidth());
        lua_settable(L, -3);

        lua_pushliteral(L, "pageHeight");
        lua_pushnumber(L, page->getHeight());
        lua_settable(L, -3);

        lua_pushliteral(L, "isAnnotated");
        lua_pushboolean(L, page->isAnnotated());
        lua_settable(L, -3);

        lua_pushliteral(L, "pageTypeFormat");
        PageType pt = page->getBackgroundType();
        std::string pageTypeFormat = PageTypeHandler::getStringForPageTypeFormat(pt.format);
        lua_pushstring(L, pageTypeFormat.c_str());
        lua_settable(L, -3);

        lua_pushliteral(L, "pdfBackgroundPageNo");
        lua_pushinteger(L, page->getPdfPageNr() + 1);
        lua_settable(L, -3);

        lua_pushstring(L, "layers");
        lua_newtable(L);  // beginning of layers table

        // add background layer
        lua_pushinteger(L, 0);
        lua_newtable(L);  // beginning of table for background layer

        lua_pushliteral(L, "isVisible");
        lua_pushboolean(L, page->isLayerVisible(0));
        lua_settable(L, -3);

        lua_pushliteral(L, "name");
        lua_pushstring(L, page->getBackgroundName().c_str());
        lua_settable(L, -3);

        lua_settable(L, -3);  // end of table for background layer

        // add (non-background) layers
        int currLayer = 0;

        for (auto l: *page->getLayers()) {
            lua_pushinteger(L, ++currLayer);
            lua_newtable(L);  // beginning of table for layer l

            lua_pushliteral(L, "name");
            lua_pushstring(L, lc->getLayerNameById(currLayer).c_str());
            lua_settable(L, -3);

            lua_pushliteral(L, "isVisible");
            lua_pushboolean(L, l->isVisible());
            lua_settable(L, -3);

            lua_pushliteral(L, "isAnnotated");
            lua_pushboolean(L, l->isAnnotated());
            lua_settable(L, -3);

            lua_settable(L, -3);  // end of table for layer l
        }
        lua_settable(L, -3);  // end of layers table

        lua_pushliteral(L, "currentLayer");
        lua_pushinteger(L, page->getSelectedLayerId());
        lua_settable(L, -3);

        lua_settable(L, -3);  // end of table for page p
    }
    lua_settable(L, -3);  // end of pages table

    lua_pushliteral(L, "currentPage");
    lua_pushinteger(L, lc->getCurrentPageId() + 1);
    lua_settable(L, -3);

    lua_pushliteral(L, "pdfBackgroundFilename");
    lua_pushstring(L, doc->getPdfFilepath().string().c_str());
    lua_settable(L, -3);

    return 1;
}

/**
 * Scrolls to the page specified relatively or absolutely (by default)
 * The page number is clamped to the range between the first and last page
 *
 * Example 1: app.scrollToPage(1, true)
 * scrolls to the next page (relative mode)
 *
 * Example 2: app.scrollToPage(10)
 * scrolls to page 10 (absolute mode)
 **/
static int applib_scrollToPage(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();

    int val = luaL_checkinteger(L, 1);
    bool relative = false;
    if (lua_isboolean(L, 2)) {
        relative = lua_toboolean(L, 2);
    }
    int page = (relative) ? control->getCurrentPageNo() + val : val - 1;

    const int first = 0;
    const int last = static_cast<int>(control->getDocument()->getPageCount()) - 1;
    control->getScrollHandler()->scrollToPage(std::clamp(page, first, last));

    return 1;
}

/**
 * Scrolls to the position on the selected page specified relatively (by default) or absolutely
 *
 * Example 1: app.scrollToPos(20,10)
 * scrolls 20pt right and 10pt down (relative mode)
 *
 * Example 2: app.scrollToPos(200, 50, false)
 * scrolls to page position 200pt right and 50pt down from the left page corner  (absolute mode)
 **/
static int applib_scrollToPos(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();
    Layout* layout = control->getWindow()->getLayout();

    double dx = luaL_checknumber(L, 1);
    double dy = luaL_checknumber(L, 2);
    bool relative = true;
    if (lua_isboolean(L, 3)) {
        relative = lua_toboolean(L, 3);
    }

    if (relative) {
        layout->scrollRelative(dx, dy);
    } else {
        layout->scrollAbs(dx, dy);
    }

    return 1;
}

/**
 * Sets the current page as indicated (without scrolling)
 * The page number passed is clamped to the range between first page and last page
 *
 * Example: app.setCurrentPage(1)
 * makes the first page the new current page
 **/
static int applib_setCurrentPage(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();
    size_t pageId = luaL_checkinteger(L, 1);
    const size_t first = 1;
    const size_t last = control->getDocument()->getPageCount();
    control->firePageSelected(std::clamp(pageId, first, last) - 1);

    return 1;
}

/**
 * Sets the width and height of the current page in pt = 1/72 inch either relatively or absolutely (by default)
 *
 * Example 1: app.setPageSize(595.275591, 841.889764)
 * makes the current page have standard (A4 paper) width and height (absolute mode)
 *
 * Example 2: app.setPageSize(0, 14.17*6, true)
 * adds 14.17*6 pt = 3cm to the height of the page (relative mode)
 **/
static int applib_setPageSize(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();
    Document* doc = control->getDocument();
    PageRef const& page = control->getCurrentPage();

    if (!page) {
        luaL_error(L, "No page!");
    }

    double width = luaL_checknumber(L, 1);
    double height = luaL_checknumber(L, 2);

    bool relative = false;
    if (lua_isboolean(L, 3)) {
        relative = lua_toboolean(L, 3);
    }

    if (relative) {
        width += page->getWidth();
        height += page->getHeight();
    }

    if (width > 0 && height > 0) {
        doc->lock();
        Document::setPageSize(page, width, height);
        doc->unlock();
    }

    size_t pageNo = doc->indexOf(page);
    if (pageNo != npos && pageNo < doc->getPageCount()) {
        control->firePageSizeChanged(pageNo);
    }

    return 1;
}

/**
 * Sets the current layer of the current page as indicated and updates visibility if specified (by default it does not)
 * Displays an error message, if the selected layer does not exist
 *
 * Example 1: app.setCurrentLayer(2, true)
 * makes the second (non-background) layer the current layer and makes layers 1, 2 and the background layer visible, the
 *others hidden
 *
 * Example 2: app.setCurrentLayer(2, false)
 * makes the second (non-background) layer the current layer and does not change visibility
 **/
static int applib_setCurrentLayer(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();
    PageRef const& page = control->getCurrentPage();

    if (!page) {
        luaL_error(L, "No page!");
    }

    size_t layerCount = page->getLayerCount();
    size_t layerId = luaL_checkinteger(L, 1);

    if (layerId < 0 || layerId > layerCount) {
        luaL_error(L, "No layer with layer ID %d", layerId);
    }

    bool update = false;
    if (lua_isboolean(L, 2)) {
        update = lua_toboolean(L, 2);
    }

    control->getLayerController()->switchToLay(layerId, update);

    return 1;
}

/*
 * Sets the visibility of the current layer
 *
 * Example: app.setLayerVisibility(true)
 * makes the current layer visible
 */
static int applib_setLayerVisibility(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();

    bool enabled = true;
    if (lua_isboolean(L, 1)) {
        enabled = lua_toboolean(L, 1);
    }

    int layerId = control->getCurrentPage()->getSelectedLayerId();
    control->getLayerController()->setLayerVisible(layerId, enabled);
    return 1;
}

/**
 * Sets currently selected layer's name.
 *
 * Example: app.setCurrentLayerName("Custom name 1")
 * Changes current layer name to "Custom name 1"
 **/
static int applib_setCurrentLayerName(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();

    if (lua_isstring(L, 1)) {
        auto name = lua_tostring(L, 1);
        control->getLayerController()->setCurrentLayerName(name);
    }

    return 1;
}

/**
 * Sets background name.
 *
 * Example: app.setBackgroundName("Custom name 1")
 * Changes background name to "Custom name 1"
 **/
static int applib_setBackgroundName(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();
    PageRef const& page = control->getCurrentPage();

    if (!page) {
        luaL_error(L, "No page!");
    }

    if (lua_isstring(L, 1)) {
        auto name = lua_tostring(L, 1);
        page->setBackgroundName(name);
    }

    return 1;
}


/**
 * Scales all text elements of the current layer by the given scale factor.
 * This means the font sizes get scaled, wheras the position of the left upper corner
 * of the bounding box remains unchanged
 *
 * Example: app.scaleTextElements(2.3)
 * scales all text elements on the current layer with factor 2.3
 **/
static int applib_scaleTextElements(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();

    double f = luaL_checknumber(L, 1);

    control->clearSelectionEndText();

    std::vector<Element*> elements = *control->getCurrentPage()->getSelectedLayer()->getElements();

    for (Element* e: elements) {
        if (e->getType() == ELEMENT_TEXT) {
            Text* t = static_cast<Text*>(e);
            t->scale(t->getX(), t->getY(), f, f, 0.0, false);
        }
    }

    elements.clear();

    return 1;
}


/**
 * Gets the display DPI.
 * Example: app.getDisplayDpi()
 **/
static int applib_getDisplayDpi(lua_State* L) {
    Plugin* plugin = Plugin::getPluginFromLua(L);
    Control* control = plugin->getControl();
    int dpi = control->getSettings()->getDisplayDpi();
    lua_pushinteger(L, dpi);

    return 1;
}


/*
 * The full Lua Plugin API.
 * See above for example usage of each function.
 */
static const luaL_Reg applib[] = {{"msgbox", applib_msgbox},
                                  {"glib_rename", applib_glib_rename},
                                  {"saveAs", applib_saveAs},
                                  {"registerUi", applib_registerUi},
                                  {"uiAction", applib_uiAction},
                                  {"uiActionSelected", applib_uiActionSelected},
                                  {"sidebarAction", applib_sidebarAction},
                                  {"layerAction", applib_layerAction},
                                  {"changeToolColor", applib_changeToolColor},
                                  {"changeCurrentPageBackground", applib_changeCurrentPageBackground},
                                  {"changeBackgroundPdfPageNr", applib_changeBackgroundPdfPageNr},
                                  {"getDocumentStructure", applib_getDocumentStructure},
                                  {"scrollToPage", applib_scrollToPage},
                                  {"scrollToPos", applib_scrollToPos},
                                  {"setCurrentPage", applib_setCurrentPage},
                                  {"setPageSize", applib_setPageSize},
                                  {"setCurrentLayer", applib_setCurrentLayer},
                                  {"setLayerVisibility", applib_setLayerVisibility},
                                  {"setCurrentLayerName", applib_setCurrentLayerName},
                                  {"setBackgroundName", applib_setBackgroundName},
                                  {"scaleTextElements", applib_scaleTextElements},
                                  {"getDisplayDpi", applib_getDisplayDpi},
                                  // Placeholder
                                  //	{"MSG_BT_OK", nullptr},

                                  {nullptr, nullptr}};

/**
 * Open application Library
 */
LUAMOD_API int luaopen_app(lua_State* L) {
    luaL_newlib(L, applib);
    //	lua_pushnumber(L, MSG_BT_OK);
    //	lua_setfield(L, -2, "MSG_BT_OK");
    return 1;
}