#include <gtk/gtk.h>
#include <epoxy/gl.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <Core/gb.h>
#include "shader.h"

#define str(x) #x
#define xstr(x) str(x)

GtkBuilder *builder;
GtkWindow *main_window;
GtkGLArea *gl_area;
shader_t shader;

GB_gameboy_t gb;
static bool paused = false;
static uint32_t pixel_buffer_1[256 * 224], pixel_buffer_2[256 * 224];
static uint32_t *active_pixel_buffer = pixel_buffer_1, *previous_pixel_buffer = pixel_buffer_2;
static bool underclock_down = false, rewind_down = false, do_rewind = false, rewind_paused = false, turbo_down = false;
static double clock_mutliplier = 1.0;

static typeof(free) *free_function = NULL;
static char *battery_save_path_ptr;


typedef struct UserData {
	bool fullscreen;
	GFile *file;
} UserData;

typedef struct{
	int16_t x, y;
	uint16_t w, h;
} Rect;

static void run(UserData *user_data);

static Rect rect;

void render_texture(void *pixels,  void *previous) {
	static void *_pixels = NULL;
	if (pixels) {
		_pixels = pixels;
	}

	glClearColor(0, 0, 0, 1);
	glClear(GL_COLOR_BUFFER_BIT);
	
	render_bitmap_with_shader(&shader, _pixels, previous, GB_get_screen_width(&gb), GB_get_screen_height(&gb), rect.x, rect.y, rect.w, rect.h);
	gtk_widget_queue_draw(GTK_WIDGET(gl_area));
}

void update_viewport(void) {
    int win_width = gtk_widget_get_allocated_width(GTK_WIDGET(gl_area));
    int win_height = gtk_widget_get_allocated_height(GTK_WIDGET(gl_area));
    
    double x_factor = win_width / (double) GB_get_screen_width(&gb);
    double y_factor = win_height / (double) GB_get_screen_height(&gb);
    
    if (true /*configuration.scaling_mode == GB_SDL_SCALING_INTEGER_FACTOR*/) {
        x_factor = (int)(x_factor);
        y_factor = (int)(y_factor);
    }
    
    /*if (configuration.scaling_mode != GB_SDL_SCALING_ENTIRE_WINDOW) {
        if (x_factor > y_factor) {
            x_factor = y_factor;
        }
        else {
            y_factor = x_factor;
        }
    }*/
    
    unsigned new_width = x_factor * GB_get_screen_width(&gb);
    unsigned new_height = y_factor * GB_get_screen_height(&gb);
    
    rect = (Rect){(win_width  - new_width) / 2, (win_height - new_height) / 2, new_width, new_height};
    
    glViewport(rect.x, rect.y, rect.w, rect.h);
}

// Determines if a ComboBox entry should be converted into a separator.
// Each element with a text value of `<separator>` will be converted into a separator element.
static gboolean is_separator(GtkTreeModel *model, GtkTreeIter *iter, gpointer data) {
	gchar *text = NULL;

	gtk_tree_model_get(model, iter, 0, &text, -1);
	gboolean result = g_strcmp0("<separator>", text) == 0;

	return result;
}

// Recursively goes through all children of the given container and sets
// our `is_separator` function to all children of type`GtkComboBox`
static void set_combo_box_row_separator_func(GtkContainer *container) {
	GList *list = gtk_container_get_children(container);

	while (list) {
		if (GTK_IS_COMBO_BOX(list->data)) {
			gtk_combo_box_set_row_separator_func(GTK_COMBO_BOX(list->data), is_separator, NULL, NULL);
		}

		if (GTK_IS_CONTAINER(list->data)) {
			set_combo_box_row_separator_func(GTK_CONTAINER(list->data));
		}

		list = list->next;
	}

	g_list_free_full(list, NULL);
}

// Returns true if the application should show a menubar
static gboolean show_menubar(void) {
	GtkSettings *settings = gtk_settings_get_default();
	gboolean result;

	g_object_get(settings, "gtk-shell-shows-menubar", &result, NULL);

	return result;
}

// Returns a GObject by ID from our GtkBuilder instance
static GObject *get_object(gchararray id) {
	return gtk_builder_get_object(builder, id);
}

// Returns a `GApplication`s `GMenuModel` by ID
// GApplication menus are loaded from `gtk/menus.ui`, `gtk/menus-traditional.ui` and `gtk/menus-common.ui`.
static GMenuModel *get_menu_model(GApplication *app, const char *id) {
	GMenu *menu;

	menu = gtk_application_get_menu_by_id(GTK_APPLICATION(app), id);

	return menu ? G_MENU_MODEL(g_object_ref_sink(menu)) : NULL;
}

// app.quit GAction
// Exits the application
static void activate_quit(GSimpleAction *action, GVariant *parameter, gpointer user_data) {
	g_application_quit(G_APPLICATION(user_data));
}

// app.about GAction
// Opens the about dialog
static void activate_about(GSimpleAction *action, GVariant *parameter, gpointer user_data) {
	GObject *dialog = get_object("about_dialog");
	gtk_dialog_run(GTK_DIALOG(dialog));
	gtk_widget_hide(GTK_WIDGET(dialog));
}

// List of GActions for the `app` prefix
static GActionEntry app_entries[] = {
	{ "quit", activate_quit, NULL, NULL, NULL },
	{ "about", activate_about, NULL, NULL, NULL },
};

G_MODULE_EXPORT void on_show_window(GtkWidget *w, gpointer window) {
	gtk_widget_show_all(GTK_WIDGET(window));
}

G_MODULE_EXPORT void on_boot_rom_location_changed(GtkWidget *w, gpointer user_data_gptr) {
	GtkComboBox *box = GTK_COMBO_BOX(w);

	g_print("Active: %s", gtk_combo_box_get_active_id(box));
}

G_MODULE_EXPORT void gl_draw(GtkWidget *window) {
	render_texture(active_pixel_buffer, NULL);
}

G_MODULE_EXPORT void gl_init(GtkWidget *window) {
	const char *renderer;

	GList *children = gtk_container_get_children(GTK_CONTAINER(window));

	while (children) {
		if (GTK_IS_GL_AREA(children->data)) {
			gl_area = GTK_GL_AREA(children->data);
			break;
		}

		children = children->next;
	}
	g_list_free(children);

	if (gl_area == NULL) {
		g_printerr("Unable to find GtkGLArea in window\n");
		return;
	}

	gtk_gl_area_make_current(gl_area);
	if (gtk_gl_area_get_error(gl_area) != NULL) {
		return;
	}

	renderer = (char *) glGetString(GL_RENDERER);
	g_print("GtkGLArea on %s\n", renderer ? renderer : "Unknown");

	if (!init_shader_with_name(&shader, /*configuration.filter*/ "OmniScale")) {
		init_shader_with_name(&shader, "NearestNeighbor");
	}
}

// This functions gets called immediately after registration of the GApplication
static void startup(GApplication *app, gpointer user_data_gptr) {
	// UserData *user_data = user_data_gptr;

	builder = gtk_builder_new_from_resource(RESOURCE_PREFIX "ui/window.ui");
	gtk_builder_connect_signals(builder, NULL);

	g_action_map_add_action_entries(G_ACTION_MAP(app), app_entries, G_N_ELEMENTS(app_entries), app);

	GtkWindow *preferences = GTK_WINDOW(get_object("preferences"));
	set_combo_box_row_separator_func(GTK_CONTAINER(preferences));

	GtkWindow *vram_viewer = GTK_WINDOW(get_object("vram_viewer"));
	set_combo_box_row_separator_func(GTK_CONTAINER(vram_viewer));

	// Handle the whole menubar situation …
	if (show_menubar()) {
		// Use a standard window as main window
		main_window = GTK_WINDOW(get_object("main_no_titlebar"));
		gtk_widget_destroy(GTK_WIDGET(get_object("main_with_titlebar")));

		// Hide hamburger button
		GtkMenuButton *hamburger_button = GTK_MENU_BUTTON(get_object("hamburger_button"));
		gtk_widget_hide(GTK_WIDGET(hamburger_button));
		gtk_widget_set_no_show_all(GTK_WIDGET(hamburger_button), TRUE);

		GMenuModel *menubar = get_menu_model(app, "menubar");
		gtk_application_set_menubar(GTK_APPLICATION(app), menubar);
	}
	else {
		// Use a window with a custom title bar
		main_window = GTK_WINDOW(get_object("main_with_titlebar"));
		gtk_widget_destroy(GTK_WIDGET(get_object("main_no_titlebar")));

		// Disable menubar
		gtk_application_set_menubar(GTK_APPLICATION(app), NULL);

		// Hook menubar up to the hamburger button
		GtkMenuButton *hamburger_button = GTK_MENU_BUTTON(get_object("hamburger_button"));
		GMenuModel *hamburger_menu = get_menu_model(app, "menubar");
		gtk_menu_button_set_menu_model(hamburger_button, hamburger_menu);
	}

	gtk_window_set_title(main_window, "SameBoy v" xstr(VERSION));

	// Define a set of window icons
	GList *icon_list = NULL;
	static char* icons[] = {
		RESOURCE_PREFIX "logo_256.png",
		RESOURCE_PREFIX "logo_128.png",
		RESOURCE_PREFIX "logo_64.png",
		RESOURCE_PREFIX "logo_48.png",
		RESOURCE_PREFIX "logo_32.png",
		RESOURCE_PREFIX "logo_16.png"
	};

	// Create list of GdkPixbufs
	for (int i = 0; i < (sizeof(icons) / sizeof(const char*)); ++i) {
		GdkPixbuf *icon = gdk_pixbuf_new_from_resource(icons[i], NULL);
		if (!icon) continue;

		icon_list = g_list_prepend(icon_list, icon);
	}

	// Let GTK choose the proper icon
	gtk_window_set_icon_list(main_window, icon_list);

	// Add missing information to the about dialog
	GtkAboutDialog *about_dialog = GTK_ABOUT_DIALOG(get_object("about_dialog"));
	gtk_about_dialog_set_logo(about_dialog, g_list_nth_data(icon_list, 3)); // reuse the 64x64 icon
	gtk_about_dialog_set_version(about_dialog, "v" xstr(VERSION));
	g_list_free(icon_list);
}

// This function gets called when the GApplication gets activated, i.e. it is ready to show widgets.
static void activate(GApplication *app, gpointer user_data_gptr) {
	UserData *user_data = user_data_gptr;

	if (user_data->fullscreen) {
		gtk_window_fullscreen(main_window);
	}

	g_signal_connect(main_window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
	gtk_application_add_window(GTK_APPLICATION(app), main_window);
	gtk_widget_show_all(GTK_WIDGET(main_window));

	update_viewport();
	run(user_data);
}

// This function gets called when there are files to open.
// Note: When `open` gets called `activate` won’t fire unless we call it ourselves.
static void open(GApplication *app, GFile **files, gint n_files, const gchar *hint, gpointer user_data_gptr) {
	UserData *user_data = user_data_gptr;

	if (n_files > 1) {
		g_printerr("More than one file specified\n");
		g_application_quit(app);
		return;
	}

	user_data->file = files[0];

	// We have handled the files, now activate the application
	activate(app, user_data_gptr);
}

// This function gets called after the parsing of the commandline options has occurred.
static gint handle_local_options(GApplication *app, GVariantDict *options, gpointer user_data_gptr) {
	UserData *user_data = user_data_gptr;
	guint32 count;

	if (g_variant_dict_lookup(options, "version", "b", &count)) {
		g_print("SameBoy v" xstr(VERSION) "\n");
		return EXIT_SUCCESS;
	}

	if (g_variant_dict_lookup(options, "fullscreen", "b", &count)) {
		user_data->fullscreen = true;
	}

	return -1;
}

static uint32_t rgb_encode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b) {
	uint32_t color = 0xFF000000 | (b << 16) | (g << 8) | r; // abgr
	return color;
}

static void vblank(GB_gameboy_t *gb) {
	// render_texture(active_pixel_buffer, NULL);

	while (gtk_events_pending()) {
		gtk_main_iteration();
	}
}

static void run(UserData *user_data) {
	GB_model_t model = GB_MODEL_CGB_E;

	if (GB_is_inited(&gb)) {
		GB_switch_model_and_reset(&gb, model);
	}
	else {
		GB_init(&gb, model);

		GB_set_vblank_callback(&gb, (GB_vblank_callback_t) vblank);
		GB_set_pixels_output(&gb, active_pixel_buffer);
		GB_set_rgb_encode_callback(&gb, rgb_encode);
		// GB_set_sample_rate(&gb, have_aspec.freq);
		// GB_set_color_correction_mode(&gb, configuration.color_correction_mode);
		// GB_set_highpass_filter_mode(&gb, configuration.highpass_mode);
		// GB_set_rewind_length(&gb, configuration.rewind_length);
		// GB_set_update_input_hint_callback(&gb, handle_events);
		// GB_apu_set_sample_callback(&gb, gb_audio_callback);
	}

	GError *gerror;
	GBytes *boot_rom_f;
	const guchar *boot_rom_data;
	gsize boot_rom_size;
	
	boot_rom_f = g_resources_lookup_data(RESOURCE_PREFIX "bootroms/cgb_boot.bin", G_RESOURCE_LOOKUP_FLAGS_NONE, &gerror);
	boot_rom_data = g_bytes_get_data(boot_rom_f, &boot_rom_size);

	GB_load_boot_rom_from_buffer(&gb, boot_rom_data, boot_rom_size);
	
	if (user_data->file != NULL) {
		GB_load_rom(&gb, g_file_get_path(user_data->file));
	}

	/* Run emulation */
	while (true) {
		if (paused || rewind_paused) {
			while (gtk_events_pending()) {
				gtk_main_iteration();
			}
		}
		else {
			if (do_rewind) {
				GB_rewind_pop(&gb);
				if (turbo_down) {
					GB_rewind_pop(&gb);
				}
				if (!GB_rewind_pop(&gb)) {
					rewind_paused = true;
				}
				do_rewind = false;
			}
			GB_run(&gb);
		}
	}
}

int main(int argc, char *argv[]) {
	// Create our GApplication and tell GTK that we are able to handle files
	GtkApplication *app = gtk_application_new(APP_ID, G_APPLICATION_HANDLES_OPEN);

	UserData user_data = { NULL };

	// Define our command line parameters
	GOptionEntry entries[] = {
		{ "version", 'v', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, NULL, "Show the application version", NULL },
		{ "fullscreen", 'f', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, NULL, "Start in fullscreen mode", NULL },
		{ NULL }
	};
	// Setup our command line information
	g_application_add_main_option_entries(G_APPLICATION(app), entries);
	g_application_set_option_context_parameter_string(G_APPLICATION(app), "[FILE…]");
	g_application_set_option_context_summary(G_APPLICATION(app), "SameBoy is an open source Game Boy (DMG) and Game Boy Color (CGB) emulator.");

	// Add signal handlers
	g_signal_connect(app, "handle-local-options", G_CALLBACK(handle_local_options), &user_data);
	g_signal_connect(app, "startup", G_CALLBACK(startup), &user_data);
	g_signal_connect(app, "activate", G_CALLBACK(activate), &user_data);
	g_signal_connect(app, "open", G_CALLBACK(open), &user_data);

	// Start our GApplication main loop
	int status = g_application_run(G_APPLICATION(app), argc, argv);
	g_object_unref(app);

	return status;
}