/*
 * Copyright (C) 2020 Jordan Halase <jordan@halase.me>
 *
 * Permission to use, copy, modify, and/or distribute this software for any 
 * purpose with or without fee is hereby granted, provided that the above 
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <stdio.h>
#include <stdlib.h>

#include <python3.7/Python.h>
#include <pygobject-3.0/pygobject.h>
#include <gtk/gtk.h>

/* Name of the Python GTK Widget class */
#define WIDGET_NAME	"MainWidget"

/* Name of the Python module */
#define MODULE_NAME	("ui." WIDGET_NAME)

/** Initialize a Python interpreter and load the main module */
static PyObject *init_python_module(const char *module_name)
{
	Py_Initialize();

	PyObject *sys_path = PySys_GetObject("path");
	PyList_Append(sys_path, PyUnicode_FromString("."));

	PyObject *module = PyImport_ImportModule(module_name);
	if (!module) {
		PyErr_Print();
	}

	return module;
}

/** Construct a new Python widget from a loaded module */
static GtkWidget *new_python_widget(PyObject *module)
{
	PyObject *widget_py = PyObject_CallMethod(module, WIDGET_NAME, "");
	if (!widget_py) {
		PyErr_Print();
		return NULL;
	}

	GObject *observed = pygobject_get(widget_py);
	if (!observed || !G_IS_OBJECT(observed)) {
		fprintf(stderr, WIDGET_NAME " not a GObject\n");
	}
	return GTK_WIDGET(observed);
}

static void on_activate(GtkApplication *app)
{
	PyObject *module = init_python_module(MODULE_NAME);

	GtkWidget *win = gtk_application_window_new(app);
	gtk_window_set_title(GTK_WINDOW(win), "PyGObject Widget from C");

	GtkWidget *widget = new_python_widget(module);
	gtk_container_add(GTK_CONTAINER(win), widget);

	g_signal_connect_swapped(win, "destroy", G_CALLBACK(gtk_widget_destroy), win);

	gtk_widget_show_all(win);
}

int main(int argc, char **argv)
{
	GtkApplication *app = gtk_application_new("com.example.GtkApplication",
			G_APPLICATION_FLAGS_NONE);
	g_signal_connect(app, "activate", G_CALLBACK(on_activate), NULL);

	g_application_run(G_APPLICATION(app), argc, argv);

	return Py_FinalizeEx();
}