/*
 * Copyright (C) 2024  Tristan Riehs
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "config.h"

#include <dlfcn.h>
#include <limits.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#include "disp.h"

#ifdef NDEBUG
extern struct disp *cli_disp;
extern struct disp *tui_disp;
extern struct disp *ray_disp;
#endif

#ifndef NDEBUG
static void *
load_generic_symbol(struct disp *disp, char *base_name)
{
	char full_name[64] = {0};
	void *ptr;

	strcpy(full_name, disp->name);
	strcat(full_name, "_");
	strcat(full_name, base_name);

	ptr = dlsym(disp->dl_handle, full_name);

	if (!ptr)
	{
		fprintf(stderr, "calculer: %s\n", dlerror());
		destroy_disp(disp);
		exit(1);
	}

	return ptr;
}
#endif

#ifndef NDEBUG
static void
load_symbols(struct disp *disp)
{
	void *handle = dlopen(disp->so_path, RTLD_LAZY);

	if (!handle)
	{
		fprintf(stderr, "calculer: %s\n", dlerror());
		destroy_disp(disp);
		exit(1);
	}

	disp->dl_handle	   = handle;
	disp->init	   = load_generic_symbol(disp, "init");
	disp->display_calc = load_generic_symbol(disp, "display_calc");
	disp->read_input   = load_generic_symbol(disp, "read_input");
	disp->display_res  = load_generic_symbol(disp, "display_res");
	disp->destroy	   = load_generic_symbol(disp, "destroy");
	disp->pre_reload   = load_generic_symbol(disp, "pre_reload");
	disp->post_reload  = load_generic_symbol(disp, "post_reload");

	printf("INFO: successfully loaded symbols from \"%s\"\n",
	       disp->so_path);
}
#endif

struct disp *
get_disp(char *disp_name)
{
#ifndef NDEBUG
	/* displays are shared libraries */
	char so_path[64] = {0};
	strcpy(so_path, "./src/.libs/");
	strcat(so_path, disp_name);
	strcat(so_path, ".so.0.0.0");
	struct disp *disp = malloc(sizeof(*disp));
	disp->so_path = strdup(so_path);
	disp->name = disp_name;

	load_symbols(disp);

	return disp;
#else
	if (strcmp(disp_name, "cli") == 0)
		return cli_disp;
	if (strcmp(disp_name, "tui") == 0)
		return tui_disp;
	if (strcmp(disp_name, "ray") == 0)
		return ray_disp;

	return NULL;
#endif
}

void
destroy_disp(struct disp *disp)
{
	if (disp->destroy)
		disp->destroy();

#ifndef NDEBUG
	if (disp->dl_handle)
		dlclose(disp->dl_handle);

	free(disp->so_path);
	free(disp);
#endif
}

#ifndef NDEBUG
void
disp_reload(struct disp *disp)
{
	printf("INFO: saving state\n");
	void *state = disp->pre_reload();

	printf("INFO: closing shared library\n");
	dlclose(disp->dl_handle);

	printf("INFO: reloading symbols\n");
	load_symbols(disp);

	printf("INFO: loading state\n");
	disp->post_reload(state);

	printf("INFO: reloading done\n");
}
#endif