/* IRCfs - IRC FileServ for *nix.
 * Copyright (C) 2002  Nick 'Zaf' Clifford <zaf@nrc.co.nz>
 * For licensing details, refer to the LICENSE file in the source 
 * code directory.
 */
#include "runtime.h"
#include "module.h"


#define MODULE_LIST(x) extern int module__ ## x ## __init(void);
#include "modlist.h"

static module_func_t module_init_funcs[] = {
#undef MODULE_LIST
#define MODULE_LIST(x) module__ ## x ## __init,
#include "modlist.h"
NULL
};
#ifdef MODULE_POST
#undef MODULE_POST
#endif
#define MODULE_POST(x) extern int x (void);
#include "modpost.h"
#undef MODULE_POST
static module_func_t module_post_funcs[] = {
#define MODULE_POST(x) x,
#include "modpost.h"
NULL
};

enum module_status {
	mod_status_unloaded, mod_status_loading, mod_status_loaded,
	mod_status_failed, mod_status_unloading
};

struct module_list {
	struct module *modinfo;
	enum module_status status;
	int load_order;
	struct module_list *next;
};

static int load_module(struct module_list *ml);
static int unload_module(struct module_list *ml, int force);
static struct module_list *find_module(const char *name);

struct module_list *head;

static POOL pool;
static int module_count;
DEBUG module_debug;

int load_modules()
{
	int i;
	module_debug = debug_register("module");
	pool = pool_new(NULL);
	for(i=0; module_init_funcs[i]; i++) {
		module_init_funcs[i]();
	}

	if (init_modules() == -1)
		return -1;
	for(i=0; module_post_funcs[i]; i++) {
		module_post_funcs[i]();
	}
	return 0;
}

int module_check_load(const char *name)
{
	struct module_list *mt;
	mt = find_module(name);
	if (mt == NULL) {
		error(module_debug,"Can't find module '%s' which is "
				"required by a module "
				"calling module_check_load",
				name);
		return -1;
	}
	switch (mt->status) {
	case mod_status_unloaded:
		if (load_module(mt) == -1) {
			return -1;
		}
		break;
	case mod_status_loading:
		error(module_debug,"Circular dependancy. "
				"A module called module_check_load(%s) "
				"however, that module is in the process of "
				"loading. (Maybe use a postinit for this "
				"module?",
				mt->modinfo->name);
		return -1;
	case mod_status_loaded:
		break;
	default:
		error(module_debug,"Dependancy on failed module on '%s'",
				mt->modinfo->name);
		return -1;
	}
	return 0;
}

int unload_modules()
{
	struct module_list *ml;
	int r=0;
	for(ml=head; ml != NULL; ml=ml->next) {
		if (ml->status != mod_status_loaded)
			continue;
		if (unload_module(ml,1) == -1) {
			r = -1;
		}
	}
	return r;
}

/* Load all unloaded modules */
int init_modules()
{
	struct module_list *ml;
	for(ml=head; ml != NULL; ml=ml->next) {
		if (ml->status == mod_status_loaded)
			continue;
		if (load_module(ml) == -1) {
			return -1;
		}
	}
	return 0;
}

struct module_list *find_module(const char *name)
{
	struct module_list *ml;
	
	for(ml=head; ml != NULL; ml=ml->next) {
		if (strcmp(ml->modinfo->name,name) == 0)
			return ml;
	}
	return NULL;
}
/* TODO
 * Rewrite, we are suppose to use load_order field to unload by,
 * not dependancies!
 */
int unload_module(struct module_list *ml, int force)
{
	struct module_list *mt;
	const char *cp;
	int i;
	/* Go through dependancy list, check if those are 
	 * loaded
	 */
	ml->status = mod_status_unloading;
	info(module_debug, "unloading module: %s",ml->modinfo->name);
	for(i = 0; ml->modinfo->depends[i] != NULL; i++) {
		cp = ml->modinfo->depends[i];
		if (*cp == 0) 
			continue;
		mt = find_module(cp);
		if (mt == NULL) {
			error(module_debug,"Can't find module '%s' which is "
					"required by module '%s'",
					cp,ml->modinfo->name);
			ml->status = mod_status_failed;
			return -1;
		}
		switch (mt->status) {
		case mod_status_unloaded:
			break;
		case mod_status_unloading:
			if (!force) {	
			error(module_debug,"Circular dependancy. Module '%s' requires "
					"module '%s'.",
					ml->modinfo->name,
					mt->modinfo->name);
			ml->status = mod_status_failed;
			}
			return -1;
		case mod_status_loaded:
			if (unload_module(mt,force) == -1 && !force) {
				ml->status = mod_status_loaded;
				return -1;
			}
			break;
		default:
			if (!force) {
			error(module_debug,"Dependancy on failed module '%s' by '%s'",
					mt->modinfo->name,
					ml->modinfo->name);
			ml->status = mod_status_failed;
			return -1;
			}
		}
		/* Module dependancy loaded */
	}
	if (ml->modinfo->destroy && ml->modinfo->destroy() != 0) {
		if (!force) {
		error(module_debug,"module %s destroy() failed",
				ml->modinfo->name);
		ml->status = mod_status_failed;
		return -1;
		}
	}
	ml->status = mod_status_unloaded;
	ml->modinfo->loaded = 0;
	module_count--;
	return 0;
}

int load_module(struct module_list *ml)
{
	struct module_list *mt;
	const char *cp;
	int i;
	/* Go through dependancy list, check if those are 
	 * loaded
	 */
	ml->status = mod_status_loading;
	info(module_debug, "loading module: %s",ml->modinfo->name);
	for(i = 0; ml->modinfo->depends[i] != NULL; i++) {
		cp = ml->modinfo->depends[i];
		if (*cp == 0) 
			continue;
		mt = find_module(cp);
		if (mt == NULL) {
			error(module_debug,"Can't find module '%s' which is "
					"required by module '%s'",
					ml->modinfo->name, cp);
			ml->status = mod_status_failed;
			return -1;
		}
		switch (mt->status) {
		case mod_status_unloaded:
			if (load_module(mt) == -1) {
				ml->status = mod_status_failed;
				return -1;
			}
			break;
		case mod_status_loading:
			
			error(module_debug,"Circular dependancy. Module '%s' requires "
					"module '%s'.",
					ml->modinfo->name,
					mt->modinfo->name);
			ml->status = mod_status_failed;
			return -1;
		case mod_status_loaded:
			break;
		default:
			error(module_debug,"Dependancy on failed module '%s' by '%s'",
					mt->modinfo->name,
					ml->modinfo->name);
			ml->status = mod_status_failed;
			return -1;
		}
		/* Module dependancy loaded */
	}
	if (ml->modinfo->init && ml->modinfo->init() != 0) {
		ml->status = mod_status_failed;
		return -1;
	}
	ml->status = mod_status_loaded;
	ml->modinfo->loaded = 1;
	ml->load_order = module_count++;
	return 0;
}

void register_module(struct module *modinfo) {
	struct module_list *ml = XMALLOC(pool,struct module_list);
	ml->modinfo = modinfo;
	ml->status = mod_status_unloaded;
	ml->next = head;
	head = ml;
}