/* Modular support
 *
 * (C) 2009 Anope Team
 * Contact us at team@anope.org
 *
 * Please read COPYING and README for further details.
 *
 * $Id$
 *
 */
#include "modules.h"
#include "language.h"
#include "version.h"
#include <algorithm> // std::find

std::vector<Module *> ModuleManager::EventHandlers[I_END];

void ModuleManager::LoadModuleList(int total_modules, char **module_list)
{
	int idx;
	Module *m;
	int status = 0;
	for (idx = 0; idx < total_modules; idx++) {
		m = findModule(module_list[idx]);
		if (!m) {
			status = ModuleManager::LoadModule(module_list[idx], NULL);
		}
	}
}

/**
 * Copy the module from the modules folder to the runtime folder.
 * This will prevent module updates while the modules is loaded from
 * triggering a segfault, as the actaul file in use will be in the
 * runtime folder.
 * @param name the name of the module to copy
 * @param output the destination to copy the module to
 * @return MOD_ERR_OK on success
 */
static int moduleCopyFile(const char *name, const char *output)
{
	int ch;
	FILE *source, *target;
#ifndef _WIN32
	int srcfp;
#endif
	char input[4096];
	int len;

	strncpy(input, services_dir.c_str(), 4095);
	len = strlen(input);
	strncat(input, "/modules/", 4095 - len);  /* Get full path with module extension */
	len = strlen(input);
	strncat(input, name, 4095 - len);
	len = strlen(output);
	strncat(input, MODULE_EXT, 4095 - len);

#ifndef _WIN32
	if ((srcfp = mkstemp(const_cast<char *>(output))) == -1)
		return MOD_ERR_FILE_IO;
#else
	if (!mktemp(const_cast<char *>(output)))
		return MOD_ERR_FILE_IO;
#endif

	if (debug)
		alog("Runtime module location: %s", output);

	/* Linux/UNIX should ignore the b param, why do we still have seperate
	 * calls for it here? -GD
	 */
#ifndef _WIN32
	if ((source = fopen(input, "r")) == NULL) {
#else
	if ((source = fopen(input, "rb")) == NULL) {
#endif
		return MOD_ERR_NOEXIST;
	}
#ifndef _WIN32
	if ((target = fdopen(srcfp, "w")) == NULL) {
#else
	if ((target = fopen(output, "wb")) == NULL) {
#endif
		return MOD_ERR_FILE_IO;
	}
	while ((ch = fgetc(source)) != EOF) {
		fputc(ch, target);
	}
	fclose(source);
	if (fclose(target) != 0) {
		return MOD_ERR_FILE_IO;
	}
	return MOD_ERR_OK;
}

static bool IsOneOfModuleTypeLoaded(MODType mt)
{
	int idx = 0;
	ModuleHash *current = NULL;
	int pmods = 0;

	for (idx = 0; idx != MAX_CMD_HASH; idx++)
	{
		for (current = MODULE_HASH[idx]; current; current = current->next)
		{
			if (current->m->type == mt)
				pmods++;
		}
	}

	/*
	 * 2, because module constructors now add modules to the hash.. so 1 (original module)
	 * and 2 (this module). -- w00t
	 */
	if (pmods == 2)
		return true;

	return false;
}

/* This code was found online at http://www.linuxjournal.com/article/3687#comment-26593
 *
 * This function will take a pointer from either dlsym or GetProcAddress and cast it in
 * a way that won't cause C++ warnings/errors to come up.
 */
template <class TYPE>
TYPE function_cast(ano_module_t symbol)
{
	union {
		ano_module_t symbol;
		TYPE function;
	} cast;
	cast.symbol = symbol;
	return cast.function;
}

int ModuleManager::LoadModule(const std::string &modname, User * u)
{
	const char *err;
	Module *(*func)(const std::string &);
	int ret = 0;

	if (modname.empty())
		return MOD_ERR_PARAMS;

	if (findModule(modname.c_str()) != NULL)
		return MOD_ERR_EXISTS;

	if (debug)
		alog("trying to load [%s]", modname.c_str());

	/* Generate the filename for the temporary copy of the module */
	std::string pbuf;
	pbuf = services_dir + "/modules/";
#ifndef _WIN32
	pbuf += "runtime/";
#else
	pbuf += "runtime\\";
#endif
	pbuf += modname;
	pbuf += MODULE_EXT;
	pbuf += ".";
	pbuf += "XXXXXX";

	/* Don't skip return value checking! -GD */
	if ((ret = moduleCopyFile(modname.c_str(), pbuf.c_str())) != MOD_ERR_OK)
	{
		/* XXX: This used to assign filename here, but I don't think that was correct..
		 * even if it was, it makes life very fucking difficult, so.
		 */
		return ret;
	}

	ano_modclearerr();

	ano_module_t handle = dlopen(pbuf.c_str(), RTLD_LAZY);
	if (handle == NULL && (err = dlerror()) != NULL)
	{
		alog("%s", err);
		return MOD_ERR_NOLOAD;
	}

	ano_modclearerr();
	func = function_cast<Module *(*)(const std::string &)>(dlsym(handle, "init_module"));
	if (func == NULL && (err = dlerror()) != NULL)
	{
		alog("No magical init function found, not an Anope module");
		dlclose(handle);
		return MOD_ERR_NOLOAD;
	}

	if (!func)
	{
		throw CoreException("Couldn't find constructor, yet moderror wasn't set?");
	}

	/* Create module. */
	std::string nick;
	if (u)
		nick = u->nick;
	else
		nick = "";

	Module *m;

	try
	{
		m = func(nick);
	}
	catch (ModuleException &ex)
	{
		alog("Error while loading %s: %s", modname.c_str(), ex.GetReason());
		return MOD_STOP;
	}

	m->filename = pbuf;
	m->handle = handle;

	if (m->type == PROTOCOL && IsOneOfModuleTypeLoaded(PROTOCOL))
	{
		DeleteModule(m);
		alog("You cannot load two protocol modules");
		return MOD_STOP;
	}
	else if (m->type == ENCRYPTION && IsOneOfModuleTypeLoaded(ENCRYPTION))
	{
		DeleteModule(m);
		alog("You cannot load two encryption modules");
		return MOD_STOP;
	}

	if (u)
	{
		ircdproto->SendGlobops(s_OperServ, "%s loaded module %s", u->nick, modname.c_str());
		notice_lang(s_OperServ, u, OPER_MODULE_LOADED, modname.c_str());
	}

	return MOD_ERR_OK;
}

int ModuleManager::UnloadModule(Module *m, User *u)
{
	if (!m || !m->handle)
	{
		if (u)
			notice_lang(s_OperServ, u, OPER_MODULE_REMOVE_FAIL, m->name.c_str());
		return MOD_ERR_PARAMS;
	}

	if (m->GetPermanent() || m->type == PROTOCOL || m->type == ENCRYPTION)
	{
		if (u)
			notice_lang(s_OperServ, u, OPER_MODULE_NO_UNLOAD);
		return MOD_ERR_NOUNLOAD;
	}

	if (u)
	{
		ircdproto->SendGlobops(s_OperServ, "%s unloaded module %s", u->nick, m->name.c_str());
		notice_lang(s_OperServ, u, OPER_MODULE_UNLOADED, m->name.c_str());
	}

	DeleteModule(m);
	return MOD_ERR_OK;
}

void ModuleManager::DeleteModule(Module *m)
{
	const char *err;
	void (*destroy_func)(Module *m);
	ano_module_t handle;

	if (!m || !m->handle) /* check m is least possibly valid */
	{
		return;
	}

	handle = m->handle;

	ano_modclearerr();
	destroy_func = function_cast<void (*)(Module *)>(dlsym(m->handle, "destroy_module"));
	if (destroy_func == NULL && (err = dlerror()) != NULL)
	{
		alog("No magical destroy function found, chancing delete...");
		delete m; /* we just have to chance they haven't overwrote the delete operator then... */
	}
	else
	{
		destroy_func(m); /* Let the module delete it self, just in case */
	}

	if (handle)
	{
		if ((dlclose(handle)) != 0)
			alog("%s", dlerror());
	}
}

bool ModuleManager::Attach(Implementation i, Module* mod)
{
	if (std::find(EventHandlers[i].begin(), EventHandlers[i].end(), mod) != EventHandlers[i].end())
		return false;

	EventHandlers[i].push_back(mod);
	return true;
}

bool ModuleManager::Detach(Implementation i, Module* mod)
{
	std::vector<Module *>::iterator x = std::find(EventHandlers[i].begin(), EventHandlers[i].end(), mod);

	if (x == EventHandlers[i].end())
		return false;

	EventHandlers[i].erase(x);
	return true;
}

void ModuleManager::Attach(Implementation* i, Module* mod, size_t sz)
{
	for (size_t n = 0; n < sz; ++n)
		Attach(i[n], mod);
}

void ModuleManager::DetachAll(Module* mod)
{
	for (size_t n = I_BEGIN + 1; n != I_END; ++n)
		Detach((Implementation)n, mod);
}

bool ModuleManager::SetPriority(Module* mod, Priority s)
{
	for (size_t n = I_BEGIN + 1; n != I_END; ++n)
		SetPriority(mod, (Implementation)n, s);

	return true;
}

bool ModuleManager::SetPriority(Module* mod, Implementation i, Priority s, Module** modules, size_t sz)
{
	/** To change the priority of a module, we first find its position in the vector,
	 * then we find the position of the other modules in the vector that this module
	 * wants to be before/after. We pick off either the first or last of these depending
	 * on which they want, and we make sure our module is *at least* before or after
	 * the first or last of this subset, depending again on the type of priority.
	 */
	size_t swap_pos = 0;
	size_t source = 0;
	bool swap = true;
	bool found = false;

	/* Locate our module. This is O(n) but it only occurs on module load so we're
	 * not too bothered about it
	 */
	for (size_t x = 0; x != EventHandlers[i].size(); ++x)
	{
		if (EventHandlers[i][x] == mod)
		{
			source = x;
			found = true;
			break;
		}
	}

	/* Eh? this module doesnt exist, probably trying to set priority on an event
	 * theyre not attached to.
	 */
	if (!found)
		return false;

	switch (s)
	{
		/* Dummy value */
		case PRIORITY_DONTCARE:
			swap = false;
		break;
		/* Module wants to be first, sod everything else */
		case PRIORITY_FIRST:
			swap_pos = 0;
		break;
		/* Module is submissive and wants to be last... awww. */
		case PRIORITY_LAST:
			if (EventHandlers[i].empty())
				swap_pos = 0;
			else
				swap_pos = EventHandlers[i].size() - 1;
		break;
		/* Place this module after a set of other modules */
		case PRIORITY_AFTER:
		{
			/* Find the latest possible position */
			swap_pos = 0;
			swap = false;
			for (size_t x = 0; x != EventHandlers[i].size(); ++x)
			{
				for (size_t n = 0; n < sz; ++n)
				{
					if ((modules[n]) && (EventHandlers[i][x] == modules[n]) && (x >= swap_pos) && (source <= swap_pos))
					{
						swap_pos = x;
						swap = true;
					}
				}
			}
		}
		break;
		/* Place this module before a set of other modules */
		case PRIORITY_BEFORE:
		{
			swap_pos = EventHandlers[i].size() - 1;
			swap = false;
			for (size_t x = 0; x != EventHandlers[i].size(); ++x)
			{
				for (size_t n = 0; n < sz; ++n)
				{
					if ((modules[n]) && (EventHandlers[i][x] == modules[n]) && (x <= swap_pos) && (source >= swap_pos))
					{
						swap = true;
						swap_pos = x;
					}
				}
			}
		}
		break;
	}

	/* Do we need to swap? */
	if (swap && (swap_pos != source))
	{
		/* Suggestion from Phoenix, "shuffle" the modules to better retain call order */
		int incrmnt = 1;

		if (source > swap_pos)
			incrmnt = -1;

		for (unsigned int j = source; j != swap_pos; j += incrmnt)
		{
			if (( j + incrmnt > EventHandlers[i].size() - 1) || (j + incrmnt < 0))
				continue;

			std::swap(EventHandlers[i][j], EventHandlers[i][j+incrmnt]);
		}
	}

	return true;
}