/*
 * Copyright (C) 2008 Martin Willi
 *
 * Copyright (C) secunet Security Networks AG
 *
 * 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 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * 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.
 */

#include <stdint.h>

#include "credential_factory.h"

#include <utils/debug.h>
#include <collections/linked_list.h>
#include <threading/thread_value.h>
#include <threading/rwlock.h>
#include <credentials/certificates/x509.h>
#include <credentials/containers/container.h>

/**
 * Maximum depth/recursion before failing to create a credential.
 */
#define CREATE_MAX_DEPTH 10

ENUM(credential_type_names, CRED_PRIVATE_KEY, CRED_CONTAINER,
	"CRED_PRIVATE_KEY",
	"CRED_PUBLIC_KEY",
	"CRED_CERTIFICATE",
	"CRED_CONTAINER",
);

typedef struct private_credential_factory_t private_credential_factory_t;

/**
 * private data of credential_factory
 */
struct private_credential_factory_t {

	/**
	 * public functions
	 */
	credential_factory_t public;

	/**
	 * list with entry_t
	 */
	linked_list_t *constructors;

	/**
	 * Thread specific recursiveness counter
	 */
	thread_value_t *recursive;

	/**
	 * lock access to builders
	 */
	rwlock_t *lock;
};

typedef struct entry_t entry_t;
struct entry_t {
	/** kind of credential builder */
	credential_type_t type;
	/** subtype of credential, e.g. certificate_type_t */
	int subtype;
	/** registered with final flag? */
	bool final;
	/** plugin that registered this algorithm */
	const char *plugin_name;
	/** builder function */
	builder_function_t constructor;
};

METHOD(credential_factory_t, add_builder, void,
	private_credential_factory_t *this, credential_type_t type, int subtype,
	bool final, const char *plugin_name, builder_function_t constructor)
{
	entry_t *entry = malloc_thing(entry_t);

	entry->type = type;
	entry->subtype = subtype;
	entry->final = final;
	entry->plugin_name = plugin_name;
	entry->constructor = constructor;
	this->lock->write_lock(this->lock);
	this->constructors->insert_last(this->constructors, entry);
	this->lock->unlock(this->lock);
}

METHOD(credential_factory_t, remove_builder, void,
	private_credential_factory_t *this, builder_function_t constructor)
{
	enumerator_t *enumerator;
	entry_t *entry;

	this->lock->write_lock(this->lock);
	enumerator = this->constructors->create_enumerator(this->constructors);
	while (enumerator->enumerate(enumerator, &entry))
	{
		if (entry->constructor == constructor)
		{
			this->constructors->remove_at(this->constructors, enumerator);
			free(entry);
		}
	}
	enumerator->destroy(enumerator);
	this->lock->unlock(this->lock);
}

METHOD(credential_factory_t, create, void*,
	private_credential_factory_t *this, credential_type_t type, int subtype, ...)
{
	enumerator_t *enumerator;
	entry_t *entry;
	va_list args;
	void *construct = NULL;
	int failures DBG_UNUSED = 0;
	uintptr_t level;
	enum_name_t *names DBG_UNUSED;

	switch (type)
	{
		case CRED_CERTIFICATE:
			names = certificate_type_names;
			break;
		case CRED_CONTAINER:
			names = container_type_names;
			break;
		case CRED_PRIVATE_KEY:
		case CRED_PUBLIC_KEY:
		default:
			names = key_type_names;
			break;
	}

	level = (uintptr_t)this->recursive->get(this->recursive);
	if (level >= CREATE_MAX_DEPTH)
	{
		DBG1(DBG_LIB, "building %N - %N failed, reached depth limit (%d)",
			 credential_type_names, type, names, subtype, CREATE_MAX_DEPTH);
		return NULL;
	}
	this->recursive->set(this->recursive, (void*)level + 1);

	this->lock->read_lock(this->lock);
	/* push this in case of a timeout during unit tests */
	thread_cleanup_push((thread_cleanup_t)this->lock->unlock, this->lock);
	enumerator = this->constructors->create_enumerator(this->constructors);
	while (enumerator->enumerate(enumerator, &entry))
	{
		if (entry->type == type && entry->subtype == subtype)
		{
			DBG2(DBG_LIB, "builder L%d %N - %N of plugin '%s'",
				 (int)level, credential_type_names, type, names, subtype,
				 entry->plugin_name);
			va_start(args, subtype);
			construct = entry->constructor(subtype, args);
			va_end(args);
			if (construct)
			{
				break;
			}
			failures++;
		}
	}
	enumerator->destroy(enumerator);
	thread_cleanup_pop(TRUE);

	if (!construct && !level)
	{
		DBG1(DBG_LIB, "building %N - %N failed, tried %d builders",
			 credential_type_names, type, names, subtype, failures);
	}
	this->recursive->set(this->recursive, (void*)level);
	return construct;
}

CALLBACK(builder_filter, bool,
	void *null, enumerator_t *orig, va_list args)
{
	entry_t *entry;
	credential_type_t *type;
	int *subtype;

	VA_ARGS_VGET(args, type, subtype);

	while (orig->enumerate(orig, &entry))
	{
		if (entry->final)
		{
			*type = entry->type;
			*subtype = entry->subtype;
			return TRUE;
		}
	}
	return FALSE;
}

METHOD(credential_factory_t, create_builder_enumerator, enumerator_t*,
	private_credential_factory_t *this)
{
	this->lock->read_lock(this->lock);
	return enumerator_create_filter(
				this->constructors->create_enumerator(this->constructors),
				builder_filter, this->lock, (void*)this->lock->unlock);
}

METHOD(credential_factory_t, destroy, void,
	private_credential_factory_t *this)
{
	this->constructors->destroy_function(this->constructors, free);
	this->recursive->destroy(this->recursive);
	this->lock->destroy(this->lock);
	free(this);
}

/*
 * see header file
 */
credential_factory_t *credential_factory_create()
{
	private_credential_factory_t *this;

	INIT(this,
		.public = {
			.create = _create,
			.create_builder_enumerator = _create_builder_enumerator,
			.add_builder = _add_builder,
			.remove_builder = _remove_builder,
			.destroy = _destroy,
		},
		.constructors = linked_list_create(),
		.recursive = thread_value_create(NULL),
		.lock = rwlock_create(RWLOCK_TYPE_DEFAULT),
	);

	return &this->public;
}