/**
 * mds — A micro-display server
 * Copyright © 2014, 2015, 2016, 2017  Mattias Andrée (maandree@kth.se)
 * 
 * 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 "client-list.h"

#include "macros.h"

#include <string.h>
#include <errno.h>


/**
 * The default initial capacity
 */
#ifndef CLIENT_LIST_DEFAULT_INITIAL_CAPACITY
# define CLIENT_LIST_DEFAULT_INITIAL_CAPACITY 8
#endif


/**
 * Computes the nearest, but higher, power of two,
 * but only if the current value is not a power of two
 * 
 * @param   value  The value to be rounded up to a power of two
 * @return         The nearest, but not smaller, power of two
 */
static size_t __attribute__((const))
to_power_of_two(size_t value)
{
	value -= 1;
	value |= value >> 1;
	value |= value >> 2;
	value |= value >> 4;
	value |= value >> 8;
	value |= value >> 16;
#if SIZE_MAX == UINT64_MAX
	value |= value >> 32;
#endif
	return value + 1;
}


/**
 * Create a client list
 * 
 * @param   this      Memory slot in which to store the new client list
 * @param   capacity  The minimum initial capacity of the client list, 0 for default
 * @return            Non-zero on error, `errno` will have been set accordingly
 */
int
client_list_create(client_list_t *restrict this, size_t capacity)
{
	/* Use default capacity of zero is specified. */
	if (!capacity)
		capacity = CLIENT_LIST_DEFAULT_INITIAL_CAPACITY;

	/* Initialise the client list. */
	this->capacity = capacity = to_power_of_two(capacity);
	this->size     = 0;
	this->clients  = NULL;
	fail_if (xmalloc(this->clients, capacity, uint64_t));

	return 0;
fail:
	return -1;
}


/**
 * Release all resources in a client list, should
 * be done even if `client_list_create` fails
 * 
 * @param  this  The client list
 */
void
client_list_destroy(client_list_t *restrict this)
{
	free(this->clients);
	this->clients = NULL;
}


/**
 * Clone a client list
 * 
 * @param   this  The client list to clone
 * @param   out   Memory slot in which to store the new client list
 * @return        Non-zero on error, `errno` will have been set accordingly
 */
int
client_list_clone(const client_list_t *restrict this, client_list_t *restrict out)
{
	fail_if (xmemdup(out->clients, this->clients, this->capacity, uint64_t));

	out->capacity = this->capacity;
	out->size     = this->size;

	return 0;

fail:
	return -1;
}


/**
 * Add a client to the list
 * 
 * @param   this    The list
 * @param   client  The client to add
 * @return          Non-zero on error, `errno` will be set accordingly
 */
int
client_list_add(client_list_t *restrict this, uint64_t client)
{
	uint64_t* old;
	if (this->size == this->capacity) {
		old = this->clients;
		if (xrealloc(old, this->capacity <<= 1, uint64_t)) {
			this->capacity >>= 1;
			this->clients = old;
			fail_if (1);
		}
	}

	this->clients[this->size++] = client;
	return 0;
fail:
	return -1;
}


/**
 * Remove a client from the list, once
 * 
 * @param  this    The list
 * @param  client  The client to remove
 */
void
client_list_remove(client_list_t *restrict this, uint64_t client)
{
	size_t i, n;
	uint64_t *old;
	for (i = 0; i < this->size; i++) {
		if (this->clients[i] == client) {
			n = (--(this->size) - i) * sizeof(uint64_t);
			memmove(this->clients + i, this->clients + i + 1, n);

			if (this->size << 1 <= this->capacity) {
				old = this->clients;
				if (xrealloc(old, this->capacity >>= 1, uint64_t)) {
					this->capacity <<= 1;
					this->clients = old;
				}
			}

			return;
		}
	}
}


/**
 * Calculate the buffer size need to marshal a client list
 * 
 * @param   this  The list
 * @return        The number of bytes to allocate to the output buffer
 */
size_t
client_list_marshal_size(const client_list_t *restrict this)
{
	return 2 * sizeof(size_t) + this->size * sizeof(uint64_t) + sizeof(int);
}


/**
 * Marshals a client list
 * 
 * @param  this  The list
 * @param  data  Output buffer for the marshalled data
 */
void
client_list_marshal(const client_list_t *restrict this, char *restrict data)
{
	buf_set_next(data, int, CLIENT_LIST_T_VERSION);
	buf_set_next(data, size_t, this->capacity);
	buf_set_next(data, size_t, this->size);

	memcpy(data, this->clients, this->size * sizeof(uint64_t));
}


/**
 * Unmarshals a client list
 * 
 * @param   this  Memory slot in which to store the new client list
 * @param   data  In buffer with the marshalled data
 * @return        Non-zero on error, `errno` will be set accordingly.
 *                Destroy the list on error.
 */
int
client_list_unmarshal(client_list_t *restrict this, char *restrict data)
{
	/* buf_get(data, int, 0, CLIENT_LIST_T_VERSION); */
	buf_next(data, int, 1);

	this->clients = NULL;

	buf_get_next(data, size_t, this->capacity);
	buf_get_next(data, size_t, this->size);

	fail_if (xmalloc(this->clients, this->capacity, uint64_t));
	memcpy(this->clients, data, this->size * sizeof(uint64_t));

	return 0;
fail:
	return -1;
}