Рефакторинг PHP кода

какой лучший рефакторинг вы сделаете для этого класса?

Я ищу здесь метод «Извлечь и объединить классы и функции», я думаю, что все функции баз данных в Coed могут быть объединены, как выборка результатов и подключения БД и всех пользователей входа в систему.

<?php
$database = mysql_connect('localhost', 'user') or die('no connection');
mysql_select_db('test', $database);
session_start();

class Blog
{
public $logged_in_users = array();

function login()
{
global $database;

$_SESSION['loggedin'] = 'no';

$sql = "select * from user where username = '" .
$_REQUEST['user'] . "' and password  = '" . $_REQUEST['password'] . "'";

$result = mysql_query($sql, $database);

if (!$result) {
$log = fopen('Log/error.log', 'a+');
fwrite($log, 'error while reading/writing log file');
fclose($log);
echo 'error while reading/writing log file';
return;
}

while($row = mysql_fetch_row($result)) {
$this->logged_in_users[] = $_REQUEST['user'];
$_SESSION['loggedin'] = 'yes';
$_SESSION['permission'] = $row[3];
$_SESSION['readonly'] = $row[4];
$_SESSION['user_id'] = $row[0];
}
}

function insertBlog()
{
global $database;

if ($_SESSION['loggedin'] == 'yes' && ($_SESSION['permission'] == 'admin' ||
$_SESSION['permission'] == 'superuser' ||
( $_SESSION['permission'] == 'normal' && $_SESSION['readonly'] == 'no'))) {
$sql = "insert into blog (text,userid) values('".$_REQUEST['text']."','" . $_SESSION['user_id'] . "')";

$result = mysql_query($sql, $database);

if (!$result) {
$log = fopen('Log/error.log', 'a+');
fwrite($log, 'error while writing new blog');
fclose($log);
echo 'error while writing new blog';
return;
}
}
}

function loadBlog()
{
global $database;

$sql = 'select * from blog';

$result = mysql_query($sql, $database);

if (!$result) {
$log = fopen('Log/error.log', 'a+');
fwrite($log, 'error while reading');
fclose($log);
echo 'error while reading';
return;
}

echo "<br><table>";

while($row =  mysql_fetch_array($result, MYSQL_NUM)) {

$sql = "select username from user where userid = " . $row[2];

echo "<tr>";

$result2 = mysql_query($sql, $database);

if (!$result2) {
$log = fopen('Log/error.log', 'a+');
fwrite($log, 'error while reading');
fclose($log);
echo 'error while reading';
return;
}

$row2 = mysql_fetch_row($result2);
echo "<td>Autor : " . $row2[0]."</td>";
echo "</tr><tr>";
echo "<td>" . $row[1] . "</td>";

echo "</tr>";
}

echo "</table>";
}

function deleteBlog()
{
global $database;

if ($_SESSION['loggedin'] == 'yes' && $_SESSION['permission'] == 'admin') {

$sql = 'delete from blog where id = ' . $_REQUEST['id'];

$result = mysql_query($sql, $database);

if (!$result) {
$log = fopen('Log/error.log', 'a+');
fwrite($log, 'error while deleting');
fclose($log);
echo 'error while deleting';
return;
}
}
}

function newUser()
{
global $database;

if ($_SESSION['loggedin'] == 'yes' && $_SESSION['permission'] == 'admin') {
$sql = "insert into user(username, password, permission, readonly) values(". "'{$_REQUEST['username']}', '{$_REQUEST['password']}', '{$_REQUEST['permission']}', '{$_REQUEST['readonly']}')";

$result = mysql_query($sql, $database);
if (!$result) {
$log = fopen('Log/error.log', 'a+');
fwrite($log, 'error while writing new user');
fclose($log);
echo 'error while writing new user';
return;
}
}
}function countBlogs()
{
global $database;

$result = mysql_query('select count(*) as anzahl from blog', $database);

if (!$result) {
$log = fopen('Log/error.log', 'a+');
fwrite($log, 'error while writing new user');
fclose($log);
echo 'error while counting';
return;
}

$row = mysql_fetch_row($result);

echo "anzahl blogs : " . $row[0];
}
}$blog = new Blog();if ($_REQUEST['action'] == 'list') {
$blog->countBlogs();
$blog->loadBlog();
} elseif($_REQUEST['action'] == 'new') {
$blog->insertBlog();
$blog->countBlogs();
$blog->loadBlog();
} elseif($_REQUEST['action'] == 'delete') {
$blog->deleteBlog();
$blog->countBlogs();
$blog->loadBlog();
} elseif($_REQUEST['action'] == 'new_user') {
$blog->newUser();
$blog->countBlogs();
$blog->loadBlog();
} elseif($_REQUEST['action'] == 'login') {
$blog->login();
$blog->countBlogs();
$blog->loadBlog();
} else {
$blog->countBlogs();
$blog->loadBlog();
}/*
CREATE TABLE `user` (
`userid` INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
`username` VARCHAR( 45 ) NOT NULL ,
`password` VARCHAR( 45 ) NOT NULL ,
`permission` VARCHAR( 45 ) NOT NULL ,
`readonly` VARCHAR( 45 ) NOT NULL
) ENGINE = InnoDB;

CREATE TABLE `blog` (
`id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
`text` TEXT NOT NULL ,
`userid` INT NOT NULL
) ENGINE = InnoDB;

--liste
http://domain/blog.php

--einloggen
http://domain/blog.php?action=login&user=admin&password=admin

--neuer eintrag
http://domain/blog.php?action=new&text=bla

--neuer user
http://domain/blog.php?action=new_user&username=test&password=test&permission=superuser&readonly=yes

--eintrag löschen
http://domain/blog.php?action=delete&id=1

*/