<?php

/*
 * MySQL class to work with the MySQL database.
 */

class MySQL
{
    const Server = MySQLSettings::Server;
    const User = MySQLSettings::User;
    const Password = MySQLSettings::Password;
    const Database = MySQLSettings::Database;

    public static $Connected = false;
    public static $ConnectionError = '';
    public static $Errors = array();
    public static $ErrorSQL = array();

    public static function Connect()
    {
        if(self::$Connected)
        {
            return true;
        }

        if(!mysql_connect(self::Server, self::User, self::Password))
        {
            self::$ConnectionError = mysql_error();
            return false;
        }

        if(!mysql_select_db(self::Database))
        {
            self::$ConnectionError = mysql_error();
            return false;
        }

        return true;
    }

    public static function CheckConnection()
    {
        if(!self::Connect())
        {
            die(self::$ConnectionError);
            return false;
        }
        else
        {
            return true;
        }
    }

    public static function Query($sql)
    {
        $result = mysql_query($sql);

        if($result)
        {
            return $result;
        }
        else
        {
            $error = 'MySQL Error: ' . mysql_error() . "\n" . "SQL: $sql\n" . "-------\n";

            if(!file_exists(Config::ErrorLogFile))
            {
                file_put_contents(Config::ErrorLogFile, '');
            }

            file_put_contents(Config::ErrorLogFile, $error, FILE_APPEND);

            throw new Exception('MySQL Error: '.mysql_error());
            return false;
        }
    }

    private static function NumRows($result)
    {
        if(!$result)
        {
            return 0;
        }
        else
        {
            return mysql_num_rows($result);
        }
    }

    private static function FetchRow($result)
    {
        if(!$result)
        {
            return false;
        }
        else
        {
            return mysql_fetch_assoc($result);
        }
    }

    public static function Sanitize($str)
    {
        if(function_exists('mysql_real_escape_string'))
            $str = mysql_real_escape_string($str);
        else
            die('Please upgrade your version of PHP to at least 4.3.0');

        return $str;
    }

    /*
     * The following function are interfaces for accessing the MySQL database
     * without having SQL scattered all throughout the code.
     */

    private static $Cache = array();

    private static function GetInfo($table, $id, &$cls) // cls is the class that corresponds to each row
    {
        self::CheckConnection();

        $table = self::Sanitize($table);
        $id = self::Sanitize($id);

        if(!isset(self::$Cache[$table]))
        {
            self::$Cache[$table] = array();
        }

        if(isset(self::$Cache[$table][$id]))
        {
            $row = self::$Cache[$table][$id];
        }
        else
        {
            $result = self::Query("SELECT * FROM $table WHERE `id` = '$id' LIMIT 1");

            if(self::NumRows($result))
            {
                return null;
            }

            $row = self::FetchRow($result);
            self::$Cache[$table][$id] = $row;
        }

        $cls->FromSQLRow($row);

        return $cls;
    }

    private static function SetInfo($table, $id, $cls)
    {
        self::CheckConnection();

        $table = self::Sanitize($table);
        $id = self::Sanitize($id);

        if(!isset(self::$Cache[$table]))
        {
            self::$Cache[$table] = array();
        }

        $row = $cls->ToSQLRow();
        $cached = (isset(self::$Cache[$table][$id]) ? self::$Cache[$table][$id] : array());
        $sqlParts = array();

        foreach($row as $key=>$val)
        {
            if($val == null) // Skip null values
                continue;

            if(!isset($cached[$key]) || $val != $cached[$key]) // Only set if it is different
            {
                $sqlParts[] = "$key='".self::Sanitize($val)."'";
            }
        }

        if(count($sqlParts) == 0) // Nothing to update
        {
            return true;
        }

        $sql = implode(',', $sqlParts);

        if(self::Query("UPDATE $table SET $sql WHERE `id`='$id' LIMIT 1"))
        {
            self::$Cache[$table][$id] = $row; // Update the cache
            return true;
        }
        else
        {
            return false;
        }
    }

    public static function GetImageInfo($id)
    {
        return self::GetInfo('images', $id, new Image());
    }

    public static function SetImageInfo($id, $image)
    {
        return self::SetInfo('images', $id, $image);
    }
}

// FIXME: Only call Connect when needed
if(!MySQL::Connect())
{
    die(MySQL::$ConnectionError);
}

?>