<?php
class Model
{
    public $connection;

    private $_select;
    private $_from;
    private $_where;
    private $_limit;
    private $_orderBy;
    private $_insertInto;
    private $_update;
    private $_remove;

    define("WHERE_OR", "OR");
    define("WHERE_AND", "AND");

    function __construct()
    {
        $xml = simplexml_load_file("./app_code/config.xml");
        $children = $xml->children();

        $dbHost = $children->database["host"];
        $dbUser = $children->database["user"];
        $dbPass = $children->database["password"];
        $dbName = $children->database["name"];

        $this->connection = mysql_connect($dbHost, $dbUser, $dbPass) or die("Unable to connect to mysql database <br />". mysql_error());
        mysql_select_db($dbName, $this->connection);
    }

    public function select($select)
    {
        $this->_select = "SELECT ".$select;
        return $this;
    }

    public function from($from)
    {
        $this->_from = "FROM ".$from;
        return $this;
    }

    public function where($field, $value, $connector = WHERE_AND)
    {
        if($this->_where = "")
        {
            $this->_where = "WHERE `".$field."` = '".$value."'";
        }
        else
        {
            $this->_where = $connector." `".$field."` = '".$value."'";
        }
        return $this;
    }

    public function limit($offset, $length = 0)
    {
        $this->_limit = "LIMIT ".$offset.", ".$length;
        return $this;
    }

    public function orderBy($by, $direction = "DESC")
    {
        $this->_orderBy = "ORDER BY ".$by." ".$direction;
        return $this;
    }

    public function InsertInto($tableName, $data)
    {
        $columnsResult = $this->GetTableFields($tableName);
        $diff = array_diff($columnsResult, $data);

        if(count($diff) > 0)
        {
            die("The fields supplied must match the fields in the table");
        }

        $this->_insertInto = "INSERT INTO `".$tableName."` (";

        $i = 1;
        foreach($data as $key => $val)
        {
            if($i != count($data))
            {
                $this->_insertInto .= "`".$key."`, ";
            }
            else
            {
                $this->_insertInto .= "`".$key."`";
            }
            $i++;
        }

        $this->_insertInto .= ") VALUES (";

        $i = 1;
        foreach($data as $key => $val)
        {
            if($i != count($data))
            {
                $this->_insertInto .= "'".$val."', ";
            }
            else
            {
                $this->_insertInto .= "'".$val."'";
            }
            $i++;
        }

        $this->_insertInto .= ")";

        $result = mysql_query($this->_insertInto);
        $this->_insertInto = "";
        return $result;
    }

    public function Update($tableName, $data, $whereField = "", $whereValue = "")
    {
        $this->where($whereField, $whereValue);

        $columnsResult = $this->GetTableFields($tableName);

        $i = 1;
        $this->_update = "UPDATE ".$tableName." SET ";
        foreach($data as $key => $val)
        {
            if(!array_key_exists($key, $columnsResult))
            {
                $this->_update = "";
                die("They field \"".$key."\" does not exist in the table \"".$tableName."\"");
            }

            if($i < count($data))
            {
                $this->_update .= "`".$key."` = '".$val."', ";
            }
            else
            {
                $this->_update .= "`".$key."` = '".$val."' ";
            }
        }

        $this->_update .= $this->_where;

        $result = mysql_query($this->_update);
        $this->_update = "";
        $this->_where = "";

        return $result;

    }

    public function Remove($tableName, $field, $whereField = "", $whereValue = "")
    {
        $this->where($whereField, $whereValue);

        $dbFields = $this->GetTableFields($tableName);

        if(!array_key_exists($field, $dbFields))
        {
            die("The field \"".$field."\" is not a field in the table \"".$tableName."\"");
        }

        $this->_remove = "DELETE FROM ".$tableName." WHERE ".$this->_where;

        $result = mysql_query($this->_remove);

        $this->_remove = "";
        $this->_where = "";

        return $result;

    }

    public function GetResult()
    {
        $query = "".$this->_select." ".$this->_from." ".$this->_where." ".$this->_limit." ".$this->_orderBy."";
        $result = mysql_query($query);

        $return = array();

        while($row = mysql_fetch_assoc($result))
        {
            $return[] = $row;
        }

        $this->_select = "";
        $this->_from = "";
        $this->_where = "";
        $this->_limit = "";
        $this->_orderBy = "";

        return $return;
    }

    private function GetTableFields($tableName)
    {

        $columnsQuery = mysql_query("SHOW FIELDS FROM ".$tableName);
        $columnsResult = array ();

        while($field = mysql_fetch_assoc($columnsQuery))
        {
            $columnsResult[$field["Field"]] = "";
        }

        return $columnsResult;
    }
}
?>