<?php

class Model
{
    private $db = NULL;
    private $cache = NULL;
    private $table = 'users';
     
    // constructor
    public function  __construct(MySQL $db, $table = '')
    {
        // store database class instance
        $this->db = $db;
        // store Cache class instance
        $this->cache = Cache::getInstance();
        if ($table !== '')
        {
        	$this->table = $table;
        }
    }

    // get all rows from specified table
    public function fetchAll()
    {
        // if the cache file is valid fetch records from cache file
        if ($this->cache->valid($this->table))
        {
           return $this->cache->get($this->table);
        }
        else
        {
            // otherwise fecth records from database table
            $rows = array();
            $this->db->query('SELECT * FROM ' . $this->table);
            while ($row = $this->db->fetch())
            {
                $rows[] = $row;
            }
            // save data set to cache file
            $this->cache->set($this->table, $rows);
            return $rows;
        }
    }

    // update/insert row
    public function save(array $data, $id = NULL)
    {
    	if (!empty($data))
    	{
            // quote strings
    		foreach ($data as $field => $value)
    		{
    			$value = mysql_escape_string($value);
    			if (!is_numeric($value))
    			{
    				$data[$field] = '\'' . $value . '\''; 
    			}
    		}
            // update row
    		if ($id !== NULL)
    		{
    			$set = '';
		        foreach($data as $field => $value)
		        {
		            $set .= $field .'=' . $value . ',';
		        }
		        $set = substr($set, 0, -1);
		        $this->db->query('UPDATE ' . $this->table . ' SET ' . $set . ' WHERE id=' . (int)$id);
    		}
            // insert new row
    		else 
    		{
	    		$fields = implode(',', array_keys($data));
		        $values = implode(',', array_values($data));
		        $this->db->query('INSERT INTO ' . $this->table . ' (' . $fields . ')' . ' VALUES (' . $values . ')');
    		}
    	}
    }
    
    // delete row
    public function delete($id = NULL)
    {
        if ($id !== NULL)
        {
            $this->db->query('DELETE FROM ' . $this->table . ' WHERE id=' . (int)$id);
        }
    }
}// End Model class