ExampleController.php

<?php
App::uses('AppController', 'Controller');
App::uses('Folder', 'Utility');
App::uses('File', 'Utility');
App::uses('CakeTime', 'Utility');

class ExempleController extends AppController {

    public function implementedEvents() 
	{
		return parent::implementedEvents() + array(
			'Crud.beforeSave' => '_beforeSave',
		);
	}

	protected $accept_types = array(
		'jpg' => 'image/jpeg', 
		'png' => 'image/png'
	);

	public function _beforeSave(CakeEvent $event) 
	{
		$root_folder = 'files'.DS.'uploads/TONFOLDER';
		$folder_site = new Folder($root_folder, true, 0755);
 
		if ( !empty($this->request->data[$this->modelClass]['CHAMPS_FICHIER']['tmp_name']) && is_uploaded_file($this->request->data[$this->modelClass]['CHAMPS_FICHIER']['tmp_name']) ) 
		{
			$file_tmp = new File($this->request->data[$this->modelClass]['CHAMPS_FICHIER']['tmp_name']);
			$type_mime = $file_tmp->mime();
			
			if(in_array($file_tmp->mime(), $this->accept_types))
			{
			    $file_origin = new File($this->request->data[$this->modelClass]['CHAMPS_FICHIER']['name']);
			    $filename = Inflector::slug($file_origin->name()).'.'.$file_origin->ext();
 
			    $file_real = new File($folder_site->path.DS.$filename);

			    $filename = $root_folder.$filename;
			    $this->testDuplicate($filename);
 
			    move_uploaded_file(
			        $this->data[$this->modelClass]['CHAMPS_FICHIER']['tmp_name'],
			        $filename
			    );
 
			    $this->request->data[$this->modelClass]['CHAMPS_FICHIER'] = $filename;
			    $this->request->data[$this->modelClass]['mime'] = $type_mime;
			    $this->request->data[$this->modelClass]['extfile'] = array_search($type_mime, $this->accept_types);
 
			    return true;
			}
			else 
			{
				unset($this->request->data[$this->modelClass]['CHAMPS_FICHIER']);
				$this->Session->setFlash(__('ONLY EXT, EXT AND EXT FILES'),'default',array('class' => 'error'));
				
				if(isset($this->request->data[$this->modelClass]['id']))
				{
					$this->redirect(array(
						'action' => 'edit',
						$this->request->data[$this->modelClass]['id'],
			 		));
				}
				else
				{
					$this->Session->write('data', $this->request->data);
					$this->redirect(array(
						'action' => 'add',
			 		));
				}
			}
		}
		else 
		{
			unset($this->request->data[$this->modelClass]['CHAMPS_FICHIER']);
			return false;
		}
	}

	/**
	* If the file $dir already exists we add a {n} before the extension
	**/
	public function testDuplicate(&$dir,$count = 0){
		$file = $dir;
		if($count > 0){
			$pathinfo = pathinfo($dir);
			$file = $pathinfo['dirname'].'/'.$pathinfo['filename'].'-'.$count.'.'.$pathinfo['extension'];
		}

		if(!file_exists(WWW_ROOT.$file)){
			$dir = $file;
		}else{
			$count++;
			$this->testDuplicate($dir,$count);
		}
	}

}