<?php
/*
Author: 		Riccardo Di Dato
Creation Date:	07/gen/2016
*/

class ConstrainedObject {
	const SET_BEHAVIOUR_NORMAL = 1;
	const SET_BEHAVIOUR_IGNORE = 2;
	const SET_BEHAVIOUR_THROW = 100;
	
	const UNSET_BEHAVIOUR_NORMAL = 1;
	const UNSET_BEHAVIOUR_IGNORE = 2;
	const UNSET_BEHAVIOUR_THROW = 100;
	
	const GET_BEHAVIOUR_NORMAL = 1;
	const GET_BEHAVIOUR_EMPTY = 2;
	const GET_BEHAVIOUR_THROW = 100;
	
	private $original;
	
	private $constraints = array();
	
	public function __construct($original){
		$this->original = $original;
	}
	
	public function __set($key, $value){
		if (array_key_exists($key, $this->constraints)){
			$constraint = $this->constraints[$key]->set;
			switch ($constraint->behaviour){
				case self::SET_BEHAVIOUR_NORMAL:
					$this->original->$key = $value;
					break;
				case self::SET_BEHAVIOUR_THROW:
					throw new ConstraintException("Constraint violation: impossible to set field '$key'");
					break;
				case self::SET_BEHAVIOUR_IGNORE:
				default:
					break;
			}
			if (property_exists($constraint, "callbackClass") && !is_null($constraint->callbackClass)){
				$this->original = $constraint->callbackClass->executeSetCallback($this->original, $key, $value);
			}
		}
		else {
			$this->original->$key = $value;
		}
	}
	
	public function __get($key){
		$rval = $this->original->$key;
		if (array_key_exists($key, $this->constraints)){
			$constraint = $this->constraints[$key]->get;
			switch ($constraint->behaviour){
				case self::GET_BEHAVIOUR_EMPTY:
					$rval = null;
					break;
				case self::GET_BEHAVIOUR_THROW:
					throw new ConstraintException("Constraint violation: impossible to get field '$key'");
					break;
				case self::GET_BEHAVIOUR_NORMAL:
				default:
					break;
			}
			if (property_exists($constraint, "callbackClass") && !is_null($constraint->callbackClass)){
				$rval = $constraint->callbackClass->executeGetCallback($this->original, $key);
			}
		}
		return $rval;
	}
	
	public function __unset($key){
		if (array_key_exists($key, $this->constraints)){
			$constraint = $this->constraints[$key]->unset;
			switch ($constraint->behaviour){
				case self::UNSET_BEHAVIOUR_NORMAL:
					unset($this->original->$key);
					break;
				case self::UNSET_BEHAVIOUR_THROW:
					throw new ConstraintException("Constraint violation: impossible to unset field '$key'");
					break;
				case self::UNSET_BEHAVIOUR_IGNORE:
				default:
					break;
			}
			if (property_exists($constraint, "callbackClass") && !is_null($constraint->callbackClass)){
				$this->original = $constraint->callbackClass->executeUnsetCallback($this->original, $key);
			}
		}
		else {
			unset($this->original->$key);
		}
	}
	
	public function createSetBehaviour($key, $behaviour, ConstraintObjectBehaviourCallable $callbackClass = null){
		$this->constraints[$key]->set = new stdClass();
		if ($behaviour < self::SET_BEHAVIOUR_NORMAL){
			$behaviour = self::SET_BEHAVIOUR_NORMAL;
		}
		else if ($behaviour > self::SET_BEHAVIOUR_THROW){
			$behaviour = self::SET_BEHAVIOUR_THROW;
		}
		$this->constraints[$key]->set->behaviour = $behaviour;
		$this->constraints[$key]->set->callbackClass = $callbackClass;
	}
	
	public function createGetBehaviour($key, $behaviour, ConstraintObjectBehaviourCallable $callbackClass = null){
		$this->constraints[$key]->get = new stdClass();
		if ($behaviour < self::GET_BEHAVIOUR_NORMAL){
			$behaviour = self::GET_BEHAVIOUR_NORMAL;
		}
		else if ($behaviour > self::GET_BEHAVIOUR_THROW){
			$behaviour = self::GET_BEHAVIOUR_THROW;
		}
		$this->constraints[$key]->get->behaviour = $behaviour;
		$this->constraints[$key]->get->callbackClass = $callbackClass;
	}
	
	public function createUnsetBehaviour($key, $behaviour, ConstraintObjectBehaviourCallable $callbackClass = null){
		$this->constraints[$key]->unset = new stdClass();
		if ($behaviour < self::UNSET_BEHAVIOUR_NORMAL){
			$behaviour = self::UNSET_BEHAVIOUR_NORMAL;
		}
		else if ($behaviour > self::UNSET_BEHAVIOUR_THROW){
			$behaviour = self::UNSET_BEHAVIOUR_THROW;
		}
		$this->constraints[$key]->unset->behaviour = $behaviour;
		$this->constraints[$key]->unset->callbackClass = $callbackClass;
	}
	
	public function get(){
		return $this->original;
	}
}

?>