<?PHP

  require_once ('twIf/i18n.php');
  require_once ('twIf/object/interface.php');
  
  /**
   * twIf abstract Object
   * 
   **/
  abstract class twIf_Object implements twIf_Object_Interface {
    const FLAG_ID_MD5 = 'md5(ID)';
    
    public $ID = '';
    
    private $wasChanged = false;
    
    // {{{ newInstance
    /**
     * Create a new instance of a class
     * 
     * @param ...
     * 
     * @access public
     * @return object
     **/
    public static function newInstance () {
      trigger_error (twIf_i18n::getText ('We can not create an abstract/empty twIf_Object'), E_USER_ERROR);
      
      return false;
    }
    // }}}
    
    // {{{ getID
    /**
     * Retrive the unique identifier of this object
     * 
     * @access public
     * @return string
     **/
    public function getID () {
      trigger_error (twIf_i18n::getText ('getID not implemented, results may be empty or not unique'), E_USER_WARNING);
      
      return $this->ID;
    }
    // }}}
    
    // {{{ isEnabled
    /**
     * Check wheter an object has an enabled status or set the flag
     * 
     * @param bool $newValue (optional) Set new enabled-Status
     * 
     * @access public
     * @return bool
     **/
    public function isEnabled ($newValue = null) {
      trigger_error (twIf_i18n::getText ('isEnabled not implemented, asuming always false'), E_USER_WARNING);
      
      return false;
    }
    // }}}
    
    // {{{ checkUpdate
    /**
     * Determine if an object should be stored / has pending updates
     * 
     * @access public
     * @return bool
     **/
    public function checkUpdate () {
      return $this->wasChanged;
    }
    // }}}
    
    // {{{ update
    /**
     * Set new value on an object
     * 
     * @param string $Name Name of the value
     * @param mixed $Value New Value
     * @param bool $Commit (optional) Commit changes directly
     * 
     * @access public
     * @return bool
     **/
    public function update ($Name, $Value, $Commit = false) {
      // Check if there is such property
      if (!isset ($this->$Name) && !empty ($this->$Name))
        return false;
      
      // Check if there is no change
      if ($this->$Name == $Value)
        return true;
      
      if ($Name == 'ID')
        trigger_error (twIf_i18n::getText ('You are about to change a primary identifier, hopefully you are sure what you are doing'), E_USER_WARNING);
      
      // Update
      $oldValue = $this->$Name;
      $this->$Name = $Value;
      
      if ($Commit && !$this->commit ()) {
        $this->$Name = $oldValue;
        
        tigger_error (twIf_i18n::getText ('Could not commit, restoring'));
        
        return false;
      }
      
      $this->wasChanged = true;
      
      return true;
    }
    // }}}
    
    // {{{ commit
    /**
     * Save changes on this object to disk or any other storage
     * 
     * @access public
     * @return bool
     **/
    public function commit () {
      trigger_error (twIf_i18n::getText ('commit is not implemented, objects will not persist'), E_USER_WARNING);
      
      return true;
    }
    // }}}
    
    // {{{ remove
    /**
     * Remove this object from its storages
     * 
     * @access public
     * @return bool false if failed, true if success immediatly, null if success but delayed
     **/
    public function remove () {
      trigger_error (twIf_i18n::getText ('remove is not implemented'), E_USER_WARNING);
      
      return false;
    }
    // }}}
  }

?>