<?php

/**
 * ArangoDB PHP client: single document 
 * 
 * @package ArangoDbPhpClient
 * @author Jan Steemann
 * @copyright Copyright 2012, triagens GmbH, Cologne, Germany
 */

namespace triagens\ArangoDb;

/**
 * Value object representing a single collection-based document
 *
 * @package ArangoDbPhpClient
 */
class Edge extends Document {
  /**
   * The edge's from (might be NULL for new documents)
   * @var mixed
   */
  protected $_from     = NULL;
  
  /**
   * The edge's to (might be NULL for new documents)
   * @var mixed
   */
  protected $_to     = NULL;
  
  /**
   * Document _from index
   */
   
  const ENTRY_FROM    = '_from';
  
  /**
   * Revision _to index
   */
  const ENTRY_TO   = '_to';

  
  /**
   * Clone a document
   * 
   * Returns the clone 
   *
   * @return void
   */
  public function __clone() {
    $this->_id = NULL;
    $this->_rev = NULL;

    // do not change the _changed flag here
  }
  

  /**
   * Set a document attribute
   *
   * The key (attribute name) must be a string.
   * 
   * This will validate the value of the attribute and might throw an
   * exception if the value is invalid.
   *
   * @throws ClientException
   * @param string $key - attribute name
   * @param mixed $value - value for attribute
   * @return void
   */
  public function set($key, $value) {
    if (!is_string($key)) {
      throw new ClientException('Invalid document attribute key');
    }

    // validate the value passed
    ValueValidator::validate($value);

    if ($key === self::ENTRY_ID) {
      $this->setInternalId($value);
      return;
    }
    
    if ($key === self::ENTRY_REV) {
      $this->setRevision($value);
      return;
    }

    if ($key === self::ENTRY_FROM) {
      $this->setFrom($value);
      return;
    }
    
    if ($key === self::ENTRY_TO) {
      $this->setTo($value);
      return;
    }

    if (!$this->_changed) {
      if (!isset($this->_values[$key]) || $this->_values[$key] !== $value) {
        // set changed flag
        $this->_changed = true;
      }
    }

    // and store the value
    $this->_values[$key] = $value;
  }
  
 
  /**
   * Get the 'from' vertex document-handler (if already known)
   *
   * @return mixed - document-handler
   */
  public function getFrom() {
    return $this->_from;
  }
  
  /**
   * Get the 'to' vertex document-handler (if already known) 
   *
   * @return mixed - document-handler
   */
  public function getTo() {
    return $this->_to;
  }
  
  /**
   * Set the 'from' vertex document-handler
   *
   * @param mixed $from - from vertex
   * @return Edge - edge object
   */
  public function setFrom($from) {
      $this->_from=$from;
    return $this;
  }
  
  /**
   * Set the 'to' vertex document-handler
   *
   * @param mixed $to - to vertex
   * @return Edge - edge object
   */
  public function setTo($to) {
      $this->_to=$to;
    return $this;
  }

}