<?php

/**
 * EBSCO API class
 *
 * PHP version 5
 *
 */

/**
 * EBSCO API class
 */
class EBSCOAPI {

  /**
   * The authentication token used for API transactions
   * @global string
   */
  private $authenticationToken;

  /**
   * The session token for API transactions
   * @global string
   */
  private $sessionToken;

  /**
   * The EBSCOConnector object used for API transactions
   * @global object EBSCOConnector
   */
  private $connector;
  private $config;

  public function __construct($config) {
    $this->config = $config;
    $this->connector = new EBSCOConnector($config);
  }

  /**
   * Create a new EBSCOConnector object or reuse an existing one
   *
   * @param none
   *
   * @return EBSCOConnector object
   * @access public
   */
  public function connector($config) {
    if (empty($this->connector)) {
      $this->connector = new EBSCOConnector($config);
    }

    return $this->connector;
  }

  /**
   * Create a new EBSCOResponse object
   *
   * @param object $response
   *
   * @return EBSCOResponse object
   * @access public
   */
  public function response($response) {
    $responseObj = new EBSCOResponse($response);
    return $responseObj;
  }

  /**
   * Request authentication and session tokens, then send the API request.
   * Retry the request if authentication errors occur
   *
   * @param string  $action     The EBSCOConnector method name
   * @param array   $params     The parameters for the HTTP request
   * @param integer $attempts   The number of retries. The default number is 3 but can be increased.
   * 3 retries can handle a situation when both autentication and session tokens need to be refreshed + the current API call
   *
   * @return array              An associative array with results.
   * @access protected
   */
  protected function request($action, $params = null, $attempts = 3) {
    try {

      $authenticationToken = $this->getAuthToken();
      $sessionToken = $this->getSessionToken($authenticationToken);

      if (empty($authenticationToken)) {
        $authenticationToken = $this->getAuthToken();
      }

      if (empty($sessionToken)) {
        $sessionToken = $this->getSessionToken($authenticationToken, 'y');
      }

      $headers = array(
        'x-authenticationToken: ' . $authenticationToken,
        'x-sessionToken: ' . $sessionToken
      );

      $response = call_user_func_array(array($this->connector($this->config), "request{$action}"), array($params, $headers));
      $result = $this->response($response)->result();
      $results = $result;
      return $results;
        } catch (EBSCOException $e) {
      try {
        // Retry the request if there were authentication errors
        $code = $e->getCode();
        switch ($code) {
          case EBSCOConnector::EDS_AUTH_TOKEN_INVALID:
            $authenticationToken = $this->getAuthToken();
            $sessionToken = $this->getSessionToken($authenticationToken);
            $headers = array(
              'x-authenticationToken: ' . $authenticationToken,
              'x-sessionToken: ' . $sessionToken
            );
            if ($attempts > 0) {
              return $this->request($action, $params, $headers, --$attempts);
            }
            break;
          case EBSCOConnector::EDS_SESSION_TOKEN_INVALID:
            $sessionToken = $this->getSessionToken($authenticationToken, 'y');
            $headers = array(
              'x-authenticationToken: ' . $authenticationToken,
              'x-sessionToken: ' . $sessionToken
            );
            if ($attempts > 0) {
              return $this->request($action, $params, $headers, --$attempts);
            }
            break;
          default:
            $result = array(
              'error' => $e->getMessage()
            );
            return $result;
            break;
        }
            } catch (Exception $e) {
        $result = array(
          'error' => $e->getMessage()
        );
        return $result;
            }
        } catch (Exception $e) {
      $result = array(
        'error' => $e->getMessage()
      );
      return $result;
        }
  }

  private function writeTokenFile() {
    $tokenFile = fopen("edstoken.txt", "w+");
    $result = $this->apiAuthenticationToken();
    fwrite($tokenFile, $result['authenticationToken'] . "\n");
    fwrite($tokenFile, $result['authenticationTimeout'] . "\n");
    fwrite($tokenFile, $result['authenticationTimeStamp']);
    fclose($tokenFile);
    return $result['authenticationToken'];
  }

  private function writeLockFile() {
    $lockFile = fopen("edslock.txt", "w+");
    fwrite($lockFile, 'lock');
    fclose($lockFile);
  }

  /*
   * Get authentication token from appication scop 
   * Check authToen's expiration 
   * if expired get a new authToken and re-new the time stamp
   * 
   * @param none
   * 
   * @access public
   */

  public function getAuthToken() {
    $lockFile = fopen("edslock.txt", "r");
    if (empty($lockFile)) {
      $this->writeLockFile();
      $lockFile = fopen("edslock.txt", "r");
    }    
    $tokenFile = fopen("edstoken.txt", "r");
    if (empty($tokenFile)) {
      $this->writetokenFile();
      $tokenFile = fopen("edstoken.txt", "r");
    }
    while (!feof($tokenFile)) {
      $authToken = rtrim(fgets($tokenFile), "\n");
      $timeout = fgets($tokenFile) - 600;
      $timestamp = fgets($tokenFile);
    }
    fclose($tokenFile);
    if (time() - $timestamp >= $timeout) {
      // Lock check.
      if (flock($lockFile, LOCK_EX)) {
        $tokenFile = fopen("edstoken.txt", "w+");
        $result = $this->apiAuthenticationToken();
        fwrite($tokenFile, $result['authenticationToken'] . "\n");
        fwrite($tokenFile, $result['authenticationTimeout'] . "\n");
        fwrite($tokenFile, $result['authenticationTimeStamp']);
        fclose($tokenFile);
        return $result['authenticationToken'];
      }
      else {
        return $authToken;
      }
    }
    else {
      return $authToken;
    }
    fclose($lockFile);
  }

  /**
   * Wrapper for authentication API call
   *
   * @param none
   *
   * @access public
   */
  public function apiAuthenticationToken() {
    $response = $this->connector->requestAuthenticationToken();
    $result = $this->response($response)->result();
    return $result;
  }

  /**
   * Get session token for a profile 
   * If session token is not available 
   * a new session token will be generated
   * 
   * @param Authentication token, Profile 
   * @access public
   */
  public function getSessionToken($authenToken, $invalid = 'n') {
    $token = '';

    // Check user's login status
    /* if(isset($_COOKIE['login'])){              
      if($invalid=='y'){
      $profile = $_SESSION['sessionToken']['profile'];
      $sessionToken = $this->apiSessionToken($authenToken, $profile,'n');
      $_SESSION['sessionToken']=$sessionToken;
      }
      $token = $_SESSION['sessionToken']['sessionToken'];
      } */
    //else 
    if (isset($_COOKIE['Guest'])) {
      if ($invalid == 'y') {
        $profile = $_SESSION['sessionToken']['profile'];
        if (empty($profile)) {
          $profile = $_COOKIE['Guest'];
        }
        $sessionToken = $this->apiSessionToken($authenToken, $profile, 'y');
        $_SESSION['sessionToken'] = $sessionToken;
      }
      $token = $_SESSION['sessionToken']['sessionToken'];
    }
    else {

      $profileId = $this->config['profile'];

      $sessionToken = $this->apiSessionToken($authenToken, $profileId, 'y');
      $_SESSION['profile'] = $profileId;
      $_SESSION['sessionToken'] = $sessionToken;
      setcookie("Guest", $profileId, 0);
      $token = $sessionToken['sessionToken'];
    }
    return $token;
  }

  /**
   * Wrapper for session API call
   *
   * @param Authentication token
   *
   * @access public
   */
  public function apiSessionToken($authenToken, $profile, $guest) {
    // Add authentication tokens to headers
    $headers = array(
      'x-authenticationToken: ' . $authenToken
    );

    $response = $this->connector($this->config)->requestSessionToken($headers, $profile, $guest);
    $result = $this->response($response)->result();
    $token = array(
      'sessionToken' => $result,
      'profile' => $profile
    );
    return $token;
  }

  /**
   * Wrapper for end session API call
   *
   * @param Authentication token
   *
   * @access public
   */
  public function apiEndSessionToken($authenToken, $sessionToken) {

    // Add authentication tokens to headers
    $headers = array(
      'x-authenticationToken: ' . $authenToken
    );

    $this->connector($this->config)->requestEndSessionToken($headers, $sessionToken);
  }

  /**
   * Wrapper for search API call
   *
   * @param 
   *
   * @throws object             PEAR Error
   * @return array              An array of query results
   * @access public
   */
  public function apiSearch($params) {

    $results = $this->request('Search', $params);
    return $results;
  }

  /**
   * Wrapper for retrieve API call
   *
   * @param array  $an          The accession number
   * @param string $start       The short database name
   *
   * @throws object             PEAR Error
   * @return array              An associative array of data
   * @access public
   */
  public function apiRetrieve($an, $db, $term) {
    // Add the HTTP query params
    $params = array(
      'an' => $an,
      'dbid' => $db,
      'highlightterms' => $term // Get currect param name
    );
    $params = http_build_query($params);
    $result = $this->request('Retrieve', $params);
    return $result;
  }

  /**
   * Wrapper for info API call
   *
   * @return array              An associative array of data
   * @access public
   */
  public function getInfo() {
    if (isset($_SESSION['info'])) {
      $InfoArray = $_SESSION['info'];
      $timestamp = $InfoArray['timestamp'];
      if (time() - $timestamp >= 3600) {
        // Get new Info for the profile
        $InfoArray = $this->apiInfo();
        $_SESSION['info'] = $InfoArray;
        $info = $InfoArray['Info'];
      }
      else {
        $info = $InfoArray['Info'];
      }
    }
    else {
      // Get new Info for the profile
      $InfoArray = $this->apiInfo();
      $_SESSION['info'] = $InfoArray;
      $info = $InfoArray['Info'];
    }
    return $info;
  }

  public function apiInfo() {

    $response = $this->request('Info', '');
    $Info = array(
      'Info' => $response,
      'timestamp' => time()
    );
    return $Info;
  }

}

?>