1: <?php
  2:     /**
  3:      * Session-based FormState handler.  Uses PHP Sessions to store the form state.
  4:      * 
  5:      * Stores the variables in the following format:
  6:      * $_SESSION['qformstate'][form_uniquid][state#]
  7:      *   where the form_uniquid is a unique id that sticks with the window that the
  8:      *   form is on, and state# is the formstate associated with that window. Multiple
  9:      *   formstates need to be saved to support the browser back button.
 10:      * 
 11:      * If requested by QForm, the index will be encrypted.
 12:      * 
 13:      * This incorporates a system of garbage collection that will allow for at most BackButtonMax
 14:      * formstates to be saved in the session.
 15:      *
 16:      * This handler is compatible with asynchronous ajax calls.
 17:      *
 18:      */
 19:     class QSessionFormStateHandler extends QBaseClass {
 20:         
 21:         public static $BackButtonMax = 20; // maximum number of back button states we remember
 22:         
 23:         public static function Save($strFormState, $blnBackButtonFlag) {
 24:             // Compress (if available)
 25:             if (function_exists('gzcompress'))
 26:                 $strFormState = gzcompress($strFormState, 9);
 27:                 
 28:             if (empty($_POST['Qform__FormState'])) {
 29:                 // no prior form state, so create a new one.
 30:                 $strFormInstance = uniqid();
 31:                 $intFormStateIndex = 1;
 32:             } else {
 33:                 $strPriorState = $_POST['Qform__FormState'];
 34:                 
 35:                 if (!is_null(QForm::$EncryptionKey)) {
 36:                     // Use QCryptography to Decrypt
 37:                     $objCrypto = new QCryptography(QForm::$EncryptionKey, true);
 38:                     $strPriorState = $objCrypto->Decrypt($strPriorState);
 39:                 }
 40:                 
 41:                 $a = explode ('_', $strPriorState);
 42:                 if (count ($a) == 2 && 
 43:                         is_numeric ($a[1]) &&
 44:                         !empty($_SESSION['qformstate'][$a[0]]['index'])) {
 45:                     $strFormInstance = $a[0];
 46:                     $intFormStateIndex = $_SESSION['qformstate'][$a[0]]['index'];
 47:                     if ($blnBackButtonFlag) { // can we reuse current state info?
 48:                         $intFormStateIndex ++; // nope
 49:                         
 50:                         // try to garbage collect
 51:                         if (count($_SESSION['qformstate'][$a[0]]) > self::$BackButtonMax) {
 52:                             foreach ($_SESSION['qformstate'][$a[0]] as $key=>$val) {
 53:                                 if (is_numeric($key) && $key < $_SESSION['qformstate'][$a[0]]['index'] - self::$BackButtonMax) {
 54:                                     unset ($_SESSION['qformstate'][$a[0]][$key]);
 55:                                 }
 56:                             }
 57:                         }
 58:                     }
 59:                 } else {
 60:                     // couldn't find old session variables, so create new one
 61:                     $strFormInstance = uniqid();
 62:                     $intFormStateIndex = 1;
 63:                 }
 64:             }
 65:                 
 66:             // Setup current state variable
 67:             if (empty($_SESSION['qformstate'])) {
 68:                 $_SESSION['qformstate'] = array();
 69:             } 
 70:             if (empty($_SESSION['qformstate'][$strFormInstance])) {
 71:                 $_SESSION['qformstate'][$strFormInstance] = array();
 72:             } 
 73:             
 74:             $_SESSION['qformstate'][$strFormInstance]['index'] = $intFormStateIndex;
 75:             $_SESSION['qformstate'][$strFormInstance][$intFormStateIndex] = $strFormState;
 76:             
 77:             $strPostDataState = $strFormInstance . '_' . $intFormStateIndex;
 78:             
 79:             // Return StateIndex
 80:             if (!is_null(QForm::$EncryptionKey)) {
 81:                 // Use QCryptography to Encrypt
 82:                 $objCrypto = new QCryptography(QForm::$EncryptionKey, true);
 83:                 return $objCrypto->Encrypt($strPostDataState);
 84:             } else
 85:                 return $strPostDataState;
 86:         }
 87: 
 88:         public static function Load($strPostDataState) {
 89:             // Pull Out intStateIndex
 90:             if (!is_null(QForm::$EncryptionKey)) {
 91:                 // Use QCryptography to Decrypt
 92:                 $objCrypto = new QCryptography(QForm::$EncryptionKey, true);
 93:                 $strPostDataState = $objCrypto->Decrypt($strPostDataState);
 94:             }
 95:         
 96:             $a = explode ('_', $strPostDataState);
 97:             if (count ($a) == 2 && 
 98:                     is_numeric ($a[1]) &&
 99:                     !empty($_SESSION['qformstate'][$a[0]][$a[1]])) {
100:                 $strSerializedForm = $_SESSION['qformstate'][$a[0]][$a[1]];
101:             } else {
102:                 return null;
103:             }
104:             
105:             // Uncompress (if available)
106:             // NOTE: if gzcompress is used, we are restoring the *BINARY* data stream of the compressed formstate
107:             // In theory, this SHOULD work.  But if there is a webserver/os/php version that doesn't like
108:             // binary session streams, you can first base64_decode before restoring from session (see note above).
109:             if (function_exists('gzcompress')) {
110:                 $strSerializedForm = gzuncompress($strSerializedForm);
111:             }
112: 
113:             return $strSerializedForm;
114:         }
115:     }