chore(config): adds SAP filter field names to config

CheckDigit.php

@@ -0,0 +1,78 @@
+<?php
+namespace meDIC\PseudoService;
+
+class CheckDigit extends PseudoService {
+
+    /**
+     * Validation check digit of Pat ID 
+     * 10 and 9 digits cases are considered 
+     *   10 digits: returns input if calculated check digit match the input check digit
+     *    9 digits: append a calculated check digit after the input Pat-ID
+     * edge cases are avoided through live form validation in the index.php
+     * 
+     * @author Egidia Cenko
+     * @param string $known_id patient ID
+     * @access public
+     * @return string known_id / -1
+     */
+    public static function validateID($known_id){
+       	// calculate check digit for Pat-ID
+        $calculatedCheckDigit = CheckDigit::calculateCheckDigit($known_id);
+
+        if (strlen($known_id) === 10) {
+            // compare calculated check digit with check digit from user input
+            $checkDigit = substr($known_id, -1);
+
+            // check digit correct?
+            if (intval($checkDigit) === $calculatedCheckDigit) {
+                // user input for Pat-ID is returned
+                return $known_id;
+            } else {
+                return -1;
+            }
+        } elseif (strlen($known_id) === 9) {
+            // return input Pat-ID with calculated check sum digit - no further check can be done
+            return $known_id . $calculatedCheckDigit;
+        }
+    } 
+
+
+    /**
+     * Calculation of the check digit based on DIN ISO 7064
+     * 10 digits: remove the check digit, add a leading 0 for calculation
+     * 9 digits: add a leading 0 for calculation
+     * 
+     * @author Egidia Cenko
+     * @param string $known_id patient ID
+     * @access public
+     * @return integer $checkDigit
+     */
+    public static function calculateCheckDigit($known_id){
+        $digits = str_split($known_id);
+
+        if (strlen($known_id) === 10) {
+            // add leading 0 to digit, remove original input check digit for calculation
+            array_unshift($digits, "0");
+            $digits = array_slice($digits, 0, -1);
+        } elseif (strlen($known_id) === 9) {
+            // add leading zero to 9-digits input
+            array_unshift($digits, "0");
+        }
+
+        if (count($digits) !== 10) {
+            throw new \Exception(strtoupper("Length mismatch after processing: ") . implode($digits));
+        }
+
+        // logic for check digit acc. to DIN ISO 7064
+        $P = 10;
+        foreach ($digits as $char) {
+            $P += intval($char);
+            if ($P > 10) $P -= 10;
+            $P *= 2;
+            if ($P >= 11) $P -= 11;
+        }
+
+        $checkDigit = 11 - $P;
+        return $checkDigit === 10 ? 0 : $checkDigit;
+    }
+}