<?php

class HL7Parser
{
    var $messageElements = array("MSH" => 18, "PID" => 30, "PV1" => 52, "IN1" => 49, "ORC" => 19, "OBR" => 43);

    function getDatabaseInput($hl7message)
    {
        if ($hl7message) {
            // hl7message exists

            $hl7ausgabe = $this->parsemsg($hl7message);

            $selectedInformation = array();

            $selectedInformation["patientID"] = $this->getDatabaseElement($hl7ausgabe, array('PID', 2));

            $selectedInformation["patientLastName"] = $this->getDatabaseElement($hl7ausgabe,array('PID', 4, 0));

            $selectedInformation["patientFirstname"] = $this->getDatabaseElement($hl7ausgabe,array('PID', 4, 1));

            if ($selectedInformation["patientFirstname"] = '' && $selectedInformation["patientLastName"] = '' ){

                $selectedInformation["patientLastName"] = $this->getDatabaseElement($hl7ausgabe,array('PID', 4));
            }

            $selectedInformation["patientCode"] = $this->getDatabaseElement($hl7ausgabe,array('OBR', 3, 0));

            $selectedInformation["patientDateOfBirth"] = $this->parseDateFormat($this->getDatabaseElement($hl7ausgabe,array('PID', 6)));

            $selectedInformation["patientWard"] = "Found in Second IN1 segment 36 at 21012.hl7";

            $selectedInformation["patientCaseNr"] = $this->getDatabaseElement($hl7ausgabe,array('PV1', 19));

            $selectedInformation["patientKlAu-Nr"] = $this->getDatabaseElement($hl7ausgabe,array('ORC', 4));

            $selectedInformation["patientKlAu-Dat"] = $this->parseDateTimeFormat($this->getDatabaseElement($hl7ausgabe,array('OBR', 7)));

            return $selectedInformation;

        }else{
            //no hl7 message found
            return false;
        }


    }

    function getDatabaseElement($array, $segments)
    {
        foreach ($segments as $segment) {

            if (is_array($array) && array_key_exists($segment, $array)) {

                $array = $array[$segment];

            } else {

                return "";
            }
        }

        return $array;

    }

    function parseDateFormat($string)
    {
        if ($string == ''){
            return '';
        }
        $string = substr_replace($string, '-', 4, 0);
        $string = substr_replace($string, '-', 7, 0);
        return $string;
    }

    function parseDateTimeFormat($string)
    {
        $string = utf8_encode($string);
        $string = str_replace(" ", "", $string);
        $string = str_replace("\t", "", $string);

        if ($string == ''){
            return '';
        }
        $date = $this->parseDateFormat(substr($string, 0, 8));
        $time = substr($string, 8);
        $time = substr_replace($time, ':', 4, 0);
        $time = substr_replace($time, ':', 2, 0);
        return $date . " " . $time;
    }

    function parsemsg($string)
    {
        //looks for the closing bar of the delimiting characters
        if (substr($string, 0, 3) != 'MSH') {
            $out['ERROR'][0] = 'Invalid HL7 Message.';
            $out['ERROR'][1] = 'Must start with MSH';
            return $out;
        }

        //get delimiting characters

        $delbarpos = strpos($string, '|', 4);
        $delchar = substr($string, 4, ($delbarpos - 4));

        if (!defined('FLD_SEP')) {
            define('FLD_SEP', substr($delchar, 0, 1));
        }
        if (!defined('SFLD_SEP')) {
            define('SFLD_SEP', substr($delchar, 1, 1));
        }
        if (!defined('REP_SEP')) {
            define('REP_SEP', substr($delchar, 2, 1));
        }
        if (!defined('ESC_CHAR')) {
            define('ESC_CHAR', substr($delchar, 3, 1));
        }

        $out = array();

        while (strlen($string) > 0) {
            $segname = substr($string, 0, strpos($string, '|'));
            if (array_key_exists($segname, $this->messageElements)) {
                //valid message element name
                $string = substr($string, 3);
                $out[$segname] = array();
                for ($elementCount = 0; $elementCount < $this->messageElements[$segname]; $elementCount++) {
                    $delbarposCurrent = strpos($string, '|');
                    $delbarposNext = strpos($string, '|', $delbarposCurrent + 1);
                    if (($elementCount + 1) == $this->messageElements[$segname]) {
                        //end of segment, next segment must be manually seperated
                        if ($delbarposNext) {
                            //next segment exists
                            $delbarposNext -= 3;
                        } else {
                            //no next segment -> end of message
                            $delbarposNext = strlen($string);
                        }

                    }

                    $element = substr($string, $delbarposCurrent + 1, $delbarposNext - 1);

                    if (strpos($element, FLD_SEP) == false) {
                        //no field seperator -> only one information in element
                        $out[$segname][] = $element;

                    } else {
                        //field seperator found -> element contains multiple information
                        $elements = array();

                        $sf = explode(FLD_SEP, $element);

                        foreach ($sf as $f) {
                            $elements[] = $f;
                        }
                        $out[$segname][] = $elements;
                    }
                    $string = substr($string, $delbarposNext);
                }
            } else {
                $out['ERROR'][0] = 'Invalid HL7 Message.';
                $out['ERROR'][1] = $segname . " is not a valid Segment";
                return $out;
            }


        }
        return $out;
    }
}

function getFiles($directory)
{
//check directory for new hl7 messages
    $handle = opendir($directory);
    $files = array();
    while ($file = readdir($handle)) {
        if ($file != "." && $file != ".." && !is_dir($file) && $file != 'Description') {
            $files[] = $file;
        }
    }
    return $files;
}