/**
    * The contents of this file are subject to the Mozilla Public License Version 1.1
    * (the "License"); you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at http://www.mozilla.org/MPL/
    * Software distributed under the License is distributed on an "AS IS" basis,
    * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the
    * specific language governing rights and limitations under the License.
    *
    * The Original Code is "PipeParser.java".  Description:
   * "An implementation of Parser that supports traditionally encoded (i.e"
   *
   * The Initial Developer of the Original Code is University Health Network. Copyright (C)
   * 2001.  All Rights Reserved.
   *
   * Contributor(s): Kenneth Beaton.
   *
   * Alternatively, the contents of this file may be used under the terms of the
   * GNU General Public License (the  �GPL�), in which case the provisions of the GPL are
   * applicable instead of those above.  If you wish to allow use of your version of this
   * file only under the terms of the GPL and not to allow others to use your version
   * of this file under the MPL, indicate your decision by deleting  the provisions above
   * and replace  them with the notice and other provisions required by the GPL License.
   * If you do not delete the provisions above, a recipient may use your version of
   * this file under either the MPL or the GPL.
   *
   */
  
  package ca.uhn.hl7v2.parser;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.StringTokenizer;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import ca.uhn.hl7v2.ErrorCode;
  import ca.uhn.hl7v2.HL7Exception;
  import ca.uhn.hl7v2.Version;
  import ca.uhn.hl7v2.model.Group;
  import ca.uhn.hl7v2.model.Message;
  import ca.uhn.hl7v2.model.Primitive;
  import ca.uhn.hl7v2.model.Segment;
  import ca.uhn.hl7v2.model.Structure;
  import ca.uhn.hl7v2.model.Type;
  import ca.uhn.hl7v2.util.FilterIterator;
  import ca.uhn.hl7v2.util.MessageIterator;
  import ca.uhn.hl7v2.util.Terser;
  
  /**
   * This is a legacy implementation of the PipeParser and should not be used
   * for new projects.
   *
   * In version 1.0 of HAPI, a behaviour was corrected where unexpected segments
   * would be placed at the tail end of the first segment group encountered. Any
   * legacy code which still depends on previous behaviour can use this
   * implementation.
   *
   * @author Bryan Tripp (bryan_tripp@sourceforge.net)
   * @deprecated
   */
  class OldPipeParser extends Parser {
      
      private static final Logger log = LoggerFactory.getLogger(OldPipeParser.class);
      
      private final static String segDelim = "\r"; //see section 2.8 of spec
      
      /** Creates a new PipeParser */
      public OldPipeParser() {
      }
  
      /** 
       * Creates a new PipeParser 
       *  
       * @param theFactory custom factory to use for model class lookup 
       */
      public OldPipeParser(ModelClassFactory theFactory) {
      	super(theFactory);
      }
      
      /**
       * Returns a String representing the encoding of the given message, if
       * the encoding is recognized.  For example if the given message appears
       * to be encoded using HL7 2.x XML rules then "XML" would be returned.
       * If the encoding is not recognized then null is returned.  That this
       * method returns a specific encoding does not guarantee that the
       * message is correctly encoded (e.g. well formed XML) - just that
       * it is not encoded using any other encoding than the one returned.
       */
      public String getEncoding(String message) {
          String encoding = null;
          
          //quit if the string is too short
          if (message.length() < 4)
              return null;
          
          //see if it looks like this message is | encoded ...
          boolean ok = true;
          
         //string should start with "MSH"
         if (!message.startsWith("MSH"))
             return null;
         
         //4th character of each segment should be field delimiter
         char fourthChar = message.charAt(3);
         StringTokenizer st = new StringTokenizer(message, segDelim, false);
         while (st.hasMoreTokens()) {
             String x = st.nextToken();
             if (x.length() > 0) {
                 if (Character.isWhitespace(x.charAt(0)))
                     x = stripLeadingWhitespace(x);
                 if (x.length() >= 4 && x.charAt(3) != fourthChar)
                     return null;
             }
         }
         
         //should be at least 11 field delimiters (because MSH-12 is required)
         int nextFieldDelimLoc = 0;
         for (int i = 0; i < 11; i++) {
             nextFieldDelimLoc = message.indexOf(fourthChar, nextFieldDelimLoc + 1);
             if (nextFieldDelimLoc < 0)
                 return null;
         }
 
         encoding = "VB";
         
         return encoding;
     }
     
     /**
      * @return the preferred encoding of this Parser
      */
     public String getDefaultEncoding() {
         return "VB";
     }
     
     /**
      * Returns true if and only if the given encoding is supported
      * by this Parser.
      */
     public boolean supportsEncoding(String encoding) {
         boolean supports = false;
         if (encoding != null && encoding.equals("VB"))
             supports = true;
         return supports;
     }
     
     /**
      * @deprecated this method should not be public 
      * @param message
      * @return
      * @throws HL7Exception
      * @throws EncodingNotSupportedException
      */
     public String getMessageStructure(String message) throws HL7Exception, EncodingNotSupportedException {
         return getStructure(message).messageStructure;
     }
     
     /**
      * @returns the message structure from MSH-9-3
      */
     private MessageStructure getStructure(String message) throws HL7Exception {
         EncodingCharacters ec = getEncodingChars(message);
         String messageStructure;
         boolean explicityDefined = true;
         String wholeFieldNine;
         try {
             String[] fields = split(message.substring(0, Math.max(message.indexOf(segDelim), message.length())),
                 String.valueOf(ec.getFieldSeparator()));
             wholeFieldNine = fields[8];
             
             //message structure is component 3 but we'll accept a composite of 1 and 2 if there is no component 3 ...
             //      if component 1 is ACK, then the structure is ACK regardless of component 2
             String[] comps = split(wholeFieldNine, String.valueOf(ec.getComponentSeparator()));
             if (comps.length >= 3) {
                 messageStructure = comps[2];
             } else if (comps.length > 0 && comps[0] != null && comps[0].equals("ACK")) {
                 messageStructure = "ACK";
             } else if (comps.length == 2) {
                 explicityDefined = false;
                 messageStructure = comps[0] + "_" + comps[1];
             }
             /*else if (comps.length == 1 && comps[0] != null && comps[0].equals("ACK")) {
                 messageStructure = "ACK"; //it's common for people to only populate component 1 in an ACK msg
             }*/
             else {
                 String buf = "Can't determine message structure from MSH-9: " + wholeFieldNine +
                         " HINT: there are only " +
                         comps.length +
                         " of 3 components present";
                 throw new HL7Exception(buf, ErrorCode.UNSUPPORTED_MESSAGE_TYPE);
             }            
         }
         catch (IndexOutOfBoundsException e) {
             throw new HL7Exception(
             "Can't find message structure (MSH-9-3): " + e.getMessage(),
             ErrorCode.UNSUPPORTED_MESSAGE_TYPE);
         }
         
         return new MessageStructure(messageStructure, explicityDefined);
     }
     
     /**
      * Returns object that contains the field separator and encoding characters
      * for this message.
      */
     private static EncodingCharacters getEncodingChars(String message) {
         return new EncodingCharacters(message.charAt(3), message.substring(4, 8));
     }
     
     /**
      * Parses a message string and returns the corresponding Message
      * object.  Unexpected segments added at the end of their group.  
      *
      * @throws HL7Exception if the message is not correctly formatted.
      * @throws EncodingNotSupportedException if the message encoded
      *      is not supported by this parser.
      */
     protected Message doParse(String message, String version) throws HL7Exception, EncodingNotSupportedException {
         
         //try to instantiate a message object of the right class
         MessageStructure structure = getStructure(message);
         Message m = instantiateMessage(structure.messageStructure, version, structure.explicitlyDefined);
 
         parse(m, message);
 
         return m;
     }
     
     /**
      * Parses a segment string and populates the given Segment object.  Unexpected fields are
      * added as Varies' at the end of the segment.  
      *
      * @throws HL7Exception if the given string does not contain the
      *      given segment or if the string is not encoded properly
      */
     public void parse(Segment destination, String segment, EncodingCharacters encodingChars) throws HL7Exception {
         int fieldOffset = 0;
         if (isDelimDefSegment(destination.getName())) {
             fieldOffset = 1;
             //set field 1 to fourth character of string
             Terser.set(destination, 1, 0, 1, 1, String.valueOf(encodingChars.getFieldSeparator()));
         }
         
         String[] fields = split(segment, String.valueOf(encodingChars.getFieldSeparator()));
         //destination.setName(fields[0]);
         for (int i = 1; i < fields.length; i++) {
             String[] reps = split(fields[i], String.valueOf(encodingChars.getRepetitionSeparator()));
             log.debug("{} reps delimited by: {}", reps.length, encodingChars.getRepetitionSeparator());                
             
             //MSH-2 will get split incorrectly so we have to fudge it ...
             boolean isMSH2 = isDelimDefSegment(destination.getName()) && i+fieldOffset == 2;
             if (isMSH2) {  
                 reps = new String[1];
                 reps[0] = fields[i];
             }
             
             for (int j = 0; j < reps.length; j++) {
                 try {
                     String statusMessage = "Parsing field " + (i + fieldOffset) +
                             " repetition " +
                             j;
                     log.debug(statusMessage);
                     //parse(destination.getField(i + fieldOffset, j), reps[j], encodingChars, false);
 
                     Type field = destination.getField(i + fieldOffset, j);
                     if (isMSH2) {
                         Terser.getPrimitive(field, 1, 1).setValue(reps[j]);
                     } else {
                         parse(field, reps[j], encodingChars);
                     }
                 }
                 catch (HL7Exception e) {
                     //set the field location and throw again ...
                     e.setFieldPosition(i);
                     e.setSegmentRepetition(MessageIterator.getIndex(destination.getParent(), destination).rep);
                     e.setSegmentName(destination.getName());
                     throw e;
                 }
             }
         }
         
         //set data type of OBX-5
         if (destination.getClass().getName().contains("OBX")) {
             FixFieldDataType.fixOBX5(destination, getFactory(), getHapiContext().getParserConfiguration());
         }
         
     }
     
     /** 
      * @return true if the segment is MSH, FHS, or BHS.  These need special treatment 
      *  because they define delimiters.
      * @param theSegmentName
      */
     private static boolean isDelimDefSegment(String theSegmentName) {
         boolean is = false;
         if (theSegmentName.equals("MSH") 
             || theSegmentName.equals("FHS") 
             || theSegmentName.equals("BHS")) 
         {
             is = true;
         }
         return is;
     }
     
     /**
      * Fills a field with values from an unparsed string representing the field.  
      * @param destinationField the field Type
      * @param data the field string (including all components and subcomponents; not including field delimiters)
      * @param encodingCharacters the encoding characters used in the message
      */
     public void parse(Type destinationField, String data, EncodingCharacters encodingCharacters) throws HL7Exception {
         String[] components = split(data, String.valueOf(encodingCharacters.getComponentSeparator()));
         for (int i = 0; i < components.length; i++) {
             String[] subcomponents = split(components[i], String.valueOf(encodingCharacters.getSubcomponentSeparator()));
             for (int j = 0; j < subcomponents.length; j++) {
                 String val = subcomponents[j];
                 if (val != null) {
                     val = Escape.unescape(val, encodingCharacters);
                 }
                 Terser.getPrimitive(destinationField, i+1, j+1).setValue(val);                
             }
         }
     }
     
     /**
      * Splits the given composite string into an array of components using the given
      * delimiter.
      */
     public static String[] split(String composite, String delim) {
         List<String> components = new ArrayList<>();
         
         //defend against evil nulls
         if (composite == null)
             composite = "";
         if (delim == null)
             delim = "";
         
         StringTokenizer tok = new StringTokenizer(composite, delim, true);
         boolean previousTokenWasDelim = true;
         while (tok.hasMoreTokens()) {
             String thisTok = tok.nextToken();
             if (thisTok.equals(delim)) {
                 if (previousTokenWasDelim)
                     components.add(null);
                 previousTokenWasDelim = true;
             }
             else {
                 components.add(thisTok);
                 previousTokenWasDelim = false;
             }
         }
         
         return components.toArray(new String[0]);
     }
     
     /**
      * Encodes the given Type, using the given encoding characters. 
      * It is assumed that the Type represents a complete field rather than a component.
      */
     public static String encode(Type source, EncodingCharacters encodingChars) {
         StringBuilder field = new StringBuilder();
         for (int i = 1; i <= Terser.numComponents(source); i++) {
             StringBuilder comp = new StringBuilder();
             for (int j = 1; j <= Terser.numSubComponents(source, i); j++) {
                 Primitive p = Terser.getPrimitive(source, i, j);
                 comp.append(encodePrimitive(p, encodingChars));
                 comp.append(encodingChars.getSubcomponentSeparator());
             }
             field.append(stripExtraDelimiters(comp.toString(), encodingChars.getSubcomponentSeparator()));
             field.append(encodingChars.getComponentSeparator());
         }
         return stripExtraDelimiters(field.toString(), encodingChars.getComponentSeparator());
         //return encode(source, encodingChars, false);
     }
     
     private static String encodePrimitive(Primitive p, EncodingCharacters encodingChars) {
         String val = p.getValue();
         if (val == null) {
             val = "";
         } else {
             val = Escape.escape(val, encodingChars);
         }
         return val;
     }
     
     /**
      * Removes unecessary delimiters from the end of a field or segment.
      * This seems to be more convenient than checking to see if they are needed
      * while we are building the encoded string.
      */
     private static String stripExtraDelimiters(String in, char delim) {
         char[] chars = in.toCharArray();
         
         //search from back end for first occurance of non-delimiter ...
         int c = chars.length - 1;
         boolean found = false;
         while (c >= 0 && !found) {
             if (chars[c--] != delim)
                 found = true;
         }
         
         String ret = "";
         if (found)
             ret = String.valueOf(chars, 0, c + 2);
         return ret;
     }
     
     /**
      * Formats a Message object into an HL7 message string using the given
      * encoding.
      * @throws HL7Exception if the data fields in the message do not permit encoding
      *      (e.g. required fields are null)
      * @throws EncodingNotSupportedException if the requested encoding is not
      *      supported by this parser.
      */
     protected String doEncode(Message source, String encoding) throws HL7Exception, EncodingNotSupportedException {
         if (!this.supportsEncoding(encoding))
             throw new EncodingNotSupportedException("This parser does not support the " + encoding + " encoding");
         
         return encode(source);
     }
     
     /**
      * Formats a Message object into an HL7 message string using this parser's
      * default encoding ("VB").
      * @throws HL7Exception if the data fields in the message do not permit encoding
      *      (e.g. required fields are null)
      */
     protected String doEncode(Message source) throws HL7Exception {
         //get encoding characters ...
         Segment="../../../../ca/uhn/hl7v2/model/Segment.html#Segment">Segment msh = (Segment) source.get("MSH");
         String fieldSepString = Terser.get(msh, 1, 0, 1, 1);
         
         if (fieldSepString == null) 
             throw new HL7Exception("Can't encode message: MSH-1 (field separator) is missing");
         
         char fieldSep = '|';
         if (fieldSepString.length() > 0)
             fieldSep = fieldSepString.charAt(0);
         
         String encCharString = Terser.get(msh, 2, 0, 1, 1);
         
         if (encCharString == null) 
             throw new HL7Exception("Can't encode message: MSH-2 (encoding characters) is missing");
                 
         if (encCharString.length() != 4)
             throw new HL7Exception(
             "Encoding characters '" + encCharString + "' invalid -- must be 4 characters",
             ErrorCode.DATA_TYPE_ERROR);
         EncodingCharactersrs.html#EncodingCharacters">EncodingCharacters en = new EncodingCharacters(fieldSep, encCharString);
         
         //pass down to group encoding method which will operate recursively on children ...
         return encode(source, en);
     }
     
     /**
      * Returns given group serialized as a pipe-encoded string - this method is called
      * by encode(Message source, String encoding).
      */
     public static String encode(Group source, EncodingCharacters encodingChars) throws HL7Exception {
         StringBuilder result = new StringBuilder();
         
         String[] names = source.getNames();
         for (String name : names) {
             Structure[] reps = source.getAll(name);
             for (Structure structure : reps) {
                 if (structure instanceof Group) {
                     result.append(encode((Group) structure, encodingChars));
                 } else {
                     String segString = encode((Segment) structure, encodingChars);
                     if (segString.length() >= 4) {
                         result.append(segString);
                         result.append('\r');
                     }
                 }
             }
         }
         return result.toString();
     }
     
     public static String encode(Segment source, EncodingCharacters encodingChars) {
         StringBuilder result = new StringBuilder();
         result.append(source.getName());
         result.append(encodingChars.getFieldSeparator());
         
         //start at field 2 for MSH segment because field 1 is the field delimiter
         int startAt = 1;
         if (isDelimDefSegment(source.getName()))
             startAt = 2;
         
         //loop through fields; for every field delimit any repetitions and add field delimiter after ...
         int numFields = source.numFields();
         for (int i = startAt; i <= numFields; i++) {
             try {
                 Type[] reps = source.getField(i);
                 for (int j = 0; j < reps.length; j++) {
                     String fieldText = encode(reps[j], encodingChars);
                     //if this is MSH-2, then it shouldn't be escaped, so unescape it again
                     if (isDelimDefSegment(source.getName()) && i == 2)
                         fieldText = Escape.unescape(fieldText, encodingChars);
                     result.append(fieldText);
                     if (j < reps.length - 1)
                         result.append(encodingChars.getRepetitionSeparator());
                 }
             }
             catch (HL7Exception e) {
                 log.error("Error while encoding segment: ", e);
             }
             result.append(encodingChars.getFieldSeparator());
         }
         
         //strip trailing delimiters ...
         return stripExtraDelimiters(result.toString(), encodingChars.getFieldSeparator());
     }
     
     /**
      * Removes leading whitespace from the given string.  This method was created to deal with frequent
      * problems parsing messages that have been hand-written in windows.  The intuitive way to delimit
      * segments is to hit <ENTER> at the end of each segment, but this creates both a carriage return
      * and a line feed, so to the parser, the first character of the next segment is the line feed.
      */
     public static String stripLeadingWhitespace(String in) {
         StringBuilder out = new StringBuilder();
         char[] chars = in.toCharArray();
         int c = 0;
         while (c < chars.length) {
             if (!Character.isWhitespace(chars[c]))
                 break;
             c++;
         }
         for (int i = c; i < chars.length; i++) {
             out.append(chars[i]);
         }
         return out.toString();
     }
     
     /**
      * <p>Returns a minimal amount of data from a message string, including only the
      * data needed to send a response to the remote system.  This includes the
      * following fields:
      * <ul><li>field separator</li>
      * <li>encoding characters</li>
      * <li>processing ID</li>
      * <li>message control ID</li></ul>
      * This method is intended for use when there is an error parsing a message,
      * (so the Message object is unavailable) but an error message must be sent
      * back to the remote system including some of the information in the inbound
      * message.  This method parses only that required information, hopefully
      * avoiding the condition that caused the original error.  The other
      * fields in the returned MSH segment are empty.</p>
      */
     public Segment getCriticalResponseData(String message) throws HL7Exception {
         //try to get MSH segment
         int locStartMSH = message.indexOf("MSH");
         if (locStartMSH < 0)
             throw new HL7Exception(
             "Couldn't find MSH segment in message: " + message,
             ErrorCode.SEGMENT_SEQUENCE_ERROR);
         int locEndMSH = message.indexOf('\r', locStartMSH + 1);
         if (locEndMSH < 0)
             locEndMSH = message.length();
         String mshString = message.substring(locStartMSH, locEndMSH);
         
         //find out what the field separator is
         char fieldSep = mshString.charAt(3);
         
         //get field array
         String[] fields = split(mshString, String.valueOf(fieldSep));
         
         Segment msh;
         try {
             //parse required fields
             String encChars = fields[1];
             char compSep = encChars.charAt(0);
             String messControlID = fields[9];
             String[] procIDComps = split(fields[10], String.valueOf(compSep));
             
             //fill MSH segment
             String version = Version.lowestAvailableVersion().getVersion(); //default
             try {
                 version = this.getVersion(message);
             }
             catch (Exception e) { /* use the default */
             }
             
             msh = Parser.makeControlMSH(version, getFactory());
             Terser.set(msh, 1, 0, 1, 1, String.valueOf(fieldSep));
             Terser.set(msh, 2, 0, 1, 1, encChars);
             Terser.set(msh, 10, 0, 1, 1, messControlID);
             Terser.set(msh, 11, 0, 1, 1, procIDComps[0]);
             Terser.set(msh, 12, 0, 1, 1, version);
             
             }
         catch (Exception e) {
             throw new HL7Exception(
             "Can't parse critical fields from MSH segment ("
             + e.getClass().getName()
             + ": "
             + e.getMessage()
             + "): "
             + mshString,
             ErrorCode.REQUIRED_FIELD_MISSING, e);
         }
         
         return msh;
     }
     
     /**
      * For response messages, returns the value of MSA-2 (the message ID of the message
      * sent by the sending system).  This value may be needed prior to main message parsing,
      * so that (particularly in a multi-threaded scenario) the message can be routed to
      * the thread that sent the request.  We need this information first so that any
      * parse exceptions are thrown to the correct thread.
      * Returns null if MSA-2 can not be found (e.g. if the message is not a
      * response message).
      */
     public String getAckID(String message) {
         String ackID = null;
         int startMSA = message.indexOf("\rMSA");
         if (startMSA >= 0) {
             int startFieldOne = startMSA + 5;
             char fieldDelim = message.charAt(startFieldOne - 1);
             int start = message.indexOf(fieldDelim, startFieldOne) + 1;
             int end = message.indexOf(fieldDelim, start);
             int segEnd = message.indexOf(segDelim, start);
             if (segEnd > start && segEnd < end)
                 end = segEnd;
             
             //if there is no field delim after MSH-2, need to go to end of message, but not including end seg delim if it exists
             if (end < 0) {
                 if (message.charAt(message.length() - 1) == '\r') {
                     end = message.length() - 1;
                 }
                 else {
                     end = message.length();
                 }
             }
             if (start > 0 && end > start) {
                 ackID = message.substring(start, end);
             }
         }
         log.debug("ACK ID: {}", ackID);
         return ackID;
     }
     
     /**
      * Returns the version ID (MSH-12) from the given message, without fully parsing the message.
      * The version is needed prior to parsing in order to determine the message class
      * into which the text of the message should be parsed.
      * @throws HL7Exception if the version field can not be found.
      */
     public String getVersion(String message) throws HL7Exception {
         int startMSH = message.indexOf("MSH");
         int endMSH = message.indexOf(OldPipeParser.segDelim, startMSH);
         if (endMSH < 0)
             endMSH = message.length();
         String msh = message.substring(startMSH, endMSH);
         String fieldSep;
         if (msh.length() > 3) {
             fieldSep = String.valueOf(msh.charAt(3));
         }
         else {
             throw new HL7Exception("Can't find field separator in MSH: " + msh, ErrorCode.UNSUPPORTED_VERSION_ID);
         }
         
         String[] fields = split(msh, fieldSep);
         
         String compSep;
         if (fields.length >= 2 && fields[1] != null && fields[1].length() == 4) {
             compSep = String.valueOf(fields[1].charAt(0)); //get component separator as 1st encoding char
         } 
         else {
             throw new HL7Exception("Invalid or incomplete encoding characters - MSH-2 is " + fields[1],  
                     ErrorCode.REQUIRED_FIELD_MISSING);
         }
         
         String version;
         if (fields.length >= 12) {
         	String[] comp = split(fields[11], compSep);
         	if (comp.length >= 1) {
         		version = comp[0];
         	} else {
         		throw new HL7Exception("Can't find version ID - MSH.12 is " + fields[11],
         				ErrorCode.REQUIRED_FIELD_MISSING);
         	}
         }
         else {
             throw new HL7Exception(
             		"Can't find version ID - MSH has only " + fields.length + " fields.",
             		ErrorCode.REQUIRED_FIELD_MISSING);
         }
         return version;
     }
 
     /**
      * {@inheritDoc }
      */
     public String doEncode(Segment structure, EncodingCharacters encodingCharacters) {
         return encode(structure, encodingCharacters);
     }
 
     /**
      * {@inheritDoc }
      */
     public String doEncode(Type type, EncodingCharacters encodingCharacters) {
         return encode(type, encodingCharacters);
     }
 
     /**
      * Throws unsupported operation exception
      *
      * @throws UnsupportedOperationException
      */
     @Override
 	protected Message doParseForSpecificPackage(String theMessage, String theVersion, String thePackageName) {
         throw new UnsupportedOperationException("Not supported yet.");
 	}
     
     public void parse(Message message, String string) throws HL7Exception {
         MessageIteratoressageIterator">MessageIterator messageIter = new MessageIterator(message, "MSH", true);
         FilterIterator.Predicate<Structure> segmentsOnly = obj -> Segment.class.isAssignableFrom(obj.getClass());
         FilterIterator<Structure> segmentIter = new FilterIterator<>(messageIter, segmentsOnly);
 
         String[] segments = split(string, segDelim);
 
         char delim = '|';
         for (int i = 0; i < segments.length; i++) {
 
             //get rid of any leading whitespace characters ...
             if (segments[i] != null && segments[i].length() > 0 && Character.isWhitespace(segments[i].charAt(0)))
                 segments[i] = stripLeadingWhitespace(segments[i]);
 
             //sometimes people put extra segment delimiters at end of msg ...
             if (segments[i] != null && segments[i].length() >= 3) {
                 final String name;
                 if (i == 0) {
                     name = segments[i].substring(0, 3);
                     delim = segments[i].charAt(3);
                 } else {
                     if (segments[i].indexOf(delim) >= 0 ) {
                         name = segments[i].substring(0, segments[i].indexOf(delim));
                       } else {
                         name = segments[i];
                       }
                  }
 
                 log.debug("Parsing segment {}", name);
 
                 messageIter.setDirection(name);
                 FilterIterator.Predicate<Structure> byDirection = obj -> {
                     log.debug("PipeParser iterating message in direction {} at {} ", name, obj.getName());
                     return obj.getName().matches(name + "\\d*");
                 };
                 FilterIterator<Structure> dirIter = new FilterIterator<>(segmentIter, byDirection);
                 if (dirIter.hasNext()) {
                     parse((Segment) dirIter.next(), segments[i], getEncodingChars(string));
                 }
             }
         }
     }
 
     
     /**
      * A struct for holding a message class string and a boolean indicating whether it 
      * was defined explicitly.  
      */
     private static class MessageStructure {
         public final String messageStructure;
         public final boolean explicitlyDefined;
         
         public MessageStructure(String theMessageStructure, boolean isExplicitlyDefined) {
             messageStructure = theMessageStructure;
             explicitlyDefined = isExplicitlyDefined;
         }
     }
     
 }