/**
 * 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 "MessageLibrary.java".  Description:
 * "Collection of HL7 messages."
 *
 * The Initial Developer of the Original Code is Leslie Mann. Copyright (C)
 * 2002.  All Rights Reserved.
 *
 * Contributor(s): ______________________________________.
 *
 * 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.util;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;

import ca.uhn.hl7v2.Log;
import ca.uhn.hl7v2.model.Message;
import ca.uhn.hl7v2.parser.DefaultXMLParser;
import ca.uhn.hl7v2.parser.GenericParser;
import ca.uhn.hl7v2.parser.Parser;
import ca.uhn.hl7v2.parser.PipeParser;


/**
 * Collection of HL7 messages.
 * Parses a text file of HL7 formatted messages into a collection
 * of {@link LibraryEntry} entries.
 * The message file consists of HL7 messages and comments. Each 
 * message should be terminated by one or more blank lines.
 * Single and multi-line comments in the message file are ignored.
 * Single line comments begin with "//".  Multi-line comments consist of all 
 * lines between "C" style comment delimiters.
 * @see LibraryEntry
 * 
 * @author Leslie Mann
 */
public class MessageLibrary extends ArrayList {
	private final String MULTI_LINE_COMMENT_START = "/*";
	private final String MULTI_LINE_COMMENT_END = "*/";
	private final String SINGLE_LINE_COMMENT = "//";
    // NB: Per the minimal lower layer protocol.
	// character indicating the termination of an HL7 message
    private static final char END_MESSAGE = '\u001c'; 
    // character indicating the start of an HL7 message
    private static final char START_MESSAGE = '\u000b';
     // the final character of a message: a carriage return
    private static final char LAST_CHARACTER = 13;
		
	private String messageFilePath;
	private String encoding;
	private int numParsingErrors = 0;
		
	/**
	 * Library with no message encoding specified.
	 * A GenericParser will be used for message parsing.
	 * 
	 * @param path path to HL7 message text file
	 */
	public MessageLibrary(String messageFilePath) {
		super.addAll(setEntries(messageFilePath));
		this.messageFilePath = messageFilePath;
		this.encoding = null;
			
	}

	/**
	 * Library using a specific message encoding.
	 * Parser appropriate to requested encoding 
	 * will be used for all messages.
	 * 
	 * @param path path to HL7 message text file
	 * @param encoding message encoding to use
	 */
	public MessageLibrary(String messageFilePath, String encoding) {
		super.addAll(setEntries(messageFilePath));
		this.messageFilePath = messageFilePath;
		this.encoding = encoding;
			
	}

	/*
	 * Parses each HL7 message from text file into a LibraryEntry
	 * Entries are collected into an ArrayList.
	 */
	private ArrayList setEntries(String messageFilePath) {
		ArrayList entries = new ArrayList();
		Parser parser;
		if (encoding=="XML") {
			parser = new DefaultXMLParser();
		} else if (encoding=="VB") {
			parser = new PipeParser();
		} else {
			parser = new GenericParser();
		}

		try {
            BufferedReader in = new BufferedReader(new InputStreamReader(
                    this.getClass().getClassLoader().getResourceAsStream(messageFilePath)));
			//BufferedReader in = new BufferedReader(new FileReader(messageFilePath));
	 
			StringBuffer msgBuf = new StringBuffer();
			HashMap segments = new HashMap();
			Message msg = null;
		
			boolean eof = false;
			boolean inComment = false;
			//process file
			while (!eof) {
				String line = in.readLine();

				// check if end of file...
				if (line == null) {
					eof = true;
				// or in comment
				} else {
					if (line.startsWith(SINGLE_LINE_COMMENT)) {
						continue;
					} else if (inComment) {
						//allow for single space indent
						if (line.substring(0,3).trim().startsWith(MULTI_LINE_COMMENT_END)) {
							inComment = false;
						}
						continue;
					} else if (line.startsWith(MULTI_LINE_COMMENT_START)) {
						inComment = true;
						continue;
					}
				}
				
				// assumes that any non blank, non comment lines are part of a message
				if (!eof && line.length()>0) {
					String[] lineSplit = line.split("\\|");
					String lineKey = lineSplit[0];
					try {
						Integer.parseInt(lineSplit[1]);
						lineKey = lineKey + "|" + lineSplit[1];
					} catch (NumberFormatException e) {
						int stop = 1;
					} catch (ArrayIndexOutOfBoundsException e) {
						int stop = 1;
					}
					segments.put(lineKey, line);
					msgBuf.append(line+"\r");
				} else if (msgBuf.length()>0) {
					//only add an entry if have added some lines
					//msgBuf.append("\r\n");
					String msgStr = msgBuf.toString();
					try {
						msg = parser.parse(msgStr);
						Status.writeStatus("Message:\n" + msgStr);
					} catch (Exception e) {
						++numParsingErrors;
						Status.writeStatus("Warning: Parsing errors with message:\n" + msgStr);
						Log.tryToLog(e, "Parsing errors with message:\n" + msgStr);
					}
					entries.add(new LibraryEntry(new String(msgStr), new HashMap(segments), msg));
					//reset for next message
					msgBuf.setLength(0);
					segments.clear();
					msg = null;
				}
			}
			in.close();
		} catch (FileNotFoundException e) {
			Status.writeStatus("Warning: Message file not found: " + messageFilePath);
			Log.tryToLog(e, "Message file not found " + messageFilePath);
		} catch (IOException e) {
			Status.writeStatus("Warning: Unable to open message file: " + messageFilePath);
			Log.tryToLog(e, "Unable to open message file: " + messageFilePath);
		}
		return entries;
	}

	/**
	 * Returns the message library entry strings as a 
	 * Minimal Lower Layer Protocol encoded stream
	 * (same output as would be generated by {@link MinLLPWriter})
	 * 
	 * @see MinLLPWriter
	 * @return a stream of HL7 messages
	 */
	public ByteArrayInputStream getAsByteArrayInputStream() {
		Iterator msgs = this.iterator();
		StringBuffer inputMessages = new StringBuffer();
		while (msgs.hasNext()) {
			LibraryEntry entry = (LibraryEntry) msgs.next();
			String temp = entry.messageString();
			inputMessages.append(START_MESSAGE + entry.messageString() + END_MESSAGE + LAST_CHARACTER);
		}			
		return new ByteArrayInputStream(inputMessages.toString().getBytes());
	}


	/**
	 * Returns the path of the HL7 message text file.
	 * @return message file path
	 */
	public String getMessageFilePath() {
		return messageFilePath;	
	}
	/**
	 * Returns the parsingErrors.
	 * @return number of parsing errors
	 */
	public int getNumParsingErrors() {
		return numParsingErrors;
	}

	/**
	 * Returns the parserType.
	 * @return parser encoding used
	 */
	public String getParserType() {
		return encoding;
	}

}