// MboxParser.java - read in a file with a series of MIME email messages, break out messages.
// By Rowland http://home.comcast.net/~rowland3/

import java.io.*;
import java.util.*;

class Joiner {
    public static String join(Object[] lines, String inbetween) {
	int count= lines.length;
	StringBuffer sb= new StringBuffer("");
	int c;
	for (c= 0; c< count-1; c++) {
	    sb.append((String)lines[c]);
	    sb.append(inbetween);
	}
	if (count> 0)
	    sb.append((String)lines[count-1]);   
	return sb.toString();
    }
    public static final String join(String[] lines) {
	return join(lines, "\n");
    }
    public static final String join(Vector vlines, String inbetween) {
	return join(vlines.toArray(), inbetween);
    }
    public static final String join(Vector vlines) {
	return join(vlines.toArray(), "\n");
    }
}

//------------------------------------------------------------------------------
public class MboxParser  {
    protected LineNumberReader in;
    protected boolean expectingStart;
    protected boolean inMessageBody= false;

    // Components of the message being harvested:
    protected String from= null;
    protected String year= null;
    protected String subject= null;
    protected String messageid= null;
    protected Vector messageBody= null;

    public MboxParser(String fileSpec) throws Exception  {
	File file= new File(fileSpec);
	if (!file.exists())  throw new IOException("No such file: "+ fileSpec);
	Reader reader= new InputStreamReader(new FileInputStream(fileSpec));
	in= new LineNumberReader(reader);
	run();
    } 
    public MboxParser(InputStreamReader reader) throws Exception  {
	in= new LineNumberReader(reader);
	run();
    }
    
    protected void run() {
	String line= null;
	try {
	    expectingStart= true;
	    while ((line=in.readLine())!= null)
		doLine(line);
	    if (inMessageBody)  doMessageEnd();
	    in.close();
	}
	catch (Exception E) {
	    System.err.println("ERR MboxParser run: "+ E.toString());
	    System.err.println("     line: "+ line);
	    E.printStackTrace();
	}
    }
    
    protected void doLine(String line) {
	if (line.length()== 0) {
	    expectingStart= true;
	    if (inMessageBody)  doMessageBodyLine(line);
	    else  inMessageBody= true;  // end of header
	}  else if (expectingStart && line.startsWith("From "))
	    doFromLine(line);
	else  if (!inMessageBody && line.startsWith("Subject: ")) {
	    expectingStart= false;
	    subject= line.substring(9);
	}
	else  if (!inMessageBody && line.startsWith("Message-ID: ")) {
	    expectingStart= false;
	    messageid= line.substring(12);
	} else {
	    expectingStart= false;
	    doMessageBodyLine(line);
	}
    }
    
    protected final void doFromLine(String line) {
	if (messageBody!= null)  doMessageEnd();  // process previous message
	StringTokenizer st= new StringTokenizer(line);
	Vector v= new Vector();
	while (st.hasMoreTokens()) {
	    String field= st.nextToken();
	    v.add(field);
	}
	st= null;

	Object[] fields= v.toArray();
	String y= (String)fields[fields.length-1];
	char c= y.charAt(0);
	if (c< '0' || c> '2') {
	    //System.err.println("Bad year: "+ year);
	    if (inMessageBody)  doMessageBodyLine(line);  // false positive
	    return;
	}

	from = (String)fields[1];
	year= y;
	v= null;
	messageBody= new Vector();
	inMessageBody= false;
	expectingStart= false;
     }

    protected final void doMessageBodyLine(String line) {
	if (messageBody== null)  messageBody= new Vector();
	//System.out.println("doMessageBodyLine: "+ line);
	messageBody.add(line);
    }

    protected final void doMessageEnd() {
	String body= Joiner.join(messageBody, "\n");
	if (messageid== null)
	    messageid= from+year+subject; // better than nothing
	doMessageCallback(messageid, from, year, subject, body);
	messageBody= null;
	inMessageBody= false;
	messageid= null;
    }

    protected void doMessageCallback(String messageid, String from, String year, String subject,
				     String body) {
	System.out.println("From: "+ from+ "   year: "+ year+ "   "+ subject);
    }
    
}