EmailMessage.java

import java.util.*;
import java.util.regex.*;

public class EmailMessage {

    private int messageNumber;
    private int sizeOctets;
    private String from = "";
    private String replyTo = "";
    private String subject = "";
    private String messageId = "";
    private Map<String, String> headers = new LinkedHashMap<>();

    private EmailMessage() {
    }

    public static EmailMessage parse(String raw, int msgNumber, int sizeOctets) {
        EmailMessage msg = new EmailMessage();
        msg.messageNumber = msgNumber;
        msg.sizeOctets = sizeOctets;
        String headerSection = raw.split("\r?\n\r?\n", 2)[0];
        String unfolded = headerSection.replaceAll("\r?\n[ \t]+", " ");

        for (String line : unfolded.split("\r?\n")) {
            int colon = line.indexOf(':');
            if (colon < 0)
                continue;
            String name = line.substring(0, colon).trim().toLowerCase();
            String value = line.substring(colon + 1).trim();
            msg.headers.putIfAbsent(name, value);
        }

        msg.from = msg.headers.getOrDefault("from", "");
        msg.replyTo = msg.headers.getOrDefault("reply-to", "");
        msg.subject = msg.headers.getOrDefault("subject", "");
        msg.messageId = msg.headers.getOrDefault("message-id", "");

        return msg;
    }

    public String getEffectiveReplyAddress() {
        return !replyTo.isEmpty() ? replyTo : from;
    }

    public static String extractAddress(String headerValue) {
        if (headerValue == null || headerValue.isEmpty())
            return "";
        Matcher m = Pattern.compile("<([^>]+)>").matcher(headerValue);
        if (m.find())
            return m.group(1).trim();
        return headerValue.trim().split("\\s+")[0].trim();
    }

    public boolean isFromMailingList() {
        // Check 1: any List-* header (RFC 2369)
        for (String key : headers.keySet())
            if (key.startsWith("list-"))
                return true;
        String prec = headers.getOrDefault("precedence", "").toLowerCase();
        if (prec.contains("bulk") || prec.contains("list") || prec.contains("junk"))
            return true;
        String autoSub = headers.getOrDefault("auto-submitted", "").toLowerCase();
        if (!autoSub.isEmpty() && !autoSub.equals("no"))
            return true;
        if (headers.containsKey("x-auto-reply-to"))
            return true;

        return false;
    }

    public boolean hasPrac7Subject() {
        return subject.trim().equalsIgnoreCase("prac7");
    }

    public int getMessageNumber() {
        return messageNumber;
    }

    public int getSizeOctets() {
        return sizeOctets;
    }

    public String getFrom() {
        return from;
    }

    public String getSubject() {
        return subject;
    }

    public String getMessageId() {
        return messageId;
    }

    public String getHeader(String name) {
        return headers.getOrDefault(name.toLowerCase(), "");
    }

}