package com.kiasoft.util;

/*
 *  ------------------------------------------------------------------
 *  Kiasoft, Inc.
 *  http://kiasoft.com
 *
 *  Copyright (c) 2003-2006 Kiasoft, Inc. All Rights Reserved. Permission
 *  to copy, modify and distribute this software and code
 *  included and its documentation (collectively, the "PROGRAM") for
 *  any purpose is hereby prohibited.
 *
 *  THE PROGRAM IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT
 *  LIMITATION, WARRANTIES THAT THE PROGRAM IS FREE OF
 *  DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE OR
 *  NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND
 *  PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD ANY PART
 *  OF THE PROGRAM PROVE DEFECTIVE IN ANY RESPECT, YOU
 *  (NOT KIASOFT) ASSUME THE COST OF ANY NECESSARY SERVICING,
 *  REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES
 *  AN ESSENTIAL PART OF THIS LICENSE. NO USE OF
 *  THE PROGRAM IS AUTHORIZED HEREUNDER EXCEPT
 *  UNDER THIS DISCLAIMER.
 *
 *  ------------------------------------------------------------------
 */


// Turbine
// import org.apache.turbine.util.Log;

// ORO
import org.apache.oro.text.regex.*;

// xbill dnsjava
import org.xbill.DNS.Record;
import org.xbill.DNS.dns;
import org.xbill.DNS.Type;

/**
 *  Email validation utility
 *
 *@author     painter
 */
public class EmailValidator {

    /*
     * string to validate email pattern
     */
    private final static String basicAddress = "^\\w+([_]*[\\-\\.]?[_]*\\w+[_]*)*@\\w+([_]*[\\-\\.]?[_]*\\w+[_]*)*(\\.\\w{1}\\w+)+$";


    /**
     *  Test the email address input string
     *
     *@param  email          Description of the Parameter
     *@return                Description of the Return Value
     *@exception  Exception  Description of the Exception
     */
    public boolean validate(String email) throws Exception {

        if (email == null) { throw new Exception("Validator: Email address is null."); }

        email = email.trim();
        if (email.length() == 0) { throw new Exception("Validator: Email address is empty (0-length)"); }

        // don't allow illegal characters in email address
        final String illegal[] =
            {"!", "#", "$", "%", "^", "&", "*", "(", ")",
            "[", "]", "{", "}", "+", "=",
            "<", ">", "?", "/", "\\", "|", ":", ";"
            };

        int illegalChar = 0;
        for (int x = 0; x < illegal.length; x++) {
            illegalChar = email.lastIndexOf(illegal[x]);
            if (illegalChar > 0) {
                throw new Exception("Validator: Email address [" + email + "] contains an illegal character - " + illegal[x]);
            }
            illegalChar = 0;
        }

        int loc = email.lastIndexOf("@");
        if (loc <= 0) {
            throw new Exception("Validator: Email address [" + email + "] does not have @ symbol.");
        }

        int groups;
        PatternMatcher matcher;
        PatternCompiler compiler;
        Pattern pattern;
        PatternMatcherInput input;
        MatchResult result;
                                                                                                                       
        compiler = new Perl5Compiler();
        matcher  = new Perl5Matcher();
                                                                                                                       
        try {
            pattern = compiler.compile(basicAddress);
        } catch(MalformedPatternException e) {
            throw new Exception("Validator: pattern cannot be compiled: " + e.getMessage() );
        }
                                                                                                                       
        input   = new PatternMatcherInput(email);
                                                                                                                       
        while(matcher.contains(input, pattern)) {
            result = matcher.getMatch();
            if ( result.length() > 0 )
            {
                boolean dtest = false;
                dtest = this.validateDomain( email );
                if ( dtest ) {
                    return true;
                } else {
                    throw new Exception("The domain found for the address: " + email + " is not valid.");
                }

            } else {
                throw new Exception("Validator: '" + email + "' does not look like an internet email address: a@b.c");
            }
        }

        return false;

    }


    /**
     *  copied from scarab implementation for validating email addresses
     *  private boolean checkRFC2505(String email)
     */
    public boolean validateDomain(String email)
    {
        // try just the end portion of the domain
        String domain = getDomain(email);
        if (domain != null)
        {
            // try to find any A records for the domain
            try {
                // Search for the MX record first, if found, then proceed
                Record[] records = dns.getRecords(domain, Type.MX);
                if (records != null || records.length > 0) { return true; }

                records = dns.getRecords(domain, Type.A);
                if (records != null || records.length > 0) { return true; }

                // now try just the domain after the @
                // this is for domains like foo.co.uk
                String fullDomain = email.substring(email.indexOf('@')+1);
                records = dns.getRecords(fullDomain, Type.A);
                if (records != null || records.length > 0) { return true; }

                // now try to find any MX records for the fullDomain
                records = dns.getRecords(fullDomain, Type.MX);
                if (records != null || records.length > 0) { return true; }
            } catch ( Exception e ) {
                // Log.error( "Error validating domain: " + e.toString() );
                return false;
            }

        }
        return false;
    }
     

    /**
     *  If email: jon@foo.bar.com then return bar.com
     *
     *@param  email  Description of the Parameter
     *@return        The domain value
     */
    private static String getDomain(String email) {
        String result = null;
        char[] emailChar = email.toCharArray();
        int dotCount = 0;
        for (int i = emailChar.length - 1; i >= 0; i--) {
            if (emailChar[i] == '.') {
                dotCount++;
            }
            if (dotCount == 2 || emailChar[i] == '@') {
                result = email.substring(i + 1, email.length());
                break;
            }
        }
        return result;
    }

}