/*
    * Copyright 2004-2008 the Seasar Foundation and the Others.
    *
    * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied. See the License for the specific language
   * governing permissions and limitations under the License.
   */
  package org.seasar.cubby.validator.validators;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.seasar.cubby.validator.MessageHelper;
  import org.seasar.cubby.validator.ScalarFieldValidator;
  import org.seasar.cubby.validator.ValidationContext;
  import org.seasar.framework.util.StringUtil;
  
  /**
   * Eメールアドレスに対する検証を行います。
   * <p>
   * デフォルトエラーメッセージキー:valid.email
   * </p>
   * 
   * @author agata
   * @author baba
   * @since 1.0.0
   */
  public class EmailValidator implements ScalarFieldValidator {
  
  	private static final String SPECIAL_CHARS = "\\(\\)<>@,;:\\\\\\\"\\.\\[\\]";
  	private static final String VALID_CHARS = "[^\\s" + SPECIAL_CHARS + "]";
  	private static final String QUOTED_USER = "(\"[^\"]*\")";
  	private static final String ATOM = VALID_CHARS + '+';
  	private static final String WORD = "(" + ATOM + "|" + QUOTED_USER + ")";
  
  	private static final String LEGAL_ASCII_PATTERN = "^[\\x00-\\x7F]+$";
  	private static final String EMAIL_PATTERN = "^(.+)@(.+)$";
  	private static final String IP_DOMAIN_PATTERN = "^(\\d{1,3})[.](\\d{1,3})[.](\\d{1,3})[.](\\d{1,3})$";
  
  	private static final String USER_PATTERN = "^" + WORD + "(\\." + WORD
  			+ ")*$";
  	private static final String DOMAIN_PATTERN = "^" + ATOM + "(\\." + ATOM
  			+ ")*$";
  	private static final String ATOM_PATTERN = "(" + ATOM + ")";
  
  	/**
  	 * メッセージヘルパ。
  	 */
  	private final MessageHelper messageHelper;
  
  	/**
  	 * コンストラクタ
  	 */
  	public EmailValidator() {
  		this("valid.email");
  	}
  
  	/**
  	 * メッセージキーを指定するコンストラクタ
  	 * 
  	 * @param messageKey
  	 */
  	public EmailValidator(final String messageKey) {
  		this.messageHelper = new MessageHelper(messageKey);
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public void validate(final ValidationContext context, final Object value) {
  		if (value == null) {
  			return;
  		}
  		if (value instanceof String) {
  			final String email = (String) value;
  			if (StringUtil.isEmpty(email)) {
  				return;
  			}
  
  			boolean match = !email.endsWith(".");
  			if (match) {
  				final Pattern pattern = Pattern.compile(LEGAL_ASCII_PATTERN);
  				final Matcher matchAsciiPat = pattern.matcher(email);
  				match = matchAsciiPat.matches();
  			}
  
  			if (match) {
  				final Pattern pattern = Pattern.compile(EMAIL_PATTERN);
  				final Matcher matcher = pattern.matcher(email);
 				match = matcher.find();
 				if (match) {
 					if (isValidUser(matcher.group(1))
 							&& isValidDomain(matcher.group(2))) {
 						return;
 					}
 				}
 			}
 		}
 
 		context.addMessageInfo(this.messageHelper.createMessageInfo());
 	}
 
 	private boolean isValidDomain(final String domain) {
 		Pattern pattern = Pattern.compile(IP_DOMAIN_PATTERN);
 		final Matcher ipAddressMatcher = pattern.matcher(domain);
 
 		if (ipAddressMatcher.find()) {
 			if (isValidIpAddress(ipAddressMatcher)) {
 				return true;
 			}
 		} else {
 			pattern = Pattern.compile(DOMAIN_PATTERN);
 			final Matcher domainMatcher = pattern.matcher(domain);
 			if (domainMatcher.matches()) {
 				if (isValidSymbolicDomain(domain)) {
 					return true;
 				}
 			}
 		}
 		return false;
 	}
 
 	private boolean isValidUser(final String user) {
 		final Pattern pattern = Pattern.compile(USER_PATTERN);
 		final Matcher userMatcher = pattern.matcher(user);
 		return userMatcher.matches();
 	}
 
 	private boolean isValidIpAddress(final Matcher ipAddressMatcher) {
 		for (int i = 1; i <= 4; i++) {
 			final String ipSegment = ipAddressMatcher.group(i);
 			if (ipSegment == null || ipSegment.length() <= 0) {
 				return false;
 			}
 
 			int iIpSegment = 0;
 
 			try {
 				iIpSegment = Integer.parseInt(ipSegment);
 			} catch (final NumberFormatException e) {
 				return false;
 			}
 
 			if (iIpSegment > 255) {
 				return false;
 			}
 
 		}
 		return true;
 	}
 
 	private boolean isValidSymbolicDomain(final String domain) {
 		final List<String> domainSegments = new ArrayList<String>();
 		boolean match = true;
 
 		final Pattern pattern = Pattern.compile(ATOM_PATTERN);
 		String domainSegment;
 		String currentDomain = domain;
 		while (match) {
 			final Matcher atomMatcher = pattern.matcher(currentDomain);
 			match = atomMatcher.find();
 			if (match) {
 				domainSegment = atomMatcher.group(1);
 				domainSegments.add(domainSegment);
 				final int domainSegmentLength = domainSegment.length() + 1;
 				currentDomain = domainSegmentLength >= currentDomain.length() ? ""
 						: currentDomain.substring(domainSegmentLength);
 			}
 		}
 
 		final int size = domainSegments.size();
 		if (size > 0) {
 			final String end = domainSegments.get(size - 1);
 			if (end.length() < 2 || end.length() > 4) {
 				return false;
 			}
 		}
 
 		if (size < 2) {
 			return false;
 		}
 
 		return true;
 	}
 
 }