/*
 * Copyright 2005 The Apache Software Foundation
 *
 * 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.apache.commons.net.ftp;

import java.text.DateFormatSymbols;
import java.util.Collection;
import java.util.Locale;
import java.util.Map;
import java.util.StringTokenizer;
import java.util.TreeMap;

/**
 * <p>
 * This class implements an alternate means of configuring the
 * {@link  org.apache.commons.net.ftp.FTPClient  FTPClient} object and
 * also subordinate objects which it uses.  Any class implementing the 
 * {@link  org.apache.commons.net.ftp.Configurable  Configurable } 
 * interface can be configured by this object. 
 * </p><p>
 * In particular this class was designed primarily to support configuration
 * of FTP servers which express file timestamps in formats and languages 
 * other than those for the US locale, which although it is the most common
 * is not universal.  Unfortunately, nothing in the FTP spec allows this to 
 * be determined in an automated way, so manual configuration such as this
 * is necessary.
 * </p><p>
 * This functionality was designed to allow existing clients to work exactly
 * as before without requiring use of this component.  This component should
 * only need to be explicitly invoked by the user of this package for problem
 * cases that previous implementations could not solve.
 * </p>
 * <h3>Examples of use of FTPClientConfig</h3>
 * Use cases:
 * You are trying to access a server that 
 * <ul> 
 * <li>lists files with timestamps that use month names in languages other 
 * than English</li>
 * <li>lists files with timestamps that use date formats other 
 * than the American English "standard" <code>MM dd yyyy</code></li>
 * <li>is in different timezone and you need accurate timestamps for 
 * dependency checking as in Ant</li>
 * </ul>
 * <p>
 * Unpaged (whole list) access on a UNIX server that uses French month names
 * but uses the "standard" <code>MMM d yyyy</code> date formatting
 * <pre>
 *    FTPClient f=FTPClient();
 *    FTPClientConfig conf = new FTPClientConfig(FTPClientConfig.SYST_UNIX);
 *    conf.setServerLanguageCode("fr");
 *    f.configure(conf);
 *    f.connect(server);
 *    f.login(username, password);
 *    FTPFile[] files = listFiles(directory);
 * </pre>
 * </p>
 * <p>
 * Paged access on a UNIX server that uses Danish month names
 * and "European" date formatting in Denmark's time zone, when you
 * are in some other time zone.
 * <pre>
 *    FTPClient f=FTPClient();
 *    FTPClientConfig conf = new FTPClientConfig(FTPClientConfig.SYST_UNIX);
 *    conf.setServerLanguageCode("da");
 *    conf.setDefaultDateFormat("d MMM yyyy");
 *    conf.setRecentDateFormat("d MMM HH:mm");
 *    conf.setTimeZoneId("Europe/Copenhagen");
 *    f.configure(conf);
 *    f.connect(server);
 *    f.login(username, password);
 *    FTPListParseEngine engine =
 *       f.initiateListParsing("com.whatever.YourOwnParser", directory);
 *
 *    while (engine.hasNext()) {
 *       FTPFile[] files = engine.getNext(25);  // "page size" you want
 *       //do whatever you want with these files, display them, etc.
 *       //expensive FTPFile objects not created until needed.
 *    }
 * </pre>
 * </p> 
 * <p>
 * Unpaged (whole list) access on a VMS server that uses month names
 * in a language not {@link #getSupportedLanguageCodes() supported} by the system.
 * but uses the "standard" <code>MMM d yyyy</code> date formatting
 * <pre>
 *    FTPClient f=FTPClient();
 *    FTPClientConfig conf = new FTPClientConfig(FTPClientConfig.SYST_VMS);
 *    conf.setShortMonthNames(
 *        "jan|feb|mar|apr|ma\u00ED|j\u00FAn|j\u00FAl|\u00e1g\u00FA|sep|okt|n\u00F3v|des");
 *    f.configure(conf);
 *    f.connect(server);
 *    f.login(username, password);
 *    FTPFile[] files = listFiles(directory);
 * </pre>
 * </p>
 * <p>
 * Unpaged (whole list) access on a Windows-NT server in a different time zone.
 * (Note, since the NT Format uses numeric date formatting, language issues
 * are irrelevant here).
 * <pre>
 *    FTPClient f=FTPClient();
 *    FTPClientConfig conf = new FTPClientConfig(FTPClientConfig.SYST_NT);
 *    conf.setTimeZoneId("America/Denver");
 *    f.configure(conf);
 *    f.connect(server);
 *    f.login(username, password);
 *    FTPFile[] files = listFiles(directory);
 * </pre>
 * </p>
 * Unpaged (whole list) access on a Windows-NT server in a different time zone
 * but which has been configured to use a unix-style listing format.
 * <pre>
 *    FTPClient f=FTPClient();
 *    FTPClientConfig conf = new FTPClientConfig(FTPClientConfig.SYST_UNIX);
 *    conf.setTimeZoneId("America/Denver");
 *    f.configure(conf);
 *    f.connect(server);
 *    f.login(username, password);
 *    FTPFile[] files = listFiles(directory);
 * </pre>
 * </p>
 * @since 1.4
 * @see org.apache.commons.net.ftp.Configurable
 * @see org.apache.commons.net.ftp.FTPClient
 * @see org.apache.commons.net.ftp.parser.FTPTimestampParserImpl#configure(FTPClientConfig)
 * @see org.apache.commons.net.ftp.parser.ConfigurableFTPFileEntryParserImpl
 */
public class FTPClientConfig
{
	
    /**
     * Identifier by which a unix-based ftp server is known throughout
     * the commons-net ftp system.
     */
    public static final String SYST_UNIX  = "UNIX";

    /**
     * Identifier by which a vms-based ftp server is known throughout
     * the commons-net ftp system.
     */
    public static final String SYST_VMS   = "VMS";
    
    /**
     * Identifier by which a WindowsNT-based ftp server is known throughout
     * the commons-net ftp system.
     */
    public static final String SYST_NT    = "WINDOWS";

    /**
     * Identifier by which an OS/2-based ftp server is known throughout
     * the commons-net ftp system.
     */
    public static final String SYST_OS2   = "OS/2";

    /**
     * Identifier by which an OS/400-based ftp server is known throughout
     * the commons-net ftp system.
     */
    public static final String SYST_OS400 = "OS/400";
    
    /**
     * Identifier by which an MVS-based ftp server is known throughout
     * the commons-net ftp system.
     */
    public static final String SYST_MVS = "MVS";
    
    private final String serverSystemKey;
	private String defaultDateFormatStr = null;
	private String recentDateFormatStr = null;
	private String serverLanguageCode = null;
	private String shortMonthNames = null;
	private String serverTimeZoneId = null;
	
	
	/**
	 * The main constructor for an FTPClientConfig object
	 * @param systemKey key representing system type of the  server being 
	 * connected to. See {@link #getServerSystemKey() serverSystemKey}
	 */
	public FTPClientConfig(String systemKey) {
		this.serverSystemKey = systemKey;
	}

	/**
	 * Convenience constructor mainly for use in testing.
	 * Constructs a UNIX configuration. 
	 */
	public FTPClientConfig() {
	    this(SYST_UNIX);
	}

	/**
	 * Constructor which allows setting of all member fields
	 * @param systemKey key representing system type of the  server being 
	 * connected to. See 
	 *  {@link #getServerSystemKey() serverSystemKey}
	 * @param defaultDateFormatStr See 
	 * 	{@link  #setDefaultDateFormatStr(String)  defaultDateFormatStr}
	 * @param recentDateFormatStr See
	 * 	{@link  #setRecentDateFormatStr(String)  recentDateFormatStr}
	 * @param serverLanguageCode See
	 * 	{@link  #setServerLanguageCode(String)  serverLanguageCode}
	 * @param shortMonthNames See
	 * 	{@link  #setShortMonthNames(String)  shortMonthNames}
	 * @param serverTimeZoneId See
	 * 	{@link  #setServerTimeZoneId(String)  serverTimeZoneId}
	 */
	public FTPClientConfig(String systemKey,
	        			   String defaultDateFormatStr,
	        			   String recentDateFormatStr,
	        			   String serverLanguageCode,
	        			   String shortMonthNames,
	        			   String serverTimeZoneId)
	{
	    this(systemKey);
		this.defaultDateFormatStr = defaultDateFormatStr;
		this.recentDateFormatStr = recentDateFormatStr;
		this.serverLanguageCode = serverLanguageCode;
		this.shortMonthNames = shortMonthNames;
		this.serverTimeZoneId = serverTimeZoneId;
	}
	
	private static Map LANGUAGE_CODE_MAP = new TreeMap();
	static {
		
		// if there are other commonly used month name encodings which
		// correspond to particular locales, please add them here.
		
		
		
		// many locales code short names for months as all three letters
		// these we handle simply.
		LANGUAGE_CODE_MAP.put("en", Locale.ENGLISH);
		LANGUAGE_CODE_MAP.put("de",Locale.GERMAN);
		LANGUAGE_CODE_MAP.put("it",Locale.ITALIAN);
		LANGUAGE_CODE_MAP.put("es", new Locale("es", "", "")); // spanish
		LANGUAGE_CODE_MAP.put("pt", new Locale("pt", "", "")); // portuguese
		LANGUAGE_CODE_MAP.put("da", new Locale("da", "", "")); // danish
		LANGUAGE_CODE_MAP.put("sv", new Locale("sv", "", "")); // swedish
		LANGUAGE_CODE_MAP.put("no", new Locale("no", "", "")); // norwegian
		LANGUAGE_CODE_MAP.put("nl", new Locale("nl", "", "")); // dutch
		LANGUAGE_CODE_MAP.put("ro", new Locale("ro", "", "")); // romanian
		LANGUAGE_CODE_MAP.put("sq", new Locale("sq", "", "")); // albanian
		LANGUAGE_CODE_MAP.put("sh", new Locale("sh", "", "")); // serbo-croatian
		LANGUAGE_CODE_MAP.put("sk", new Locale("sk", "", "")); // slovak		
		LANGUAGE_CODE_MAP.put("sl", new Locale("sl", "", "")); // slovenian


		// some don't
		LANGUAGE_CODE_MAP.put("fr",	
		        "jan|f\u00e9v|mar|avr|mai|jun|jui|ao\u00fb|sep|oct|nov|d\u00e9c");  //french
			
	}
	
	/**
	 * Getter for the serverSystemKey property.  This property
     * specifies the general type of server to which the client connects.
     * Should be either one of the <code>FTPClientConfig.SYST_*</code> codes
     * or else the fully qualified class name of a parser implementing both
     * the <code>FTPFileEntryParser</code> and <code>Configurable</code>
     * interfaces.
	 * @return Returns the serverSystemKey property.
	 */
	public String getServerSystemKey() {
		return serverSystemKey;
	}
	
	/**
	 * getter for the {@link  #setDefaultDateFormatStr(String)  defaultDateFormatStr} 
	 * property.  
	 * @return Returns the defaultDateFormatStr property.
	 */
	public String getDefaultDateFormatStr() {
		return defaultDateFormatStr;
	}
	
	/**
	 * getter for the {@link  #setRecentDateFormatStr(String)  recentDateFormatStr} property.
	 * @return Returns the recentDateFormatStr property.
	 */

	public String getRecentDateFormatStr() {
		return recentDateFormatStr;
	}
	
	/**
	 * getter for the {@link  #setServerTimeZoneId(String)  serverTimeZoneId} property.
	 * @return Returns the serverTimeZoneId property.
	 */
	public String getServerTimeZoneId() {
		return serverTimeZoneId;
	}
	
	/**
	 * <p>
	 * getter for the {@link  #setShortMonthNames(String)  shortMonthNames} 
	 * property.  
	 * </p>
	 * @return Returns the shortMonthNames.
	 */
	public String getShortMonthNames() {
		return shortMonthNames;
	}
	
	/**
	 * <p>
	 * getter for the {@link  #setServerLanguageCode(String)  serverLanguageCode} property.
	 * </p>  
* 	 * @return Returns the serverLanguageCode property.
	 */
	public String getServerLanguageCode() {
		return serverLanguageCode;
	}
	
	/**
	 * <p>
	 * setter for the defaultDateFormatStr property.  This property
	 * specifies the main date format that will be used by a parser configured
	 * by this configuration to parse file timestamps.  If this is not
	 * specified, such a parser will use as a default value, the most commonly
	 * used format which will be in as used in <code>en_US</code> locales.
	 * </p><p>
	 * This should be in the format described for 
	 * <code>java.text.SimpleDateFormat</code>. 
	 * property.
	 * </p>
	 * @param defaultDateFormatStr The defaultDateFormatStr to set.
	 */
	public void setDefaultDateFormatStr(String defaultDateFormatStr) {
		this.defaultDateFormatStr = defaultDateFormatStr;
	}
	
	/**
	 * <p>
	 * setter for the recentDateFormatStr property.  This property
	 * specifies a secondary date format that will be used by a parser 
	 * configured by this configuration to parse file timestamps, typically 
	 * those less than a year old.  If this is  not specified, such a parser 
	 * will not attempt to parse using an alternate format.
	 * </p>
	 * This is used primarily in unix-based systems.
	 * </p>
	 * This should be in the format described for 
	 * <code>java.text.SimpleDateFormat</code>.
	 * </p>
	 * @param recentDateFormatStr The recentDateFormatStr to set.
	 */
	public void setRecentDateFormatStr(String recentDateFormatStr) {
		this.recentDateFormatStr = recentDateFormatStr;
	}
	
	/**
	 * <p>
	 * setter for the serverTimeZoneId property.  This property
	 * allows a time zone to be specified corresponding to that known to be 
	 * used by an FTP server in file listings.  This might be particularly 
	 * useful to clients such as Ant that try to use these timestamps for 
	 * dependency checking.
	 * </p><p>
	 * This should be one of the identifiers used by 
	 * <code>java.util.TimeZone</code> to refer to time zones, for example, 
	 * <code>America/Chicago</code> or <code>Asia/Rangoon</code>.
	 * </p>
	 * @param serverTimeZoneId The serverTimeZoneId to set.
	 */
	public void setServerTimeZoneId(String serverTimeZoneId) {
		this.serverTimeZoneId = serverTimeZoneId;
	}
	
	/**
	 * <p>
	 * setter for the shortMonthNames property.  
	 * This property allows the user to specify a set of month names
	 * used by the server that is different from those that may be 
	 * specified using the {@link  #setServerLanguageCode(String)  serverLanguageCode}
	 * property.
	 * </p><p>
	 * This should be a string containing twelve strings each composed of
	 * three characters, delimited by pipe (|) characters.  Currently, 
	 * only 8-bit ASCII characters are known to be supported.  For example,
	 * a set of month names used by a hypothetical Icelandic FTP server might 
	 * conceivably be specified as 
	 * <code>"jan|feb|mar|apr|ma&#xED;|j&#xFA;n|j&#xFA;l|&#xE1;g&#xFA;|sep|okt|n&#xF3;v|des"</code>.  
	 * </p>
	 * @param shortMonthNames The value to set to the shortMonthNames property.
	 */
	public void setShortMonthNames(String shortMonthNames) {
		this.shortMonthNames = shortMonthNames;
	}
	
	/**
	 * <p>
	 * setter for the serverLanguageCode property.  This property allows
	 * user to specify a 
	 * <a href="http://www.ics.uci.edu/pub/ietf/http/related/iso639.txt">
	 * two-letter ISO-639 language code</a> that will be used to 
	 * configure the set of month names used by the file timestamp parser.
	 * If neither this nor the {@link #setShortMonthNames(String) shortMonthNames} 
	 * is specified, parsing will assume English month names, which may or 
	 * may not be significant, depending on whether the date format(s) 
	 * specified via {@link  #setDefaultDateFormatStr(String)  defaultDateFormatStr} 
	 * and/or {@link  #setRecentDateFormatStr(String)  recentDateFormatStr} are using 
	 * numeric or alphabetic month names.
	 * </p>
	 * <p>If the code supplied is not supported here, <code>en_US</code>
	 * month names will be used.  We are supporting here those language 
	 * codes which, when a <code> java.util.Locale</code> is constucted
	 * using it, and a <code>java.text.SimpleDateFormat</code> is 
	 * constructed using that Locale, the array returned by the 
	 * SimpleDateFormat's <code>getShortMonths()</code> method consists
	 * solely of three 8-bit ASCII character strings.  Additionally, 
	 * languages which do not meet this requirement are included if a 
	 * common alternative set of short month names is known to be used.
	 * This means that users who can tell us of additional such encodings
	 * may get them added to the list of supported languages by contacting
	 * the jakarta-commons-net team.
	 * </p>
	 * <p><strong>
	 * Please note that this attribute will NOT be used to determine a 
	 * locale-based date format for the language.  </strong>  
	 * Experience has shown that many if not most FTP servers outside the
	 * United States employ the standard <code>en_US</code> date format 
	 * orderings of <code>MMM d yyyy</code> and <code>MMM d HH:mm</code> 
	 * and attempting to deduce this automatically here would cause more
	 * problems than it would solve.  The date format must be changed 
	 * via the {@link  #setDefaultDateFormatStr(String)  defaultDateFormatStr} and/or 
	 * {@link  #setRecentDateFormatStr(String)  recentDateFormatStr} parameters.
	 * </p>	  
	 * @param serverLanguageCode The value to set to the serverLanguageCode property.  
	 */
	public void setServerLanguageCode(String serverLanguageCode) {
		this.serverLanguageCode = serverLanguageCode;
	}
	
	/**
	 * Looks up the supplied language code in the internally maintained table of 
	 * language codes.  Returns a DateFormatSymbols object configured with 
	 * short month names corresponding to the code.  If there is no corresponding
	 * entry in the table, the object returned will be that for 
	 * <code>Locale.US</code> 
	 * @param languageCode See {@link  #setServerLanguageCode(String)  serverLanguageCode}
	 * @return a DateFormatSymbols object configured with short month names 
	 * corresponding to the supplied code, or with month names for  
	 * <code>Locale.US</code> if there is no corresponding entry in the internal
	 * table.
	 */
	public static DateFormatSymbols lookupDateFormatSymbols(String languageCode) 
	{
		Object lang = LANGUAGE_CODE_MAP.get(languageCode);
		if (lang != null) {
			if (lang instanceof Locale) {
				return new DateFormatSymbols((Locale) lang);
			} else if (lang instanceof String){
				return getDateFormatSymbols((String) lang);
			}
		}
		return new DateFormatSymbols(Locale.US);
	}
	
	/**
	 * Returns a DateFormatSymbols object configured with short month names
	 * as in the supplied string
	 * @param shortmonths This  should be as described in 
	 *  {@link  #setShortMonthNames(String)  shortMonthNames}
	 * @return a DateFormatSymbols object configured with short month names
	 * as in the supplied string
	 */
	public static DateFormatSymbols getDateFormatSymbols(String shortmonths) 
	{
		String[] months = splitShortMonthString(shortmonths);
		DateFormatSymbols dfs = new DateFormatSymbols(Locale.US);
		dfs.setShortMonths(months);
		return dfs;
	}
	
	private static String[] splitShortMonthString(String shortmonths) {
		StringTokenizer st = new StringTokenizer(shortmonths, "|");
		int monthcnt = st.countTokens();
		if (12 != monthcnt) {
			throw new IllegalArgumentException(
					"expecting a pipe-delimited string containing 12 tokens");
		}
		String[] months = new String[13];
		int pos = 0;
		while(st.hasMoreTokens()) {
			months[pos++] = st.nextToken();
		}
		months[pos]="";
		return months;
	}

	/**
	 * Returns a Collection of all the language codes currently supported
	 * by this class. See {@link  #setServerLanguageCode(String)  serverLanguageCode}  
	 * for a functional descrption of language codes within this system. 
	 * 	
	 * @return a Collection of all the language codes currently supported
	 * by this class
	 */
	public static Collection getSupportedLanguageCodes() {
	    return LANGUAGE_CODE_MAP.keySet();
	}
	
	
}
