/*
 * Copyright  2000-2004 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.tools.ant.taskdefs;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Locale;
import java.util.NoSuchElementException;
import java.util.StringTokenizer;
import java.util.TimeZone;
import java.util.Vector;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Location;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.types.EnumeratedAttribute;

/**
 * Sets properties to the current time, or offsets from the current time.
 * The default properties are TSTAMP, DSTAMP and TODAY;
 *
 * @since Ant 1.1
 * @ant.task category="utility"
 */
public class Tstamp extends Task {

    private Vector customFormats = new Vector();
    private String prefix = "";

    /**
     * Set a prefix for the properties. If the prefix does not end with a "."
     * one is automatically added
     * @since Ant 1.5
     */
    public void setPrefix(String prefix) {
        this.prefix = prefix;
        if (!this.prefix.endsWith(".")) {
            this.prefix += ".";
        }
    }

    /**
     * create the timestamps. Custom ones are done before
     * the standard ones, to get their retaliation in early.
     * @throws BuildException
     */
    public void execute() throws BuildException {
        try {
            Date d = new Date();

            Enumeration i = customFormats.elements();
            while (i.hasMoreElements()) {
                CustomFormat cts = (CustomFormat) i.nextElement();
                cts.execute(getProject(), d, getLocation());
            }

            SimpleDateFormat dstamp = new SimpleDateFormat ("yyyyMMdd");
            setProperty("DSTAMP", dstamp.format(d));

            SimpleDateFormat tstamp = new SimpleDateFormat ("HHmm");
            setProperty("TSTAMP", tstamp.format(d));

            SimpleDateFormat today
                = new SimpleDateFormat ("MMMM d yyyy", Locale.US);
            setProperty("TODAY", today.format(d));

        } catch (Exception e) {
            throw new BuildException(e);
        }
    }

    /**
     * create a custom format with the current prefix.
     * @return a ready to fill-in format
     */
    public CustomFormat createFormat() {
        CustomFormat cts = new CustomFormat();
        customFormats.addElement(cts);
        return cts;
    }

    /**
     * helper that encapsulates prefix logic and property setting
     * policy (i.e. we use setNewProperty instead of setProperty).
     */
    private void setProperty(String name, String value) {
        getProject().setNewProperty(prefix + name, value);
    }

    /**
     * This nested element that allows a property to be set
     * to the current date and time in a given format.
     * The date/time patterns are as defined in the
     * Java SimpleDateFormat class.
     * The format element also allows offsets to be applied to
     * the time to generate different time values.
     * @todo consider refactoring out into a re-usable element.
     */
    public class CustomFormat {
        private TimeZone timeZone;
        private String propertyName;
        private String pattern;
        private String language;
        private String country;
        private String variant;
        private int offset = 0;
        private int field = Calendar.DATE;

        /**
         * Create a format
         */
        public CustomFormat() {
        }

        /**
         *  The property to receive the date/time string in the given pattern
         * @param propertyName
         */
        public void setProperty(String propertyName) {
            this.propertyName = propertyName;
        }

        /**
         * The date/time pattern to be used. The values are as
         * defined by the Java SimpleDateFormat class.
         * @param pattern
         * @see java.text.SimpleDateFormat
         */
        public void setPattern(String pattern) {
            this.pattern = pattern;
        }

        /**
         * The locale used to create date/time string.
         * The general form is "language, country, variant" but
         * either variant or variant and country may be omitted.
         * For more information please refer to documentation
         * for the java.util.Locale  class.
         * @param locale
         * @see java.util.Locale
         */
        public void setLocale(String locale) {
            StringTokenizer st = new StringTokenizer(locale, " \t\n\r\f,");
            try {
                language = st.nextToken();
                if (st.hasMoreElements()) {
                    country = st.nextToken();
                    if (st.hasMoreElements()) {
                        variant = st.nextToken();
                        if (st.hasMoreElements()) {
                            throw new BuildException("bad locale format",
                                                      getLocation());
                        }
                    }
                } else {
                    country = "";
                }
            } catch (NoSuchElementException e) {
                throw new BuildException("bad locale format", e,
                                         getLocation());
            }
        }

        /**
         * The timezone to use for displaying time.
         * The values are as defined by the Java TimeZone class.
         * @param id
         * @see java.util.TimeZone
         */
        public void setTimezone(String id) {
            timeZone = TimeZone.getTimeZone(id);
        }

        /**
         * The numeric offset to the current time.
         * @param offset
         */
        public void setOffset(int offset) {
            this.offset = offset;
        }

        /**
         * @deprecated setUnit(String) is deprecated and is replaced with
         *             setUnit(Tstamp.Unit) to make Ant's
         *             Introspection mechanism do the work and also to
         *             encapsulate operations on the unit in its own
         *             class.
         */
        public void setUnit(String unit) {
            log("DEPRECATED - The setUnit(String) method has been deprecated."
                + " Use setUnit(Tstamp.Unit) instead.");
            Unit u = new Unit();
            u.setValue(unit);
            field = u.getCalendarField();
        }

        /**
         * The unit of the offset to be applied to the current time.
         * Valid Values are
         * <ul>
         *    <li>millisecond</li>
         *    <li>second</li>
         *    <li>minute</li>
         *    <li>hour</li>
         *    <li>day</li>
         *    <li>week</li>
         *    <li>month</li>
         *    <li>year</li>
         * </ul>
         * The default unit is day.
         * @param unit
         */
        public void setUnit(Unit unit) {
            field = unit.getCalendarField();
        }

        /**
         * validate parameter and execute the format
         * @param project project to set property in
         * @param date date to use as a starting point
         * @param location line in file (for errors)
         */
        public void execute(Project project, Date date, Location location) {
            if (propertyName == null) {
                throw new BuildException("property attribute must be provided",
                                         location);
            }

            if (pattern == null) {
                throw new BuildException("pattern attribute must be provided",
                                         location);
            }

            SimpleDateFormat sdf;
            if (language == null) {
                sdf = new SimpleDateFormat(pattern);
            } else if (variant == null) {
                sdf = new SimpleDateFormat(pattern,
                                           new Locale(language, country));
            } else {
                sdf = new SimpleDateFormat(pattern,
                                           new Locale(language, country,
                                                      variant));
            }
            if (offset != 0) {
                Calendar calendar = Calendar.getInstance();
                calendar.setTime(date);
                calendar.add(field, offset);
                date = calendar.getTime();
            }
            if (timeZone != null) {
                sdf.setTimeZone(timeZone);
            }
            Tstamp.this.setProperty(propertyName, sdf.format(date));
        }
    }

    /**
     * set of valid units to use for time offsets.
     */
    public static class Unit extends EnumeratedAttribute {

        private static final String MILLISECOND = "millisecond";
        private static final String SECOND = "second";
        private static final String MINUTE = "minute";
        private static final String HOUR = "hour";
        private static final String DAY = "day";
        private static final String WEEK = "week";
        private static final String MONTH = "month";
        private static final String YEAR = "year";

        private static final String[] units = {
                                                MILLISECOND,
                                                SECOND,
                                                MINUTE,
                                                HOUR,
                                                DAY,
                                                WEEK,
                                                MONTH,
                                                YEAR
                                              };

        private Hashtable calendarFields = new Hashtable();

        public Unit() {
            calendarFields.put(MILLISECOND,
                               new Integer(Calendar.MILLISECOND));
            calendarFields.put(SECOND, new Integer(Calendar.SECOND));
            calendarFields.put(MINUTE, new Integer(Calendar.MINUTE));
            calendarFields.put(HOUR, new Integer(Calendar.HOUR_OF_DAY));
            calendarFields.put(DAY, new Integer(Calendar.DATE));
            calendarFields.put(WEEK, new Integer(Calendar.WEEK_OF_YEAR));
            calendarFields.put(MONTH, new Integer(Calendar.MONTH));
            calendarFields.put(YEAR, new Integer(Calendar.YEAR));
        }

        public int getCalendarField() {
            String key = getValue().toLowerCase();
            Integer i = (Integer) calendarFields.get(key);
            return i.intValue();
        }

        public String[] getValues() {
            return units;
        }
    }
}