/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2008 Sun Microsystems, Inc.
 * Portions Copyright 2015-2016 ForgeRock AS.
 */
package org.forgerock.opendj.config;

import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/** This enumeration defines various duration units. */
public enum DurationUnit {

    /** A day unit. */
    DAYS(24 * 60 * 60 * 1000, "d", "days"),

    /** An hour unit. */
    HOURS(60 * 60 * 1000, "h", "hours"),

    /** A millisecond unit. */
    MILLI_SECONDS(1L, "ms", "milliseconds"),

    /** A minute unit. */
    MINUTES(60 * 1000, "m", "minutes"),

    /** A second unit. */
    SECONDS(1000L, "s", "seconds"),

    /** A week unit. */
    WEEKS(7 * 24 * 60 * 60 * 1000, "w", "weeks");

    /** A lookup table for resolving a unit from its name. */
    private static final Map<String, DurationUnit> NAME_TO_UNIT = new HashMap<>();
    static {

        for (DurationUnit unit : DurationUnit.values()) {
            NAME_TO_UNIT.put(unit.shortName, unit);
            NAME_TO_UNIT.put(unit.longName, unit);
        }
    }

    /**
     * Get the unit corresponding to the provided unit name.
     *
     * @param s
     *            The name of the unit. Can be the abbreviated or long name and
     *            can contain white space and mixed case characters.
     * @return Returns the unit corresponding to the provided unit name.
     * @throws IllegalArgumentException
     *             If the provided name did not correspond to a known duration
     *             unit.
     */
    public static DurationUnit getUnit(String s) {
        DurationUnit unit = NAME_TO_UNIT.get(s.trim().toLowerCase());
        if (unit == null) {
            throw new IllegalArgumentException("Illegal duration unit \"" + s + "\"");
        }
        return unit;
    }

    /**
     * Parse the provided duration string and return its equivalent duration in
     * milliseconds. The duration string must specify the unit e.g. "10s". This
     * method will parse duration string representations produced from the
     * {@link #toString(long)} method. Therefore, a duration can comprise of
     * multiple duration specifiers, for example <code>1d15m25s</code>.
     *
     * @param s
     *            The duration string to be parsed.
     * @return Returns the parsed duration in milliseconds.
     * @throws NumberFormatException
     *             If the provided duration string could not be parsed.
     * @see #toString(long)
     */
    public static long parseValue(String s) {
        return parseValue(s, null);
    }

    /**
     * Parse the provided duration string and return its equivalent duration in
     * milliseconds. This method will parse duration string representations
     * produced from the {@link #toString(long)} method. Therefore, a duration
     * can comprise of multiple duration specifiers, for example
     * <code>1d15m25s</code>.
     *
     * @param s
     *            The duration string to be parsed.
     * @param defaultUnit
     *            The default unit to use if there is no unit specified in the
     *            duration string, or <code>null</code> if the string must
     *            always contain a unit.
     * @return Returns the parsed duration in milliseconds.
     * @throws NumberFormatException
     *             If the provided duration string could not be parsed.
     * @see #toString(long)
     */
    public static long parseValue(String s, DurationUnit defaultUnit) {
        String ns = s.trim();
        if (ns.length() == 0) {
            throw new NumberFormatException("Empty duration value \"" + s + "\"");
        }

        Pattern p1 =
            Pattern.compile("^\\s*((\\d+)\\s*w)?" + "\\s*((\\d+)\\s*d)?" + "\\s*((\\d+)\\s*h)?"
                + "\\s*((\\d+)\\s*m)?" + "\\s*((\\d+)\\s*s)?" + "\\s*((\\d+)\\s*ms)?\\s*$", Pattern.CASE_INSENSITIVE);
        Matcher m1 = p1.matcher(ns);
        if (m1.matches()) {
            // Value must be of the form produced by toString(long).
            String weeks = m1.group(2);
            String days = m1.group(4);
            String hours = m1.group(6);
            String minutes = m1.group(8);
            String seconds = m1.group(10);
            String ms = m1.group(12);

            long duration = 0;

            try {
                if (weeks != null) {
                    duration += Long.valueOf(weeks) * WEEKS.getDuration();
                }

                if (days != null) {
                    duration += Long.valueOf(days) * DAYS.getDuration();
                }

                if (hours != null) {
                    duration += Long.valueOf(hours) * HOURS.getDuration();
                }

                if (minutes != null) {
                    duration += Long.valueOf(minutes) * MINUTES.getDuration();
                }

                if (seconds != null) {
                    duration += Long.valueOf(seconds) * SECONDS.getDuration();
                }

                if (ms != null) {
                    duration += Long.valueOf(ms) * MILLI_SECONDS.getDuration();
                }
            } catch (NumberFormatException e) {
                throw new NumberFormatException("Invalid duration value \"" + s + "\"");
            }

            return duration;
        } else {
            // Value must be a floating point number followed by a unit.
            Pattern p2 = Pattern.compile("^\\s*(\\d+(\\.\\d+)?)\\s*(\\w+)?\\s*$");
            Matcher m2 = p2.matcher(ns);

            if (!m2.matches()) {
                throw new NumberFormatException("Invalid duration value \"" + s + "\"");
            }

            // Group 1 is the float.
            double d;
            try {
                d = Double.valueOf(m2.group(1));
            } catch (NumberFormatException e) {
                throw new NumberFormatException("Invalid duration value \"" + s + "\"");
            }

            // Group 3 is the unit.
            String unitString = m2.group(3);
            DurationUnit unit;
            if (unitString == null) {
                if (defaultUnit == null) {
                    throw new NumberFormatException("Invalid duration value \"" + s + "\"");
                } else {
                    unit = defaultUnit;
                }
            } else {
                try {
                    unit = getUnit(unitString);
                } catch (IllegalArgumentException e) {
                    throw new NumberFormatException("Invalid duration value \"" + s + "\"");
                }
            }

            return unit.toMilliSeconds(d);
        }
    }

    /**
     * Returns a string representation of the provided duration. The string
     * representation can be parsed using the {@link #parseValue(String)}
     * method. The string representation is comprised of one or more of the
     * number of weeks, days, hours, minutes, seconds, and milliseconds. Here
     * are some examples:
     *
     * <pre>
     * toString(0)       // 0 ms
     * toString(999)     // 999 ms
     * toString(1000)    // 1 s
     * toString(1500)    // 1 s 500 ms
     * toString(3650000) // 1 h 50 s
     * toString(3700000) // 1 h 1 m 40 s
     * </pre>
     *
     * @param duration
     *            The duration in milliseconds.
     * @return Returns a string representation of the provided duration.
     * @throws IllegalArgumentException
     *             If the provided duration is negative.
     * @see #parseValue(String)
     * @see #parseValue(String, DurationUnit)
     */
    public static String toString(long duration) {
        if (duration < 0) {
            throw new IllegalArgumentException("Negative duration " + duration);
        }

        if (duration == 0) {
            return "0 ms";
        }

        DurationUnit[] units = new DurationUnit[] { WEEKS, DAYS, HOURS, MINUTES, SECONDS, MILLI_SECONDS };
        long remainder = duration;
        StringBuilder builder = new StringBuilder();
        boolean isFirst = true;
        for (DurationUnit unit : units) {
            long count = remainder / unit.getDuration();
            if (count > 0) {
                if (!isFirst) {
                    builder.append(' ');
                }
                builder.append(count);
                builder.append(' ');
                builder.append(unit.getShortName());
                remainder = remainder - (count * unit.getDuration());
                isFirst = false;
            }
        }
        return builder.toString();
    }

    /** The long name of the unit. */
    private final String longName;

    /** The abbreviation of the unit. */
    private final String shortName;

    /** The size of the unit in milliseconds. */
    private final long sz;

    /** Private constructor. */
    private DurationUnit(long sz, String shortName, String longName) {
        this.sz = sz;
        this.shortName = shortName;
        this.longName = longName;
    }

    /**
     * Converts the specified duration in milliseconds to this unit.
     *
     * @param duration
     *            The duration in milliseconds.
     * @return Returns milliseconds in this unit.
     */
    public double fromMilliSeconds(long duration) {
        return (double) duration / sz;
    }

    /**
     * Get the number of milliseconds that this unit represents.
     *
     * @return Returns the number of milliseconds that this unit represents.
     */
    public long getDuration() {
        return sz;
    }

    /**
     * Get the long name of this unit.
     *
     * @return Returns the long name of this unit.
     */
    public String getLongName() {
        return longName;
    }

    /**
     * Get the abbreviated name of this unit.
     *
     * @return Returns the abbreviated name of this unit.
     */
    public String getShortName() {
        return shortName;
    }

    /**
     * Converts the specified duration in this unit to milliseconds.
     *
     * @param duration
     *            The duration as a quantity of this unit.
     * @return Returns the number of milliseconds that the duration represents.
     */
    public long toMilliSeconds(double duration) {
        return (long) (sz * duration);
    }

    /**
     * {@inheritDoc}
     * <p>
     * This implementation returns the abbreviated name of this duration unit.
     */
    @Override
    public String toString() {
        return shortName;
    }
}