package net.sf.saxon.value;

import net.sf.saxon.trans.Err;
import net.sf.saxon.functions.Component;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.StandardNames;
import net.sf.saxon.sort.ComparisonKey;
import net.sf.saxon.trans.NoDynamicContextException;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.ConversionResult;
import net.sf.saxon.type.ValidationFailure;

import java.util.*;

/**
 * Abstract superclass for the primitive types containing date components: xs:date, xs:gYear,
 * xs:gYearMonth, xs:gMonth, xs:gMonthDay, xs:gDay
 */
public abstract class GDateValue extends CalendarValue {
    protected int year;         // unlike the lexical representation, includes a year zero
    protected byte month;
    protected byte day;
    /**
     * Test whether a candidate date is actually a valid date in the proleptic Gregorian calendar
     */

    protected static byte[] daysPerMonth = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    protected static final short[] monthData = {306, 337, 0, 31, 61, 92, 122, 153, 184, 214, 245, 275};

    /**
     * Get the year component of the date (in local form)
     * @return the year component
     */

    public int getYear() {
        return year;
    }

    /**
     * Get the month component of the date (in local form)
     * @return the month component (1-12)
     */

    public byte getMonth() {
        return month;
    }

    /**
     * Get the day component of the date (in local form)
     * @return the day component (1-31)
     */

    public byte getDay() {
        return day;
    }

    public GregorianCalendar getCalendar() {

        int tz = (hasTimezone() ? getTimezoneInMinutes() : 0);
        TimeZone zone = new SimpleTimeZone(tz * 60000, "LLL");
        GregorianCalendar calendar = new GregorianCalendar(zone);
        calendar.setGregorianChange(new Date(Long.MIN_VALUE));
        calendar.clear();
        calendar.setLenient(false);
        int yr = year;
        if (year <= 0) {
            yr = 1 - year;
            calendar.set(Calendar.ERA, GregorianCalendar.BC);
        }
        calendar.set(yr, month - 1, day);
        calendar.set(Calendar.ZONE_OFFSET, tz * 60000);
        calendar.set(Calendar.DST_OFFSET, 0);
        calendar.getTime();
        return calendar;
    }

    /**
     * Convert to Java object (for passing to external functions)
     */

//    public Object convertAtomicToJava(Class target, XPathContext context) throws XPathException {
//        if (target.isAssignableFrom(Date.class)) {
//            return getCalendar().getTime();
//        } else if (target.isAssignableFrom(GregorianCalendar.class)) {
//            return getCalendar();
//        } else if (target.isAssignableFrom(DateValue.class)) {
//            return this;
//        } else if (target == Object.class) {
//            return getStringValue();
//        } else {
//            Object o = convertSequenceToJava(target, context);
//            if (o == null) {
//                throw new XPathException("Conversion of date to " + target.getName() +
//                        " is not supported");
//            }
//            return o;
//        }
//    }
//
    /**
     * Initialize the DateValue using a character string in the format yyyy-mm-dd and an optional time zone.
     * Input must have format [-]yyyy-mm-dd[([+|-]hh:mm | Z)]
     * @param d the "raw" DateValue to be populated
     * @param s the supplied string value
     * @return either the supplied GDateValue, with its data initialized; or a ValidationFailure
     */

    protected static ConversionResult setLexicalValue(GDateValue d, CharSequence s) {
        StringTokenizer tok = new StringTokenizer(Whitespace.trimWhitespace(s).toString(), "-:+Z", true);
        try {
            if (!tok.hasMoreElements()) {
                return badDate("Too short", s);
            }
            String part = (String)tok.nextElement();
            int era = +1;
            if ("+".equals(part)) {
                return badDate("Date may not start with '+' sign", s);
            } else if ("-".equals(part)) {
                era = -1;
                part = (String)tok.nextElement();
            }

            if (part.length() < 4) {
                return badDate("Year is less than four digits", s);
            }
            if (part.length() > 4 && part.charAt(0) == '0') {
                return badDate("When year exceeds 4 digits, leading zeroes are not allowed", s);
            }
            int value = DurationValue.simpleInteger(part);
            if (value < 0) {
                return badDate("Non-numeric year component", s);
            }
            d.year = value * era;
            if (d.year == 0) {
                return badDate("Year zero is not allowed", s);
            }
            if (era < 0) {
                d.year++;     // internal representation allows a year zero.
            }
            if (!tok.hasMoreElements()) {
                return badDate("Too short", s);
            }
            if (!"-".equals(tok.nextElement())) {
                return badDate("Wrong delimiter after year", s);
            }

            if (!tok.hasMoreElements()) {
                return badDate("Too short", s);
            }
            part = (String)tok.nextElement();
            if (part.length() != 2) {
                return badDate("Month must be two digits", s);
            }
            value = DurationValue.simpleInteger(part);
            if (value < 0) {
                return badDate("Non-numeric month component", s);
            }
            d.month = (byte)value;
            if (d.month < 1 || d.month > 12) {
                return badDate("Month is out of range", s);
            }
            if (!tok.hasMoreElements()) {
                return badDate("Too short", s);
            }
            if (!"-".equals(tok.nextElement())) {
                return badDate("Wrong delimiter after month", s);
            }

            if (!tok.hasMoreElements()) {
                return badDate("Too short", s);
            }
            part = (String)tok.nextElement();
            if (part.length() != 2) {
                return badDate("Day must be two digits", s);
            }
            value = DurationValue.simpleInteger(part);
            if (value < 0) {
                return badDate("Non-numeric day component", s);
            }
            d.day = (byte)value;
            if (d.day < 1 || d.day > 31) {
                return badDate("Day is out of range", s);
            }

            int tzOffset;
            if (tok.hasMoreElements()) {

                String delim = (String)tok.nextElement();

                if ("Z".equals(delim)) {
                    tzOffset = 0;
                    if (tok.hasMoreElements()) {
                        return badDate("Continues after 'Z'", s);
                    }
                    d.setTimezoneInMinutes(tzOffset);

                } else if (!(!"+".equals(delim) && !"-".equals(delim))) {
                    if (!tok.hasMoreElements()) {
                        return badDate("Missing timezone", s);
                    }
                    part = (String)tok.nextElement();
                    value = DurationValue.simpleInteger(part);
                    if (value < 0) {
                        return badDate("Non-numeric timezone hour component", s);
                    }
                    int tzhour = value;
                    if (part.length() != 2) {
                        return badDate("Timezone hour must be two digits", s);
                    }
                    if (tzhour > 14) {
                        return badDate("Timezone hour is out of range", s);
                    }
                    if (!tok.hasMoreElements()) {
                        return badDate("No minutes in timezone", s);
                    }
                    if (!":".equals(tok.nextElement())) {
                        return badDate("Wrong delimiter after timezone hour", s);
                    }

                    if (!tok.hasMoreElements()) {
                        return badDate("No minutes in timezone", s);
                    }
                    part = (String)tok.nextElement();
                    value = DurationValue.simpleInteger(part);
                    if (value < 0) {
                        return badDate("Non-numeric timezone minute component", s);
                    }
                    int tzminute = value;
                    if (part.length() != 2) {
                        return badDate("Timezone minute must be two digits", s);
                    }
                    if (tzminute > 59) {
                        return badDate("Timezone minute is out of range", s);
                    }
                    if (tok.hasMoreElements()) {
                        return badDate("Continues after timezone", s);
                    }

                    tzOffset = (tzhour * 60 + tzminute);
                    if ("-".equals(delim)) {
                        tzOffset = -tzOffset;
                    }
                    d.setTimezoneInMinutes(tzOffset);

                } else {
                    return badDate("Timezone format is incorrect", s);
                }
            }

            if (!isValidDate(d.year, d.month, d.day)) {
                return badDate("Non-existent date", s);
            }

        } catch (NumberFormatException err) {
            return badDate("Non-numeric component", s);
        }
        return d;
    }

    private static ValidationFailure badDate(String msg, CharSequence value) {
        ValidationFailure err = new ValidationFailure(
                "Invalid date " + Err.wrap(value, Err.VALUE) + " (" + msg + ")");
        err.setErrorCode("FORG0001");
        return err;
    }

    /**
     * Determine whether a given date is valid
     * @param year the year
     * @param month the month (1-12)
     * @param day the day (1-31)
     * @return true if this is a valid date
     */

    public static boolean isValidDate(int year, int month, int day) {
        return month > 0 && month <= 12 && day > 0 && day <= daysPerMonth[month - 1]
                || month == 2 && day == 29 && isLeapYear(year);
    }

    /**
     * Test whether a year is a leap year
     * @param year the year
     * @return true if the supplied year is a leap year
     */

    public static boolean isLeapYear(int year) {
        return (year % 4 == 0) && !(year % 100 == 0 && !(year % 400 == 0));
    }

    /**
     * The equals() methods on atomic values is defined to follow the semantics of eq when applied
     * to two atomic values. When the other operand is not an atomic value, the result is undefined
     * (may be false, may be an exception). When the other operand is an atomic value that cannot be
     * compared with this one, the method returns false.
     * <p/>
     * <p>The hashCode() method is consistent with equals().</p>
     *
     * <p>This implementation performs a context-free comparison: it fails with ClassCastException
     * if one value has a timezone and the other does not.</p>
     *
     * @param o the other value
     * @return true if the other operand is an atomic value and the two values are equal as defined
     *         by the XPath eq operator
     * @throws ClassCastException if the values are not comparable
     */

    public boolean equals(Object o) {
        GDateValue gdv = (GDateValue)o;
        if (getPrimitiveType() == gdv.getPrimitiveType()) {
            return toDateTime().equals(gdv.toDateTime());
        } else {
            throw new ClassCastException(GDateValue.class.getName());
        }
    }

    public int hashCode() {
        return DateTimeValue.hashCode(year, month, day, (byte)12, (byte)0, (byte)0, 0, getTimezoneInMinutes());
    }

    /**
     * Compare this value to another value of the same type, using the supplied context object
     * to get the implicit timezone if required. This method implements the XPath comparison semantics.
     * @param other the value to be compared
     * @param context the XPath dynamic evaluation context (needed only to get the implicit timezone)
     * @return -1 if this value is less, 0 if equal, +1 if greater
     */

    public int compareTo(CalendarValue other, XPathContext context) throws NoDynamicContextException {
        if (getPrimitiveType() != other.getPrimitiveType()) {
            throw new ClassCastException("Cannot compare dates of different types");
            // covers, for example, comparing a gYear to a gYearMonth
        }
        GDateValue v2 = (GDateValue)other;
        if (getTimezoneInMinutes() == other.getTimezoneInMinutes()) {
            // both values are in the same timezone (explicitly or implicitly)
            if (year != v2.year) {
                return IntegerValue.signum(year - v2.year);
            }
            if (month != v2.month) {
                return IntegerValue.signum(month - v2.month);
            }
            if (day != v2.day) {
                return IntegerValue.signum(day - v2.day);
            }
            return 0;
        }
        return toDateTime().compareTo(other.toDateTime(), context);
    }

    /**
     * Convert to DateTime.
     * @return the starting instant of the GDateValue (with the same timezone)
     */

    public DateTimeValue toDateTime() {
        return new DateTimeValue(year, month, day, (byte)0, (byte)0, (byte)0, 0, getTimezoneInMinutes());
    }


    public Comparable getSchemaComparable() {
        return new GDateComparable();
    }

    /**
    * Get a component of the value. Returns null if the timezone component is
    * requested and is not present.
    */

    public AtomicValue getComponent(int component) throws XPathException {
        switch (component) {
        case Component.YEAR_ALLOWING_ZERO:
            return Int64Value.makeIntegerValue(year);
        case Component.YEAR:
            return Int64Value.makeIntegerValue(year > 0 ? year : year-1);
        case Component.MONTH:
            return Int64Value.makeIntegerValue(month);
        case Component.DAY:
            return Int64Value.makeIntegerValue(day);
        case Component.TIMEZONE:
            if (hasTimezone()) {
                return DayTimeDurationValue.fromMilliseconds(getTimezoneInMinutes()*60000);
            } else {
                return null;
            }
        default:
            throw new IllegalArgumentException("Unknown component for date: " + component);
        }
    }

    private class GDateComparable implements Comparable {

        public GDateValue asGDateValue() {
            return GDateValue.this;
        }

        public int compareTo(Object o) {
            if (o instanceof GDateComparable) {
                if (asGDateValue().getPrimitiveType() != ((GDateComparable)o).asGDateValue().getPrimitiveType()) {
                    return INDETERMINATE_ORDERING;
                }
                DateTimeValue dt0 = GDateValue.this.toDateTime();
                DateTimeValue dt1 = ((GDateComparable)o).asGDateValue().toDateTime();
                return dt0.getSchemaComparable().compareTo(dt1.getSchemaComparable());
            } else {
                return INDETERMINATE_ORDERING;
            }
        }

        public boolean equals(Object o) {
            return compareTo(o) == 0;
        }

        public int hashCode() {
            return GDateValue.this.toDateTime().getSchemaComparable().hashCode();
        }
    }

    /**
     * Get a comparison key for this value. Two values are equal if and only if they their comparison
     * keys are equal
     * @param context XPath dynamic evaluation context
     * @throws NoDynamicContextException if the implicit timezone is required and is not available
     * (because the method is being called at compile time)
     */


    public ComparisonKey getComparisonKey(XPathContext context) throws NoDynamicContextException {
        return new ComparisonKey(StandardNames.XS_DATE, toDateTime().normalize(context));
    }

}

//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (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.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Contributor(s):
//

