/*
 *  Copyright 2001-2011 Stephen Colebourne
 *
 *  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.joda.time.base;

import java.io.Serializable;

import org.joda.time.Chronology;
import org.joda.time.DateTimeUtils;
import org.joda.time.Duration;
import org.joda.time.DurationFieldType;
import org.joda.time.MutablePeriod;
import org.joda.time.PeriodType;
import org.joda.time.ReadWritablePeriod;
import org.joda.time.ReadableDuration;
import org.joda.time.ReadableInstant;
import org.joda.time.ReadablePartial;
import org.joda.time.ReadablePeriod;
import org.joda.time.chrono.ISOChronology;
import org.joda.time.convert.ConverterManager;
import org.joda.time.convert.PeriodConverter;
import org.joda.time.field.FieldUtils;

/**
 * BasePeriod is an abstract implementation of ReadablePeriod that stores
 * data in a <code>PeriodType</code> and an <code>int[]</code>.
 * <p>
 * This class should generally not be used directly by API users.
 * The {@link ReadablePeriod} interface should be used when different 
 * kinds of period objects are to be referenced.
 * <p>
 * BasePeriod subclasses may be mutable and not thread-safe.
 *
 * @author Brian S O'Neill
 * @author Stephen Colebourne
 * @since 1.0
 */
public abstract class BasePeriod
        extends AbstractPeriod
        implements ReadablePeriod, Serializable {

    /** Serialization version */
    private static final long serialVersionUID = -2110953284060001145L;
    /** Serialization version */
    private static final ReadablePeriod DUMMY_PERIOD = new AbstractPeriod() {
        public int getValue(int index) {
            return 0;
        }
        public PeriodType getPeriodType() {
            return PeriodType.time();
        }
    };

    /** The type of period */
    private final PeriodType iType;
    /** The values */
    private final int[] iValues;

    //-----------------------------------------------------------------------
    /**
     * Creates a period from a set of field values.
     *
     * @param years  amount of years in this period, which must be zero if unsupported
     * @param months  amount of months in this period, which must be zero if unsupported
     * @param weeks  amount of weeks in this period, which must be zero if unsupported
     * @param days  amount of days in this period, which must be zero if unsupported
     * @param hours  amount of hours in this period, which must be zero if unsupported
     * @param minutes  amount of minutes in this period, which must be zero if unsupported
     * @param seconds  amount of seconds in this period, which must be zero if unsupported
     * @param millis  amount of milliseconds in this period, which must be zero if unsupported
     * @param type  which set of fields this period supports
     * @throws IllegalArgumentException if period type is invalid
     * @throws IllegalArgumentException if an unsupported field's value is non-zero
     */
    protected BasePeriod(int years, int months, int weeks, int days,
                         int hours, int minutes, int seconds, int millis,
                         PeriodType type) {
        super();
        type = checkPeriodType(type);
        iType = type;
        iValues = setPeriodInternal(years, months, weeks, days, hours, minutes, seconds, millis); // internal method
    }

    /**
     * Creates a period from the given interval endpoints.
     *
     * @param startInstant  interval start, in milliseconds
     * @param endInstant  interval end, in milliseconds
     * @param type  which set of fields this period supports, null means standard
     * @param chrono  the chronology to use, null means ISO default
     * @throws IllegalArgumentException if period type is invalid
     */
    protected BasePeriod(long startInstant, long endInstant, PeriodType type, Chronology chrono) {
        super();
        type = checkPeriodType(type);
        chrono = DateTimeUtils.getChronology(chrono);
        iType = type;
        iValues = chrono.get(this, startInstant, endInstant);
    }

    /**
     * Creates a period from the given interval endpoints.
     *
     * @param startInstant  interval start, null means now
     * @param endInstant  interval end, null means now
     * @param type  which set of fields this period supports, null means standard
     * @throws IllegalArgumentException if period type is invalid
     */
    protected BasePeriod(ReadableInstant startInstant, ReadableInstant endInstant, PeriodType type) {
        super();
        type = checkPeriodType(type);
        if (startInstant == null && endInstant == null) {
            iType = type;
            iValues = new int[size()];
        } else {
            long startMillis = DateTimeUtils.getInstantMillis(startInstant);
            long endMillis = DateTimeUtils.getInstantMillis(endInstant);
            Chronology chrono = DateTimeUtils.getIntervalChronology(startInstant, endInstant);
            iType = type;
            iValues = chrono.get(this, startMillis, endMillis);
        }
    }

    /**
     * Creates a period from the given duration and end point.
     * <p>
     * The two partials must contain the same fields, thus you can
     * specify two <code>LocalDate</code> objects, or two <code>LocalTime</code>
     * objects, but not one of each.
     * As these are Partial objects, time zones have no effect on the result.
     * <p>
     * The two partials must also both be contiguous - see
     * {@link DateTimeUtils#isContiguous(ReadablePartial)} for a
     * definition. Both <code>LocalDate</code> and <code>LocalTime</code> are contiguous.
     *
     * @param start  the start of the period, must not be null
     * @param end  the end of the period, must not be null
     * @param type  which set of fields this period supports, null means standard
     * @throws IllegalArgumentException if the partials are null or invalid
     * @since 1.1
     */
    protected BasePeriod(ReadablePartial start, ReadablePartial end, PeriodType type) {
        super();
        if (start == null || end == null) {
            throw new IllegalArgumentException("ReadablePartial objects must not be null");
        }
        if (start instanceof BaseLocal && end instanceof BaseLocal && start.getClass() == end.getClass()) {
            // for performance
            type = checkPeriodType(type);
            long startMillis = ((BaseLocal) start).getLocalMillis();
            long endMillis = ((BaseLocal) end).getLocalMillis();
            Chronology chrono = start.getChronology();
            chrono = DateTimeUtils.getChronology(chrono);
            iType = type;
            iValues = chrono.get(this, startMillis, endMillis);
        } else {
            if (start.size() != end.size()) {
                throw new IllegalArgumentException("ReadablePartial objects must have the same set of fields");
            }
            for (int i = 0, isize = start.size(); i < isize; i++) {
                if (start.getFieldType(i) != end.getFieldType(i)) {
                    throw new IllegalArgumentException("ReadablePartial objects must have the same set of fields");
                }
            }
            if (DateTimeUtils.isContiguous(start) == false) {
                throw new IllegalArgumentException("ReadablePartial objects must be contiguous");
            }
            iType = checkPeriodType(type);
            Chronology chrono = DateTimeUtils.getChronology(start.getChronology()).withUTC();
            iValues = chrono.get(this, chrono.set(start, 0L), chrono.set(end, 0L));
        }
    }

    /**
     * Creates a period from the given start point and duration.
     *
     * @param startInstant  the interval start, null means now
     * @param duration  the duration of the interval, null means zero-length
     * @param type  which set of fields this period supports, null means standard
     */
    protected BasePeriod(ReadableInstant startInstant, ReadableDuration duration, PeriodType type) {
        super();
        type = checkPeriodType(type);
        long startMillis = DateTimeUtils.getInstantMillis(startInstant);
        long durationMillis = DateTimeUtils.getDurationMillis(duration);
        long endMillis = FieldUtils.safeAdd(startMillis, durationMillis);
        Chronology chrono = DateTimeUtils.getInstantChronology(startInstant);
        iType = type;
        iValues = chrono.get(this, startMillis, endMillis);
    }

    /**
     * Creates a period from the given duration and end point.
     *
     * @param duration  the duration of the interval, null means zero-length
     * @param endInstant  the interval end, null means now
     * @param type  which set of fields this period supports, null means standard
     */
    protected BasePeriod(ReadableDuration duration, ReadableInstant endInstant, PeriodType type) {
        super();
        type = checkPeriodType(type);
        long durationMillis = DateTimeUtils.getDurationMillis(duration);
        long endMillis = DateTimeUtils.getInstantMillis(endInstant);
        long startMillis = FieldUtils.safeSubtract(endMillis, durationMillis);
        Chronology chrono = DateTimeUtils.getInstantChronology(endInstant);
        iType = type;
        iValues = chrono.get(this, startMillis, endMillis);
    }

    /**
     * Creates a period from the given millisecond duration with the standard period type
     * and ISO rules, ensuring that the calculation is performed with the time-only period type.
     * <p>
     * The calculation uses the hour, minute, second and millisecond fields.
     *
     * @param duration  the duration, in milliseconds
     */
    protected BasePeriod(long duration) {
        super();
        // bug [3264409]
        // calculation uses period type from a period object (bad design)
        // thus we use a dummy period object with the time type
        iType = PeriodType.standard();
        int[] values = ISOChronology.getInstanceUTC().get(DUMMY_PERIOD, duration);
        iValues = new int[8];
        System.arraycopy(values, 0, iValues, 4, 4);
    }

    /**
     * Creates a period from the given millisecond duration, which is only really
     * suitable for durations less than one day.
     * <p>
     * Only fields that are precise will be used.
     * Thus the largest precise field may have a large value.
     *
     * @param duration  the duration, in milliseconds
     * @param type  which set of fields this period supports, null means standard
     * @param chrono  the chronology to use, null means ISO default
     * @throws IllegalArgumentException if period type is invalid
     */
    protected BasePeriod(long duration, PeriodType type, Chronology chrono) {
        super();
        type = checkPeriodType(type);
        chrono = DateTimeUtils.getChronology(chrono);
        iType = type;
        iValues = chrono.get(this, duration);
    }

    /**
     * Creates a new period based on another using the {@link ConverterManager}.
     *
     * @param period  the period to convert
     * @param type  which set of fields this period supports, null means use type from object
     * @param chrono  the chronology to use, null means ISO default
     * @throws IllegalArgumentException if period is invalid
     * @throws IllegalArgumentException if an unsupported field's value is non-zero
     */
    protected BasePeriod(Object period, PeriodType type, Chronology chrono) {
        super();
        PeriodConverter converter = ConverterManager.getInstance().getPeriodConverter(period);
        type = (type == null ? converter.getPeriodType(period) : type);
        type = checkPeriodType(type);
        iType = type;
        if (this instanceof ReadWritablePeriod) {
            iValues = new int[size()];
            chrono = DateTimeUtils.getChronology(chrono);
            converter.setInto((ReadWritablePeriod) this, period, chrono);
        } else {
            iValues = new MutablePeriod(period, type, chrono).getValues();
        }
    }

    /**
     * Constructor used when we trust ourselves.
     * Do not expose publically.
     *
     * @param values  the values to use, not null, not cloned
     * @param type  which set of fields this period supports, not null
     */
    protected BasePeriod(int[] values, PeriodType type) {
        super();
        iType = type;
        iValues = values;
    }

    //-----------------------------------------------------------------------
    /**
     * Validates a period type, converting nulls to a default value and
     * checking the type is suitable for this instance.
     * 
     * @param type  the type to check, may be null
     * @return the validated type to use, not null
     * @throws IllegalArgumentException if the period type is invalid
     */
    protected PeriodType checkPeriodType(PeriodType type) {
        return DateTimeUtils.getPeriodType(type);
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the period type.
     *
     * @return the period type
     */
    public PeriodType getPeriodType() {
        return iType;
    }

    /**
     * Gets the value at the specified index.
     *
     * @param index  the index to retrieve
     * @return the value of the field at the specified index
     * @throws IndexOutOfBoundsException if the index is invalid
     */
    public int getValue(int index) {
        return iValues[index];
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the total millisecond duration of this period relative to a start instant.
     * <p>
     * This method adds the period to the specified instant in order to
     * calculate the duration.
     * <p>
     * An instant must be supplied as the duration of a period varies.
     * For example, a period of 1 month could vary between the equivalent of
     * 28 and 31 days in milliseconds due to different length months.
     * Similarly, a day can vary at Daylight Savings cutover, typically between
     * 23 and 25 hours.
     *
     * @param startInstant  the instant to add the period to, thus obtaining the duration
     * @return the total length of the period as a duration relative to the start instant
     * @throws ArithmeticException if the millis exceeds the capacity of the duration
     */
    public Duration toDurationFrom(ReadableInstant startInstant) {
        long startMillis = DateTimeUtils.getInstantMillis(startInstant);
        Chronology chrono = DateTimeUtils.getInstantChronology(startInstant);
        long endMillis = chrono.add(this, startMillis, 1);
        return new Duration(startMillis, endMillis);
    }

    /**
     * Gets the total millisecond duration of this period relative to an
     * end instant.
     * <p>
     * This method subtracts the period from the specified instant in order
     * to calculate the duration.
     * <p>
     * An instant must be supplied as the duration of a period varies.
     * For example, a period of 1 month could vary between the equivalent of
     * 28 and 31 days in milliseconds due to different length months.
     * Similarly, a day can vary at Daylight Savings cutover, typically between
     * 23 and 25 hours.
     *
     * @param endInstant  the instant to subtract the period from, thus obtaining the duration
     * @return the total length of the period as a duration relative to the end instant
     * @throws ArithmeticException if the millis exceeds the capacity of the duration
     */
    public Duration toDurationTo(ReadableInstant endInstant) {
        long endMillis = DateTimeUtils.getInstantMillis(endInstant);
        Chronology chrono = DateTimeUtils.getInstantChronology(endInstant);
        long startMillis = chrono.add(this, endMillis, -1);
        return new Duration(startMillis, endMillis);
    }

    //-----------------------------------------------------------------------
    /**
     * Checks whether a field type is supported, and if so adds the new value
     * to the relevant index in the specified array.
     * 
     * @param type  the field type
     * @param values  the array to update
     * @param newValue  the new value to store if successful
     */
    private void checkAndUpdate(DurationFieldType type, int[] values, int newValue) {
        int index = indexOf(type);
        if (index == -1) {
            if (newValue != 0) {
                throw new IllegalArgumentException(
                    "Period does not support field '" + type.getName() + "'");
            }
        } else {
            values[index] = newValue;
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Sets all the fields of this period from another.
     * 
     * @param period  the period to copy from, not null
     * @throws IllegalArgumentException if an unsupported field's value is non-zero
     */
    protected void setPeriod(ReadablePeriod period) {
        if (period == null) {
            setValues(new int[size()]);
        } else {
            setPeriodInternal(period);
        }
    }

    /**
     * Private method called from constructor.
     */
    private void setPeriodInternal(ReadablePeriod period) {
        int[] newValues = new int[size()];
        for (int i = 0, isize = period.size(); i < isize; i++) {
            DurationFieldType type = period.getFieldType(i);
            int value = period.getValue(i);
            checkAndUpdate(type, newValues, value);
        }
        setValues(newValues);
    }

    /**
     * Sets the eight standard the fields in one go.
     * 
     * @param years  amount of years in this period, which must be zero if unsupported
     * @param months  amount of months in this period, which must be zero if unsupported
     * @param weeks  amount of weeks in this period, which must be zero if unsupported
     * @param days  amount of days in this period, which must be zero if unsupported
     * @param hours  amount of hours in this period, which must be zero if unsupported
     * @param minutes  amount of minutes in this period, which must be zero if unsupported
     * @param seconds  amount of seconds in this period, which must be zero if unsupported
     * @param millis  amount of milliseconds in this period, which must be zero if unsupported
     * @throws IllegalArgumentException if an unsupported field's value is non-zero
     */
    protected void setPeriod(int years, int months, int weeks, int days,
                             int hours, int minutes, int seconds, int millis) {
        int[] newValues = setPeriodInternal(years, months, weeks, days, hours, minutes, seconds, millis);
        setValues(newValues);
    }

    /**
     * Private method called from constructor.
     */
    private int[] setPeriodInternal(int years, int months, int weeks, int days,
                                   int hours, int minutes, int seconds, int millis) {
        int[] newValues = new int[size()];
        checkAndUpdate(DurationFieldType.years(), newValues, years);
        checkAndUpdate(DurationFieldType.months(), newValues, months);
        checkAndUpdate(DurationFieldType.weeks(), newValues, weeks);
        checkAndUpdate(DurationFieldType.days(), newValues, days);
        checkAndUpdate(DurationFieldType.hours(), newValues, hours);
        checkAndUpdate(DurationFieldType.minutes(), newValues, minutes);
        checkAndUpdate(DurationFieldType.seconds(), newValues, seconds);
        checkAndUpdate(DurationFieldType.millis(), newValues, millis);
        return newValues;
    }

    //-----------------------------------------------------------------------
    /**
     * Sets the value of a field in this period.
     * 
     * @param field  the field to set
     * @param value  the value to set
     * @throws IllegalArgumentException if field is is null or not supported.
     */
    protected void setField(DurationFieldType field, int value) {
        setFieldInto(iValues, field, value);
    }

    /**
     * Sets the value of a field in this period.
     * 
     * @param values  the array of values to update
     * @param field  the field to set
     * @param value  the value to set
     * @throws IllegalArgumentException if field is null or not supported.
     */
    protected void setFieldInto(int[] values, DurationFieldType field, int value) {
        int index = indexOf(field);
        if (index == -1) {
            if (value != 0 || field == null) {
                throw new IllegalArgumentException(
                    "Period does not support field '" + field + "'");
            }
        } else {
            values[index] = value;
        }
    }

    /**
     * Adds the value of a field in this period.
     * 
     * @param field  the field to set
     * @param value  the value to set
     * @throws IllegalArgumentException if field is is null or not supported.
     */
    protected void addField(DurationFieldType field, int value) {
        addFieldInto(iValues, field, value);
    }

    /**
     * Adds the value of a field in this period.
     * 
     * @param values  the array of values to update
     * @param field  the field to set
     * @param value  the value to set
     * @throws IllegalArgumentException if field is is null or not supported.
     */
    protected void addFieldInto(int[] values, DurationFieldType field, int value) {
        int index = indexOf(field);
        if (index == -1) {
            if (value != 0 || field == null) {
                throw new IllegalArgumentException(
                    "Period does not support field '" + field + "'");
            }
        } else {
            values[index] = FieldUtils.safeAdd(values[index], value);
        }
    }

    /**
     * Merges the fields from another period.
     * 
     * @param period  the period to add from, not null
     * @throws IllegalArgumentException if an unsupported field's value is non-zero
     */
    protected void mergePeriod(ReadablePeriod period) {
        if (period != null) {
            setValues(mergePeriodInto(getValues(), period));
        }
    }

    /**
     * Merges the fields from another period.
     * 
     * @param values  the array of values to update
     * @param period  the period to add from, not null
     * @return the updated values
     * @throws IllegalArgumentException if an unsupported field's value is non-zero
     */
    protected int[] mergePeriodInto(int[] values, ReadablePeriod period) {
        for (int i = 0, isize = period.size(); i < isize; i++) {
            DurationFieldType type = period.getFieldType(i);
            int value = period.getValue(i);
            checkAndUpdate(type, values, value);
        }
        return values;
    }

    /**
     * Adds the fields from another period.
     * 
     * @param period  the period to add from, not null
     * @throws IllegalArgumentException if an unsupported field's value is non-zero
     */
    protected void addPeriod(ReadablePeriod period) {
        if (period != null) {
            setValues(addPeriodInto(getValues(), period));
        }
    }

    /**
     * Adds the fields from another period.
     * 
     * @param values  the array of values to update
     * @param period  the period to add from, not null
     * @return the updated values
     * @throws IllegalArgumentException if an unsupported field's value is non-zero
     */
    protected int[] addPeriodInto(int[] values, ReadablePeriod period) {
        for (int i = 0, isize = period.size(); i < isize; i++) {
            DurationFieldType type = period.getFieldType(i);
            int value = period.getValue(i);
            if (value != 0) {
                int index = indexOf(type);
                if (index == -1) {
                    throw new IllegalArgumentException(
                        "Period does not support field '" + type.getName() + "'");
                } else {
                    values[index] = FieldUtils.safeAdd(getValue(index), value);
                }
            }
        }
        return values;
    }

    //-----------------------------------------------------------------------
    /**
     * Sets the value of the field at the specified index.
     * 
     * @param index  the index
     * @param value  the value to set
     * @throws IndexOutOfBoundsException if the index is invalid
     */
    protected void setValue(int index, int value) {
        iValues[index] = value;
    }

    /**
     * Sets the values of all fields.
     * <p>
     * In version 2.0 and later, this method copies the array into the original.
     * This is because the instance variable has been changed to be final to satisfy the Java Memory Model.
     * This only impacts subclasses that are mutable.
     * 
     * @param values  the array of values
     */
    protected void setValues(int[] values) {
        System.arraycopy(values, 0, iValues, 0, iValues.length);
    }

}
