/*
 * Copyright 2002-2020 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.scheduling.support;

import java.time.DateTimeException;
import java.time.temporal.ChronoField;
import java.time.temporal.Temporal;
import java.time.temporal.ValueRange;
import java.util.function.BiFunction;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

Single field in a cron pattern. Created using the parse* methods, main and only entry point is nextOrSame(T). 
Author:
Arjen Poutsma
Since:
5.3/**
 * Single field in a cron pattern. Created using the {@code parse*} methods,
 * main and only entry point is {@link #nextOrSame(Temporal)}.
 *
 * @author Arjen Poutsma
 * @since 5.3
 */
abstract class CronField {

	private static final String[] MONTHS = new String[]{"JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP",
			"OCT", "NOV", "DEC"};

	private static final String[] DAYS = new String[]{"MON", "TUE", "WED", "THU", "FRI", "SAT", "SUN"};

	private final Type type;


	protected CronField(Type type) {
		this.type = type;
	}

	
Return a CronField enabled for 0 nano seconds. /**
	 * Return a {@code CronField} enabled for 0 nano seconds.
	 */
	public static CronField zeroNanos() {
		return BitsCronField.zeroNanos();
	}

	
Parse the given value into a seconds CronField, the first entry of a cron expression. /**
	 * Parse the given value into a seconds {@code CronField}, the first entry of a cron expression.
	 */
	public static CronField parseSeconds(String value) {
		return BitsCronField.parseSeconds(value);
	}

	
Parse the given value into a minutes CronField, the second entry of a cron expression. /**
	 * Parse the given value into a minutes {@code CronField}, the second entry of a cron expression.
	 */
	public static CronField parseMinutes(String value) {
		return BitsCronField.parseMinutes(value);
	}

	
Parse the given value into a hours CronField, the third entry of a cron expression. /**
	 * Parse the given value into a hours {@code CronField}, the third entry of a cron expression.
	 */
	public static CronField parseHours(String value) {
		return BitsCronField.parseHours(value);
	}

	
Parse the given value into a days of months CronField, the fourth entry of a cron expression. /**
	 * Parse the given value into a days of months {@code CronField}, the fourth entry of a cron expression.
	 */
	public static CronField parseDaysOfMonth(String value) {
		if (!QuartzCronField.isQuartzDaysOfMonthField(value)) {
			return BitsCronField.parseDaysOfMonth(value);
		}
		else {
			return parseList(value, Type.DAY_OF_MONTH, (field, type) -> {
				if (QuartzCronField.isQuartzDaysOfMonthField(field)) {
					return QuartzCronField.parseDaysOfMonth(field);
				}
				else {
					return BitsCronField.parseDaysOfMonth(field);
				}
			});
		}
	}

	
Parse the given value into a month CronField, the fifth entry of a cron expression. /**
	 * Parse the given value into a month {@code CronField}, the fifth entry of a cron expression.
	 */
	public static CronField parseMonth(String value) {
		value = replaceOrdinals(value, MONTHS);
		return BitsCronField.parseMonth(value);
	}

	
Parse the given value into a days of week CronField, the sixth entry of a cron expression. /**
	 * Parse the given value into a days of week {@code CronField}, the sixth entry of a cron expression.
	 */
	public static CronField parseDaysOfWeek(String value) {
		value = replaceOrdinals(value, DAYS);
		if (!QuartzCronField.isQuartzDaysOfWeekField(value)) {
			return BitsCronField.parseDaysOfWeek(value);
		}
		else {
			return parseList(value, Type.DAY_OF_WEEK, (field, type) -> {
				if (QuartzCronField.isQuartzDaysOfWeekField(field)) {
					return QuartzCronField.parseDaysOfWeek(field);
				}
				else {
					return BitsCronField.parseDaysOfWeek(field);
				}
			});
		}
	}


	private static CronField parseList(String value, Type type, BiFunction<String, Type, CronField> parseFieldFunction) {
		Assert.hasLength(value, "Value must not be empty");
		String[] fields = StringUtils.delimitedListToStringArray(value, ",");
		CronField[] cronFields = new CronField[fields.length];
		for (int i = 0; i < fields.length; i++) {
			cronFields[i] = parseFieldFunction.apply(fields[i], type);
		}
		return CompositeCronField.compose(cronFields, type, value);
	}

	private static String replaceOrdinals(String value, String[] list) {
		value = value.toUpperCase();
		for (int i = 0; i < list.length; i++) {
			String replacement = Integer.toString(i + 1);
			value = StringUtils.replace(value, list[i], replacement);
		}
		return value;
	}


	
Get the next or same Temporal in the sequence matching this cron field. 
Params:
temporal – the seed value
Returns:
the next or same temporal matching the pattern/**
	 * Get the next or same {@link Temporal} in the sequence matching this
	 * cron field.
	 * @param temporal the seed value
	 * @return the next or same temporal matching the pattern
	 */
	@Nullable
	public abstract <T extends Temporal & Comparable<? super T>> T nextOrSame(T temporal);


	protected Type type() {
		return this.type;
	}


	
Represents the type of cron field, i.e. seconds, minutes, hours,
day-of-month, month, day-of-week.
/**
	 * Represents the type of cron field, i.e. seconds, minutes, hours,
	 * day-of-month, month, day-of-week.
	 */
	protected enum Type {
		NANO(ChronoField.NANO_OF_SECOND),
		SECOND(ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
		MINUTE(ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
		HOUR(ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
		DAY_OF_MONTH(ChronoField.DAY_OF_MONTH, ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
		MONTH(ChronoField.MONTH_OF_YEAR, ChronoField.DAY_OF_MONTH, ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
		DAY_OF_WEEK(ChronoField.DAY_OF_WEEK, ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND);


		private final ChronoField field;

		private final ChronoField[] lowerOrders;


		Type(ChronoField field, ChronoField... lowerOrders) {
			this.field = field;
			this.lowerOrders = lowerOrders;
		}


		
Return the value of this type for the given temporal.
Returns:
the value of this type/**
		 * Return the value of this type for the given temporal.
		 * @return the value of this type
		 */
		public int get(Temporal date) {
			return date.get(this.field);
		}

		
Return the general range of this type. For instance, this methods will return 0-31 for MONTH. 
Returns:
the range of this field/**
		 * Return the general range of this type. For instance, this methods
		 * will return 0-31 for {@link #MONTH}.
		 * @return the range of this field
		 */
		public ValueRange range() {
			return this.field.range();
		}

		
Check whether the given value is valid, i.e. whether it falls in range. 
Params:
value – the value to check
Throws:
IllegalArgumentException – if the given value is invalid
Returns:
the value that was passed in/**
		 * Check whether the given value is valid, i.e. whether it falls in
		 * {@linkplain #range() range}.
		 * @param value the value to check
		 * @return the value that was passed in
		 * @throws IllegalArgumentException if the given value is invalid
		 */
		public int checkValidValue(int value) {
			if (this == DAY_OF_WEEK && value == 0) {
				return value;
			}
			else {
				try {
					return this.field.checkValidIntValue(value);
				}
				catch (DateTimeException ex) {
					throw new IllegalArgumentException(ex.getMessage(), ex);
				}
			}
		}

		
Elapse the given temporal for the difference between the current value of this field and the goal value. Typically, the returned temporal will have the given goal as the current value for this type, but this is not the case for DAY_OF_MONTH. For instance, if goal is 31, and temporal is April 16th, this method returns May 1st, because April 31st does not exist. 
Params:
temporal – the temporal to elapse
goal – the goal value
Type parameters:
<T> – the type of temporal
Returns:
the elapsed temporal, typically with goal as value for this type./**
		 * Elapse the given temporal for the difference between the current
		 * value of this field and the goal value. Typically, the returned
		 * temporal will have the given goal as the current value for this type,
		 * but this is not the case for {@link #DAY_OF_MONTH}. For instance,
		 * if {@code goal} is 31, and {@code temporal} is April 16th,
		 * this method returns May 1st, because April 31st does not exist.
		 * @param temporal the temporal to elapse
		 * @param goal the goal value
		 * @param <T> the type of temporal
		 * @return the elapsed temporal, typically with {@code goal} as value
		 * for this type.
		 */
		public <T extends Temporal & Comparable<? super T>> T elapseUntil(T temporal, int goal) {
			int current = get(temporal);
			if (current < goal) {
				return this.field.getBaseUnit().addTo(temporal, goal - current);
			}
			else {
				ValueRange range = temporal.range(this.field);
				long amount = goal + range.getMaximum() - current + 1 - range.getMinimum();
				return this.field.getBaseUnit().addTo(temporal, amount);
			}
		}

		
Roll forward the give temporal until it reaches the next higher order field. Calling this method is equivalent to calling elapseUntil(T, int) with goal set to the minimum value of this field's range. 
Params:
temporal – the temporal to roll forward
Type parameters:
<T> – the type of temporal
Returns:
the rolled forward temporal/**
		 * Roll forward the give temporal until it reaches the next higher
		 * order field. Calling this method is equivalent to calling
		 * {@link #elapseUntil(Temporal, int)} with goal set to the
		 * minimum value of this field's range.
		 * @param temporal the temporal to roll forward
		 * @param <T> the type of temporal
		 * @return the rolled forward temporal
		 */
		public <T extends Temporal & Comparable<? super T>> T rollForward(T temporal) {
			int current = get(temporal);
			ValueRange range = temporal.range(this.field);
			long amount = range.getMaximum() - current + 1;
			return this.field.getBaseUnit().addTo(temporal, amount);
		}

		
Reset this and all lower order fields of the given temporal to their minimum value. For instance for MINUTE, this method resets nanos, seconds, and minutes to 0.
Params:
temporal – the temporal to reset
Type parameters:
<T> – the type of temporal
Returns:
the reset temporal/**
		 * Reset this and all lower order fields of the given temporal to their
		 * minimum value. For instance for {@link #MINUTE}, this method
		 * resets nanos, seconds, <strong>and</strong> minutes to 0.
		 * @param temporal the temporal to reset
		 * @param <T> the type of temporal
		 * @return the reset temporal
		 */
		public <T extends Temporal> T reset(T temporal) {
			for (ChronoField lowerOrder : this.lowerOrders) {
				if (temporal.isSupported(lowerOrder)) {
					temporal = lowerOrder.adjustInto(temporal, temporal.range(lowerOrder).getMinimum());
				}
			}
			return temporal;
		}

		@Override
		public String toString() {
			return this.field.toString();
		}
	}

}