/*
 * Copyright 2002-2017 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.format.datetime;

import java.util.Calendar;
import java.util.Date;

import org.springframework.core.convert.converter.Converter;
import org.springframework.core.convert.converter.ConverterRegistry;
import org.springframework.format.FormatterRegistrar;
import org.springframework.format.FormatterRegistry;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

Configures basic date formatting for use with Spring, primarily for DateTimeFormat declarations. Applies to fields of type Date, Calendar and long. 
Designed for direct instantiation but also exposes the static addDateConverters(ConverterRegistry) utility method for ad-hoc use against any ConverterRegistry instance. 
Author:
Phillip Webb
See Also:
DateTimeFormatterRegistrar
JodaTimeFormatterRegistrar
FormatterRegistrar.registerFormatters
Since:
3.2/**
 * Configures basic date formatting for use with Spring, primarily for
 * {@link org.springframework.format.annotation.DateTimeFormat} declarations.
 * Applies to fields of type {@link Date}, {@link Calendar} and {@code long}.
 *
 * <p>Designed for direct instantiation but also exposes the static
 * {@link #addDateConverters(ConverterRegistry)} utility method for
 * ad-hoc use against any {@code ConverterRegistry} instance.
 *
 * @author Phillip Webb
 * @since 3.2
 * @see org.springframework.format.datetime.standard.DateTimeFormatterRegistrar
 * @see org.springframework.format.datetime.joda.JodaTimeFormatterRegistrar
 * @see FormatterRegistrar#registerFormatters
 */
public class DateFormatterRegistrar implements FormatterRegistrar {

	@Nullable
	private DateFormatter dateFormatter;


	
Set a global date formatter to register.
If not specified, no general formatter for non-annotated Date and Calendar fields will be registered. /**
	 * Set a global date formatter to register.
	 * <p>If not specified, no general formatter for non-annotated
	 * {@link Date} and {@link Calendar} fields will be registered.
	 */
	public void setFormatter(DateFormatter dateFormatter) {
		Assert.notNull(dateFormatter, "DateFormatter must not be null");
		this.dateFormatter = dateFormatter;
	}


	@Override
	public void registerFormatters(FormatterRegistry registry) {
		addDateConverters(registry);
		// In order to retain back compatibility we only register Date/Calendar
		// types when a user defined formatter is specified (see SPR-10105)
		if (this.dateFormatter != null) {
			registry.addFormatter(this.dateFormatter);
			registry.addFormatterForFieldType(Calendar.class, this.dateFormatter);
		}
		registry.addFormatterForFieldAnnotation(new DateTimeFormatAnnotationFormatterFactory());
	}

	
Add date converters to the specified registry.
Params:
converterRegistry – the registry of converters to add to/**
	 * Add date converters to the specified registry.
	 * @param converterRegistry the registry of converters to add to
	 */
	public static void addDateConverters(ConverterRegistry converterRegistry) {
		converterRegistry.addConverter(new DateToLongConverter());
		converterRegistry.addConverter(new DateToCalendarConverter());
		converterRegistry.addConverter(new CalendarToDateConverter());
		converterRegistry.addConverter(new CalendarToLongConverter());
		converterRegistry.addConverter(new LongToDateConverter());
		converterRegistry.addConverter(new LongToCalendarConverter());
	}


	private static class DateToLongConverter implements Converter<Date, Long> {

		@Override
		public Long convert(Date source) {
			return source.getTime();
		}
	}


	private static class DateToCalendarConverter implements Converter<Date, Calendar> {

		@Override
		public Calendar convert(Date source) {
			Calendar calendar = Calendar.getInstance();
			calendar.setTime(source);
			return calendar;
		}
	}


	private static class CalendarToDateConverter implements Converter<Calendar, Date> {

		@Override
		public Date convert(Calendar source) {
			return source.getTime();
		}
	}


	private static class CalendarToLongConverter implements Converter<Calendar, Long> {

		@Override
		public Long convert(Calendar source) {
			return source.getTimeInMillis();
		}
	}


	private static class LongToDateConverter implements Converter<Long, Date> {

		@Override
		public Date convert(Long source) {
			return new Date(source);
		}
	}


	private static class LongToCalendarConverter implements Converter<Long, Calendar> {

		@Override
		public Calendar convert(Long source) {
			Calendar calendar = Calendar.getInstance();
			calendar.setTimeInMillis(source);
			return calendar;
		}
	}

}