package org.oxerr.commons.ws.rs.provider;
   
   import java.lang.annotation.Annotation;
   import java.lang.reflect.Type;
   import java.math.BigDecimal;
   import java.time.Instant;
   import java.time.format.DateTimeParseException;
   
   import javax.inject.Singleton;
  import javax.ws.rs.ProcessingException;
  import javax.ws.rs.ext.ParamConverter;
  import javax.ws.rs.ext.ParamConverterProvider;
  import javax.ws.rs.ext.Provider;
  
  import com.fasterxml.jackson.datatype.jsr310.DecimalUtils;
  
  /**
   * {@code ParamConverterProvider} for converting between a {@code String} and
   * {@link Instant}.
   */
  @Provider
  @Singleton
  public class InstantProvider implements ParamConverterProvider {
  
  	/**
  	 * {@inheritDoc}
  	 */
  	@Override
  	public <T> ParamConverter<T> getConverter(Class<T> rawType,
  			Type genericType, Annotation[] annotations) {
  		return (rawType != Instant.class) ? null : new ParamConverter<T>() {
  
  			@Override
  			public T fromString(final String value) {
  				return rawType.cast(InstantProvider.fromString(value));
  			}
  
  			@Override
  			public String toString(final T value) throws IllegalArgumentException {
  				return InstantProvider.<T>toString(value);
  			}
  		};
  	}
  
  	public static Instant fromString(final String value) {
  		if (value == null) {
  			throw new IllegalArgumentException("value cannot be null");
  		}
  
  		try {
  			final BigDecimal d = new BigDecimal(value);
  			long seconds = d.longValue();
  			int nanoseconds = DecimalUtils.extractNanosecondDecimal(d, seconds);
  			return Instant.ofEpochSecond(seconds, nanoseconds);
  		} catch (Exception e) {
  			// ignore
  		}
  
  		try {
  			return Instant.parse(value);
  		} catch (DateTimeParseException ex) {
  			throw new ProcessingException(ex);
  		}
  	}
  
  	public static <T> String toString(final T value)
  			throws IllegalArgumentException {
  		if (value == null) {
  			throw new IllegalArgumentException("value cannot be null.");
  		}
  		return value.toString();
  	}
  
  }