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  /*
   * This file is available under and governed by the GNU General Public
   * License version 2 only, as published by the Free Software Foundation.
   * However, the following notice accompanied the original version of this
   * file:
   *
   * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
   *
   * All rights reserved.
   *
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  package java.time.temporal;
  
  import java.time.DateTimeException;
  import java.util.Objects;
  
  /**
   * Framework-level interface defining read-only access to a temporal object,
   * such as a date, time, offset or some combination of these.
   * <p>
   * This is the base interface type for date, time and offset objects.
   * It is implemented by those classes that can provide information
   * as {@linkplain TemporalField fields} or {@linkplain TemporalQuery queries}.
   * <p>
   * Most date and time information can be represented as a number.
   * These are modeled using {@code TemporalField} with the number held using
   * a {@code long} to handle large values. Year, month and day-of-month are
   * simple examples of fields, but they also include instant and offsets.
   * See {@link ChronoField} for the standard set of fields.
   * <p>
   * Two pieces of date/time information cannot be represented by numbers,
   * the {@linkplain java.time.chrono.Chronology chronology} and the
   * {@linkplain java.time.ZoneId time-zone}.
   * These can be accessed via {@linkplain #query(TemporalQuery) queries} using
   * the static methods defined on {@link TemporalQuery}.
   * <p>
   * A sub-interface, {@link Temporal}, extends this definition to one that also
   * supports adjustment and manipulation on more complete temporal objects.
   * <p>
   * This interface is a framework-level interface that should not be widely
   * used in application code. Instead, applications should create and pass
   * around instances of concrete types, such as {@code LocalDate}.
   * There are many reasons for this, part of which is that implementations
   * of this interface may be in calendar systems other than ISO.
   * See {@link java.time.chrono.ChronoLocalDate} for a fuller discussion of the issues.
   *
   * @implSpec
   * This interface places no restrictions on the mutability of implementations,
   * however immutability is strongly recommended.
   *
   * @since 1.8
   */
  public interface TemporalAccessor {
  
      /**
       * Checks if the specified field is supported.
       * <p>
       * This checks if the date-time can be queried for the specified field.
       * If false, then calling the {@link #range(TemporalField) range} and {@link #get(TemporalField) get}
       * methods will throw an exception.
       *
       * @implSpec
       * Implementations must check and handle all fields defined in {@link ChronoField}.
       * If the field is supported, then true must be returned, otherwise false must be returned.
       * <p>
       * If the field is not a {@code ChronoField}, then the result of this method
       * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
       * passing {@code this} as the argument.
       * <p>
       * Implementations must ensure that no observable state is altered when this
       * read-only method is invoked.
       *
       * @param field  the field to check, null returns false
       * @return true if this date-time can be queried for the field, false if not
       */
      boolean isSupported(TemporalField field);
  
      /**
       * Gets the range of valid values for the specified field.
       * <p>
       * All fields can be expressed as a {@code long} integer.
       * This method returns an object that describes the valid range for that value.
       * The value of this temporal object is used to enhance the accuracy of the returned range.
       * If the date-time cannot return the range, because the field is unsupported or for
       * some other reason, an exception will be thrown.
       * <p>
       * Note that the result only describes the minimum and maximum valid values
       * and it is important not to read too much into them. For example, there
       * could be values within the range that are invalid for the field.
       *
       * @implSpec
       * Implementations must check and handle all fields defined in {@link ChronoField}.
       * If the field is supported, then the range of the field must be returned.
       * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.
       * <p>
       * If the field is not a {@code ChronoField}, then the result of this method
       * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessorl)}
       * passing {@code this} as the argument.
       * <p>
       * Implementations must ensure that no observable state is altered when this
       * read-only method is invoked.
       * <p>
       * The default implementation must behave equivalent to this code:
       * <pre>
       *  if (field instanceof ChronoField) {
       *    if (isSupported(field)) {
       *      return field.range();
       *    }
       *    throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
       *  }
       *  return field.rangeRefinedBy(this);
       * </pre>
       *
       * @param field  the field to query the range for, not null
       * @return the range of valid values for the field, not null
       * @throws DateTimeException if the range for the field cannot be obtained
       * @throws UnsupportedTemporalTypeException if the field is not supported
       */
      default ValueRange range(TemporalField field) {
          if (field instanceof ChronoField) {
              if (isSupported(field)) {
                  return field.range();
              }
              throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
          }
          Objects.requireNonNull(field, "field");
          return field.rangeRefinedBy(this);
      }
  
      /**
       * Gets the value of the specified field as an {@code int}.
       * <p>
       * This queries the date-time for the value of the specified field.
       * The returned value will always be within the valid range of values for the field.
       * If the date-time cannot return the value, because the field is unsupported or for
       * some other reason, an exception will be thrown.
       *
       * @implSpec
       * Implementations must check and handle all fields defined in {@link ChronoField}.
       * If the field is supported and has an {@code int} range, then the value of
       * the field must be returned.
       * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.
       * <p>
       * If the field is not a {@code ChronoField}, then the result of this method
       * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
       * passing {@code this} as the argument.
       * <p>
       * Implementations must ensure that no observable state is altered when this
       * read-only method is invoked.
       * <p>
       * The default implementation must behave equivalent to this code:
       * <pre>
       *  if (range(field).isIntValue()) {
       *    return range(field).checkValidIntValue(getLong(field), field);
       *  }
       *  throw new UnsupportedTemporalTypeException("Invalid field " + field + " + for get() method, use getLong() instead");
       * </pre>
       *
       * @param field  the field to get, not null
       * @return the value for the field, within the valid range of values
       * @throws DateTimeException if a value for the field cannot be obtained or
       *         the value is outside the range of valid values for the field
       * @throws UnsupportedTemporalTypeException if the field is not supported or
       *         the range of values exceeds an {@code int}
       * @throws ArithmeticException if numeric overflow occurs
       */
      default int get(TemporalField field) {
          ValueRange range = range(field);
          if (range.isIntValue() == false) {
              throw new UnsupportedTemporalTypeException("Invalid field " + field + " for get() method, use getLong() instead");
          }
          long value = getLong(field);
          if (range.isValidValue(value) == false) {
              throw new DateTimeException("Invalid value for " + field + " (valid values " + range + "): " + value);
          }
          return (int) value;
      }
  
      /**
       * Gets the value of the specified field as a {@code long}.
       * <p>
       * This queries the date-time for the value of the specified field.
       * The returned value may be outside the valid range of values for the field.
       * If the date-time cannot return the value, because the field is unsupported or for
       * some other reason, an exception will be thrown.
       *
       * @implSpec
       * Implementations must check and handle all fields defined in {@link ChronoField}.
       * If the field is supported, then the value of the field must be returned.
       * If unsupported, then an {@code UnsupportedTemporalTypeException} must be thrown.
       * <p>
       * If the field is not a {@code ChronoField}, then the result of this method
       * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
       * passing {@code this} as the argument.
       * <p>
       * Implementations must ensure that no observable state is altered when this
       * read-only method is invoked.
       *
       * @param field  the field to get, not null
       * @return the value for the field
       * @throws DateTimeException if a value for the field cannot be obtained
       * @throws UnsupportedTemporalTypeException if the field is not supported
       * @throws ArithmeticException if numeric overflow occurs
       */
      long getLong(TemporalField field);
  
      /**
       * Queries this date-time.
       * <p>
       * This queries this date-time using the specified query strategy object.
       * <p>
       * Queries are a key tool for extracting information from date-times.
       * They exists to externalize the process of querying, permitting different
       * approaches, as per the strategy design pattern.
       * Examples might be a query that checks if the date is the day before February 29th
       * in a leap year, or calculates the number of days to your next birthday.
       * <p>
       * The most common query implementations are method references, such as
       * {@code LocalDate::from} and {@code ZoneId::from}.
       * Additional implementations are provided as static methods on {@link TemporalQuery}.
       *
       * @implSpec
       * The default implementation must behave equivalent to this code:
       * <pre>
       *  if (query == TemporalQueries.zoneId() ||
       *        query == TemporalQueries.chronology() || query == TemporalQueries.precision()) {
       *    return null;
       *  }
       *  return query.queryFrom(this);
       * </pre>
       * Future versions are permitted to add further queries to the if statement.
       * <p>
       * All classes implementing this interface and overriding this method must call
       * {@code TemporalAccessor.super.query(query)}. JDK classes may avoid calling
       * super if they provide behavior equivalent to the default behaviour, however
       * non-JDK classes may not utilize this optimization and must call {@code super}.
       * <p>
       * If the implementation can supply a value for one of the queries listed in the
       * if statement of the default implementation, then it must do so.
       * For example, an application-defined {@code HourMin} class storing the hour
       * and minute must override this method as follows:
       * <pre>
       *  if (query == TemporalQueries.precision()) {
       *    return MINUTES;
       *  }
       *  return TemporalAccessor.super.query(query);
       * </pre>
       * <p>
       * Implementations must ensure that no observable state is altered when this
       * read-only method is invoked.
       *
       * @param <R> the type of the result
       * @param query  the query to invoke, not null
       * @return the query result, null may be returned (defined by the query)
       * @throws DateTimeException if unable to query
       * @throws ArithmeticException if numeric overflow occurs
       */
      default <R> R query(TemporalQuery<R> query) {
          if (query == TemporalQueries.zoneId()
                  || query == TemporalQueries.chronology()
                  || query == TemporalQueries.precision()) {
              return null;
          }
          return query.queryFrom(this);
      }
  
  }
  