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#ifndef DateComponents_h
#define DateComponents_h

#include "platform/PlatformExport.h"
#include "wtf/Allocator.h"
#include "wtf/Forward.h"
#include "wtf/text/Unicode.h"
#include <limits>

namespace blink {

// A DateComponents instance represents one of the following date and time
// combinations:
// * Month type: year-month
// * Date type: year-month-day
// * Week type: year-week
// * Time type: hour-minute-second-millisecond
// * DateTime or DateTimeLocal type:
//   year-month-day hour-minute-second-millisecond
class PLATFORM_EXPORT DateComponents {
  DISALLOW_NEW();

 public:
  DateComponents()
      : m_millisecond(0),
        m_second(0),
        m_minute(0),
        m_hour(0),
        m_monthDay(0),
        m_month(0),
        m_year(0),
        m_week(0),
        m_type(Invalid) {}

  enum Type {
    Invalid,
    Date,
    DateTime,
    DateTimeLocal,
    Month,
    Time,
    Week,
  };

  int millisecond() const { return m_millisecond; }
  int second() const { return m_second; }
  int minute() const { return m_minute; }
  int hour() const { return m_hour; }
  int monthDay() const { return m_monthDay; }
  int weekDay() const;
  int month() const { return m_month; }
  int fullYear() const { return m_year; }
  int week() const { return m_week; }
  Type getType() const { return m_type; }

  enum SecondFormat {
    None,    // Suppress the second part and the millisecond part if they are 0.
    Second,  // Always show the second part, and suppress the millisecond part
             // if it is 0.
    Millisecond  // Always show the second part and the millisecond part.
  };

  // Returns an ISO 8601 representation for this instance.
  // The format argument is valid for DateTime, DateTimeLocal, and Time types.
  String toString(SecondFormat format = None) const;

  // parse*() and setMillisecondsSince*() functions are initializers for an
  // DateComponents instance. If these functions return false, the instance
  // might be invalid.

  // The following six functions parse the input 'src' whose length is
  // 'length', and updates some fields of this instance. The parsing starts at
  // src[start] and examines characters before src[length].
  // 'src' must be non-null. The 'src' string doesn't need to be
  // null-terminated.
  // The functions return true if the parsing succeeds, and set 'end' to the
  // next index after the last consumed. Extra leading characters cause parse
  // failures, and the trailing extra characters don't cause parse failures.

  // Sets year and month.
  bool parseMonth(const String&, unsigned start, unsigned& end);
  // Sets year, month and monthDay.
  bool parseDate(const String&, unsigned start, unsigned& end);
  // Sets year and week.
  bool parseWeek(const String&, unsigned start, unsigned& end);
  // Sets hour, minute, second and millisecond.
  bool parseTime(const String&, unsigned start, unsigned& end);
  // Sets year, month, monthDay, hour, minute, second and millisecond.
  bool parseDateTimeLocal(const String&, unsigned start, unsigned& end);

  // The following setMillisecondsSinceEpochFor*() functions take
  // the number of milliseconds since 1970-01-01 00:00:00.000 UTC as
  // the argument, and update all fields for the corresponding
  // DateComponents type. The functions return true if it succeeds, and
  // false if they fail.

  // For Date type. Updates m_year, m_month and m_monthDay.
  bool setMillisecondsSinceEpochForDate(double ms);
  // For DateTime type. Updates m_year, m_month, m_monthDay, m_hour, m_minute,
  // m_second and m_millisecond.
  bool setMillisecondsSinceEpochForDateTime(double ms);
  // For DateTimeLocal type. Updates m_year, m_month, m_monthDay, m_hour,
  // m_minute, m_second and m_millisecond.
  bool setMillisecondsSinceEpochForDateTimeLocal(double ms);
  // For Month type. Updates m_year and m_month.
  bool setMillisecondsSinceEpochForMonth(double ms);
  // For Week type. Updates m_year and m_week.
  bool setMillisecondsSinceEpochForWeek(double ms);

  // For Time type. Updates m_hour, m_minute, m_second and m_millisecond.
  bool setMillisecondsSinceMidnight(double ms);

  // Another initializer for Month type. Updates m_year and m_month.
  bool setMonthsSinceEpoch(double months);
  // Another initializer for Week type. Updates m_year and m_week.
  bool setWeek(int year, int weekNumber);

  // Returns the number of milliseconds from 1970-01-01 00:00:00 UTC.
  // For a DateComponents initialized with parseDateTimeLocal(),
  // millisecondsSinceEpoch() returns a value for UTC timezone.
  double millisecondsSinceEpoch() const;
  // Returns the number of months from 1970-01.
  // Do not call this for types other than Month.
  double monthsSinceEpoch() const;
  static inline double invalidMilliseconds() {
    return std::numeric_limits<double>::quiet_NaN();
  }

  // Minimum and maxmimum limits for setMillisecondsSince*(),
  // setMonthsSinceEpoch(), millisecondsSinceEpoch(), and monthsSinceEpoch().
  static inline double minimumDate() {
    return -62135596800000.0;
  }  // 0001-01-01T00:00Z
  static inline double minimumDateTime() {
    return -62135596800000.0;
  }  // ditto.
  static inline double minimumMonth() {
    return (1 - 1970) * 12.0 + 1 - 1;
  }                                                 // 0001-01
  static inline double minimumTime() { return 0; }  // 00:00:00.000
  static inline double minimumWeek() {
    return -62135596800000.0;
  }  // 0001-01-01, the first Monday of 0001.
  static inline double maximumDate() {
    return 8640000000000000.0;
  }  // 275760-09-13T00:00Z
  static inline double maximumDateTime() {
    return 8640000000000000.0;
  }  // ditto.
  static inline double maximumMonth() {
    return (275760 - 1970) * 12.0 + 9 - 1;
  }                                                        // 275760-09
  static inline double maximumTime() { return 86399999; }  // 23:59:59.999
  static inline double maximumWeek() {
    return 8639999568000000.0;
  }  // 275760-09-08, the Monday of the week including 275760-09-13.

  // HTML5 uses ISO-8601 format with year >= 1. Gregorian calendar started in
  // 1582. However, we need to support 0001-01-01 in Gregorian calendar rule.
  static inline int minimumYear() { return 1; }
  // Date in ECMAScript can't represent dates later than 275760-09-13T00:00Z.
  // So, we have the same upper limit in HTML5 date/time types.
  static inline int maximumYear() { return 275760; }
  static const int minimumWeekNumber;
  static const int maximumWeekNumber;

 private:
  // Returns the maximum week number in this DateComponents's year.
  // The result is either of 52 and 53.
  int maxWeekNumberInYear() const;
  bool parseYear(const String&, unsigned start, unsigned& end);
  bool addDay(int);
  bool addMinute(int);
  bool parseTimeZone(const String&, unsigned start, unsigned& end);
  // Helper for millisecondsSinceEpoch().
  double millisecondsSinceEpochForTime() const;
  // Helpers for setMillisecondsSinceEpochFor*().
  bool setMillisecondsSinceEpochForDateInternal(double ms);
  void setMillisecondsSinceMidnightInternal(double ms);
  // Helper for toString().
  String toStringForTime(SecondFormat) const;

  // m_weekDay values
  enum {
    Sunday = 0,
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday,
  };

  int m_millisecond;  // 0 - 999
  int m_second;
  int m_minute;
  int m_hour;
  int m_monthDay;  // 1 - 31
  int m_month;     // 0:January - 11:December
  int m_year;      //  1582 -
  int m_week;      // 1 - 53

  Type m_type;
};

}  // namespace blink

#endif  // DateComponents_h
