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#include "v8.h"

#include "global-handles.h"
#include "snapshot.h"
#include "cctest.h"

using namespace v8::internal;

class DateCacheMock: public DateCache {
 public:
  struct Rule {
    int year, start_month, start_day, end_month, end_day, offset_sec;
  };

  DateCacheMock(int local_offset, Rule* rules, int rules_count)
      : local_offset_(local_offset), rules_(rules), rules_count_(rules_count) {}

 protected:
  virtual int GetDaylightSavingsOffsetFromOS(int64_t time_sec) {
    int days = DaysFromTime(time_sec * 1000);
    int time_in_day_sec = TimeInDay(time_sec * 1000, days) / 1000;
    int year, month, day;
    YearMonthDayFromDays(days, &year, &month, &day);
    Rule* rule = FindRuleFor(year, month, day, time_in_day_sec);
    return rule == NULL ? 0 : rule->offset_sec * 1000;
  }


  virtual int GetLocalOffsetFromOS() {
    return local_offset_;
  }

 private:
  Rule* FindRuleFor(int year, int month, int day, int time_in_day_sec) {
    Rule* result = NULL;
    for (int i = 0; i < rules_count_; i++)
      if (Match(&rules_[i], year, month, day, time_in_day_sec)) {
        result = &rules_[i];
      }
    return result;
  }


  bool Match(Rule* rule, int year, int month, int day, int time_in_day_sec) {
    if (rule->year != 0 && rule->year != year) return false;
    if (rule->start_month > month) return false;
    if (rule->end_month < month) return false;
    int start_day = ComputeRuleDay(year, rule->start_month, rule->start_day);
    if (rule->start_month == month && start_day > day) return false;
    if (rule->start_month == month && start_day == day &&
        2 * 3600 > time_in_day_sec)
      return false;
    int end_day = ComputeRuleDay(year, rule->end_month, rule->end_day);
    if (rule->end_month == month && end_day < day) return false;
    if (rule->end_month == month && end_day == day &&
        2 * 3600 <= time_in_day_sec)
      return false;
    return true;
  }


  int ComputeRuleDay(int year, int month, int day) {
    if (day != 0) return day;
    int days = DaysFromYearMonth(year, month);
    // Find the first Sunday of the month.
    while (Weekday(days + day) != 6) day++;
    return day + 1;
  }

  int local_offset_;
  Rule* rules_;
  int rules_count_;
};

static int64_t TimeFromYearMonthDay(DateCache* date_cache,
                                    int year,
                                    int month,
                                    int day) {
  int64_t result = date_cache->DaysFromYearMonth(year, month);
  return (result + day - 1) * DateCache::kMsPerDay;
}


static void CheckDST(int64_t time) {
  Isolate* isolate = CcTest::i_isolate();
  DateCache* date_cache = isolate->date_cache();
  int64_t actual = date_cache->ToLocal(time);
  int64_t expected = time + date_cache->GetLocalOffsetFromOS() +
                     date_cache->GetDaylightSavingsOffsetFromOS(time / 1000);
  CHECK_EQ(actual, expected);
}


TEST(DaylightSavingsTime) {
  LocalContext context;
  v8::Isolate* isolate = context->GetIsolate();
  v8::HandleScope scope(isolate);
  DateCacheMock::Rule rules[] = {
    {0, 2, 0, 10, 0, 3600},  // DST from March to November in any year.
    {2010, 2, 0, 7, 20, 3600},  // DST from March to August 20 in 2010.
    {2010, 7, 20, 8, 10, 0},  // No DST from August 20 to September 10 in 2010.
    {2010, 8, 10, 10, 0, 3600},  // DST from September 10 to November in 2010.
  };

  int local_offset_ms = -36000000;  // -10 hours.

  DateCacheMock* date_cache =
    new DateCacheMock(local_offset_ms, rules, ARRAY_SIZE(rules));

  reinterpret_cast<Isolate*>(isolate)->set_date_cache(date_cache);

  int64_t start_of_2010 = TimeFromYearMonthDay(date_cache, 2010, 0, 1);
  int64_t start_of_2011 = TimeFromYearMonthDay(date_cache, 2011, 0, 1);
  int64_t august_20 = TimeFromYearMonthDay(date_cache, 2010, 7, 20);
  int64_t september_10 = TimeFromYearMonthDay(date_cache, 2010, 8, 10);
  CheckDST((august_20 + september_10) / 2);
  CheckDST(september_10);
  CheckDST(september_10 + 2 * 3600);
  CheckDST(september_10 + 2 * 3600 - 1000);
  CheckDST(august_20 + 2 * 3600);
  CheckDST(august_20 + 2 * 3600 - 1000);
  CheckDST(august_20);
  // Check each day of 2010.
  for (int64_t time = start_of_2011 + 2 * 3600;
       time >= start_of_2010;
       time -= DateCache::kMsPerDay) {
    CheckDST(time);
    CheckDST(time - 1000);
    CheckDST(time + 1000);
  }
  // Check one day from 2010 to 2100.
  for (int year = 2100; year >= 2010; year--) {
    CheckDST(TimeFromYearMonthDay(date_cache, year, 5, 5));
  }
  CheckDST((august_20 + september_10) / 2);
  CheckDST(september_10);
  CheckDST(september_10 + 2 * 3600);
  CheckDST(september_10 + 2 * 3600 - 1000);
  CheckDST(august_20 + 2 * 3600);
  CheckDST(august_20 + 2 * 3600 - 1000);
  CheckDST(august_20);
}
