private void GetDaylightChangeRules(ref DateTime time, TzDatabase.TzZone targetZone, DateTimeKind inflectionKind, out TzDatabase.TzRule one, out TzDatabase.TzRule two, out DaylightTime daylightTime)
{
one = two = null;
daylightTime = null;
// First, figure out which zone we're in
if (targetZone != null)
{
// The zone might not have any daylight savings time rules
if (targetZone.RuleName != TzDatabase.NotApplicableValue)
{
int index = FindRuleIndex(targetZone, time);
if (index != -1)
{
one = m_info.Rules[index];
two = GetCompanionRule(targetZone, one, index, time);
if (one != null && two != null)
{
DateTime from = one.GetDateTime(time.Year, targetZone.UtcOffset, two);
DateTime to = two.GetDateTime(time.Year, targetZone.UtcOffset, one);
if (from > to && Info.IsLatitudeNorth)
{
DateTime swap = to;
to = from;
from = swap;
TzDatabase.TzRule swapRule = one;
one = two;
two = swapRule;
}
else if (from < to && !Info.IsLatitudeNorth)
{
DateTime swap = to;
to = from;
from = swap;
TzDatabase.TzRule swapRule = one;
one = two;
two = swapRule;
}
TimeSpan delta = one.SaveTime;
if (delta.Ticks == 0)
{
delta = two.SaveTime;
}
daylightTime = new DaylightTime(from, to, delta);
}
}
}
}
}
private PublicDomain.TzDatabase.TzRule GetCompanionRule(TzDatabase.TzZone zone, PublicDomain.TzDatabase.TzRule rule, int ruleIndex, DateTime point)
{
TzDatabase.TzRule result = null;
int companionIndex = FindRuleIndex(zone, point, rule.Modifier, rule.Modifier == TzDatabase.NotApplicableValue ? ruleIndex : -1, false);
if (companionIndex != -1)
{
result = m_info.Rules[companionIndex];
}
return result;
}
/// <summary>
/// Finds the index of the rule.
/// </summary>
/// <param name="zone">The zone.</param>
/// <param name="point">The point.</param>
/// <returns></returns>
public int FindRuleIndex(TzDatabase.TzZone zone, DateTime point)
{
return FindRuleIndex(zone, point, null, -1, true);
}
/// <summary>
/// Finds the rule.
/// </summary>
/// <param name="zone">The zone.</param>
/// <param name="point">The point.</param>
/// <param name="avoidModifier">The avoid modifier.</param>
/// <param name="avoidIndex">Index of the avoid.</param>
/// <param name="exactComparison">if set to <c>true</c> [exact comparison].</param>
/// <returns></returns>
public int FindRuleIndex(TzDatabase.TzZone zone, DateTime point, string avoidModifier, int avoidIndex, bool exactComparison)
{
// Now, we have the zone, we can start to figure out the amount
// of time to add to UTC to get standard time
// Get the standard time from the UTC Offset for the zone
// Use the rules to see if we need to apply daylight savings time
// "If this field is - then standard time
// always applies in the time zone."
string ruleName = zone.RuleName;
int curRuleIndex = -1;
if (ruleName != TzDatabase.NotApplicableValue)
{
// Iterate over the rules to find the
// applicable rule
int rulesLength = m_info.Rules.Count;
if (rulesLength == 0 && !string.IsNullOrEmpty(ruleName))
{
throw new BaseException("No rules found for rule name {0}", ruleName);
}
for (int j = 0; j < rulesLength; j++)
{
PublicDomain.TzDatabase.TzRule r = m_info.Rules[j];
if (r.RuleName == ruleName && (avoidIndex == -1 || (avoidIndex != -1 && avoidIndex != j)))
{
curRuleIndex = j;
if ((exactComparison && point >= r.GetFromDateTime(zone.UtcOffset) && point < r.GetToDateTime(zone.UtcOffset)) ||
(!exactComparison && point.Year >= r.FromYear && point.Year <= r.ToYear))
{
if (avoidModifier == null || avoidModifier != r.Modifier || avoidIndex != -1)
{
break;
}
}
}
}
if (curRuleIndex == -1)
{
throw new TzException("Could not find rule");
}
}
return curRuleIndex;
}
/// <summary>
/// Finds the rule.
/// </summary>
/// <param name="zone">The zone.</param>
/// <param name="point">The point.</param>
/// <returns></returns>
public TzDatabase.TzRule FindRule(TzDatabase.TzZone zone, DateTime point)
{
int ruleIndex = FindRuleIndex(zone, point);
return ruleIndex == -1 ? null : m_info.Rules[ruleIndex];
}
