/// <summary>Finds the index of the <see cref="IRingEntry" /> which should be played at the specified <paramref name="time" />.</summary>
/// <param name="ring">The target <see cref="IRing" /></param>
/// <param name="ringItems">The sorted array of the ring items.</param>
/// <param name="time">
/// The time where you want to gather the playing <see cref="IRingEntry" />. If <paramref name="time" /> equals null
/// <see cref="DateTime.Now" /> will be used.
/// </param>
public static RingEntrySpecification <TItem> Find_Item_At_Time <TItem>(this IRing <TItem> ring, TItem[] ringItems, DateTime?time = null) where TItem : IRingEntry
{
if (ring == null)
{
throw RingEngineException_InvalidArgument.NullOrEmpty(nameof(ring));
}
RingEngineException_InvalidRing.ThrowIfInvalid(ring);
if (time == null)
{
time = DateTime.Now;
}
var ringStart = ring.Find_LastRingStart(time);
// The current position in the ring in ticks
var searchedTickInRing = (time.Value - ringStart).Ticks;
for (var i = 0; i < ringItems.Length; i++)
{
var item = ringItems[i];
if (item.RingEntryStartTime.Ticks < searchedTickInRing)
{
continue;
}
int itemIndex;
if (i == 0)
{
itemIndex = ringItems.Length - 1;
}
else
{
itemIndex = i - 1;
}
return(new RingEntrySpecification <TItem>(ringStart, ringItems[itemIndex], itemIndex));
}
return(new RingEntrySpecification <TItem>(ringStart, ringItems[0], 0));
}
/// <summary>Calculates the last time the <see cref="IRing" /> was restarted.</summary>
/// <param name="ring">The target <see cref="IRing" />.</param>
/// <param name="time">The reference time. Could be datetime now.</param>
public static DateTime Find_LastRingStart <TItem>(this IRing <TItem> ring, DateTime?time = null) where TItem : IRingEntry
{
if (ring == null)
{
throw RingEngineException_InvalidArgument.NullOrEmpty(nameof(ring));
}
RingEngineException_InvalidRing.ThrowIfInvalid(ring);
if (time == null)
{
time = DateTime.Now;
}
//Contains the ticks which are past since the last ring start.
var ticksSinceLastStart = (time.Value - ring.RingStartTime).Ticks % ring.RingPeriod.Ticks;
var ringStart = new DateTime(time.Value.Ticks - ticksSinceLastStart);
return(ringStart);
}
/// <summary>Increases the specified <paramref name="index" /> by the <paramref name="value" /> keeping <see cref="IRing" /> metrics.</summary>
internal static int IncreaseIndexBy <TItem>(this IRing <TItem> ring, TItem[] ringItems, int index, int value) where TItem : IRingEntry
{
if (value < 0)
{
throw RingEngineException_InvalidArgument.SmallerThenZero(nameof(value), value);
}
if (index < 0)
{
throw RingEngineException_InvalidArgument.SmallerThenZero(nameof(index), index);
}
if (ring == null)
{
throw RingEngineException_InvalidArgument.NullOrEmpty(nameof(ring));
}
if (index >= ringItems.Length)
{
throw RingEngineException_InvalidArgument.OutOfRange(nameof(index), index, ringItems.Length - 1);
}
RingEngineException_InvalidRing.ThrowIfInvalid(ring);
if (value == 0)
{
return(index);
}
value = value % ringItems.Length; // if the number is greater then the ring itself.
var result = index + value;
if (result < ringItems.Length)
{
return(result);
}
//result is greather then the ring length
result = result - ringItems.Length; // if it is exactly the length take the first element and so on.
return(result);
}
/// <summary>
/// Finds the time when the <see cref="IRingEntry" /> with the specified <paramref name="index" /> will be played next time after
/// the speciefied <paramref name="time" />.
/// </summary>
/// <param name="ring">The ring</param>
/// <param name="ringItems">The sorted array of the ring items.</param>
/// <param name="index">The index of the <see cref="IRingEntry" /> inside the <paramref name="ring" />.</param>
/// <param name="time">The time after which the time is searched.</param>
public static DateTime Find_Time_At_NextPlay <TItem>(this IRing <TItem> ring, TItem[] ringItems, int index, DateTime?time = null) where TItem : IRingEntry
{
if (ring == null)
{
throw RingEngineException_InvalidArgument.NullOrEmpty(nameof(ring));
}
if (index < 0)
{
throw RingEngineException_InvalidArgument.SmallerThenZero(nameof(index), index);
}
if (index >= ringItems.Length)
{
throw RingEngineException_InvalidArgument.OutOfRange(nameof(index), index, ringItems.Length - 1);
}
RingEngineException_InvalidRing.ThrowIfInvalid(ring);
if (time == null)
{
time = DateTime.Now;
}
var ringStart = ring.Find_LastRingStart(time);
var item = ringItems[index];
var result = ringStart.Add(item.RingEntryStartTime);
if (result >= time) // if the resulting value is in the future return
{
return(result);
}
//Otherwise take next ring start and then add start time.
return(ringStart.Add(ring.RingPeriod).Add(item.RingEntryStartTime));
}
