48 lines
1.5 KiB
C#
48 lines
1.5 KiB
C#
using ErsatzTV.Core.Domain;
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using ErsatzTV.Core.Extensions;
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using ErsatzTV.Core.Interfaces.Scheduling;
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namespace ErsatzTV.Core.Scheduling;
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public class RandomizedMediaCollectionEnumerator : IMediaCollectionEnumerator
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{
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private readonly Lazy<Option<TimeSpan>> _lazyMinimumDuration;
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private readonly IList<MediaItem> _mediaItems;
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private readonly Random _random;
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private int _index;
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public RandomizedMediaCollectionEnumerator(IList<MediaItem> mediaItems, CollectionEnumeratorState state)
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{
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_mediaItems = mediaItems;
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_lazyMinimumDuration =
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new Lazy<Option<TimeSpan>>(() => _mediaItems.Bind(i => i.GetNonZeroDuration()).OrderBy(identity).HeadOrNone());
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_random = new Random(state.Seed);
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State = new CollectionEnumeratorState { Seed = state.Seed };
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// we want to move at least once so we start with a random item and not the first
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// because _index defaults to 0
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while (State.Index <= state.Index)
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{
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MoveNext();
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}
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}
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public void ResetState(CollectionEnumeratorState state) =>
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// seed never changes here, no need to reset
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State.Index = state.Index;
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public CollectionEnumeratorState State { get; }
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public Option<MediaItem> Current => _mediaItems.Any() ? _mediaItems[_index] : None;
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public void MoveNext()
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{
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_index = _random.Next() % _mediaItems.Count;
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State.Index++;
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}
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public Option<TimeSpan> MinimumDuration => _lazyMinimumDuration.Value;
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public int Count => _mediaItems.Count;
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}
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