81 lines
2.2 KiB
C#
81 lines
2.2 KiB
C#
namespace Snake.Core;
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public sealed class Snake
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{
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private readonly LinkedList<Position> _segments = new();
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public Snake(Position start, int length, Direction direction)
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{
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if (length < 1)
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throw new ArgumentOutOfRangeException(nameof(length), "Length must be at least 1.");
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Direction = direction;
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var offset = DirectionToOffset(direction);
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for (var i = 0; i < length; i++)
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{
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_segments.AddLast(new Position(
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start.X - offset.X * i,
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start.Y - offset.Y * i));
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}
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}
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public Direction Direction { get; private set; }
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public Position Head => _segments.First!.Value;
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public IReadOnlyCollection<Position> Segments => _segments;
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public void SetDirection(Direction direction)
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{
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if (direction == Direction)
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return;
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if (AreOpposite(Direction, direction))
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return;
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Direction = direction;
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}
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public Position PeekNextHead()
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{
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var offset = DirectionToOffset(Direction);
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return new Position(Head.X + offset.X, Head.Y + offset.Y);
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}
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public Position Move(bool grow = false)
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{
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var newHead = PeekNextHead();
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_segments.AddFirst(newHead);
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if (!grow)
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_segments.RemoveLast();
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return newHead;
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}
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public bool Occupies(Position position) =>
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_segments.Contains(position);
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private static Position DirectionToOffset(Direction direction) =>
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direction switch
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{
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Direction.Up => new Position(0, -1),
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Direction.Down => new Position(0, 1),
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Direction.Left => new Position(-1, 0),
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Direction.Right => new Position(1, 0),
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_ => throw new ArgumentOutOfRangeException(nameof(direction))
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};
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private static bool AreOpposite(Direction current, Direction next) =>
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(current, next) switch
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{
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(Direction.Up, Direction.Down) => true,
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(Direction.Down, Direction.Up) => true,
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(Direction.Left, Direction.Right) => true,
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(Direction.Right, Direction.Left) => true,
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_ => false
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};
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}
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