Merged in better-communication (pull request #49)

Better communication

Shogi.Domain/Pieces/Piece.cs

@@ -0,0 +1,78 @@
+using Shogi.Domain.Pathing;
+using System.Diagnostics;
+
+namespace Shogi.Domain.Pieces
+{
+	[DebuggerDisplay("{WhichPiece} {Owner}")]
+	public abstract class Piece
+	{
+		/// <summary>
+		/// Creates a clone of an existing piece.
+		/// </summary>
+		public static Piece Create(Piece piece) => Create(piece.WhichPiece, piece.Owner, piece.IsPromoted);
+		public static Piece Create(WhichPiece piece, WhichPlayer owner, bool isPromoted = false)
+		{
+			return piece switch
+			{
+				WhichPiece.King => new King(owner, isPromoted),
+				WhichPiece.GoldGeneral => new GoldGeneral(owner, isPromoted),
+				WhichPiece.SilverGeneral => new SilverGeneral(owner, isPromoted),
+				WhichPiece.Bishop => new Bishop(owner, isPromoted),
+				WhichPiece.Rook => new Rook(owner, isPromoted),
+				WhichPiece.Knight => new Knight(owner, isPromoted),
+				WhichPiece.Lance => new Lance(owner, isPromoted),
+				WhichPiece.Pawn => new Pawn(owner, isPromoted),
+				_ => throw new ArgumentException($"Unknown {nameof(WhichPiece)} when cloning a {nameof(Piece)}.")
+			};
+		}
+
+		// TODO: MoveSet doesn't account for Player2's pieces which are upside-down.
+		public abstract IEnumerable<Path> MoveSet { get; }
+		public WhichPiece WhichPiece { get; }
+		public WhichPlayer Owner { get; private set; }
+		public bool IsPromoted { get; private set; }
+		public bool IsUpsideDown => Owner == WhichPlayer.Player2;
+
+		protected Piece(WhichPiece piece, WhichPlayer owner, bool isPromoted = false)
+		{
+			WhichPiece = piece;
+			Owner = owner;
+			IsPromoted = isPromoted;
+		}
+
+		public bool CanPromote => !IsPromoted
+			&& WhichPiece != WhichPiece.King
+			&& WhichPiece != WhichPiece.GoldGeneral;
+
+		public void Promote() => IsPromoted = CanPromote;
+
+		/// <summary>
+		/// Prep the piece for capture by changing ownership and demoting.
+		/// </summary>
+		public void Capture(WhichPlayer newOwner)
+		{
+			Owner = newOwner;
+			IsPromoted = false;
+		}
+
+		public IEnumerable<Vector2> GetPathFromStartToEnd(Vector2 start, Vector2 end)
+		{
+			var steps = new List<Vector2>(10);
+
+			var path = this.MoveSet.GetNearestPath(start, end);
+			var position = start;
+			while (Vector2.Distance(start, position) < Vector2.Distance(start, end))
+			{
+				position += path.Direction;
+				steps.Add(position);
+			}
+
+			if (position == end)
+			{
+				return steps;
+			}
+
+			return Array.Empty<Vector2>();
+		}
+	}
+}