checkpoint

Shogi.Api/Application/ShogiApplication.cs

@@ -129,4 +129,38 @@ public class ShogiApplication(
 
 		return userManager.Users.FirstOrDefault(u => u.Id == userId)?.UserName!;
 	}
+
+	public async Task<IActionResult> ReadSessionSnapshots(string sessionId)
+	{
+		var session = this.ReadSession(sessionId);
+		if (session == null)
+		{
+			return new NotFoundResult();
+		}
+
+		var snapshots = await queryRepository.ReadSessionSnapshots(sessionId);
+
+		var boardStates = snapshots.Select(snap => new Contracts.Types.BoardState
+		{
+			Board = snap.Board.ToDictionary(
+				kvp => kvp.Key,
+				kvp => kvp.Value == null
+					? null
+					: new Contracts.Types.Piece
+					{
+						IsPromoted = kvp.Value.IsPromoted,
+						Owner = (Contracts.Types.WhichPlayer)kvp.Value.Owner,
+						WhichPiece = (Contracts.Types.WhichPiece)kvp.Value.WhichPiece,
+					}),
+			Player1Hand = snap.Player1Hand.Cast<Contracts.Types.WhichPiece>().ToArray(),
+			Player2Hand = snap.Player2Hand.Cast<Contracts.Types.WhichPiece>().ToArray(),
+			PlayerInCheck = snap.PlayerInCheck == null ? null : (Contracts.Types.WhichPlayer)snap.PlayerInCheck,
+			Victor = snap.IsGameOver
+				? snap.PlayerInCheck == Repositories.Dto.SessionState.WhichPlayer.Player1 ? Contracts.Types.WhichPlayer.Player2 : Contracts.Types.WhichPlayer.Player1
+				: null,
+			WhoseTurn = (Contracts.Types.WhichPlayer)snap.WhoseTurn,
+		});
+
+		return new OkObjectResult(boardStates.ToArray());
+	}
 }

Shogi.Api/Controllers/SessionsController.cs

@@ -65,8 +65,8 @@ public class SessionsController(
 			BoardState = new BoardState
 			{
 				Board = session.Board.BoardState.State.ToContract(),
-				Player1Hand = session.Board.BoardState.Player1Hand.ToContract(),
-				Player2Hand = session.Board.BoardState.Player2Hand.ToContract(),
+				Player1Hand = session.Board.BoardState.Player1Hand.Select(p => p.WhichPiece.ToContract()).ToArray(),
+				Player2Hand = session.Board.BoardState.Player2Hand.Select(p => p.WhichPiece.ToContract()).ToArray(),
 				PlayerInCheck = session.Board.BoardState.InCheck?.ToContract(),
 				WhoseTurn = session.Board.BoardState.WhoseTurn.ToContract(),
 				Victor = session.Board.BoardState.IsCheckmate
@@ -118,4 +118,14 @@ public class SessionsController(
 
 		return await application.MovePiece(id, sessionId, command);
 	}
+
+	/// <summary>
+	/// Returns an array of board states, one per player move of the given session, in the same order that player moves occurred.
+	/// </summary>
+	[HttpGet("{sessionId}/History")]
+	[AllowAnonymous]
+	public async Task<IActionResult> GetHistory([FromRoute] string sessionId)
+	{
+		return await application.ReadSessionSnapshots(sessionId);
+	}
 }

Shogi.Api/Extensions/ContractsExtensions.cs

@@ -38,14 +38,6 @@ public static class ContractsExtensions
 		WhichPiece = piece.WhichPiece.ToContract()
 	};
 
-	public static IReadOnlyList<Piece> ToContract(this List<Domain.ValueObjects.Piece> pieces)
-	{
-		return pieces
-			.Select(ToContract)
-			.ToList()
-			.AsReadOnly();
-	}
-
 	public static Dictionary<string, Piece?> ToContract(this ReadOnlyDictionary<string, Domain.ValueObjects.Piece?> boardState) =>
 		boardState.ToDictionary(kvp => kvp.Key, kvp => kvp.Value?.ToContract());
 

Shogi.Api/Repositories/QueryRepository.cs

@@ -1,7 +1,9 @@
 using Dapper;
 using Shogi.Api.Repositories.Dto;
+using Shogi.Api.Repositories.Dto.SessionState;
 using System.Data;
 using System.Data.SqlClient;
+using System.Text.Json;
 
 namespace Shogi.Api.Repositories;
 
@@ -21,4 +23,27 @@ public class QueryRepository(IConfiguration configuration)
 
 		return await results.ReadAsync<SessionDto>();
 	}
+
+	public async Task<List<SessionStateDocument>> ReadSessionSnapshots(string sessionId)
+	{
+		using var connection = new SqlConnection(this.connectionString);
+		var command = connection.CreateCommand();
+		command.CommandText = "session.ReadStatesBySession";
+		command.CommandType = CommandType.StoredProcedure;
+		command.Parameters.AddWithValue("SessionId", sessionId);
+
+		await using var reader = await command.ExecuteReaderAsync();
+		var documents = new List<SessionStateDocument>(20);
+		while (await reader.ReadAsync())
+		{
+			var json = reader.GetString("Document");
+			var document = JsonSerializer.Deserialize<SessionStateDocument>(json);
+			if (document != null)
+			{
+				documents.Add(document);
+			}
+		}
+
+		return documents;
+	}
 }