Add challenge APIs.

src/Aiursoft.ChessServer/Controllers/ChallengeController.cs

@@ -0,0 +1,41 @@
+using Microsoft.AspNetCore.Mvc;
+
+namespace Aiursoft.ChessServer.Controllers;
+
+[Route("challenges")]
+public class ChallengeController : ControllerBase
+{
+    [HttpPost]
+    [Route("create")]
+    public IActionResult Create(Guid userId)
+    {
+        // Create a new challenge. Add to database.
+        return Ok();
+    }
+
+    [HttpGet]
+    [Route("list")]
+    public IActionResult List()
+    {
+        // Show all public challenges.
+        return Ok();
+    }
+    
+    [HttpPost]
+    [Route("accept/{id:int}")]
+    public IActionResult Accept(int id, Guid userId)
+    {
+        // Accept a challenge. Remove the challenge from database.
+        // Create a new game. Redirect both players to the game.
+        return Ok();
+    }
+    
+    [HttpPost]
+    [Route("reject/{id:int}")]
+    public IActionResult Edit(int id, Guid userId)
+    {
+        // If challenge owner is the same as user id,
+        // Edit a challenge in database.
+        return Ok();
+    }
+}

src/Aiursoft.ChessServer/Models/Game.cs

@@ -10,4 +10,30 @@ public class Game
     public AsyncObservable<string> FenChangedChannel { get; } = new();
     
     public object MovePieceLock { get; } = new();
+}
+
+public enum RoleRule
+{
+    CreatorWhite,
+    AccepterWhite,
+    Random
+}
+
+public enum ChallengePermission
+{
+    Public,
+    Unlisted,
+}
+
+public class Challenge
+{
+    public Guid CreatorId { get; set; }
+
+    public Guid? AccepterId { get; set; } = null;
+    
+    public RoleRule RoleRule { get; set; } = RoleRule.Random;
+    
+    public TimeSpan TimeLimit { get; set; } = TimeSpan.FromMinutes(10);
+    
+    public ChallengePermission Permission { get; set; } = ChallengePermission.Public;
 }