feat: create chat message

src/AnthropicClient/Models/ChatMessage.cs

@@ -0,0 +1,48 @@
+using System.Text.Json.Serialization;
+
+using AnthropicClient.Utils;
+
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a chat message.
+/// </summary>
+public class ChatMessage
+{
+  /// <summary>
+  /// Gets the role of the message.
+  /// </summary>
+  public string Role { get; init; } = string.Empty;
+
+  /// <summary>
+  /// Gets the contents of the message.
+  /// </summary>
+  public List<Content> Content { get; init; } = [];
+
+  [JsonConstructor]
+  internal ChatMessage()
+  {
+  }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="ChatMessage"/> class.
+  /// </summary>
+  /// <param name="role">The role of the message.</param>
+  /// <param name="content">The contents of the message.</param>
+  /// <exception cref="ArgumentException">Thrown when the role is invalid.</exception>
+  /// <exception cref="ArgumentNullException">Thrown when the role or content is null.</exception>
+  /// <returns>A new instance of the <see cref="ChatMessage"/> class.</returns>
+  public ChatMessage(string role, List<Content> content)
+  {
+    ArgumentValidator.ThrowIfNull(role, nameof(role));
+    ArgumentValidator.ThrowIfNull(content, nameof(content));
+
+    if (MessageRole.IsValidRole(role) is false)
+    {
+      throw new ArgumentException($"Invalid role: {role}");
+    }
+
+    Role = role;
+    Content = content;
+  }
+}