feat: implement ListAllModelsAsync and ListModelsAsync

src/AnthropicClient/AnthropicApiClient.cs

@@ -1,6 +1,7 @@
 using System.Net.Http.Headers;
 using System.Text;
 using System.Text.Json;
+using System.Threading.Tasks;
 
 using AnthropicClient.Json;
 using AnthropicClient.Models;
@@ -39,15 +40,15 @@ public interface IAnthropicApiClient
   /// </summary>
   /// <param name="request">The paging request to use for listing the models.</param>
   /// <returns>A task that represents the asynchronous operation. The task result contains the response as an <see cref="AnthropicResult{T}"/> where T is <see cref="Page{T}"/> where T is <see cref="AnthropicModel"/>.</returns>
-  Task<AnthropicResult<Page<AnthropicModel>>> ListModelsAsync(PagingRequest request);
+  Task<AnthropicResult<Page<AnthropicModel>>> ListModelsAsync(PagingRequest? request = null);
 
   /// <summary>
-  /// Lists the models asynchronously.
+  /// Lists the models asynchronously
   /// </summary>
   /// <param name="limit">The maximum number of models to return in each page.</param>
   /// <returns>An asynchronous enumerable that yields the response as an <see cref="AnthropicResult{T}"/> where T is <see cref="Page{T}"/> where T is <see cref="AnthropicModel"/>.</returns>
   /// 
-  IAsyncEnumerable<AnthropicResult<Page<AnthropicModel>>> ListModelsAsync(int limit = 20);
+  IAsyncEnumerable<AnthropicResult<Page<AnthropicModel>>> ListAllModelsAsync(int limit = 20);
 }
 
 /// <inheritdoc cref="IAnthropicApiClient"/>
@@ -57,6 +58,7 @@ public class AnthropicApiClient : IAnthropicApiClient
   private const string ApiKeyHeader = "x-api-key";
   private const string MessagesEndpoint = "messages";
   private const string CountTokensEndpoint = "messages/count_tokens";
+  private const string ModelsEndpoint = "models";
   private const string JsonContentType = "application/json";
   private const string EventPrefix = "event:";
   private const string DataPrefix = "data:";
@@ -292,10 +294,64 @@ public class AnthropicApiClient : IAnthropicApiClient
     }
 
     var msgResponse = Deserialize<TokenCountResponse>(responseContent) ?? new TokenCountResponse();
-
     return AnthropicResult<TokenCountResponse>.Success(msgResponse, anthropicHeaders);
   }
 
+  /// <inheritdoc/>
+  public async Task<AnthropicResult<Page<AnthropicModel>>> ListModelsAsync(PagingRequest? request = null)
+  {
+    var pagingRequest = request ?? new PagingRequest();
+    var endpoint = $"{ModelsEndpoint}?{pagingRequest.ToQueryParameters()}";
+    var response = await SendRequestAsync(endpoint);
+    var anthropicHeaders = new AnthropicHeaders(response.Headers);
+    var responseContent = await response.Content.ReadAsStringAsync();
+
+    if (response.IsSuccessStatusCode is false)
+    {
+      var error = Deserialize<AnthropicError>(responseContent) ?? new AnthropicError();
+      return AnthropicResult<Page<AnthropicModel>>.Failure(error, anthropicHeaders);
+    }
+
+    var page = Deserialize<Page<AnthropicModel>>(responseContent) ?? new Page<AnthropicModel>();
+    return AnthropicResult<Page<AnthropicModel>>.Success(page, anthropicHeaders);
+  }
+
+  /// <inheritdoc/>
+  public async IAsyncEnumerable<AnthropicResult<Page<AnthropicModel>>> ListAllModelsAsync(int limit = 20)
+  {
+    var pagingRequest = new PagingRequest(limit: limit);
+    string Endpoint() => $"{ModelsEndpoint}?{pagingRequest.ToQueryParameters()}";
+    bool hasMore;
+
+    do
+    {
+      var response = await SendRequestAsync(Endpoint());
+      var anthropicHeaders = new AnthropicHeaders(response.Headers);
+      var responseContent = await response.Content.ReadAsStringAsync();
+
+      if (response.IsSuccessStatusCode is false)
+      {
+        var error = Deserialize<AnthropicError>(responseContent) ?? new AnthropicError();
+        yield return AnthropicResult<Page<AnthropicModel>>.Failure(error, anthropicHeaders);
+        yield break;
+      }
+
+      var page = Deserialize<Page<AnthropicModel>>(responseContent) ?? new Page<AnthropicModel>();
+
+      if (page.HasMore && page.LastId is not null)
+      {
+        hasMore = true;
+        pagingRequest = new PagingRequest(limit: limit, afterId: page.LastId);
+      }
+      else
+      {
+        hasMore = false;
+      }
+
+      yield return AnthropicResult<Page<AnthropicModel>>.Success(page, anthropicHeaders);
+    } while (hasMore);
+  }
+
   private ToolCall? GetToolCall(MessageResponse response, List<Tool> tools)
   {
     var toolUse = response.Content.OfType<ToolUseContent>().FirstOrDefault();
@@ -315,6 +371,11 @@ public class AnthropicApiClient : IAnthropicApiClient
     return new ToolCall(tool, toolUse);
   }
 
+  private async Task<HttpResponseMessage> SendRequestAsync(string endpoint)
+  {
+    return await _httpClient.GetAsync(endpoint);
+  }
+
   private async Task<HttpResponseMessage> SendRequestAsync<T>(string endpoint, T request)
   {
     var requestJson = Serialize(request);
@@ -324,16 +385,4 @@ public class AnthropicApiClient : IAnthropicApiClient
 
   private string Serialize<T>(T obj) => JsonSerializer.Serialize(obj, JsonSerializationOptions.DefaultOptions);
   private T? Deserialize<T>(string json) => JsonSerializer.Deserialize<T>(json, JsonSerializationOptions.DefaultOptions);
-
-  /// <inheritdoc/>
-  public Task<AnthropicResult<Page<AnthropicModel>>> ListModelsAsync(PagingRequest request)
-  {
-    throw new NotImplementedException();
-  }
-
-  /// <inheritdoc/>
-  public IAsyncEnumerable<AnthropicResult<Page<AnthropicModel>>> ListModelsAsync(int limit = 20)
-  {
-    throw new NotImplementedException();
-  }
 }

src/AnthropicClient/Models/Page.cs

@@ -11,13 +11,13 @@ public class Page
   /// The id of the first item in the page.
   /// </summary>
   [JsonPropertyName("first_id")]
-  public string FirstId { get; init; } = string.Empty;
+  public string? FirstId { get; init; } = string.Empty;
 
   /// <summary>
   /// The id of the last item in the page.
   /// </summary>
   [JsonPropertyName("last_id")]
-  public string LastId { get; init; } = string.Empty;
+  public string? LastId { get; init; } = string.Empty;
 
   /// <summary>
   /// Indicates whether there is more data to be retrieved.

src/AnthropicClient/Models/PagingRequest.cs

@@ -70,10 +70,7 @@ public class PagingRequest
       parameters.Add($"after_id={AfterId}");
     }
 
-    if (Limit is not DefaultLimit)
-    {
     parameters.Add($"limit={Limit}");
-    }
 
     return string.Join("&", parameters);
   }

tests/AnthropicClient.Tests/EndToEnd/AnthropicApiClientTests.cs

@@ -303,4 +303,32 @@ public class ClientTests(ConfigurationFixture configFixture) : EndToEndTest(conf
     result.Value.Should().BeOfType<TokenCountResponse>();
     result.Value.InputTokens.Should().BeGreaterThan(0);
   }
+
+  [Fact]
+  public async Task ListModelsAsync_WhenCalled_ItShouldReturnResponse()
+  {
+    var result = await _client.ListModelsAsync();
+
+    result.IsSuccess.Should().BeTrue();
+    result.Value.Should().BeOfType<Page<AnthropicModel>>();
+    result.Value.Data.Should().HaveCountGreaterThan(0);
+  }
+
+  [Fact]
+  public async Task ListModelsAsync_WhenCalledWithPagination_ItShouldReturnResponse()
+  {
+    var result = await _client.ListModelsAsync(new PagingRequest(limit: 1));
+
+    result.IsSuccess.Should().BeTrue();
+    result.Value.Should().BeOfType<Page<AnthropicModel>>();
+    result.Value.Data.Should().HaveCount(1);
+  }
+
+  [Fact]
+  public async Task ListAllModelsAsync_WhenCalled_ItShouldReturnResponse()
+  {
+    var responses = await _client.ListAllModelsAsync(limit: 1).ToListAsync();
+
+    responses.Should().HaveCountGreaterThan(0);
+  }
 }

tests/AnthropicClient.Tests/Integration/AnthropicApiClientTests.cs

@@ -503,4 +503,387 @@ public class AnthropicApiClientTests : IntegrationTest
     result.Error.Should().BeOfType<AnthropicError>();
     result.Error.Error.Should().BeOfType<ApiError>();
   }
+
+  [Fact]
+  public async Task ListModelsAsync_WhenCalledWithPagingRequestUsingDefaultValues_ItShouldReturnListOfModels()
+  {
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .Respond(
+        HttpStatusCode.OK,
+        "application/json",
+        @"{
+            ""data"": [
+              {
+                ""type"": ""model"",
+                ""id"": ""claude-3-5-sonnet-20241022"",
+                ""display_name"": ""Claude 3.5 Sonnet (New)"",
+                ""created_at"": ""2024-10-22T00:00:00Z""
+              }
+            ],
+            ""has_more"": true,
+            ""first_id"": ""first_id"",
+            ""last_id"": ""last_id""
+          }"
+      );
+
+    var result = await Client.ListModelsAsync();
+
+    result.IsSuccess.Should().BeTrue();
+    result.Value.Should().BeOfType<Page<AnthropicModel>>();
+    result.Value.HasMore.Should().BeTrue();
+    result.Value.FirstId.Should().Be("first_id");
+    result.Value.LastId.Should().Be("last_id");
+    result.Value.Data.Should().BeEquivalentTo(new AnthropicModel[]
+    {
+      new()
+      {
+        Type = "model",
+        Id = "claude-3-5-sonnet-20241022",
+        DisplayName = "Claude 3.5 Sonnet (New)",
+        CreatedAt = DateTimeOffset.Parse("2024-10-22T00:00:00Z")
+      }
+    });
+  }
+
+  [Fact]
+  public async Task ListModelsAsync_WhenCalledWithPagingRequestUsingCustomValues_ItShouldReturnListOfModels()
+  {
+    var pagingRequest = new PagingRequest("prev_id", "next_id", 10);
+
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .WithQueryString(new Dictionary<string, string>
+      {
+        { "before_id", pagingRequest.BeforeId },
+        { "after_id", pagingRequest.AfterId },
+        { "limit", pagingRequest.Limit.ToString() },
+      })
+      .Respond(
+        HttpStatusCode.OK,
+        "application/json",
+        @"{
+            ""data"": [
+              {
+                ""type"": ""model"",
+                ""id"": ""claude-3-5-sonnet-20241022"",
+                ""display_name"": ""Claude 3.5 Sonnet (New)"",
+                ""created_at"": ""2024-10-22T00:00:00Z""
+              }
+            ],
+            ""has_more"": true,
+            ""first_id"": ""first_id"",
+            ""last_id"": ""last_id""
+          }"
+      );
+
+    var result = await Client.ListModelsAsync(pagingRequest);
+
+    result.IsSuccess.Should().BeTrue();
+    result.Value.Should().BeOfType<Page<AnthropicModel>>();
+    result.Value.HasMore.Should().BeTrue();
+    result.Value.FirstId.Should().Be("first_id");
+    result.Value.LastId.Should().Be("last_id");
+    result.Value.Data.Should().BeEquivalentTo(new AnthropicModel[]
+    {
+      new()
+      {
+        Type = "model",
+        Id = "claude-3-5-sonnet-20241022",
+        DisplayName = "Claude 3.5 Sonnet (New)",
+        CreatedAt = DateTimeOffset.Parse("2024-10-22T00:00:00Z")
+      }
+    });
+  }
+
+  [Fact]
+  public async Task ListModelsAsync_WhenCalledAndNoModelsReturned_ItShouldReturnEmptyList()
+  {
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .Respond(
+        HttpStatusCode.OK,
+        "application/json",
+        @"{
+            ""data"": [],
+            ""has_more"": false,
+            ""first_id"": null,
+            ""last_id"": null
+          }"
+      );
+
+    var result = await Client.ListModelsAsync();
+
+    result.IsSuccess.Should().BeTrue();
+    result.Value.Should().BeOfType<Page<AnthropicModel>>();
+    result.Value.HasMore.Should().BeFalse();
+    result.Value.FirstId.Should().BeNull();
+    result.Value.LastId.Should().BeNull();
+    result.Value.Data.Should().BeEmpty();
+  }
+
+  [Fact]
+  public async Task ListModelsAsync_WhenCalledAndErrorReturned_ItShouldHandleError()
+  {
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .Respond(
+        HttpStatusCode.BadRequest,
+        "application/json",
+        @"{
+            ""type"": ""error"",
+            ""error"": {
+              ""type"": ""invalid_request_error"",
+              ""message"": ""messages: roles must alternate between user and assistant, but found multiple user roles in a row""
+            }
+          }"
+      );
+
+    var result = await Client.ListModelsAsync();
+
+    result.IsSuccess.Should().BeFalse();
+    result.Error.Should().BeOfType<AnthropicError>();
+    result.Error.Error.Should().BeOfType<InvalidRequestError>();
+  }
+
+  [Fact]
+  public async Task ListModelsAsync_WhenCalledRequestFailsAndCanNotSerializeError_ItShouldReturnUnknownError()
+  {
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .Respond(
+        HttpStatusCode.BadRequest,
+        "application/json",
+        @"{}"
+      );
+
+    var result = await Client.ListModelsAsync();
+
+    result.IsSuccess.Should().BeFalse();
+    result.Error.Should().BeOfType<AnthropicError>();
+    result.Error.Error.Should().BeOfType<ApiError>();
+  }
+
+  [Fact]
+  public async Task ListAllModelsAsync_WhenCalled_ItShouldReturnAllModels()
+  {
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .WithExactQueryString(new Dictionary<string, string>()
+      {
+        { "limit", "20" },
+      })
+      .Respond(
+        HttpStatusCode.OK,
+        "application/json",
+        @"{
+            ""data"": [
+              {
+                ""type"": ""model"",
+                ""id"": ""claude-3-5-sonnet-20241022"",
+                ""display_name"": ""Claude 3.5 Sonnet (New)"",
+                ""created_at"": ""2024-10-22T00:00:00Z""
+              }
+            ],
+            ""has_more"": true,
+            ""first_id"": ""1"",
+            ""last_id"": ""1""
+          }"
+      );
+
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .WithExactQueryString(new Dictionary<string, string>()
+      {
+        { "after_id", "1" },
+        { "limit", "20" },
+      })
+      .Respond(
+        HttpStatusCode.OK,
+        "application/json",
+        @"{
+            ""data"": [
+              {
+                ""type"": ""model"",
+                ""id"": ""claude-3-5-sonnet-20241023"",
+                ""display_name"": ""Claude 3.5 Sonnet (New)"",
+                ""created_at"": ""2024-10-23T00:00:00Z""
+              }
+            ],
+            ""has_more"": false,
+            ""first_id"": ""2"",
+            ""last_id"": ""2""
+          }"
+      );
+
+    var pageResponses = Client.ListAllModelsAsync();
+    var collectedPages = new List<Page<AnthropicModel>>();
+
+    await foreach (var response in pageResponses)
+    {
+      response.IsSuccess.Should().BeTrue();
+      response.Value.Should().BeOfType<Page<AnthropicModel>>();
+      collectedPages.Add(response.Value);
+    }
+
+    collectedPages.Should().HaveCount(2);
+    collectedPages.Should().BeEquivalentTo(new Page<AnthropicModel>[]
+    {
+      new()
+      {
+        HasMore = true,
+        FirstId = "1",
+        LastId = "1",
+        Data = [
+          new()
+          {
+            Type = "model",
+            Id = "claude-3-5-sonnet-20241022",
+            DisplayName = "Claude 3.5 Sonnet (New)",
+            CreatedAt = DateTimeOffset.Parse("2024-10-22T00:00:00Z")
+          }
+        ]
+      },
+      new()
+      {
+        HasMore = false,
+        FirstId = "2",
+        LastId = "2",
+        Data = [
+          new()
+          {
+            Type = "model",
+            Id = "claude-3-5-sonnet-20241023",
+            DisplayName = "Claude 3.5 Sonnet (New)",
+            CreatedAt = DateTimeOffset.Parse("2024-10-23T00:00:00Z")
+          }
+        ]
+      }
+    });
+  }
+
+  [Fact]
+  public async Task ListAllModelsAsync_WhenCalledAndErrorReturned_ItShouldHandleError()
+  {
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .Respond(
+        HttpStatusCode.BadRequest,
+        "application/json",
+        @"{
+            ""type"": ""error"",
+            ""error"": {
+              ""type"": ""invalid_request_error"",
+              ""message"": ""messages: roles must alternate between user and assistant, but found multiple user roles in a row""
+            }
+          }"
+      );
+
+    var responses = Client.ListAllModelsAsync();
+    var count = 0;
+
+    await foreach (var page in responses)
+    {
+      count++;
+      page.IsSuccess.Should().BeFalse();
+      page.Error.Should().BeOfType<AnthropicError>();
+      page.Error.Error.Should().BeOfType<InvalidRequestError>();
+    }
+
+    count.Should().Be(1);
+  }
+
+  [Fact]
+  public async Task ListAllModelsAsync_WhenCalledRequestFailsAndCanNotSerializeError_ItShouldReturnUnknownError()
+  {
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .Respond(
+        HttpStatusCode.BadRequest,
+        "application/json",
+        @"{}"
+      );
+
+    var responses = Client.ListAllModelsAsync();
+    var count = 0;
+
+    await foreach (var page in responses)
+    {
+      count++;
+      page.IsSuccess.Should().BeFalse();
+      page.Error.Should().BeOfType<AnthropicError>();
+      page.Error.Error.Should().BeOfType<ApiError>();
+    }
+
+    count.Should().Be(1);
+  }
+
+  [Fact]
+  public async Task ListAllModelsAsync_WhenFirstPageSucceedsAndSecondPageFails_ItShouldReturnFirstPageAndError()
+  {
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .WithExactQueryString(new Dictionary<string, string>
+      {
+        { "limit", "20" },
+      })
+      .Respond(
+        HttpStatusCode.OK,
+        "application/json",
+        @"{
+            ""data"": [
+              {
+                ""type"": ""model"",
+                ""id"": ""claude-3-5-sonnet-20241022"",
+                ""display_name"": ""Claude 3.5 Sonnet (New)"",
+                ""created_at"": ""2024-10-22T00:00:00Z""
+              }
+            ],
+            ""has_more"": true,
+            ""first_id"": ""1"",
+            ""last_id"": ""1""
+          }"
+      );
+
+    _mockHttpMessageHandler
+      .WhenListModelsRequest()
+      .WithExactQueryString(new Dictionary<string, string>
+      {
+        { "after_id", "1" },
+        { "limit", "20" },
+      })
+      .Respond(
+        HttpStatusCode.BadRequest,
+        "application/json",
+        @"{
+            ""type"": ""error"",
+            ""error"": {
+              ""type"": ""invalid_request_error"",
+              ""message"": ""messages: roles must alternate between user and assistant, but found multiple user roles in a row""
+            }
+          }"
+      );
+
+    var responses = Client.ListAllModelsAsync();
+    var count = 0;
+
+    await foreach (var page in responses)
+    {
+      count++;
+
+      if (count == 1)
+      {
+        page.IsSuccess.Should().BeTrue();
+        page.Value.Should().BeOfType<Page<AnthropicModel>>();
+      }
+      else
+      {
+        page.IsSuccess.Should().BeFalse();
+        page.Error.Should().BeOfType<AnthropicError>();
+        page.Error.Error.Should().BeOfType<InvalidRequestError>();
+      }
+    }
+
+    count.Should().Be(2);
+  }
 }

tests/AnthropicClient.Tests/Integration/IntegrationTest.cs

@@ -16,6 +16,7 @@ public static class MockHttpMessageHandlerExtensions
   private const string BaseUrl = "https://api.anthropic.com/v1";
   private static readonly string MessagesEndpoint = $"{BaseUrl}/messages";
   private static readonly string CountTokensEndpoint = $"{BaseUrl}/messages/count_tokens";
+  private static readonly string ModelsEndpoint = $"{BaseUrl}/models";
 
   private static MockedRequest SetupBaseRequest(
     this MockHttpMessageHandler mockHttpMessageHandler,
@@ -51,4 +52,10 @@ public static class MockHttpMessageHandlerExtensions
     return mockHttpMessageHandler
       .SetupBaseRequest(HttpMethod.Post, CountTokensEndpoint);
   }
+
+  public static MockedRequest WhenListModelsRequest(this MockHttpMessageHandler mockHttpMessageHandler)
+  {
+    return mockHttpMessageHandler
+      .SetupBaseRequest(HttpMethod.Get, ModelsEndpoint);
+  }
 }

tests/AnthropicClient.Tests/Unit/Models/PagingRequestTests.cs

@@ -25,7 +25,7 @@ public class PagingRequestTests : SerializationTest
 
     var result = pagingRequest.ToQueryParameters();
 
-    result.Should().BeEmpty();
+    result.Should().Be("limit=20");
   }
 
   [Fact]
@@ -35,7 +35,7 @@ public class PagingRequestTests : SerializationTest
 
     var result = pagingRequest.ToQueryParameters();
 
-    result.Should().Be("before_id=before-id");
+    result.Should().Be("before_id=before-id&limit=20");
   }
 
   [Fact]
@@ -45,7 +45,7 @@ public class PagingRequestTests : SerializationTest
 
     var result = pagingRequest.ToQueryParameters();
 
-    result.Should().Be("after_id=after-id");
+    result.Should().Be("after_id=after-id&limit=20");
   }
 
   [Fact]