feat: Implement anthropic_sdk_dart, a Dart client for Anthropic API

packages/anthropic_sdk_dart/CHANGELOG.md

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+## 0.0.1-dev.1
+
+- Bootstrap package.

packages/anthropic_sdk_dart/LICENSE

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+MIT License
+
+Copyright (c) 2023 David Miguel Lozano
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

packages/anthropic_sdk_dart/README.md

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+# Anthropic Dart Client
+
+[![tests](https://img.shields.io/github/actions/workflow/status/davidmigloz/langchain_dart/test.yaml?logo=github&label=tests)](https://github.com/davidmigloz/langchain_dart/actions/workflows/test.yaml)
+[![anthropic_sdk_dart](https://img.shields.io/pub/v/anthropic_sdk_dart.svg)](https://pub.dev/packages/anthropic_sdk_dart)
+[![](https://dcbadge.vercel.app/api/server/x4qbhqecVR?style=flat)](https://discord.gg/x4qbhqecVR)
+[![MIT](https://img.shields.io/badge/license-MIT-purple.svg)](https://github.com/davidmigloz/langchain_dart/blob/main/LICENSE)
+
+Unofficial Dart client for [Anthropic](https://docs.anthropic.com/en/api) API (aka Claude API).
+
+## Features
+
+- Fully type-safe, [documented](https://pub.dev/documentation/anthropic_sdk_dart/latest) and tested
+- All platforms supported (including streaming on web)
+- Custom base URL, headers and query params support (e.g. HTTP proxies)
+- Custom HTTP client support (e.g. SOCKS5 proxies or advanced use cases)
+
+**Supported endpoints:**
+
+- Messages (with streaming support)
+
+## Table of contents
+
+- [Usage](#usage)
+  * [Authentication](#authentication)
+  * [Messages](#messages)
+- [Advance Usage](#advance-usage)
+  * [Default HTTP client](#default-http-client)
+  * [Custom HTTP client](#custom-http-client)
+  * [Using a proxy](#using-a-proxy)
+    + [HTTP proxy](#http-proxy)
+    + [SOCKS5 proxy](#socks5-proxy)
+- [Acknowledgements](#acknowledgements)
+- [License](#license)
+
+## Usage
+
+Refer to the [documentation](https://docs.anthropic.com) for more information about the API.
+
+### Authentication
+
+The Anthropic API uses API keys for authentication. Visit the [Anthropic console](https://console.anthropic.com/settings/keys) to retrieve the API key you'll use in your requests.
+
+> **Remember that your API key is a secret!**  
+> Do not share it with others or expose it in any client-side code (browsers, apps). Production requests must be routed through your own backend server where your API key can be securely loaded from an environment variable or key management service.
+
+```dart
+final apiKey = Platform.environment['ANTHROPIC_API_KEY'];
+final client = AnthropicClient(apiKey: apiKey);
+```
+
+### Messages
+
+Send a structured list of input messages with text and/or image content, and the model will generate the next message in the conversation.
+
+**Create a Message:**
+
+```dart
+final res = await client.createMessage(
+  request: CreateMessageRequest(
+    model: Model.model(Models.claude3Opus20240229),
+    maxTokens: 1024,
+    messages: [
+      Message(
+        role: MessageRole.user,
+        content: 'Hello, Claude',
+      ),
+    ],
+  ),
+);
+print(res.content.text);
+// Hi there! How can I help you today?
+```
+
+`Model` is a sealed class that offers two ways to specify the model:
+- `Model.modelId('model-id')`: the model ID as string (e.g. `'claude-3-haiku-20240307'`).
+- `Model.model(Models.claude3Opus20240229)`: a value from `Models` enum which lists all the available models.
+
+Mind that this list may not be up-to-date. Refer to the [documentation](https://docs.anthropic.com/en/docs/models-overview) for the updated list.
+
+**Streaming messages:**
+
+```dart
+final stream = await client.createMessageStream(
+  request: CreateMessageRequest(
+    model: Model.model(Models.claude3Opus20240229),
+    maxTokens: 1024,
+    messages: [
+      Message(
+        role: MessageRole.user,
+        content: 'Hello, Claude',
+      ),
+    ],
+  ),
+);
+String text = '';
+await for (final res in stream) {
+  res.map(
+      messageStart: (e) {},
+      messageDelta: (e) {},
+      messageStop: (e) {},
+      contentBlockStart: (e) {},
+      contentBlockDelta: (e) {
+        text += e.delta.text;
+      },
+      contentBlockStop: (e) {},
+      ping: (e) {},
+  );
+}
+print(text);
+// Hi there! How can I help you today?
+```
+
+## Advance Usage
+
+### Default HTTP client
+
+By default, the client uses `https://api.anthropic.com/v1` as the `baseUrl` and the following implementations of `http.Client`:
+
+- Non-web: [`IOClient`](https://pub.dev/documentation/http/latest/io_client/IOClient-class.html)
+- Web: [`FetchClient`](https://pub.dev/documentation/fetch_client/latest/fetch_client/FetchClient-class.html) (to support streaming on web)
+
+### Custom HTTP client
+
+You can always provide your own implementation of `http.Client` for further customization:
+
+```dart
+final client = AnthropicClient(
+  apiKey: 'MISTRAL_API_KEY',
+  client: MyHttpClient(),
+);
+```
+
+### Using a proxy
+
+#### HTTP proxy
+
+You can use your own HTTP proxy by overriding the `baseUrl` and providing your required `headers`:
+
+```dart 
+final client = AnthropicClient(
+  baseUrl: 'https://my-proxy.com',
+  headers: {
+      'x-my-proxy-header': 'value',
+  },
+);
+```
+
+If you need further customization, you can always provide your own `http.Client`.
+
+#### SOCKS5 proxy
+
+To use a SOCKS5 proxy, you can use the [`socks5_proxy`](https://pub.dev/packages/socks5_proxy) package:
+
+```dart
+final baseHttpClient = HttpClient();
+SocksTCPClient.assignToHttpClient(baseHttpClient, [
+  ProxySettings(InternetAddress.loopbackIPv4, 1080),
+]);
+final httpClient = IOClient(baseClient);
+
+final client = AnthropicClient(
+  client: httpClient,
+);
+```
+
+## Acknowledgements
+
+The generation of this client was made possible by the [openapi_spec](https://github.com/tazatechnology/openapi_spec) package.
+
+## License
+
+Anthropic Dart Client is licensed under the [MIT License](https://github.com/davidmigloz/langchain_dart/blob/main/LICENSE).

packages/anthropic_sdk_dart/analysis_options.yaml

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+include: ../../analysis_options.yaml

packages/anthropic_sdk_dart/build.yaml

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+targets:
+  $default:
+    builders:
+      source_gen|combining_builder:
+        options:
+          ignore_for_file:
+            - prefer_final_parameters
+            - require_trailing_commas
+            - non_constant_identifier_names
+            - unnecessary_null_checks
+      json_serializable:
+        options:
+          explicit_to_json: true

packages/anthropic_sdk_dart/lib/anthropic_sdk_dart.dart

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+/// Dart Client for the Anthropic API (Claude 3 Opus, Sonnet, Haiku, etc.).
+library anthropic_sdk_dart;
+
+export 'src/client.dart';
+export 'src/extensions.dart';
+export 'src/generated/client.dart' show AnthropicClientException;
+export 'src/generated/schema/schema.dart';

packages/anthropic_sdk_dart/lib/src/client.dart

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+// ignore_for_file: use_super_parameters
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:http/http.dart' as http;
+
+import 'generated/client.dart' as g;
+import 'generated/schema/schema.dart';
+import 'http_client/http_client.dart';
+
+/// Client for Anthropic API.
+///
+/// Please see https://docs.anthropic.com/en/api for more details.
+class AnthropicClient extends g.AnthropicClient {
+  /// Create a new Anthropic API client.
+  ///
+  /// Main configuration options:
+  /// - `apiKey`: your Anthropic API key. You can find your API key in the
+  ///   [Anthropic console](https://console.anthropic.com/settings/keys).
+  ///
+  /// Advance configuration options:
+  /// - `baseUrl`: the base URL to use. Defaults to `https://api.anthropic.com/v1`.
+  ///   You can override this to use a different API URL, or to use a proxy.
+  /// - `headers`: global headers to send with every request. You can use
+  ///   this to set custom headers, or to override the default headers.
+  /// - `queryParams`: global query parameters to send with every request. You
+  ///   can use this to set custom query parameters.
+  /// - `client`: the HTTP client to use. You can set your own HTTP client if
+  ///   you need further customization (e.g. to use a Socks5 proxy).
+  AnthropicClient({
+    final String? apiKey,
+    final String? baseUrl,
+    final Map<String, String>? headers,
+    final Map<String, dynamic>? queryParams,
+    final http.Client? client,
+  }) : super(
+          apiKey: apiKey ?? '',
+          baseUrl: baseUrl,
+          headers: {
+            'anthropic-version': '2023-06-01',
+            ...?headers,
+          },
+          queryParams: queryParams ?? const {},
+          client: client ?? createDefaultHttpClient(),
+        );
+
+  // ------------------------------------------
+  // METHOD: createMessageStream
+  // ------------------------------------------
+
+  /// Create a Message
+  ///
+  /// Send a structured list of input messages with text and/or image content, and the
+  /// model will generate the next message in the conversation.
+  ///
+  /// The Messages API can be used for either single queries or stateless multi-turn
+  /// conversations.
+  ///
+  /// `request`: The request parameters for creating a message.
+  ///
+  /// `POST` `https://api.anthropic.com/v1/messages`
+  Stream<MessageStreamEvent> createMessageStream({
+    required final CreateMessageRequest request,
+  }) async* {
+    final r = await makeRequestStream(
+      baseUrl: 'https://api.anthropic.com/v1',
+      path: '/messages',
+      method: g.HttpMethod.post,
+      requestType: 'application/json',
+      responseType: 'application/json',
+      body: request.copyWith(stream: true),
+      headerParams: {
+        if (apiKey.isNotEmpty) 'x-api-key': apiKey,
+      },
+    );
+    yield* r.stream
+        .transform(const _AnthropicStreamTransformer()) //
+        .map(
+          (final d) => MessageStreamEvent.fromJson(json.decode(d)),
+        );
+  }
+
+  @override
+  Future<http.BaseRequest> onRequest(final http.BaseRequest request) {
+    return onRequestHandler(request);
+  }
+}
+
+class _AnthropicStreamTransformer
+    extends StreamTransformerBase<List<int>, String> {
+  const _AnthropicStreamTransformer();
+
+  @override
+  Stream<String> bind(final Stream<List<int>> stream) {
+    return stream //
+        .transform(utf8.decoder) //
+        .transform(const LineSplitter()) //
+        .where((final i) => i.startsWith('data: '))
+        .map((final item) => item.substring(6));
+  }
+}

packages/anthropic_sdk_dart/lib/src/extensions.dart

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+import 'generated/schema/schema.dart';
+
+/// Extension methods for [MessageContent].
+extension MessageContentX on MessageContent {
+  /// Returns the text content of the message.
+  String get text {
+    return map(
+      text: (text) => text.value,
+      blocks: (blocks) =>
+          blocks.value.whereType<TextBlock>().map((t) => t.text).join('\n'),
+    );
+  }
+}