Add Ollama provider

lib/src/providers/implementations/ollama_provider.dart

@@ -0,0 +1,136 @@
+import 'dart:convert';
+
+import 'package:flutter/foundation.dart';
+import 'package:ollama_dart/ollama_dart.dart';
+
+import '../../llm_exception.dart';
+import '../interface/attachments.dart';
+import '../interface/chat_message.dart';
+import '../interface/llm_provider.dart';
+import '../interface/message_origin.dart';
+
+/// A provider for Ollama's language models.
+///
+/// This provider implements the [LlmProvider] interface to integrate Ollama's
+/// locally hosted models into the chat interface.
+class OllamaProvider extends LlmProvider with ChangeNotifier {
+  /// Creates an Ollama provider instance.
+  ///
+  /// [baseUrl] defaults to 'http://localhost:11434/api' if not provided.
+  /// [model] specifies which Ollama model to use (e.g., 'llama3.2-vision', 'gemma, etc.)
+  OllamaProvider({
+    String? baseUrl,
+    Map<String, String>? headers,
+    Map<String, String>? queryParams,
+    required String model,
+  })  : _client = OllamaClient(
+          baseUrl: baseUrl,
+          headers: headers,
+          queryParams: queryParams,
+        ),
+        _model = model,
+        _history = [];
+
+  final OllamaClient _client;
+  final String _model;
+  final List<ChatMessage> _history;
+
+  @override
+  Stream<String> generateStream(
+    String prompt, {
+    Iterable<Attachment> attachments = const [],
+  }) async* {
+    final messages = _mapToOllamaMessages([
+      ChatMessage.user(prompt, attachments),
+    ]);
+
+    yield* _generateStream(messages);
+  }
+
+  @override
+  Stream<String> sendMessageStream(
+    String prompt, {
+    Iterable<Attachment> attachments = const [],
+  }) async* {
+    final userMessage = ChatMessage.user(prompt, attachments);
+    final llmMessage = ChatMessage.llm();
+    _history.addAll([userMessage, llmMessage]);
+
+    final messages = _mapToOllamaMessages(_history);
+    final stream = _generateStream(messages);
+
+    // don't write this code if you're targeting the web until this is fixed:
+    // https://github.com/dart-lang/sdk/issues/47764
+    // await for (final chunk in stream) {
+    //   llmMessage.append(chunk);
+    //   yield chunk;
+    // }
+    yield* stream.map((chunk) {
+      llmMessage.append(chunk);
+      return chunk;
+    });
+
+    notifyListeners();
+  }
+
+  @override
+  Iterable<ChatMessage> get history => _history;
+
+  @override
+  set history(Iterable<ChatMessage> history) {
+    _history.clear();
+    _history.addAll(history);
+    notifyListeners();
+  }
+
+  Stream<String> _generateStream(List<Message> messages) async* {
+    final stream = _client.generateChatCompletionStream(
+      request: GenerateChatCompletionRequest(
+        model: _model,
+        messages: messages,
+      ),
+    );
+
+    yield* stream.map((res) => res.message.content);
+  }
+
+  List<Message> _mapToOllamaMessages(List<ChatMessage> messages) {
+    return messages.map((message) {
+      switch (message.origin) {
+        case MessageOrigin.user:
+          if (message.attachments.isEmpty) {
+            return Message(
+              role: MessageRole.user,
+              content: message.text ?? '',
+            );
+          }
+
+          return Message(
+            role: MessageRole.user,
+            content: message.text ?? '',
+            images: [
+              for (final attachment in message.attachments)
+                if (attachment is ImageFileAttachment)
+                  base64Encode(attachment.bytes)
+                else
+                  throw LlmFailureException(
+                    'Unsupported attachment type: $attachment',
+                  ),
+            ],
+          );
+
+        case MessageOrigin.llm:
+          return Message(
+            role: MessageRole.assistant,
+            content: message.text ?? '',
+          );
+      }
+    }).toList(growable: false);
+  }
+
+  @override
+  void dispose() {
+    _client.endSession();
+    super.dispose();
+  }
+}

lib/src/providers/providers.dart

@@ -4,6 +4,7 @@
 
 export 'implementations/echo_provider.dart';
 export 'implementations/gemini_provider.dart';
+export 'implementations/ollama_provider.dart';
 export 'implementations/vertex_provider.dart';
 export 'interface/attachments.dart';
 export 'interface/chat_message.dart';

pubspec.yaml

@@ -21,10 +21,11 @@ dependencies:
   google_generative_ai: ^0.4.3
   image_picker: ^1.1.2
   mime: ^2.0.0
+  ollama_dart: ^0.2.2+1
   universal_platform: ^1.1.0
   uuid: ^4.4.2
   waveform_recorder: ^1.3.0
-  
+
 dev_dependencies:
   flutter_lints: ^5.0.0
   flutter_test: