AI 接入 V0.1

2026-09-23 17:23:59 +08:00
parent a83cda63f5
commit 34bc2e04b0
9 changed files with 1018 additions and 116 deletions
@@ -0,0 +1,147 @@
+import 'dart:convert';
+
+import 'package:dio/dio.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../core/network/api_exception.dart';
+import '../core/network/dio_client.dart';
+import '../models/ai.dart';
+import '../models/json_util.dart';
+
+final aiApiProvider = Provider<AiApi>((ref) => AiApi(ref.watch(dioProvider)));
+
+/// AI 助手接口
+class AiApi {
+  final Dio _dio;
+
+  AiApi(this._dio);
+
+  /// 后端是否配好了 key（没配的话 App 显示提示而不是让用户白问一句）
+  Future<bool> status() async {
+    try {
+      final res = await _dio.get('/ai/status');
+      final data = res.data;
+      return data is Map && data['enabled'] == true;
+    } on DioException {
+      return false;
+    }
+  }
+
+  Future<List<ChatSessionItem>> sessions() async {
+    try {
+      final res = await _dio.get('/ai/sessions');
+      final data = res.data;
+      if (data is! List) return const [];
+      return asMapList(data).map(ChatSessionItem.fromJson).toList();
+    } on DioException catch (e) {
+      final err = e.error;
+      throw err is ApiException ? err : ApiException(-1, '会话列表加载失败');
+    }
+  }
+
+  Future<List<ChatMessageItem>> messages(int sessionId) async {
+    try {
+      final res = await _dio.get('/ai/sessions/$sessionId/messages');
+      final data = res.data;
+      if (data is! List) return const [];
+      return asMapList(data).map(ChatMessageItem.fromJson).toList();
+    } on DioException catch (e) {
+      final err = e.error;
+      throw err is ApiException ? err : ApiException(-1, '消息加载失败');
+    }
+  }
+
+  Future<void> deleteSession(int sessionId) async {
+    try {
+      await _dio.delete('/ai/sessions/$sessionId');
+    } on DioException catch (e) {
+      final err = e.error;
+      throw err is ApiException ? err : ApiException(-1, '删除会话失败');
+    }
+  }
+
+  /// 发起对话，返回事件流。
+  ///
+  /// 用 dio 的 [ResponseType.stream] 拿原始字节流、自己按 SSE 协议切分 ——
+  /// dio 没有内置 SSE 支持，但 OpenAI 兼容接口的流格式很简单
+  /// （`event: xxx` / `data: {...}` / 空行分隔），手动解析比多引一个依赖可控。
+  ///
+  /// 注意：[sessionId] 传 null 表示开新会话，会话 ID 会由后端在 done 事件里返回。
+  Stream<AiEvent> chat({int? sessionId, required String content}) async* {
+    final Response<ResponseBody> res;
+    try {
+      res = await _dio.post<ResponseBody>(
+        '/ai/chat',
+        data: {'sessionId': sessionId, 'content': content},
+        options: Options(
+          responseType: ResponseType.stream,
+          // LLM 生成慢 + 工具循环可能跑好几轮，给足；后端 SseEmitter 是 180s
+          receiveTimeout: const Duration(minutes: 3),
+          headers: {'Accept': 'text/event-stream'},
+        ),
+      );
+    } on DioException catch (e) {
+      final err = e.error;
+      yield AiEvent.error(err is ApiException ? err.message : 'AI 请求失败');
+      return;
+    }
+
+    final body = res.data;
+    if (body == null) {
+      yield const AiEvent.error('AI 没有返回内容');
+      return;
+    }
+
+    try {
+      // utf8.decoder 作为流转换器能正确处理「多字节字符被 chunk 切断」的情况，
+      // 直接对每块调 utf8.decode 会在这里出乱码。
+      // cast 是必须的：dio 给的是 Stream<Uint8List>，而 utf8.decoder 是
+      // StreamTransformer<List<int>, String>，Dart 的泛型不支持这个方向的隐式转换。
+      final lines = body.stream
+          .cast<List<int>>()
+          .transform(utf8.decoder)
+          .transform(const LineSplitter());
+
+      var event = '';
+      final data = StringBuffer();
+
+      await for (final line in lines) {
+        if (line.isEmpty) {
+          // 空行 = 一个事件结束
+          final payload = data.toString();
+          data.clear();
+          if (payload.isNotEmpty) {
+            final parsed = _parseEvent(event, payload);
+            if (parsed != null) yield parsed;
+          }
+          event = '';
+          continue;
+        }
+        if (line.startsWith('event:')) {
+          event = line.substring(6).trim();
+        } else if (line.startsWith('data:')) {
+          data.write(line.substring(5).trim());
+        }
+      }
+    } on DioException catch (e) {
+      final err = e.error;
+      yield AiEvent.error(err is ApiException ? err.message : 'AI 连接中断');
+    } catch (_) {
+      yield const AiEvent.error('AI 连接中断');
+    }
+  }
+
+  AiEvent? _parseEvent(String event, String payload) {
+    final decoded = jsonDecode(payload);
+    if (decoded is! Map<String, dynamic>) return null;
+
+    return switch (event) {
+      'delta' => AiEvent.delta(asString(decoded['content'])),
+      'tool' => AiEvent.tool(asString(decoded['name'], fallback: '查询')),
+      'done' => AiEvent.done(asNullableInt(decoded['sessionId'])),
+      'error' => AiEvent.error(asString(decoded['message'], fallback: 'AI 服务出错')),
+      // 未知事件直接忽略，后端以后加新事件类型时老版本 App 不会崩
+      _ => null,
+    };
+  }
+}