这是indexloc提供的服务，不要输入任何密码
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Add document vector store with chunking #13

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Merged
merged 1 commit into from
Jun 20, 2025
Merged

Add document vector store with chunking #13

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119 changes: 60 additions & 59 deletions lib/providers/chat_providers.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ import '../models/chat_session.dart';
import '../models/message.dart';
import '../services/llm_service.dart';
import '../services/llm_service_factory.dart';
import '../services/vector_store.dart';

// Provider for the LLM service factory
final llmServiceFactoryProvider = Provider<LlmServiceFactory>((ref) {
Expand All @@ -22,33 +23,35 @@ final selectedLlmServiceProvider = Provider<LlmService>((ref) {
});

// Provider for the list of chat sessions
final chatSessionsProvider = StateNotifierProvider<ChatSessionsNotifier, List<ChatSession>>((ref) {
return ChatSessionsNotifier();
});
final chatSessionsProvider =
StateNotifierProvider<ChatSessionsNotifier, List<ChatSession>>((ref) {
return ChatSessionsNotifier();
});

// Provider for the currently active chat session
final activeChatSessionProvider = StateNotifierProvider<ActiveChatSessionNotifier, ChatSession?>((ref) {
return ActiveChatSessionNotifier(ref);
});
final activeChatSessionProvider =
StateNotifierProvider<ActiveChatSessionNotifier, ChatSession?>((ref) {
return ActiveChatSessionNotifier(ref);
});

// Provider for the loading state
final isLoadingProvider = StateProvider<bool>((ref) => false);

// Notifier for managing the list of chat sessions
class ChatSessionsNotifier extends StateNotifier<List<ChatSession>> {
ChatSessionsNotifier() : super([]);

void addSession(ChatSession session) {
state = [...state, session];
}

void updateSession(ChatSession updatedSession) {
state = [
for (final session in state)
if (session.id == updatedSession.id) updatedSession else session,
];
}

void deleteSession(String sessionId) {
state = state.where((session) => session.id != sessionId).toList();
}
Expand All @@ -62,7 +65,7 @@ class ChatSessionsNotifier extends StateNotifier<List<ChatSession>> {
session,
];
}

ChatSession? getSessionById(String id) {
try {
return state.firstWhere((session) => session.id == id);
Expand All @@ -75,50 +78,46 @@ class ChatSessionsNotifier extends StateNotifier<List<ChatSession>> {
// Notifier for managing the active chat session
class ActiveChatSessionNotifier extends StateNotifier<ChatSession?> {
final Ref _ref;

ActiveChatSessionNotifier(this._ref) : super(null);

void setActiveSession(ChatSession session) {
state = session;
}

void createNewSession(LlmServiceType serviceType) {
final newSession = ChatSession(
serviceType: serviceType,
title: 'New Chat',
);

final newSession = ChatSession(serviceType: serviceType, title: 'New Chat');

// Add to the list of sessions
_ref.read(chatSessionsProvider.notifier).addSession(newSession);

// Set as active session
state = newSession;
}

Future<void> sendMessage(String content) async {
if (state == null) return;

// Create user message
final userMessage = Message(
role: MessageRole.user,
content: content,
);

final userMessage = Message(role: MessageRole.user, content: content);

// Add user message to the session
final updatedSession = state!.addMessage(userMessage);
state = updatedSession;
_ref.read(chatSessionsProvider.notifier).updateSession(updatedSession);

// Set loading state
_ref.read(isLoadingProvider.notifier).state = true;

try {
// Get the selected LLM service
final llmService = _ref.read(selectedLlmServiceProvider);

// Send the message to the LLM service
final assistantMessage = await llmService.sendMessage(updatedSession.messages);

final assistantMessage = await llmService.sendMessage(
updatedSession.messages,
);

// Add the assistant's response to the session
final finalSession = updatedSession.addMessage(assistantMessage);
state = finalSession;
Expand All @@ -129,7 +128,7 @@ class ActiveChatSessionNotifier extends StateNotifier<ChatSession?> {
role: MessageRole.assistant,
content: 'Error: ${e.toString()}',
);

final finalSession = updatedSession.addMessage(errorMessage);
state = finalSession;
_ref.read(chatSessionsProvider.notifier).updateSession(finalSession);
Expand All @@ -139,10 +138,7 @@ class ActiveChatSessionNotifier extends StateNotifier<ChatSession?> {
}
}

Future<void> sendMessageWithImage(
String content,
String base64Image,
) async {
Future<void> sendMessageWithImage(String content, String base64Image) async {
if (state == null) return;

final userMessage = Message(
Expand Down Expand Up @@ -182,42 +178,47 @@ class ActiveChatSessionNotifier extends StateNotifier<ChatSession?> {
}
}

Future<void> sendMessageWithPdf(
String content,
String pdfText,
) async {
Future<void> sendMessageWithPdf(String content, String pdfText) async {
if (state == null) return;

ChatSession? updatedSession;

_ref.read(isLoadingProvider.notifier).state = true;

try {
final llmService = _ref.read(selectedLlmServiceProvider);

final embedding = await llmService.embedText(pdfText);
// Index the PDF text into the shared vector store
await VectorStore.instance.upsertDocument(pdfText, llmService);

final userMessage = Message(
role: MessageRole.user,
content: content,
embedding: embedding,
// Retrieve relevant chunks based on the user's question
final relevantChunks = await VectorStore.instance.search(
content,
llmService,
);

updatedSession = state!.addMessage(userMessage);
state = updatedSession;
_ref.read(chatSessionsProvider.notifier).updateSession(updatedSession!);

final messagesWithPdf = [
...updatedSession.messages,
Message(role: MessageRole.user, content: pdfText),
final contextMessage = relevantChunks.isEmpty
? null
: Message(
role: MessageRole.user,
content: relevantChunks.join('\n\n'),
);

// Build messages with the retrieved context before the question
final messagesForLlm = [
...state!.messages,
if (contextMessage != null) contextMessage,
Message(role: MessageRole.user, content: content),
];

final assistantMessage =
await llmService.sendMessage(messagesWithPdf);
final assistantMessage = await llmService.sendMessage(messagesForLlm);

final finalSession = updatedSession.addMessage(assistantMessage);
state = finalSession;
_ref.read(chatSessionsProvider.notifier).updateSession(finalSession);
// Update session with user question and assistant response
updatedSession = state!
.addMessage(Message(role: MessageRole.user, content: content))
.addMessage(assistantMessage);

state = updatedSession;
_ref.read(chatSessionsProvider.notifier).updateSession(updatedSession);
} catch (e) {
final errorMessage = Message(
role: MessageRole.assistant,
Expand All @@ -232,4 +233,4 @@ class ActiveChatSessionNotifier extends StateNotifier<ChatSession?> {
_ref.read(isLoadingProvider.notifier).state = false;
}
}
}
}
123 changes: 123 additions & 0 deletions lib/services/vector_store.dart
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Original file line number Diff line number Diff line change
@@ -0,0 +1,123 @@
import 'dart:convert';
import 'dart:math';
import 'dart:io';

import 'package:crypto/crypto.dart';
import 'package:path_provider/path_provider.dart';

import 'llm_service.dart';

class DocumentChunk {
final String id;
final String text;
final List<double> embedding;

DocumentChunk({
required this.id,
required this.text,
required this.embedding,
});

Map<String, dynamic> toJson() => {
'id': id,
'text': text,
'embedding': embedding,
};

factory DocumentChunk.fromJson(Map<String, dynamic> json) {
return DocumentChunk(
id: json['id'],
text: json['text'],
embedding: (json['embedding'] as List)
.map((e) => (e as num).toDouble())
.toList(),
);
}
}

class VectorStore {
VectorStore._internal();
static final VectorStore instance = VectorStore._internal();

final Map<String, DocumentChunk> _chunks = {};
bool _loaded = false;

Future<void> _load() async {
if (_loaded) return;
final dir = await getApplicationSupportDirectory();
final file = File('${dir.path}/doc_index.json');
if (await file.exists()) {
final data = jsonDecode(await file.readAsString());
for (final item in data) {
final chunk = DocumentChunk.fromJson(item);
_chunks[chunk.id] = chunk;
}
}
_loaded = true;
}

Future<void> _save() async {
final dir = await getApplicationSupportDirectory();
final file = File('${dir.path}/doc_index.json');
await file.writeAsString(
jsonEncode(_chunks.values.map((c) => c.toJson()).toList()),
);
}

Future<void> upsertDocument(
String text,
LlmService llmService, {
int chunkSize = 1000,
}) async {
await _load();
final chunks = _splitIntoChunks(text, chunkSize);
for (final chunk in chunks) {
final id = _fingerprint(chunk);
if (!_chunks.containsKey(id)) {
final embedding = await llmService.embedText(chunk);
_chunks[id] = DocumentChunk(id: id, text: chunk, embedding: embedding);
}
}
await _save();
}

Future<List<String>> search(
String query,
LlmService llmService, {
int topK = 3,
}) async {
await _load();
if (_chunks.isEmpty) return [];
final queryEmbedding = await llmService.embedText(query);
final scores = <DocumentChunk, double>{};
for (final chunk in _chunks.values) {
final score = _cosineSimilarity(queryEmbedding, chunk.embedding);
scores[chunk] = score;
}
final sorted = scores.entries.toList()
..sort((a, b) => b.value.compareTo(a.value));
return sorted.take(topK).map((e) => e.key.text).toList();
}

List<String> _splitIntoChunks(String text, int size) {
final regex = RegExp('.{1,$size}', dotAll: true);
return regex.allMatches(text).map((m) => m.group(0)!).toList();
}

String _fingerprint(String text) {
return sha256.convert(utf8.encode(text)).toString();
}

double _cosineSimilarity(List<double> a, List<double> b) {
double dot = 0;
double normA = 0;
double normB = 0;
for (var i = 0; i < a.length; i++) {
dot += a[i] * b[i];
normA += a[i] * a[i];
normB += b[i] * b[i];
}
if (normA == 0 || normB == 0) return 0.0;
return dot / (sqrt(normA) * sqrt(normB));
}
}
1 change: 1 addition & 0 deletions pubspec.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,7 @@ dependencies:
image_picker: ^1.0.4
file_picker: ^10.2.0
doc_text_extractor: ^1.0.0
crypto: ^3.0.3

dev_dependencies:
flutter_test:
Expand Down