feat: v1.2.0 - 图片去重与管理、微信机器人优化、搜索设置可配置
主要功能: - 图片上传时 OCR 内容去重（3个上传端点统一使用公共函数 _check_ocr_duplicate） - 图片管理 Tab：展示所有图片、手动删除、一键去重 - 搜索结果详情弹窗增加删除按钮（带确认弹窗） - 图片管理卡片点击查看详情（复用 showOcrDetailModal） - 搜索限制和 LLM 批量判断数量可通过网站设置 - MiniMax API 调用添加 reasoning_split=True - 企业微信机器人：WebSocket 长连接、图片搜索、配置化搜索数量 - 版本号升级至 1.2.0
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EduBrain Dev
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app/services/search_engine.py
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185
app/services/search_engine.py
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"""
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BM25 倒排索引搜索引擎
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用于图片 OCR 内容的全文搜索
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参考 Meilisearch / Whoosh 设计
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"""
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from __future__ import annotations
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import re
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import math
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import logging
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from collections import Counter, defaultdict
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from typing import List, Dict, Optional, Tuple
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logger = logging.getLogger(__name__)
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# 尝试导入 jieba，失败则用简单的字符分割
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try:
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import jieba
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jieba.setLogLevel(logging.WARNING)
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def tokenize(text: str) -> List[str]:
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"""中文分词"""
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return [w for w in jieba.cut_for_search(text) if len(w.strip()) > 1]
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except ImportError:
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logger.warning("jieba 未安装，使用简单分词（pip install jieba 获得更好效果）")
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def tokenize(text: str) -> List[str]:
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"""简单分词：按空格和标点分割"""
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return [w for w in re.split(r'[\s,.\-;:!?"\'/\\|()\[\]{}<>，。；：！？""''、（）【】]+', text) if len(w.strip()) > 1]
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class BM25Index:
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"""
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BM25 倒排索引
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- 支持增量添加文档
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- 支持删除文档
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- 支持中文分词（jieba）
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- BM25 评分排序
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"""
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def __init__(self, k1: float = 1.5, b: float = 0.75):
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"""
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Args:
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k1: 词频饱和参数（默认 1.5）
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b: 文档长度归一化参数（默认 0.75）
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"""
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self.k1 = k1
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self.b = b
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# 倒排索引：term -> {doc_id: tf}
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self.inverted_index: Dict[str, Dict[int, int]] = defaultdict(lambda: defaultdict(int))
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# 文档信息
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self.doc_lengths: Dict[int, int] = {} # doc_id -> 文档长度（词数）
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self.doc_count: int = 0
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self.avg_doc_length: float = 0.0
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# 文档存储（存完整数据）
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self.documents: Dict[int, dict] = {}
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# IDF 缓存
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self._idf_cache: Dict[str, float] = {}
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def add_document(self, doc_id: int, text: str, metadata: Optional[dict] = None):
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"""
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添加文档到索引
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Args:
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doc_id: 文档 ID
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text: 待索引的文本内容
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metadata: 附加元数据（如 file_path, tags 等）
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"""
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# 如果已存在，先删除
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if doc_id in self.documents:
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self.remove_document(doc_id)
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tokens = tokenize(text)
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self.doc_lengths[doc_id] = len(tokens)
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self.documents[doc_id] = {
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"text": text,
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"tokens": tokens,
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"metadata": metadata or {},
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}
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# 构建倒排索引
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tf = Counter(tokens)
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for term, count in tf.items():
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self.inverted_index[term][doc_id] = count
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self.doc_count += 1
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self._update_avg_doc_length()
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self._idf_cache.clear() # 文档数变了，IDF 需要重算
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def remove_document(self, doc_id: int):
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"""从索引中删除文档"""
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if doc_id not in self.documents:
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return
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# 从倒排索引中移除
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tokens = self.documents[doc_id].get("tokens", [])
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for term in set(tokens):
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if term in self.inverted_index and doc_id in self.inverted_index[term]:
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del self.inverted_index[term][doc_id]
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if not self.inverted_index[term]:
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del self.inverted_index[term]
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del self.documents[doc_id]
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del self.doc_lengths[doc_id]
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self.doc_count -= 1
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self._update_avg_doc_length()
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self._idf_cache.clear()
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def _update_avg_doc_length(self):
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"""更新平均文档长度"""
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if self.doc_count > 0:
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self.avg_doc_length = sum(self.doc_lengths.values()) / self.doc_count
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else:
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self.avg_doc_length = 0.0
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def _idf(self, term: str) -> float:
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"""
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计算逆文档频率 IDF
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IDF(t) = ln((N - df(t) + 0.5) / (df(t) + 0.5) + 1)
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其中 N 是文档总数，df(t) 是包含 term 的文档数
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"""
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if term in self._idf_cache:
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return self._idf_cache[term]
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df = len(self.inverted_index.get(term, {}))
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idf = math.log((self.doc_count - df + 0.5) / (df + 0.5) + 1)
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self._idf_cache[term] = idf
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return idf
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def search(self, query: str, top_k: int = 10) -> List[Tuple[int, float]]:
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"""
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BM25 搜索
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Args:
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query: 搜索查询（会自动分词）
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top_k: 返回前 K 个结果
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Returns:
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[(doc_id, score), ...] 按 BM25 分数降序排列
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"""
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if self.doc_count == 0 or self.avg_doc_length == 0:
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return []
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query_tokens = tokenize(query)
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if not query_tokens:
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return []
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scores: Dict[int, float] = defaultdict(float)
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for term in query_tokens:
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idf = self._idf(term)
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postings = self.inverted_index.get(term, {})
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for doc_id, tf in postings.items():
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dl = self.doc_lengths[doc_id]
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# BM25 公式
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numerator = tf * (self.k1 + 1)
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denominator = tf + self.k1 * (1 - self.b + self.b * dl / self.avg_doc_length)
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scores[doc_id] += idf * numerator / denominator
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# 按分数降序排序
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ranked = sorted(scores.items(), key=lambda x: x[1], reverse=True)
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return ranked[:top_k]
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def get_document(self, doc_id: int) -> Optional[dict]:
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"""获取文档完整数据"""
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return self.documents.get(doc_id)
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def clear(self):
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"""清空索引"""
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self.inverted_index.clear()
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self.doc_lengths.clear()
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self.documents.clear()
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self._idf_cache.clear()
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self.doc_count = 0
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self.avg_doc_length = 0.0
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@property
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def size(self) -> int:
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"""索引中的文档数量"""
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return self.doc_count
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