# -*- coding: utf-8 -*-
"""
知识库服务 - 管理文档的添加、删除和检索
"""
import os
import shutil
from datetime import datetime
from config import KNOWLEDGE_DIR, UPLOAD_DIR
from document_parser import parse_document, is_supported_file
from text_splitter import split_text
from vector_store import vector_store

class KnowledgeService:
    def __init__(self):
        self.vector_store = vector_store
    
    def init(self):
        """初始化服务，加载已有索引"""
        self.vector_store.load_index()
    
    def scan_and_index_folder(self):
        """
        扫描知识库文件夹并索引所有文档
        用于启动时或手动重建索引
        """
        print(f"开始扫描知识库文件夹: {KNOWLEDGE_DIR}")
        
        # 获取已索引的文件
        stats = self.vector_store.get_stats()
        indexed_files = set(stats.get('files', []))
        
        # 扫描文件夹
        new_files = []
        for root, dirs, files in os.walk(KNOWLEDGE_DIR):
            for filename in files:
                if is_supported_file(filename):
                    file_path = os.path.join(root, filename)
                    rel_path = os.path.relpath(file_path, KNOWLEDGE_DIR)
                    
                    if rel_path not in indexed_files:
                        new_files.append((filename, file_path, rel_path))
        
        # 索引新文件
        indexed_count = 0
        for filename, file_path, rel_path in new_files:
            try:
                result = self.add_document(file_path, filename)
                if result['success']:
                    indexed_count += 1
                    print(f"  已索引: {rel_path}")
            except Exception as e:
                print(f"  索引失败 {rel_path}: {e}")
        
        print(f"扫描完成，新索引 {indexed_count} 个文件")
        return {
            'scanned': len(new_files),
            'indexed': indexed_count
        }
    
    def add_document(self, file_path, filename=None):
        """
        添加单个文档到知识库
        
        Args:
            file_path: 文件路径
            filename: 文件名（可选）
        
        Returns:
            处理结果
        """
        if filename is None:
            filename = os.path.basename(file_path)
        
        if not os.path.exists(file_path):
            return {'success': False, 'error': '文件不存在'}
        
        if not is_supported_file(filename):
            return {'success': False, 'error': '不支持的文件类型'}
        
        # 解析文档
        print(f"正在解析文档: {filename}")
        content = parse_document(file_path)
        
        if not content or not content.strip():
            return {'success': False, 'error': '文档内容为空'}
        
        # 分块
        chunks = split_text(content)
        
        if not chunks:
            return {'success': False, 'error': '文档分块失败'}
        
        # 元数据
        metadata = {
            'filename': filename,
            'file_path': file_path,
            'indexed_at': datetime.now().isoformat(),
            'char_count': len(content)
        }
        
        # 添加到向量存储
        added = self.vector_store.add_documents(chunks, metadata)
        
        return {
            'success': True,
            'filename': filename,
            'chunks': added,
            'char_count': len(content)
        }
    
    def upload_and_index(self, file_storage, copy_to_knowledge=True):
        """
        处理上传的文件并索引
        
        Args:
            file_storage: Flask 的 FileStorage 对象
            copy_to_knowledge: 是否复制到知识库文件夹
        
        Returns:
            处理结果
        """
        from file_watcher import mark_uploading, unmark_uploading
        
        filename = file_storage.filename
        
        if not is_supported_file(filename):
            return {'success': False, 'error': '不支持的文件类型'}
        
        # 标记文件正在上传，防止文件监控器干扰
        mark_uploading(filename)
        
        # 保存到临时目录
        temp_path = os.path.join(UPLOAD_DIR, filename)
        file_storage.save(temp_path)
        
        try:
            # 索引文档
            result = self.add_document(temp_path, filename)
            
            if result['success'] and copy_to_knowledge:
                # 复制到知识库文件夹
                dest_path = os.path.join(KNOWLEDGE_DIR, filename)
                shutil.copy2(temp_path, dest_path)
                result['saved_to'] = dest_path
            
            return result
        finally:
            # 清理临时文件
            if os.path.exists(temp_path):
                os.remove(temp_path)
            
            # 延迟取消上传标记，给文件监控器足够时间忽略事件
            import threading
            def delayed_unmark():
                import time
                time.sleep(5)
                unmark_uploading(filename)
            threading.Thread(target=delayed_unmark, daemon=True).start()
    
    def delete_document(self, filename):
        """
        删除文档
        
        Args:
            filename: 文件名
        
        Returns:
            删除结果
        """
        # 从向量存储删除
        deleted = self.vector_store.delete_by_filename(filename)
        
        # 从知识库文件夹删除
        file_path = os.path.join(KNOWLEDGE_DIR, filename)
        file_deleted = False
        if os.path.exists(file_path):
            os.remove(file_path)
            file_deleted = True
        
        return {
            'success': deleted > 0 or file_deleted,
            'chunks_deleted': deleted,
            'file_deleted': file_deleted
        }
    
    def search(self, query, top_k=5):
        """
        搜索相关文档
        
        Args:
            query: 查询文本
            top_k: 返回结果数量
        
        Returns:
            搜索结果
        """
        results = self.vector_store.search(query, top_k)
        return results
    
    def get_stats(self):
        """获取知识库统计信息"""
        return self.vector_store.get_stats()
    
    def list_documents(self):
        """列出所有已索引的文档"""
        stats = self.vector_store.get_stats()
        files = stats.get('files', [])
        
        documents = []
        for filename in files:
            # 统计该文件的块数
            chunk_count = sum(1 for doc in self.vector_store.documents 
                            if doc.get('metadata', {}).get('filename') == filename)
            
            # 获取文件信息
            file_path = os.path.join(KNOWLEDGE_DIR, filename)
            file_size = os.path.getsize(file_path) if os.path.exists(file_path) else 0
            
            documents.append({
                'filename': filename,
                'chunks': chunk_count,
                'size': file_size,
                'exists': os.path.exists(file_path)
            })
        
        return documents
    
    def rebuild_index(self):
        """重建整个索引"""
        print("开始重建索引...")
        
        # 清空现有索引
        self.vector_store.clear()
        
        # 重新扫描并索引
        result = self.scan_and_index_folder()
        
        return {
            'success': True,
            'indexed': result['indexed']
        }

# 全局实例
knowledge_service = KnowledgeService()