"""
文件监控服务
"""
import os
import time
import logging
import threading
from pathlib import Path
from typing import Optional, Callable
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler, FileCreatedEvent, FileModifiedEvent, FileDeletedEvent

from ..core.config import get_settings
from ..core.database import get_db
from .knowledge_base_service import KnowledgeBaseService

logger = logging.getLogger(__name__)
settings = get_settings()


class KnowledgeBaseHandler(FileSystemEventHandler):
    """知识库文件监控处理器"""
    
    def __init__(self, knowledge_base_service: KnowledgeBaseService):
        self.kb_service = knowledge_base_service
        self.knowledge_base_dir = Path(settings.knowledge_base_dir)
        self.supported_extensions = settings.allowed_extensions
        
    def on_created(self, event):
        """处理文件创建事件"""
        if not event.is_directory and self._is_supported_file(event.src_path):
            logger.info(f"检测到新文件: {event.src_path}")
            self._process_file_async(event.src_path, "created")
    
    def on_modified(self, event):
        """处理文件修改事件"""
        if not event.is_directory and self._is_supported_file(event.src_path):
            logger.info(f"检测到文件修改: {event.src_path}")
            self._process_file_async(event.src_path, "modified")
    
    def on_deleted(self, event):
        """处理文件删除事件"""
        if not event.is_directory and self._is_supported_file(event.src_path):
            logger.info(f"检测到文件删除: {event.src_path}")
            self._handle_file_deletion(event.src_path)
    
    def _is_supported_file(self, file_path: str) -> bool:
        """检查是否为支持的文件类型"""
        return Path(file_path).suffix.lower() in self.supported_extensions
    
    def _process_file_async(self, file_path: str, event_type: str):
        """异步处理文件"""
        def process():
            try:
                # 等待文件写入完成
                time.sleep(1)
                
                result = self.kb_service.process_file(file_path)
                logger.info(f"文件处理结果 ({event_type}): {result}")
                
            except Exception as e:
                logger.error(f"处理文件失败: {file_path}, 错误: {str(e)}")
        
        # 在后台线程中处理
        thread = threading.Thread(target=process)
        thread.daemon = True
        thread.start()
    
    def _handle_file_deletion(self, file_path: str):
        """处理文件删除"""
        try:
            # 查找并删除对应的数据库记录
            from ..models.document import Document
            from sqlalchemy import and_
            
            document = self.kb_service.db.query(Document).filter(
                and_(
                    Document.file_path == file_path,
                    Document.source_type == "knowledge_base"
                )
            ).first()
            
            if document:
                result = self.kb_service.delete_document(document.id)
                logger.info(f"文件删除处理结果: {result}")
            else:
                logger.info(f"未找到对应的数据库记录: {file_path}")
                
        except Exception as e:
            logger.error(f"处理文件删除失败: {file_path}, 错误: {str(e)}")


class FileWatcherService:
    """文件监控服务"""
    
    def __init__(self):
        self.observer: Optional[Observer] = None
        self.knowledge_base_dir = Path(settings.knowledge_base_dir)
        self.is_running = False
        
    def start(self):
        """启动文件监控"""
        if self.is_running:
            logger.info("文件监控服务已在运行")
            return
        
        if not settings.enable_file_watcher:
            logger.info("文件监控服务已禁用")
            return
        
        if not self.knowledge_base_dir.exists():
            logger.info(f"知识库目录不存在: {self.knowledge_base_dir}")
            return
        
        try:
            # 创建数据库会话
            db = next(get_db())
            kb_service = KnowledgeBaseService(db)
            
            # 创建事件处理器
            event_handler = KnowledgeBaseHandler(kb_service)
            
            # 创建观察者
            self.observer = Observer()
            self.observer.schedule(
                event_handler,
                str(self.knowledge_base_dir),
                recursive=True  # 递归监控子目录
            )
            
            # 启动观察者
            self.observer.start()
            self.is_running = True
            
            logger.info(f"文件监控服务已启动，监控目录: {self.knowledge_base_dir}")
            
            # 确保子目录对应的系统知识库存在
            logger.info("确保系统知识库与目录同步...")
            kb_service.ensure_system_knowledge_bases()

            # 执行初始扫描
            logger.info("执行初始知识库扫描...")
            scan_result = kb_service.scan_directory()
            logger.info(f"初始扫描结果: {scan_result}")
            
        except Exception as e:
            logger.error(f"启动文件监控服务失败: {str(e)}")
            self.is_running = False
    
    def stop(self):
        """停止文件监控"""
        if self.observer and self.is_running:
            self.observer.stop()
            self.observer.join()
            self.is_running = False
            logger.info("文件监控服务已停止")
    
    def is_active(self) -> bool:
        """检查监控服务是否活跃"""
        return self.is_running and self.observer and self.observer.is_alive()
    
    def get_status(self) -> dict:
        """获取监控服务状态"""
        return {
            "is_running": self.is_running,
            "is_active": self.is_active(),
            "knowledge_base_dir": str(self.knowledge_base_dir),
            "directory_exists": self.knowledge_base_dir.exists(),
            "enable_file_watcher": settings.enable_file_watcher
        }


# 全局文件监控服务实例
file_watcher_service: Optional[FileWatcherService] = None


def get_file_watcher_service() -> FileWatcherService:
    """获取文件监控服务实例"""
    global file_watcher_service
    if file_watcher_service is None:
        file_watcher_service = FileWatcherService()
    return file_watcher_service


def start_file_watcher():
    """启动文件监控服务"""
    watcher = get_file_watcher_service()
    watcher.start()


def stop_file_watcher():
    """停止文件监控服务"""
    watcher = get_file_watcher_service()
    watcher.stop()