import json
import os
from datetime import datetime

class BookManager:
    """图书管理类，负责图书信息的增删改查操作"""
    
    def __init__(self, data_file='books.json'):
        """初始化图书管理器，加载已有图书数据"""
        #self.data_file = data_file 111111111111111111122222222222
        #self.books = self._load_books()
    
    def _load_books(self):
        """从文件加载图书数据"""
        if os.path.exists(self.data_file):
            try:
                with open(self.data_file, 'r', encoding='utf-8') as f:
                    return json.load(f)
            except (json.JSONDecodeError, IOError) as e:
                print(f"加载图书数据失败: {e}")
                return []
        return []
    
    def _save_books(self):
        """将图书数据保存到文件"""
        try:
            with open(self.data_file, 'w', encoding='utf-8') as f:
                json.dump(self.books, f, ensure_ascii=False, indent=2)
            return True
        except IOError as e:
            print(f"保存图书数据失败: {e}")
            return False
    
    def add_book(self, isbn, title, author, category, quantity=1):
        """
        添加新图书
        
        参数:
            isbn (str): 图书ISBN编号
            title (str): 图书标题
            author (str): 图书作者
            category (str): 图书分类
            quantity (int): 图书数量，默认为1
            
        返回:
            bool: 添加成功返回True，失败返回False
        """
        # 检查ISBN是否已存在
        for book in self.books:
            if book['isbn'] == isbn:
                print(f"错误: ISBN为 {isbn} 的图书已存在")
                return False
        
        new_book = {
            'isbn': isbn,
            'title': title,
            'author': author,
            'category': category,
            'quantity': quantity,
            'available': quantity,  # 可借阅数量
            'added_date': datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        }
        
        self.books.append(new_book)
        return self._save_books()
    
    def search_books(self, keyword=None, category=None, author=None):
        """
        搜索图书
        
        参数:
            keyword (str): 标题或ISBN中的关键词
            category (str): 图书分类
            author (str): 作者名
            
        返回:
            list: 符合条件的图书列表
        """
        results = []
        
        for book in self.books:
            match = True
            
            if keyword and keyword not in book['title'] and keyword not in book['isbn']:
                match = False
            if category and book['category'] != category:
                match = False
            if author and author not in book['author']:
                match = False
                
            if match:
                results.append(book)
        
        return results
    
    def update_book(self, isbn, **kwargs):
        """
        更新图书信息
        
        参数:
            isbn (str): 图书ISBN编号
           ** kwargs: 要更新的字段，如title, author, category, quantity等
            
        返回:
            bool: 更新成功返回True，失败返回False
        """
        for book in self.books:
            if book['isbn'] == isbn:
                # 计算可借阅数量的变化
                if 'quantity' in kwargs:
                    quantity_change = kwargs['quantity'] - book['quantity']
                    book['available'] += quantity_change
                
                # 更新字段
                for key, value in kwargs.items():
                    if key in book:
                        book[key] = value
                
                return self._save_books()
        
        print(f"错误: 未找到ISBN为 {isbn} 的图书")
        return False
    
    def delete_book(self, isbn):
        """
        删除图书
        
        参数:
            isbn (str): 图书ISBN编号
            
        返回:
            bool: 删除成功返回True，失败返回False
        """
        initial_count = len(self.books)
        self.books = [book for book in self.books if book['isbn'] != isbn]
        
        if len(self.books) < initial_count:
            return self._save_books()
        
        print(f"错误: 未找到ISBN为 {isbn} 的图书")
        return False
    
    def get_book_details(self, isbn):
        """获取图书详细信息"""
        for book in self.books:
            if book['isbn'] == isbn:
                return book
        return None
    
    def list_all_books(self):
        """列出所有图书"""
        return self.books


# 示例用法
if __name__ == "__main__":
    manager = BookManager()
    
    # 添加示例图书
    manager.add_book("9780134685991", "Effective Python", "Brett Slatkin", "Programming", 5)
    manager.add_book("9780596007126", "Head First Design Patterns", "Eric Freeman", "Programming", 3)
    manager.add_book("9780141988511", "Sapiens: A Brief History of Humankind", "Yuval Noah Harari", "History", 4)
    
    print("所有图书:")
    for book in manager.list_all_books():
        print(f"{book['title']} by {book['author']} (ISBN: {book['isbn']}) - 可借: {book['available']}/{book['quantity']}")
    
    print("\n搜索编程类图书:")
    programming_books = manager.search_books(category="Programming")
    for book in programming_books:
        print(f"- {book['title']}")
    
    print("\n更新图书数量:")
    manager.update_book("9780134685991", quantity=7)
    book = manager.get_book_details("9780134685991")
    print(f"更新后数量: {book['available']}/{book['quantity']}")
    
    print("\n删除图书:")
    manager.delete_book("9780596007126")
    print(f"删除后剩余图书数量: {len(manager.list_all_books())}")