"""备份服务：一键备份网站数据和资源"""
import os
import shutil
import zipfile
from datetime import datetime
from flask import current_app


class BackupService:
    """备份服务类"""
    
    # 备份目录（项目根目录下的 backups 文件夹）
    BACKUP_DIR = 'backups'
    
    @classmethod
    def get_backup_dir(cls):
        """获取备份目录路径"""
        # 相对于项目根目录
        root_dir = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(__file__))))
        backup_dir = os.path.join(root_dir, cls.BACKUP_DIR)
        
        # 确保备份目录存在
        if not os.path.exists(backup_dir):
            os.makedirs(backup_dir)
        
        return backup_dir
    
    @classmethod
    def create_backup(cls, include_uploads=True):
        """
        创建完整备份
        
        Args:
            include_uploads: 是否包含上传的图片附件
        
        Returns:
            tuple: (backup_file_path, error_message)
        """
        try:
            # 获取项目根目录
            root_dir = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(__file__))))
            
            # 备份文件名：techblog_backup_YYYYMMDD_HHMMSS.zip
            timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
            backup_filename = f'techblog_backup_{timestamp}.zip'
            backup_filepath = os.path.join(cls.get_backup_dir(), backup_filename)
            
            # 数据库文件路径
            db_path = os.path.join(root_dir, 'data', 'techblog.db')
            
            # 创建数据库备份文件（带时间戳）
            db_backup_filename = f'techblog_backup_{timestamp}.db'
            db_backup_path = os.path.join(root_dir, 'data', db_backup_filename)
            
            # 复制数据库文件
            if os.path.exists(db_path):
                shutil.copy2(db_path, db_backup_path)
            
            # 上传目录路径
            uploads_path = os.path.join(root_dir, 'uploads')
            
            # 创建 ZIP 备份文件
            with zipfile.ZipFile(backup_filepath, 'w', zipfile.ZIP_DEFLATED) as zipf:
                # 1. 备份数据库（备份文件）
                if os.path.exists(db_backup_path):
                    zipf.write(db_backup_path, f'data/{db_backup_filename}')
                    # 删除临时备份文件
                    os.remove(db_backup_path)
                
                # 2. 备份上传的图片和附件（保持目录结构）
                if include_uploads and os.path.exists(uploads_path):
                    for root, dirs, files in os.walk(uploads_path):
                        for file in files:
                            file_path = os.path.join(root, file)
                            # 计算相对路径，保持目录结构
                            rel_path = os.path.relpath(file_path, uploads_path)
                            arcname = os.path.join('uploads', rel_path)
                            zipf.write(file_path, arcname)
                
                # 3. 写入备份信息
                info_content = f"""tech-blog 备份信息
========================
备份时间: {datetime.now().strftime('%Y-%m-%d %H:%M:%S')}
数据库备份: {db_backup_filename}
上传文件: {'已包含' if include_uploads else '未包含'}

恢复说明:
1. 解压备份文件
2. 将 data/{db_backup_filename} 复制为 data/techblog.db
3. 将 uploads/ 目录复制到项目根目录
"""
                zipf.writestr('backup_info.txt', info_content)
            
            # 获取备份文件大小
            file_size = os.path.getsize(backup_filepath)
            
            return {
                'success': True,
                'filepath': backup_filepath,
                'filename': backup_filename,
                'size': file_size,
                'timestamp': datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
                'db_backup_name': db_backup_filename
            }, None
            
        except Exception as e:
            # 清理临时文件
            if 'db_backup_path' in locals() and os.path.exists(db_backup_path):
                os.remove(db_backup_path)
            return None, str(e)
    
    @classmethod
    def list_backups(cls):
        """
        列出所有备份文件
        
        Returns:
            list: 备份文件列表，每个元素包含文件名、大小、时间
        """
        backup_dir = cls.get_backup_dir()
        backups = []
        
        if not os.path.exists(backup_dir):
            return backups
        
        for filename in os.listdir(backup_dir):
            if filename.endswith('.zip') and filename.startswith('techblog_backup_'):
                filepath = os.path.join(backup_dir, filename)
                stat = os.stat(filepath)
                
                backups.append({
                    'filename': filename,
                    'filepath': filepath,
                    'size': stat.st_size,
                    'created_at': datetime.fromtimestamp(stat.st_mtime)
                })
        
        # 按时间倒序排列
        backups.sort(key=lambda x: x['created_at'], reverse=True)
        
        return backups
    
    @classmethod
    def delete_backup(cls, filename):
        """
        删除备份文件
        
        Args:
            filename: 备份文件名
        
        Returns:
            tuple: (success, error_message)
        """
        try:
            backup_dir = cls.get_backup_dir()
            filepath = os.path.join(backup_dir, filename)
            
            if not os.path.exists(filepath):
                return False, '备份文件不存在'
            
            os.remove(filepath)
            return True, None
            
        except Exception as e:
            return False, str(e)
    
    @classmethod
    def get_backup_path(cls, filename):
        """获取备份文件的完整路径"""
        return os.path.join(cls.get_backup_dir(), filename)
    
    @classmethod
    def format_filesize(cls, size_bytes):
        """格式化文件大小"""
        for unit in ['B', 'KB', 'MB', 'GB']:
            if size_bytes < 1024.0:
                return f"{size_bytes:.2f} {unit}"
            size_bytes /= 1024.0
        return f"{size_bytes:.2f} TB"