refactor: 项目结构优化与FastAPI生命周期更新

重构项目目录结构，提高代码组织性和可维护性

将schemas目录重命名为domain，更好地表达领域模型概念
将services目录细分为service/chat、service/image等子目录
将api目录重命名为router，更符合FastAPI惯例
创建utils目录存放通用工具函数
更新FastAPI应用程序生命周期管理

替换已弃用的on_event方法为推荐的lifespan事件处理器
添加应用程序关闭时的日志记录
代码质量改进

抽取常量到constants.py，减少硬编码值
添加helpers.py提供通用工具函数
优化配置管理，使用环境变量和默认值
完善文档字符串，提高代码可读性

app/utils/__init__.py

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+"""
+工具包初始化模块
+"""

app/utils/helpers.py

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+"""
+通用工具函数模块
+"""
+import json
+import re
+import base64
+import requests
+from typing import Dict, Any, List, Optional, Tuple
+
+from app.core.constants import DATA_URL_PATTERN, IMAGE_URL_PATTERN, VALID_IMAGE_RATIOS
+
+
+def extract_mime_type_and_data(base64_string: str) -> Tuple[Optional[str], str]:
+    """
+    从 base64 字符串中提取 MIME 类型和数据
+    
+    Args:
+        base64_string: 可能包含 MIME 类型信息的 base64 字符串
+        
+    Returns:
+        tuple: (mime_type, encoded_data)
+    """
+    # 检查字符串是否以 "data:" 格式开始
+    if base64_string.startswith('data:'):
+        # 提取 MIME 类型和数据
+        pattern = DATA_URL_PATTERN
+        match = re.match(pattern, base64_string)
+        if match:
+            mime_type = "image/jpeg" if match.group(1) == "image/jpg" else match.group(1)
+            encoded_data = match.group(2)
+            return mime_type, encoded_data
+    
+    # 如果不是预期格式，假定它只是数据部分
+    return None, base64_string
+
+
+def convert_image_to_base64(url: str) -> str:
+    """
+    将图片URL转换为base64编码
+    
+    Args:
+        url: 图片URL
+        
+    Returns:
+        str: base64编码的图片数据
+        
+    Raises:
+        Exception: 如果获取图片失败
+    """
+    response = requests.get(url)
+    if response.status_code == 200:
+        # 将图片内容转换为base64
+        img_data = base64.b64encode(response.content).decode('utf-8')
+        return img_data
+    else:
+        raise Exception(f"Failed to fetch image: {response.status_code}")
+
+
+def format_json_response(data: Dict[str, Any], indent: int = 2) -> str:
+    """
+    格式化JSON响应
+    
+    Args:
+        data: 要格式化的数据
+        indent: 缩进空格数
+        
+    Returns:
+        str: 格式化后的JSON字符串
+    """
+    return json.dumps(data, indent=indent, ensure_ascii=False)
+
+
+def parse_prompt_parameters(prompt: str, default_ratio: str = "1:1") -> Tuple[str, int, str]:
+    """
+    从prompt中解析参数
+    
+    支持的格式:
+    - {n:数量} 例如: {n:2} 生成2张图片
+    - {ratio:比例} 例如: {ratio:16:9} 使用16:9比例
+    
+    Args:
+        prompt: 提示文本
+        default_ratio: 默认比例
+        
+    Returns:
+        tuple: (清理后的提示文本, 图片数量, 比例)
+    """
+    # 默认值
+    n = 1
+    aspect_ratio = default_ratio
+    
+    # 解析n参数
+    n_match = re.search(r'{n:(\d+)}', prompt)
+    if n_match:
+        n = int(n_match.group(1))
+        if n < 1 or n > 4:
+            raise ValueError(f"Invalid n value: {n}. Must be between 1 and 4.")
+        prompt = prompt.replace(n_match.group(0), '').strip()
+        
+    # 解析ratio参数    
+    ratio_match = re.search(r'{ratio:(\d+:\d+)}', prompt)
+    if ratio_match:
+        aspect_ratio = ratio_match.group(1)
+        if aspect_ratio not in VALID_IMAGE_RATIOS:
+            raise ValueError(
+                f"Invalid ratio: {aspect_ratio}. Must be one of: {', '.join(VALID_IMAGE_RATIOS)}"
+            )
+        prompt = prompt.replace(ratio_match.group(0), '').strip()
+        
+    return prompt, n, aspect_ratio
+
+
+def extract_image_urls_from_markdown(text: str) -> List[str]:
+    """
+    从Markdown文本中提取图片URL
+    
+    Args:
+        text: Markdown文本
+        
+    Returns:
+        List[str]: 图片URL列表
+    """
+    pattern = IMAGE_URL_PATTERN
+    matches = re.findall(pattern, text)
+    return [match[1] for match in matches]
+
+
+def is_valid_api_key(key: str) -> bool:
+    """
+    检查API密钥格式是否有效
+    
+    Args:
+        key: API密钥
+        
+    Returns:
+        bool: 如果密钥格式有效则返回True
+    """
+    # 检查Gemini API密钥格式
+    if key.startswith('AIza'):
+        return len(key) >= 30
+    
+    # 检查OpenAI API密钥格式
+    if key.startswith('sk-'):
+        return len(key) >= 30
+    
+    return False

app/utils/uploader.py

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+import requests
+from app.domain.image_models import ImageMetadata, ImageUploader, UploadResponse
+from enum import Enum
+from typing import Optional, Any
+
+class UploadErrorType(Enum):
+    """上传错误类型枚举"""
+    NETWORK_ERROR = "network_error"  # 网络请求错误
+    AUTH_ERROR = "auth_error"        # 认证错误
+    INVALID_FILE = "invalid_file"    # 无效文件
+    SERVER_ERROR = "server_error"    # 服务器错误
+    PARSE_ERROR = "parse_error"      # 响应解析错误
+    UNKNOWN = "unknown"              # 未知错误
+
+
+class UploadError(Exception):
+    """图片上传错误异常类"""
+    
+    def __init__(
+        self,
+        message: str,
+        error_type: UploadErrorType = UploadErrorType.UNKNOWN,
+        status_code: Optional[int] = None,
+        details: Optional[dict] = None,
+        original_error: Optional[Exception] = None
+    ):
+        """
+        初始化上传错误异常
+        
+        Args:
+            message: 错误消息
+            error_type: 错误类型
+            status_code: HTTP状态码
+            details: 详细错误信息
+            original_error: 原始异常
+        """
+        self.message = message
+        self.error_type = error_type
+        self.status_code = status_code
+        self.details = details or {}
+        self.original_error = original_error
+        
+        # 构建完整错误信息
+        full_message = f"[{error_type.value}] {message}"
+        if status_code:
+            full_message = f"{full_message} (Status: {status_code})"
+        if details:
+            full_message = f"{full_message} - Details: {details}"
+            
+        super().__init__(full_message)
+    
+    @classmethod
+    def from_response(cls, response: Any, message: Optional[str] = None) -> "UploadError":
+        """
+        从HTTP响应创建错误实例
+        
+        Args:
+            response: HTTP响应对象
+            message: 自定义错误消息
+        """
+        try:
+            error_data = response.json()
+            details = error_data.get("data", {})
+            return cls(
+                message=message or error_data.get("message", "Unknown error"),
+                error_type=UploadErrorType.SERVER_ERROR,
+                status_code=response.status_code,
+                details=details
+            )
+        except Exception:
+            return cls(
+                message=message or "Failed to parse error response",
+                error_type=UploadErrorType.PARSE_ERROR,
+                status_code=response.status_code
+            )
+
+
+class SmMsUploader(ImageUploader):
+    API_URL = "https://sm.ms/api/v2/upload"
+    
+    def __init__(self, api_key: str):
+        self.api_key = api_key
+        
+    def upload(self, file: bytes, filename: str) -> UploadResponse:
+        try:
+            # 准备请求头
+            headers = {
+                "Authorization": f"Basic {self.api_key}"
+            }
+            
+            # 准备文件数据
+            files = {
+                "smfile": (filename, file, "image/png")
+            }
+            
+            # 发送请求
+            response = requests.post(
+                self.API_URL,
+                headers=headers,
+                files=files
+            )
+            
+            # 检查响应状态
+            response.raise_for_status()
+            
+            # 解析响应
+            result = response.json()
+            
+            # 验证上传是否成功
+            if not result.get("success"):
+                raise UploadError(result.get("message", "Upload failed"))
+                
+            # 转换为统一格式
+            data = result["data"]
+            image_metadata = ImageMetadata(
+                width=data["width"],
+                height=data["height"],
+                filename=data["filename"],
+                size=data["size"],
+                url=data["url"],
+                delete_url=data["delete"]
+            )
+            
+            return UploadResponse(
+                success=True,
+                code="success",
+                message="Upload success",
+                data=image_metadata
+            )
+            
+        except requests.RequestException as e:
+            # 处理网络请求相关错误
+            raise UploadError(f"Upload request failed: {str(e)}")
+        except (KeyError, ValueError) as e:
+            # 处理响应解析错误
+            raise UploadError(f"Invalid response format: {str(e)}")
+        except Exception as e:
+            # 处理其他未预期的错误
+            raise UploadError(f"Upload failed: {str(e)}")
+    
+    
+class QiniuUploader(ImageUploader):
+    def __init__(self, access_key: str, secret_key: str):
+        self.access_key = access_key
+        self.secret_key = secret_key
+        
+    def upload(self, file: bytes, filename: str) -> UploadResponse:
+        # 实现七牛云的具体上传逻辑
+        pass
+    
+    
+class PicGoUploader(ImageUploader):
+    """Chevereto API 图片上传器"""
+    
+    def __init__(self, api_key: str, api_url: str = "https://www.picgo.net/api/1/upload"):
+        """
+        初始化 Chevereto 上传器
+        
+        Args:
+            api_key: Chevereto API 密钥
+            api_url: Chevereto API 上传地址
+        """
+        self.api_key = api_key
+        self.api_url = api_url
+        
+    def upload(self, file: bytes, filename: str) -> UploadResponse:
+        """
+        上传图片到 Chevereto 服务
+        
+        Args:
+            file: 图片文件二进制数据
+            filename: 文件名
+            
+        Returns:
+            UploadResponse: 上传响应对象
+            
+        Raises:
+            UploadError: 上传失败时抛出异常
+        """
+        try:
+            # 准备请求头
+            headers = {
+                "X-API-Key": self.api_key
+            }
+            
+            # 准备文件数据
+            files = {
+                "source": (filename, file)
+            }
+            
+            # 发送请求
+            response = requests.post(
+                self.api_url,
+                headers=headers,
+                files=files
+            )
+            
+            # 检查响应状态
+            response.raise_for_status()
+            
+            # 解析响应
+            result = response.json()
+            
+            # 验证上传是否成功
+            if result.get("status_code") != 200:
+                error_message = "Upload failed"
+                if "error" in result:
+                    error_message = result["error"].get("message", error_message)
+                raise UploadError(
+                    message=error_message,
+                    error_type=UploadErrorType.SERVER_ERROR,
+                    status_code=result.get("status_code"),
+                    details=result.get("error")
+                )
+                
+            # 从响应中提取图片信息
+            image_data = result.get("image", {})
+            
+            # 构建图片元数据
+            image_metadata = ImageMetadata(
+                width=image_data.get("width", 0),
+                height=image_data.get("height", 0),
+                filename=image_data.get("filename", filename),
+                size=image_data.get("size", 0),
+                url=image_data.get("url", ""),
+                delete_url=image_data.get("delete_url", None)
+            )
+            
+            return UploadResponse(
+                success=True,
+                code="success",
+                message=result.get("success", {}).get("message", "Upload success"),
+                data=image_metadata
+            )
+            
+        except requests.RequestException as e:
+            # 处理网络请求相关错误
+            raise UploadError(
+                message=f"Upload request failed: {str(e)}",
+                error_type=UploadErrorType.NETWORK_ERROR,
+                original_error=e
+            )
+        except (KeyError, ValueError, TypeError) as e:
+            # 处理响应解析错误
+            raise UploadError(
+                message=f"Invalid response format: {str(e)}",
+                error_type=UploadErrorType.PARSE_ERROR,
+                original_error=e
+            )
+        except UploadError:
+            # 重新抛出已经是 UploadError 类型的异常
+            raise
+        except Exception as e:
+            # 处理其他未预期的错误
+            raise UploadError(
+                message=f"Upload failed: {str(e)}",
+                error_type=UploadErrorType.UNKNOWN,
+                original_error=e
+            )
+
+
+class CloudFlareImgBedUploader(ImageUploader):
+    """CloudFlare图床上传器"""
+    
+    def __init__(self, auth_code: str, api_url: str):
+        """
+        初始化CloudFlare图床上传器
+        
+        Args:
+            auth_code: 认证码
+            api_url: 上传API地址
+        """
+        self.auth_code = auth_code
+        self.api_url = api_url
+        
+    def upload(self, file: bytes, filename: str) -> UploadResponse:
+        """
+        上传图片到CloudFlare图床
+        
+        Args:
+            file: 图片文件二进制数据
+            filename: 文件名
+            
+        Returns:
+            UploadResponse: 上传响应对象
+            
+        Raises:
+            UploadError: 上传失败时抛出异常
+        """
+        try:
+            # 准备请求URL（添加认证码参数，如果存在）
+            if self.auth_code:
+                request_url = f"{self.api_url}?authCode={self.auth_code}&uploadNameType=origin"
+            else:
+                request_url = f"{self.api_url}?uploadNameType=origin"
+            
+            # 准备文件数据
+            files = {
+                "file": (filename, file)
+            }
+            
+            # 发送请求
+            response = requests.post(
+                request_url,
+                files=files
+            )
+            
+            # 检查响应状态
+            response.raise_for_status()
+            
+            # 解析响应
+            result = response.json()
+            
+            # 验证响应格式
+            if not result or not isinstance(result, list) or len(result) == 0:
+                raise UploadError(
+                    message="Invalid response format",
+                    error_type=UploadErrorType.PARSE_ERROR
+                )
+                
+            # 获取文件URL
+            file_path = result[0].get("src")
+            if not file_path:
+                raise UploadError(
+                    message="Missing file URL in response",
+                    error_type=UploadErrorType.PARSE_ERROR
+                )
+                
+            # 构建完整URL（如果返回的是相对路径）
+            base_url = self.api_url.split("/upload")[0]
+            full_url = file_path if file_path.startswith(("http://", "https://")) else f"{base_url}{file_path}"
+                
+            # 构建图片元数据（注意：CloudFlare-ImgBed不返回所有元数据，所以部分字段为默认值）
+            image_metadata = ImageMetadata(
+                width=0,  # CloudFlare-ImgBed不返回宽度
+                height=0,  # CloudFlare-ImgBed不返回高度
+                filename=filename,
+                size=0,  # CloudFlare-ImgBed不返回大小
+                url=full_url,
+                delete_url=None  # CloudFlare-ImgBed不返回删除URL
+            )
+            
+            return UploadResponse(
+                success=True,
+                code="success",
+                message="Upload success",
+                data=image_metadata
+            )
+            
+        except requests.RequestException as e:
+            # 处理网络请求相关错误
+            raise UploadError(
+                message=f"Upload request failed: {str(e)}",
+                error_type=UploadErrorType.NETWORK_ERROR,
+                original_error=e
+            )
+        except (KeyError, ValueError, TypeError, IndexError) as e:
+            # 处理响应解析错误
+            raise UploadError(
+                message=f"Invalid response format: {str(e)}",
+                error_type=UploadErrorType.PARSE_ERROR,
+                original_error=e
+            )
+        except UploadError:
+            # 重新抛出已经是 UploadError 类型的异常
+            raise
+        except Exception as e:
+            # 处理其他未预期的错误
+            raise UploadError(
+                message=f"Upload failed: {str(e)}",
+                error_type=UploadErrorType.UNKNOWN,
+                original_error=e
+            )
+    
+class ImageUploaderFactory:
+    @staticmethod
+    def create(provider: str, **credentials) -> ImageUploader:
+        if provider == "smms":
+            return SmMsUploader(credentials["api_key"])
+        elif provider == "qiniu":
+            return QiniuUploader(
+                credentials["access_key"], 
+                credentials["secret_key"]
+            )
+        elif provider == "picgo":
+            api_url = credentials.get("api_url", "https://www.picgo.net/api/1/upload")
+            return PicGoUploader(credentials["api_key"], api_url)
+        elif provider == "cloudflare_imgbed":
+            return CloudFlareImgBedUploader(
+                credentials["auth_code"],
+                credentials["base_url"]
+            )
+        raise ValueError(f"Unknown provider: {provider}")