feat: Add Files API support with upload, list, get and delete operations

- Implement complete Files API compatible with Gemini API format
- Support resumable file uploads with chunked transfer (tested with 15MB video)
- Create file management service with database tracking
- Add file domain models and API request/response objects
- Implement file routes with proper authentication
- Use fixed API key for Files API requests (due to Google API restrictions)
- Support file state management (PROCESSING, ACTIVE, FAILED)
- Add scheduled task for automatic expired file cleanup
- Integrate seamlessly with existing key management and load balancing

app/database/models.py

@@ -2,7 +2,8 @@
 数据库模型模块
 """
 import datetime
-from sqlalchemy import Column, Integer, String, Text, DateTime, JSON, Boolean
+from sqlalchemy import Column, Integer, String, Text, DateTime, JSON, Boolean, BigInteger, Enum
+import enum
 
 from app.database.connection import Base
 
@@ -60,3 +61,69 @@ class RequestLog(Base):
 
     def __repr__(self):
         return f"<RequestLog(id='{self.id}', key='{self.api_key[:4]}...', success='{self.is_success}')>"
+
+
+class FileState(enum.Enum):
+    """文件状态枚举"""
+    PROCESSING = "PROCESSING"
+    ACTIVE = "ACTIVE"
+    FAILED = "FAILED"
+
+
+class FileRecord(Base):
+    """
+    文件记录表，用于存储上传到 Gemini 的文件信息
+    """
+    __tablename__ = "t_file_records"
+    
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    
+    # 文件基本信息
+    name = Column(String(255), unique=True, nullable=False, comment="文件名称，格式: files/{file_id}")
+    display_name = Column(String(255), nullable=True, comment="用户上传时的原始文件名")
+    mime_type = Column(String(100), nullable=False, comment="MIME 类型")
+    size_bytes = Column(BigInteger, nullable=False, comment="文件大小（字节）")
+    sha256_hash = Column(String(255), nullable=True, comment="文件的 SHA256 哈希值")
+    
+    # 状态信息
+    state = Column(Enum(FileState), nullable=False, default=FileState.PROCESSING, comment="文件状态")
+    
+    # 时间戳
+    create_time = Column(DateTime, nullable=False, comment="创建时间")
+    update_time = Column(DateTime, nullable=False, comment="更新时间")
+    expiration_time = Column(DateTime, nullable=False, comment="过期时间")
+    
+    # API 相关
+    uri = Column(String(500), nullable=False, comment="文件访问 URI")
+    api_key = Column(String(100), nullable=False, comment="上传时使用的 API Key")
+    upload_url = Column(Text, nullable=True, comment="临时上传 URL（用于分块上传）")
+    
+    # 额外信息
+    user_token = Column(String(100), nullable=True, comment="上传用户的 token")
+    upload_completed = Column(DateTime, nullable=True, comment="上传完成时间")
+    
+    def __repr__(self):
+        return f"<FileRecord(name='{self.name}', state='{self.state.value if self.state else 'None'}', api_key='{self.api_key[:8]}...')>"
+    
+    def to_dict(self):
+        """转换为字典格式，用于 API 响应"""
+        return {
+            "name": self.name,
+            "displayName": self.display_name,
+            "mimeType": self.mime_type,
+            "sizeBytes": str(self.size_bytes),
+            "createTime": self.create_time.isoformat() + "Z",
+            "updateTime": self.update_time.isoformat() + "Z",
+            "expirationTime": self.expiration_time.isoformat() + "Z",
+            "sha256Hash": self.sha256_hash,
+            "uri": self.uri,
+            "state": self.state.value if self.state else "PROCESSING"
+        }
+    
+    def is_expired(self):
+        """检查文件是否已过期"""
+        # 确保比较时都是 timezone-aware
+        expiration_time = self.expiration_time
+        if expiration_time.tzinfo is None:
+            expiration_time = expiration_time.replace(tzinfo=datetime.timezone.utc)
+        return datetime.datetime.now(datetime.timezone.utc) > expiration_time