import os
from typing import Dict, Literal

from pydantic import BaseModel, Field
from pydantic_settings import BaseSettings


class DBConfig(BaseModel):
		type: Literal['mysql', 'postgresql']
		host: str
		port: int
		username: str
		password: str
		database: str
		echo: bool = False
		max_overflow: int = 10
		pool_size: int = 50
		pool_recycle: int = 3600
		pool_timeout: int = 30


class DBSettings(BaseSettings):
		databases: Dict[str, DBConfig] = Field(default_factory=dict)  # 新增字段
		
		def __init__(self, **kwargs):
				super().__init__(**kwargs)
				self.databases = self._load_databases()
		
		@staticmethod
		def _load_databases() -> Dict[str, DBConfig]:
				db_dict = {}
				
				# 默认数据库 - 直接从环境变量加载
				default_env_vars = {
						'type': os.environ.get('DB_TYPE', 'mysql'),
						'host': os.environ.get('DB_HOST'),
						'port': int(os.environ.get('DB_PORT', 3306)),
						'username': os.environ.get('DB_USERNAME'),
						'password': os.environ.get('DB_PASSWORD'),
						'database': os.environ.get('DB_DATABASE'),
						'echo': os.environ.get('DB_ECHO', 'false').lower() == 'true',
						'max_overflow': int(os.environ.get('DB_MAX_OVERFLOW', 10)),
						'pool_size': int(os.environ.get('DB_POOL_SIZE', 50)),
						'pool_recycle': int(os.environ.get('DB_POOL_RECYCLE', 3600)),
						'pool_timeout': int(os.environ.get('DB_POOL_TIMEOUT', 30)),
				}
				
				# 验证必要字段
				if not default_env_vars['host'] or not default_env_vars['port']:
						raise ValueError("Default database requires DB_HOST and DB_PORT")
				
				default_db = DBConfig(**default_env_vars)
				db_dict['default'] = default_db
				
				# 多数据库支持
				for key in os.environ:
						if not key.startswith('DB_'):
								continue
						
						suffix = key[3:]
						if '_' not in suffix:
								continue  # 不含下划线，视为全局配置
						
						prefix = suffix.split('_', 1)[0]
						if not prefix:  # 空前缀跳过
								continue
						
						if prefix in db_dict:
								continue  # 已加载过该数据库
						
						host_key = f"DB_{prefix}_HOST"
						port_key = f"DB_{prefix}_PORT"
						
						host = os.environ.get(host_key)
						port = os.environ.get(port_key)
						
						if not host or not port:
								continue  # 必要字段缺失，跳过
						
						try:
								db_dict[prefix] = DBConfig(
										type=os.environ.get(f"DB_{prefix}_TYPE", default_db.type),
										host=host,
										port=int(port),
										username=os.environ.get(f"DB_{prefix}_USERNAME", default_db.username),
										password=os.environ.get(f"DB_{prefix}_PASSWORD", default_db.password),
										database=os.environ.get(f"DB_{prefix}_DATABASE", default_db.database),
										echo=os.environ.get(f"DB_{prefix}_ECHO", str(default_db.echo)).lower() == 'true',
										max_overflow=int(os.environ.get(f"DB_{prefix}_MAX_OVERFLOW", default_db.max_overflow)),
										pool_size=int(os.environ.get(f"DB_{prefix}_POOL_SIZE", default_db.pool_size)),
										pool_recycle=int(os.environ.get(f"DB_{prefix}_POOL_RECYCLE", default_db.pool_recycle)),
										pool_timeout=int(os.environ.get(f"DB_{prefix}_POOL_TIMEOUT", default_db.pool_timeout)),
								)
								db_dict[prefix.lower()] = db_dict[prefix]
						except Exception as e:
								print(f"Failed to load DB config for {prefix}: {e}")
				
				return db_dict