[rewrite] Work on user registration, slightly polished schemas structure

backend/app/core/config.py

@@ -35,7 +35,7 @@ class EnvConfigField():
         regex: Optional[str] = None,
         parser: Optional[Callable[[str], Any]] = None,
     ):
-        self.value = None
+        self.env_value = None
         self.env_name = env_name
         self.data_type = data_type
         self.default = default
@@ -56,7 +56,7 @@ class EnvConfigField():
                 env_name=self.env_name,
             )
 
-        self.value = self.validate(raw_value)
+        self.env_value = self.validate(raw_value)
 
     def validate(self, value: Any) -> Any:
         """Validates the value based on provided constraints."""
@@ -90,7 +90,7 @@ class EnvConfigField():
 
     @property
     def value(self):
-        return self.value
+        return self.env_value
 
     @value.setter
     def value(self, new):
@@ -155,7 +155,17 @@ class EnvConfigField():
                           value=value)
 
 
-class EnvConfig():
+class EnvConfig:
+    """Singleton configuration loader for environment variables."""
+
+    _instance = None
+
+    def __new__(cls):
+        """Ensures only one instance of EnvConfig is created."""
+        if cls._instance is None:
+            cls._instance = super().__new__(cls)
+        return cls._instance
+
     def __init__(self):
         self.logger = logging.getLogger(__name__)
 
@@ -172,13 +182,13 @@ class EnvConfig():
 
         for field in self.fields.values():
             try:
-                field.load
+                field.load()
             except ConfigError as e:
                 self.logger.error("Configuration error: %s", e)
                 raise
 
     def __getitem__(self, key: str):
-        return self.fields["key"].value
+        return self.fields[key].value
 
     def __contains__(self, key: str) -> bool:
         return key in self.fields