Config scan from bot channel implementation

breadtube_bot/config.py

@@ -1,3 +1,5 @@
+from __future__ import annotations as _annotations
+
 from dataclasses import asdict, dataclass
 
 
@@ -5,17 +7,33 @@ from dataclasses import asdict, dataclass
 class Config:
     bot_channel: str = 'breadtube-bot'
     bot_role: str = 'BreadTube'
+    bot_channel_scan_interval: float = 30.
     bot_channel_init_retries: int = 3
+    bot_message_duration: float = 150.
+    request_timeout: float = 3.
 
     def to_str(self) -> str:
         return '\n'.join(['config', *[f'{k}={v}' for k, v in asdict(self).items()]])
 
-    def from_str(self, text: str):
+    @staticmethod
+    def from_str(text: str) -> Config:
+        annotations = Config.__annotations__
+        global_types = globals()['__builtins__']
+        config = Config()
         lines = text.strip().splitlines()
         if not lines:
-            raise RuntimeError('Config cannot load: empty input')
+            raise RuntimeError('Cannot load config: empty input')
         if lines[0] != 'config':
-            raise RuntimeError('Config cannot load: first line is not "config"')
-        for line in lines[1:]:
+            raise RuntimeError('Cannot load config: first line is not "config"')
+        config_dict = {}
+        for line_number, line in enumerate(lines[1:]):
             key, value = line.split('=', maxsplit=1)
-            setattr(self, key, self.__annotations__[key](value))
+            if key not in annotations:
+                raise RuntimeError(f'Invalid config: invalid key {key} at line {line_number + 1}')
+            if key in config_dict:
+                raise RuntimeError(f'Invalid config: duplicated key {key} at line {line_number + 1}')
+            config_dict[key] = value
+
+        for key, value in config_dict.items():
+            setattr(config, key, global_types[annotations[key]](value))
+        return config