feat: implement WebADIS authentication and add medianumber retrieval functionality

src/logic/webrequest.py

@@ -1,3 +1,4 @@
+from enum import Enum
 from typing import Any, Optional, Union
 
 import requests
@@ -33,6 +34,14 @@ RATE_LIMIT = 20
 RATE_PERIOD = 30
 
 
+class TransformerType(Enum):
+    ARRAY = "ARRAY"
+    COinS = "COinS"
+    BibTeX = "BibTeX"
+    RIS = "RIS"
+    RDS = "RDS"
+
+
 class WebRequest:
     def __init__(self) -> None:
         """Request data from the web, and format it depending on the mode."""
@@ -185,10 +194,16 @@ class BibTextTransformer:
         ValueError: Raised if mode is not in valid_modes
     """
 
-    valid_modes = ["ARRAY", "COinS", "BibTeX", "RIS", "RDS"]
+    valid_modes = [
+        TransformerType.ARRAY,
+        TransformerType.COinS,
+        TransformerType.BibTeX,
+        TransformerType.RIS,
+        TransformerType.RDS,
+    ]
 
-    def __init__(self, mode: str = "ARRAY") -> None:
-        self.mode = mode
+    def __init__(self, mode: TransformerType = TransformerType.ARRAY) -> None:
+        self.mode = mode.value
         self.field = None
         self.signature = None
         if mode not in self.valid_modes: