feat: key will repeat over every characters even if it isn't in alphabet

src/codewars/kata_cipher_helper.py

@@ -1,9 +1,40 @@
 class VigenereCipher(object):
     def __init__(self, key, alphabet):
-        pass
+        self.key = key
+        self.alphabet = alphabet
 
     def encode(self, text):
-        pass
+        encoded = []
+        idx_key = 0
+
+        for char in text:
+            if char in self.alphabet:
+                text_pos = self.alphabet.index(char)
+                key_char = self.key[idx_key % len(self.key)]
+                key_pos = self.alphabet.index(key_char)
+
+                pos = (text_pos + key_pos) % len(self.alphabet)
+                encoded.append(self.alphabet[pos])
+            else:
+                encoded.append(char)
+            idx_key += 1
+
+        return "".join(encoded)
 
     def decode(self, text):
-        pass
+        decoded = []
+        idx_key = 0
+
+        for char in text:
+            if char in self.alphabet:
+                text_pos = self.alphabet.index(char)
+                key_char = self.key[idx_key % len(self.key)]
+                key_pos = self.alphabet.index(key_char)
+
+                pos = (text_pos - key_pos) % len(self.alphabet)
+                decoded.append(self.alphabet[pos])
+            else:
+                decoded.append(char)
+            idx_key += 1
+
+        return "".join(decoded)

tests/codewars/test_cipher_helper.py

@@ -1,5 +1,16 @@
-"""from src.codewars.kata_cipher_helper import *
+from src.codewars.kata_cipher_helper import VigenereCipher
 
 
 def test_cipher_helper():
-    pass"""
+    abc = "abcdefghijklmnopqrstuvwxyz"
+    key = "password"
+    c = VigenereCipher(key, abc)
+
+    assert c.encode("codewars") == "rovwsoiv"
+    assert c.decode("rovwsoiv") == "codewars"
+
+    assert c.encode("waffles") == "laxxhsj"
+    assert c.decode("laxxhsj") == "waffles"
+
+    assert c.encode("CODEWARS") == "CODEWARS"
+    assert c.decode("CODEWARS") == "CODEWARS"