encode and decode baconian ciphers with any characters

ciphers/baconian_cipher.py

@@ -1,8 +1,3 @@
-"""
-Program to encode and decode Baconian or Bacon's Cipher
-Wikipedia reference : https://en.wikipedia.org/wiki/Bacon%27s_cipher
-"""
-
 encode_dict = {
     "a": "AAAAA",
     "b": "AAAAB",
@@ -33,57 +28,67 @@
     " ": " ",
 }
 
-
 decode_dict = {value: key for key, value in encode_dict.items()}
 
-
-def encode(word: str) -> str:
-    """
-    Encodes to Baconian cipher
-
-    >>> encode("hello")
-    'AABBBAABAAABABAABABAABBAB'
-    >>> encode("hello world")
-    'AABBBAABAAABABAABABAABBAB BABAAABBABBAAAAABABAAAABB'
-    >>> encode("hello world!")
-    Traceback (most recent call last):
-        ...
-    Exception: encode() accepts only letters of the alphabet and spaces
-    """
+def encode(word: str, symbols=("A","B")) -> str:
+    a_sym, b_sym = symbols
     encoded = ""
     for letter in word.lower():
         if letter.isalpha() or letter == " ":
-            encoded += encode_dict[letter]
+            # replace A with a_symbol, B with b_symbol
+            bacon = encode_dict[letter]
+            bacon_custom = bacon.replace("A", a_sym).replace("B", b_sym)
+            encoded += bacon_custom
         else:
             raise Exception("encode() accepts only letters of the alphabet and spaces")
     return encoded
 
-
-def decode(coded: str) -> str:
-    """
-    Decodes from Baconian cipher
-
-    >>> decode("AABBBAABAAABABAABABAABBAB BABAAABBABBAAAAABABAAAABB")
-    'hello world'
-    >>> decode("AABBBAABAAABABAABABAABBAB")
-    'hello'
-    >>> decode("AABBBAABAAABABAABABAABBAB BABAAABBABBAAAAABABAAAABB!")
-    Traceback (most recent call last):
-        ...
-    Exception: decode() accepts only 'A', 'B' and spaces
-    """
-    if set(coded) - {"A", "B", " "} != set():
-        raise Exception("decode() accepts only 'A', 'B' and spaces")
-    decoded = ""
-    for word in coded.split():
-        while len(word) != 0:
-            decoded += decode_dict[word[:5]]
-            word = word[5:]
-        decoded += " "
-    return decoded.strip()
-
+def decode(coded: str, symbols=("A","B")) -> str:
+    sym1, sym2 = symbols
+    #  check if we need to remap
+    unique_symbols = set(coded.replace(" ", ""))
+    if unique_symbols - {sym1, sym2} != set():
+        raise Exception(f"decode() accepts only symbols {sym1} and {sym2} and spaces")
+
+    # Try both mappings: symbol1 maps to A, symbol2 maps to B or symbol1 maps to B, symbol2 maps A
+    candidates = []
+    for mapping in [(sym1, sym2), (sym2, sym1)]:
+        s1, s2 = mapping
+        # convert coded symbols to standard A/B
+        standard = coded.replace(s1, "A").replace(s2, "B")
+        try:
+            decoded = ""
+            for word in standard.split():
+                while len(word) != 0:
+                    chunk = word[:5]
+                    if chunk not in decode_dict:
+                        raise ValueError
+                    decoded += decode_dict[chunk]
+                    word = word[5:]
+                decoded += " "
+            candidates.append(decoded.strip())
+        except ValueError:
+            candidates.append(None)
+
+    # return the valid decoding
+    for candidate in candidates:
+        if candidate is not None:
+            return candidate
+    raise Exception("No valid decoding found with the given symbols")
+def detect_unique_char (cipher):
+    #CD CD DC returns C, D
+    cipher = cipher.replace(" ","")
+    unique_chars = set(cipher)
+    unique_letters = [char for char in unique_chars if char.isalpha()]
+    if len(unique_letters) != 2:
+        raise Exception("Cipher must contain exactly two unique alphabetic characters for encoding.")
+    else:
+        list_unique = list(unique_letters)
+        return list_unique[0], list_unique[1]
 
 if __name__ == "__main__":
-    from doctest import testmod
-
-    testmod()
+    # Example usage
+    cipher_text = "FEEFE EEFFF EEFEE EFFFF FEEFF EFEEE EEEFE EFEEF EEEEF FEEEE EFFEF FEFEE EFFEE EEFEF EFFEF FEFEF"
+    symbol_1, symbol_2 = detect_unique_char(cipher_text)
+    decoded = decode(cipher_text, symbols=(symbol_1, symbol_2))
+    print(decoded)  # prints the quick brown fox