Point out which codes are too close

france/france_rsvp/codes.py

@@ -11,6 +11,50 @@ assert len(ALPHABET) == 32
 LENGTH = 4
 
 
+def list_errors(code):
+    for place in range(LENGTH):
+        for replacement in ALPHABET:
+            if replacement == code[place]:
+                continue
+            new_code = code[:place] + replacement + code[place + 1:]
+            yield new_code
+
+
+correct_codes = set()
+errored_codes = {}
+
+
+def _load_codes():
+    global correct_codes
+    global errored_codes
+
+    # Get the current codes
+    with get_db() as db:
+        correct_codes = set(row[0] for row in db.execute(
+            '''\
+            SELECT code FROM families;
+            ''',
+        ))
+
+    # Augment them with possible errored codes
+    errored_codes = {}
+    for code in correct_codes:
+        for error in list_errors(code):
+            if error in errored_codes:
+                raise ValueError("%s too close to %s" % (
+                    code,
+                    errored_codes[error],
+                ))
+            errored_codes[error] = code
+    assert (
+        len(errored_codes)
+        == LENGTH * (len(ALPHABET) - 1) * len(correct_codes)
+    )
+
+
+_load_codes()
+
+
 CORRECT = {
     'i': '1',
     'l': '1',
@@ -21,16 +65,8 @@ CORRECT = {
 def correct_code(code):
     code = code.lower()
     fixed_code = ''.join(CORRECT.get(c, c) for c in code)
-    return fixed_code
-
-
-def list_errors(code):
-    for place in range(LENGTH):
-        for replacement in ALPHABET:
-            if replacement == code[place]:
-                continue
-            new_code = code[:place] + replacement + code[place + 1:]
-            yield new_code
+    fixed_code = errored_codes.get(fixed_code, None)
+    return fixed_code or code
 
 
 def main():
@@ -43,20 +79,6 @@ def main():
     else:
         raise ValueError
 
-    # Get the current codes
-    with get_db() as db:
-        correct_codes = set(row[0] for row in db.execute(
-            '''\
-            SELECT code FROM families;
-            ''',
-        ))
-
-    # Augment them with possible errored codes
-    errored_codes = set()
-    for code in correct_codes:
-        errored_codes.update(list_errors(code))
-    assert len(errored_codes) == LENGTH * (len(ALPHABET) - 1) * len(correct_codes)
-
     # Generate new codes
     generated = 0
     while generated < number:
@@ -64,6 +86,7 @@ def main():
         if code in correct_codes or code in errored_codes:
             continue
         correct_codes.add(code)
-        errored_codes.update(list_errors(code))
+        for error in list_errors(code):
+            errored_codes[error] = code
         print(code)
         generated += 1