Refactor, breaking code into modules.

game.py

@@ -0,0 +1,76 @@
+#!/usr/bin/python
+
+import random
+from enum import Enum
+
+import dictionary
+
+
+class LetterResult(Enum):
+    """Is an individual letter in a word in the result?"""
+
+    CORRECT = "C"
+    MOVE = "M"
+    INCORRECT = "I"
+    UNKNOWN = "U"
+
+
+class InvalidWord(Exception):
+    """Thrown when an input word is not a valid Wordle."""
+
+    pass
+
+
+def select_word(words=dictionary.words()):
+    return random.choice(list(words))
+
+
+def grade_word(target, guess, words=dictionary.words()):
+    # We don't check word length, since all valid words are 5 letters.
+    if guess not in words:
+        raise InvalidWord(f"{guess} is not a valid Wordle.")
+
+    result = [LetterResult.UNKNOWN] * dictionary.WORDLE_LENGTH
+
+    # We copy target, and remove letters if we find them. This handles duplicate letters correctly.
+    # For example, if the target is "pulls" and we guess "apple", only the first "p" should be a
+    # MOVE. The second should be INCORRECT.
+    remaining = list(target)
+
+    # Find all correct results first.
+    for i in range(dictionary.WORDLE_LENGTH):
+        if target[i] == guess[i]:
+            result[i] = LetterResult.CORRECT
+            remaining.remove(guess[i])
+
+    for i in range(dictionary.WORDLE_LENGTH):
+        if result[i] == LetterResult.UNKNOWN:
+            if guess[i] in remaining:
+                # Letter is in the wrong place.
+                result[i] = LetterResult.MOVE
+                remaining.remove(guess[i])
+            else:
+                # Letter is not in target.
+                result[i] = LetterResult.INCORRECT
+
+    return result
+
+
+def display_result(result, text):
+    opening = {
+        LetterResult.CORRECT: "\033[92m",
+        LetterResult.MOVE: "\033[33m",
+        LetterResult.INCORRECT: "\033[36m",
+        LetterResult.UNKNOWN: "",
+    }
+    closing = "\033[0m"
+
+    return f"{opening[result]}{text}{closing}"
+
+
+def success_result(result):
+    for r in result:
+        if r != LetterResult.CORRECT:
+            return False
+
+    return True