From ddba750d1209bce822999bc0a122fd3d48aa9048 Mon Sep 17 00:00:00 2001
From: Lynn <lynn@foldr.moe>
Date: Mon, 24 Jan 2022 18:16:26 +0100
Subject: [PATCH] Check yellow counts even in Hard difficulty (fixes #58)

---
 src/clue.ts | 65 +++++++++++++++++++++++++----------------------------
 1 file changed, 30 insertions(+), 35 deletions(-)

diff --git a/src/clue.ts b/src/clue.ts
index 8df55b8..aeed2e1 100644
--- a/src/clue.ts
+++ b/src/clue.ts
@@ -66,46 +66,41 @@ export function violation(
   if (difficulty === Difficulty.Normal) {
     return undefined;
   }
+  const ultra = difficulty === Difficulty.UltraHard;
   let i = 0;
   for (const { letter, clue } of clues) {
-    const upper = letter.toUpperCase();
+    const clueCount = clues.filter(
+      (c) => c.letter === letter && c.clue !== Clue.Absent
+    ).length;
+    const guessCount = guess.split(letter).length - 1;
+    const glyph = letter.toUpperCase();
+    const glyphs = glyph + (clueCount !== 1 ? "s" : "");
     const nth = ordinal(i + 1);
-    if (clue === Clue.Correct) {
-      if (guess[i] !== letter) {
-        return nth + " letter must be " + upper;
-      }
-    } else if (clue === Clue.Elsewhere) {
-      if (!guess.includes(letter)) {
-        return "Guess must contain " + upper;
-      }
+
+    // Hard: enforce greens stay in place.
+    if (clue === Clue.Correct && guess[i] !== letter) {
+      return nth + " letter must be " + glyph;
     }
-    if (difficulty === Difficulty.UltraHard) {
-      if (clue !== Clue.Correct && guess[i] === letter) {
-        return nth + " letter can't be " + upper;
-      }
-      const clueCount = clues.filter(
-        (c) => c.letter === letter && c.clue !== Clue.Absent
-      ).length;
-      const guessCount = guess.split(letter).length - 1;
-      const hasAbsent = clues.some(
-        (c) => c.letter === letter && c.clue === Clue.Absent
-      );
-      const amount = englishNumbers[clueCount];
-      const s = clueCount !== 1 ? "s" : "";
-      if (hasAbsent) {
-        if (guessCount !== clueCount) {
-          if (clueCount === 0) {
-            return `Guess can't contain ${upper}`;
-          } else {
-            return `Guess must contain exactly ${amount} ${upper}${s}`;
-          }
-        }
-      } else {
-        if (guessCount < clueCount) {
-          return `Guess must contain at least ${amount} ${upper}${s}`;
-        }
-      }
+
+    // Hard: enforce yellows are used.
+    if (guessCount < clueCount) {
+      const atLeastN =
+        clueCount > 1 ? `at least ${englishNumbers[clueCount]} ` : "";
+      return `Guess must contain ${atLeastN}${glyphs}`;
     }
+
+    // Ultra Hard: disallow would-be greens.
+    if (ultra && clue !== Clue.Correct && guess[i] === letter) {
+      return nth + " letter can't be " + glyph;
+    }
+
+    // Ultra Hard: if the exact amount is known because of an Absent clue, enforce it.
+    if (ultra && clue === Clue.Absent && guessCount !== clueCount) {
+      return clueCount === 0
+        ? `Guess can't contain ${glyph}`
+        : `Guess must contain exactly ${englishNumbers[clueCount]} ${glyphs}`;
+    }
+
     ++i;
   }
   return undefined;