feat: enhance custom game difficulty calculation and UI

src/components/CustomGameModal.vue

@@ -41,12 +41,12 @@ const handleSnap = () => {
   customSize.value = snapToStep(Number(customSize.value), 5);
 };
 
-const difficultyLevel = computed(() => {
-  return calculateDifficulty(fillRate.value / 100);
+const difficultyInfo = computed(() => {
+  return calculateDifficulty(fillRate.value / 100, customSize.value);
 });
 
 const difficultyColor = computed(() => {
-  switch(difficultyLevel.value) {
+  switch(difficultyInfo.value.level) {
     case 'extreme': return '#ff3333';
     case 'hardest': return '#ff9933';
     case 'harder': return '#ffff33';
@@ -97,7 +97,7 @@ const confirm = () => {
           v-model="fillRate" 
           min="10" 
           max="90"
-          step="5"
+          step="1"
         />
         <div class="range-scale">
           <span>10%</span>
@@ -106,10 +106,9 @@ const confirm = () => {
       </div>
 
       <div class="difficulty-indicator">
-        <span class="label">{{ t('custom.difficulty') }}:</span>
-        <span class="value" :style="{ color: difficultyColor }">
-          {{ t(`difficulty.${difficultyLevel}`) }}
-        </span>
+        <div class="label">{{ t('custom.difficulty') }}</div>
+        <div class="level" :style="{ color: difficultyColor }">{{ t(`difficulty.${difficultyInfo.level}`) }}</div>
+        <div class="percentage" :style="{ color: difficultyColor }">{{ difficultyInfo.value }}%</div>
       </div>
       
       <p v-if="errorMsg" class="error">{{ errorMsg }}</p>
@@ -219,12 +218,30 @@ input[type="range"]::-moz-range-thumb {
     justify-content: space-between;
     color: var(--text-muted);
     font-size: 0.85rem;
+.difficulty-indicator {
+    margin: 20px 0 30px 0;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    gap: 5px;
 }
 
-.difficulty-indicator {
-    margin: 20px 0;
-    font-size: 1.2rem;
-    display: flex;
+.label {
+    font-size: 1rem;
+    color: var(--text-muted);
+}
+
+.level {
+    font-size: 1.4rem;
+    font-weight: bold;
+    text-transform: uppercase;
+    line-height: 1.2;
+}
+
+.percentage {
+    font-size: 1rem;
+    font-weight: bold;
+}   display: flex;
     justify-content: center;
     gap: 10px;
     align-items: center;

src/components/WinModal.vue

@@ -231,7 +231,8 @@ const buildShareSVG = () => {
 
   // Difficulty Logic
   const densityPercent = Math.round(store.currentDensity * 100);
-  const difficultyKey = calculateDifficulty(store.currentDensity);
+  const diffInfo = calculateDifficulty(store.currentDensity, store.size);
+  const difficultyKey = diffInfo.level;
   let diffColor = '#33ff33';
   if (difficultyKey === 'extreme') diffColor = '#ff3333';
   else if (difficultyKey === 'hardest') diffColor = '#ff9933';

src/utils/puzzleUtils.js

@@ -52,24 +52,36 @@ export function generateRandomGrid(size, density = 0.5) {
     return grid;
 }
 
-export function calculateDifficulty(density) {
+export function calculateDifficulty(density, size = 10) {
     // Shannon Entropy: H(x) = -x*log2(x) - (1-x)*log2(1-x)
     // Normalized to 0-1 range (since max entropy at 0.5 is 1)
     
     // Avoid log(0)
-    if (density <= 0 || density >= 1) return 'easy';
+    if (density <= 0 || density >= 1) return { level: 'easy', value: 0 };
     
     const entropy = -density * Math.log2(density) - (1 - density) * Math.log2(1 - density);
     
-    // Thresholds based on entropy
-    // 0.5 density -> entropy 1.0 (Extreme)
-    // 0.4/0.6 density -> entropy ~0.97 (Extreme)
-    // 0.3/0.7 density -> entropy ~0.88 (Hardest)
-    // 0.2/0.8 density -> entropy ~0.72 (Harder)
-    // <0.2/>0.8 density -> entropy <0.72 (Easy)
+    // Difficulty score combines entropy (complexity) and size (scale)
+    // We use sqrt(size) to dampen the effect of very large grids, 
+    // ensuring that density still plays a major role.
+    // Normalized against max size (80)
+    const sizeFactor = Math.sqrt(size / 80);
+    const score = entropy * sizeFactor * 100;
+    const value = Math.round(score);
     
-    if (entropy >= 0.96) return 'extreme'; // approx 38% - 62%
-    if (entropy >= 0.85) return 'hardest'; // approx 28% - 38% & 62% - 72%
-    if (entropy >= 0.65) return 'harder';  // approx 17% - 28% & 72% - 83%
-    return 'easy';
+    // Thresholds
+    let level = 'easy';
+    if (value >= 80) level = 'extreme';
+    else if (value >= 60) level = 'hardest';
+    else if (value >= 40) level = 'harder';
+    else if (value >= 20) level = 'medium'; // Using 'medium' key if available, or we need to add it?
+    // Wait, useI18n only has: easy, harder, hardest, extreme.
+    // Let's stick to those keys but adjust ranges.
+    
+    if (value >= 75) level = 'extreme';
+    else if (value >= 50) level = 'hardest';
+    else if (value >= 25) level = 'harder';
+    else level = 'easy';
+
+    return { level, value };
 }