fillSpace: distribute remainder

src/lib/utils/fillSpace.ts

@@ -1,12 +1,16 @@
 function fillSpace(availableSpace: number, items: { min: number, max: number }[]) {
+    if (items.length === 0) {
+        return [];
+    }
+
     const middleSize = findMiddleSize(availableSpace, items);
-    return items.map(item => clamp(middleSize, item.min, item.max));
+    const sizes = items.map(item => clamp(middleSize, item.min, item.max));
+    if (middleSize !== Math.floor(availableSpace / items.length)) {
+        distributeRemainder(availableSpace, middleSize, sizes, items);
+    }
+    return sizes;
 
     function findMiddleSize(availableSpace: number, items: { min: number, max: number }[]) {
-        if (items.length === 0) {
-            return 0;
-        }
-
         const ranges = buildRanges(items);
         let requiredSpace = items.reduce((acc, item) => acc + item.min, 0);
         for (const range of ranges) {
@@ -50,6 +54,28 @@ function fillSpace(availableSpace: number, items: { min: number, max: number }[]
         return array;
     }
 
+    function distributeRemainder(availableSpace: number, middleSize: number, sizes: number[], constraints: { max: number }[]) {
+        const indexes = Array.from(sizes.keys())
+            .filter(i => sizes[i] === middleSize);
+        indexes.sort((a, b) => constraints[a].max - constraints[b].max);
+
+        const requiredSpace = sum(...sizes);
+        let remainder = availableSpace - requiredSpace;
+        let n = indexes.length;
+        for (const i of indexes) {
+            if (remainder <= 0) {
+                break;
+            }
+            const enlargable = constraints[i].max - sizes[i];
+            if (enlargable > 0) {
+                const enlarge = Math.min(enlargable, Math.ceil(remainder / n));
+                sizes[i] += enlarge;
+                remainder -= enlarge;
+            }
+            n--;
+        }
+    }
+
     type Range = {
         start: number,
         end: number,

src/tests/units/utils/fillSpace.ts

@@ -58,7 +58,7 @@ tests.register("fillSpace", 1, () => {
                 { min: 400, max: 500 },
                 { min: 10, max: 300 },
             ],
-            expected: [116, 116, 400, 116],
+            expected: [117, 117, 400, 116],
         },
         {
             availableSpace: 750,
@@ -98,7 +98,7 @@ tests.register("fillSpace", 1, () => {
                 { min: 109, max: 800 },
                 { min: 10, max: 800 },
             ],
-            expected: [114, 93, 93, 93, 93, 93, 110, 110],
+            expected: [114, 93, 93, 93, 93, 93, 111, 110],
         },
         {
             availableSpace: 801,
@@ -126,7 +126,7 @@ tests.register("fillSpace", 1, () => {
                 { min: 109, max: 800 },
                 { min: 10, max: 95 },
             ],
-            expected: [120, 93, 93, 93, 93, 93, 120, 95],
+            expected: [121, 93, 93, 93, 93, 93, 120, 95],
         },
         {
             availableSpace: 799,
@@ -140,7 +140,7 @@ tests.register("fillSpace", 1, () => {
                 { min: 10, max: 91},
                 { min: 105, max: 800 },
             ],
-            expected: [79, 107, 107, 107, 107, 107, 79, 105],
+            expected: [80, 107, 107, 107, 107, 107, 79, 105],
         },
         {
             availableSpace: 1029,
@@ -184,7 +184,7 @@ tests.register("fillSpace", 1, () => {
                 { min: 10, max: 600 },
                 { min: 10, max: 600 },
             ],
-            expected: [204, 199, 199, 199],
+            expected: [204, 200, 200, 199],
         },
         {
             availableSpace: 900,