Add: totalAmount, totalUser field into item leaderboard

sparcs-kaist · Sep 1, 2024 · 05126ee · 05126ee
1 parent e7ef57b
commit 05126ee
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Showing 3 changed files with 27 additions and 6 deletions.
diff --git a/src/lottery/modules/stores/mongo.js b/src/lottery/modules/stores/mongo.js
@@ -106,7 +106,13 @@ const itemSchema = Schema({
     required: true,
     min: 0,
     validate: integerValidator,
-  },
+  }, // 의미 없는 값, 기존 코드와의 호환성을 위해 남겨둡니다.
+  realStock: {
+    type: Number,
+    required: true,
+    min: 1,
+    validate: integerValidator,
+  }, // 상품의 실제 재고
   itemType: {
     type: Number,
     enum: [0, 1, 2, 3],

diff --git a/src/lottery/routes/docs/items.js b/src/lottery/routes/docs/items.js
@@ -102,7 +102,7 @@ itemsDocs[`${apiPrefix}/leaderboard/{itemId}`] = {
           "application/json": {
             schema: {
               type: "object",
-              required: ["leaderboard"],
+              required: ["leaderboard", "totalAmount", "totalUser"],
               properties: {
                 leaderboard: {
                   type: "array",
@@ -139,6 +139,16 @@ itemsDocs[`${apiPrefix}/leaderboard/{itemId}`] = {
                     },
                   },
                 },
+                totalAmount: {
+                  type: "number",
+                  description: "상품의 총 판매량",
+                  example: 100,
+                },
+                totalUser: {
+                  type: "number",
+                  description: "상품을 구입한 유저의 수",
+                  example: 50,
+                },
                 rank: {
                   type: "number",
                   description: "현재 유저의 리더보드 순위. 1부터 시작합니다.",

diff --git a/src/lottery/services/items.js b/src/lottery/services/items.js
@@ -26,10 +26,13 @@ const getItemsHandler = async (req, res) => {
 };
 
 // 유도 과정은 services/publicNotice.js 파일에 정의된 calculateProbabilityV2 함수의 주석 참조
-const calculateWinProbability = (stock, users, amount, totalAmount) => {
-  if (users.length <= stock) return 1;
+const calculateWinProbability = (realStock, users, amount, totalAmount) => {
+  if (users.length <= realStock) return 1;
 
-  const base = Math.pow(1 - stock / users.length, users.length / totalAmount);
+  const base = Math.pow(
+    1 - realStock / users.length,
+    users.length / totalAmount
+  );
   return 1 - Math.pow(base, amount);
 };
 
@@ -93,7 +96,7 @@ const getItemLeaderboardHandler = async (req, res) => {
       userId: user._id,
       amount: user.amount,
       probability: calculateWinProbability(
-        item.stock,
+        item.realStock,
         users,
         user.amount,
         totalAmount
@@ -121,6 +124,8 @@ const getItemLeaderboardHandler = async (req, res) => {
 
     return res.json({
       leaderboard,
+      totalAmount,
+      totalUser: users.length,
       amount: user?.amount,
       probability: user?.probability,
       rank: user?.rank,