votes ranking system

package.json

@@ -19,6 +19,7 @@
     "@fastify/cookie": "^9.3.1",
     "@prisma/client": "^5.9.1",
     "fastify": "^4.26.0",
+    "ioredis": "^5.3.2",
     "zod": "^3.22.4"
   }
 }

src/http/routes/get-poll.ts

@@ -1,6 +1,7 @@
 import { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
 import z from "zod";
 import { prisma } from "../../lib/prisma";
+import { redis } from "../../lib/redis";
 
 export async function getPoll(app: FastifyInstance) {
   app.get(
@@ -26,7 +27,33 @@ export async function getPoll(app: FastifyInstance) {
         },
       });
 
-      return reply.send({ poll });
+      if (!poll) {
+        return reply.status(404).send({ message: "Poll not found." });
+      }
+
+      const result = await redis.zrange(pollId, 0, -1, "WITHSCORES");
+
+      const votes = result.reduce((obj, line, index) => {
+        if (index % 2 === 0) {
+          const score = result[index + 1];
+          Object.assign(obj, { [line]: Number(score) });
+        }
+        return obj;
+      }, {} as Record<string, number>);
+
+      return reply.send({
+        poll: {
+          id: poll.id,
+          title: poll.title,
+          options: poll.options.map((option) => {
+            return {
+              id: option.id,
+              title: option.title,
+              score: option.id in votes ? votes[option.id] : 0,
+            };
+          }),
+        },
+      });
     }
   );
 }

src/http/routes/vote-on-poll.ts

@@ -2,6 +2,7 @@ import { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
 import z from "zod";
 import { randomUUID } from "node:crypto";
 import { prisma } from "../../lib/prisma";
+import { redis } from "../../lib/redis";
 
 export async function voteOnPoll(app: FastifyInstance) {
   app.post(
@@ -39,6 +40,8 @@ export async function voteOnPoll(app: FastifyInstance) {
               id: userPreviousVoteOnPoll.id,
             },
           });
+
+          await redis.zincrby(pollId, -1, userPreviousVoteOnPoll.pollOptionId);
         } else if (userPreviousVoteOnPoll) {
           return reply
             .status(400)
@@ -65,6 +68,8 @@ export async function voteOnPoll(app: FastifyInstance) {
         },
       });
 
+      await redis.zincrby(pollId, 1, pollOptionId);
+
       return reply.status(201);
     }
   );

src/lib/redis.ts

@@ -0,0 +1,3 @@
+import { Redis } from "ioredis";
+
+export const redis = new Redis();