Add base calculator

package.json

@@ -34,6 +34,7 @@
     "express": "^4.18.2",
     "memory-cache": "^0.2.0",
     "npm-run-all": "^4.1.5",
+    "pluralistic": "github:gitcoinco/pluralistic.js#431f4fe2d429f65f2de03bdfcc66bba451da2ba7",
     "serve-index": "^1.9.1",
     "statuses-bitmap": "github:gitcoinco/statuses-bitmap#3d8fd370f209ccbaffd3781cf2b6d2895237c21c",
     "typescript": "^4.9.5",

src/calculator.ts

@@ -0,0 +1,69 @@
+import fs from "fs";
+import { linearQF, Contribution, Calculation } from "pluralistic";
+
+type AugmentedResult = Calculation & {
+  projectName: string;
+  payoutAddress: string;
+};
+
+export default class Calculator {
+  private baseDataPath: string;
+  private chainId: string;
+  private roundId: string;
+
+  constructor(baseDataPath: string, chainId: string, roundId: string) {
+    this.baseDataPath = baseDataPath;
+    this.chainId = chainId;
+    this.roundId = roundId;
+  }
+
+  calculate() {
+    const rawContributions = this.parseJSONFile(
+      `${this.chainId}/rounds/${this.roundId}/votes.json`
+    );
+    const projects = this.parseJSONFile(`${this.chainId}/projects.json`);
+    const applications = this.parseJSONFile(
+      `${this.chainId}/rounds/${this.roundId}/projects.json`
+    );
+
+    const contributions: Array<Contribution> = rawContributions.map(
+      (raw: any) => ({
+        contributor: raw.voter,
+        recipient: raw.projectId,
+        amount: raw.amountUSD,
+      })
+    );
+
+    const results = linearQF(contributions, 333000, {
+      minimumAmount: 1,
+      ignoreSaturation: true,
+    });
+
+    const augmented: Array<AugmentedResult> = [];
+    for (const id in results) {
+      const calc = results[id];
+      const project = projects.find((p: any) => p.id === id);
+      const application = applications.find((a: any) => a.id === id);
+
+      augmented.push({
+        totalReceived: calc.totalReceived,
+        sumOfSqrt: calc.sumOfSqrt,
+        matched: calc.matched,
+        projectName: project?.metadata?.title,
+        payoutAddress: application?.payoutAddress,
+      });
+    }
+
+    return augmented;
+  }
+
+  parseJSONFile(path: string) {
+    const fullPath = `${this.baseDataPath}/${path}`;
+    const data = fs.readFileSync(fullPath, {
+      encoding: "utf8",
+      flag: "r",
+    });
+
+    return JSON.parse(data);
+  }
+}

src/server.ts

@@ -3,6 +3,7 @@ import cors from "cors";
 import serveIndex from "serve-index";
 
 import config from "./config.js";
+import Calculator from "./calculator.js";
 
 const app = express();
 
@@ -23,6 +24,16 @@ app.get("/", (_req, res) => {
   res.redirect("/data");
 });
 
+app.get("/chains/:chainId/rounds/:roundId/matches", (req, res) => {
+  const chainId = req.params.chainId;
+  const roundId = req.params.roundId;
+
+  const c = new Calculator("./data", chainId, roundId);
+  const matches = c.calculate();
+
+  res.send(matches);
+});
+
 app.listen(config.port, () => {
   console.log(`Server listening on port ${config.port}`);
 });