add: persistant storage of elo ranking

scripts/serve.js

@@ -3,9 +3,16 @@ const http = require("http");
 const path = require("path");
 
 const { repoRoot } = require("./lib/meals");
+const {
+  defaultStatePath,
+  loadRankingsState,
+  recordVote,
+  resetRankingsState,
+} = require("./lib/rankings-state");
 
 const DEFAULT_HOST = "127.0.0.1";
 const DEFAULT_PORT = 4321;
+const MAX_REQUEST_BODY_BYTES = 16 * 1024;
 const MIME_TYPES = {
   ".css": "text/css; charset=utf-8",
   ".gif": "image/gif",
@@ -29,6 +36,7 @@ function parseArgs(argv) {
   const options = {
     host: process.env.HOST || DEFAULT_HOST,
     port: Number.parseInt(process.env.PORT || String(DEFAULT_PORT), 10),
+    rankingsStatePath: path.resolve(process.env.RANKINGS_STATE_PATH || defaultStatePath),
   };
 
   for (let index = 0; index < argv.length; index += 1) {
@@ -44,6 +52,12 @@ function parseArgs(argv) {
     if (arg === "--port" && value) {
       options.port = Number.parseInt(value, 10);
       index += 1;
+      continue;
+    }
+
+    if (arg === "--rankings-state-path" && value) {
+      options.rankingsStatePath = path.resolve(value);
+      index += 1;
     }
   }
 
@@ -58,9 +72,15 @@ function getContentType(filePath) {
   return MIME_TYPES[path.extname(filePath).toLowerCase()] || "application/octet-stream";
 }
 
-function resolveRequestPath(requestUrl) {
-  const url = new URL(requestUrl, "http://localhost");
-  const pathname = decodeURIComponent(url.pathname);
+function hasHiddenSegment(pathname) {
+  return pathname.split("/").some((segment) => segment.startsWith(".") && segment.length > 1);
+}
+
+function resolveRequestPath(pathname) {
+  if (hasHiddenSegment(pathname)) {
+    return null;
+  }
+
   const requestedPath = pathname === "/" ? "/index.html" : pathname;
   const absolutePath = path.resolve(repoRoot, `.${requestedPath}`);
   const withinRepo =
@@ -77,6 +97,56 @@ function resolveRequestPath(requestUrl) {
   return absolutePath;
 }
 
+function sendJson(response, statusCode, payload) {
+  response.writeHead(statusCode, {
+    "Cache-Control": "no-store",
+    "Content-Type": "application/json; charset=utf-8",
+  });
+  response.end(`${JSON.stringify(payload, null, 2)}\n`);
+}
+
+function sendText(response, statusCode, body) {
+  response.writeHead(statusCode, {
+    "Cache-Control": "no-store",
+    "Content-Type": "text/plain; charset=utf-8",
+  });
+  response.end(body);
+}
+
+function parseJsonBody(request) {
+  return new Promise((resolve, reject) => {
+    const chunks = [];
+    let totalBytes = 0;
+
+    request.on("data", (chunk) => {
+      totalBytes += chunk.length;
+
+      if (totalBytes > MAX_REQUEST_BODY_BYTES) {
+        reject(new Error("Request body is too large"));
+        request.destroy();
+        return;
+      }
+
+      chunks.push(chunk);
+    });
+
+    request.on("end", () => {
+      if (chunks.length === 0) {
+        resolve({});
+        return;
+      }
+
+      try {
+        resolve(JSON.parse(Buffer.concat(chunks).toString("utf8")));
+      } catch (error) {
+        reject(new Error("Request body must be valid JSON"));
+      }
+    });
+
+    request.on("error", reject);
+  });
+}
+
 function sendFile(response, filePath) {
   const stream = fs.createReadStream(filePath);
 
@@ -87,24 +157,81 @@ function sendFile(response, filePath) {
 
   stream.pipe(response);
   stream.on("error", () => {
-    response.writeHead(500, { "Content-Type": "text/plain; charset=utf-8" });
-    response.end("Failed to read file");
+    sendText(response, 500, "Failed to read file");
   });
 }
 
-function createServer() {
-  return http.createServer((request, response) => {
-    const filePath = resolveRequestPath(request.url || "/");
+async function handleApiRequest(request, response, pathname, options) {
+  if (pathname === "/api/rankings" && request.method === "GET") {
+    sendJson(response, 200, loadRankingsState({ statePath: options.rankingsStatePath }));
+    return true;
+  }
+
+  if (pathname === "/api/rankings/vote" && request.method === "POST") {
+    const body = await parseJsonBody(request);
+    sendJson(response, 200, recordVote(body, { statePath: options.rankingsStatePath }));
+    return true;
+  }
+
+  if (pathname === "/api/rankings/reset" && request.method === "POST") {
+    sendJson(response, 200, resetRankingsState({ statePath: options.rankingsStatePath }));
+    return true;
+  }
+
+  if (pathname === "/api/rankings" || pathname === "/api/rankings/vote" || pathname === "/api/rankings/reset") {
+    sendText(response, 405, "Method not allowed");
+    return true;
+  }
+
+  if (pathname.startsWith("/api/")) {
+    sendText(response, 404, "Not found");
+    return true;
+  }
+
+  return false;
+}
+
+function createServer(options) {
+  return http.createServer(async (request, response) => {
+    let pathname;
+
+    try {
+      pathname = decodeURIComponent(new URL(request.url || "/", "http://localhost").pathname);
+    } catch (error) {
+      sendText(response, 400, "Bad request");
+      return;
+    }
+
+    try {
+      if (await handleApiRequest(request, response, pathname, options)) {
+        return;
+      }
+    } catch (error) {
+      const statusCode =
+        error.message === "Request body must be valid JSON" ||
+        error.message === "Request body is too large" ||
+        error.message.startsWith("Vote payload") ||
+        error.message === "winnerId and loserId must be different"
+          ? 400
+          : 500;
+
+      if (statusCode >= 500) {
+        console.error(error);
+      }
+
+      sendJson(response, statusCode, { error: error.message });
+      return;
+    }
+
+    const filePath = resolveRequestPath(pathname);
 
     if (!filePath) {
-      response.writeHead(403, { "Content-Type": "text/plain; charset=utf-8" });
-      response.end("Forbidden");
+      sendText(response, 403, "Forbidden");
       return;
     }
 
     if (!fs.existsSync(filePath) || !fs.statSync(filePath).isFile()) {
-      response.writeHead(404, { "Content-Type": "text/plain; charset=utf-8" });
-      response.end("Not found");
+      sendText(response, 404, "Not found");
       return;
     }
 
@@ -114,10 +241,11 @@ function createServer() {
 
 function main() {
   const options = parseArgs(process.argv.slice(2));
-  const server = createServer();
+  const server = createServer(options);
 
   server.listen(options.port, options.host, () => {
     console.log(`Serving ${repoRoot} at http://${options.host}:${options.port}`);
+    console.log(`Rankings state path: ${options.rankingsStatePath}`);
   });
 }