fix: Rate limit (#27)

* [chore] adding electron-fetch dependency

* [feat] adding requests module skeleton

* [feat] not doing any http request to get latest ns version if data is fresh

* [fix] data is considered fresh if less than 5 minutes old

* [feat] adding requests.getLatestNsVersionLink implementation

* [refactor] fully using requests module (with associated cache)

* [docs] adding documentation to requests module

* [refactor] adding a key to get nsLatestRelease cache results

* [chore] removing request deprecated dependency

* [feat] using follow-redirects instead of electron-fetch

* [chore] removing electron-fetch dependency

* fixed formatting

Single quotes to double, proper textwidth for comments, and proper
comment style, the usual... Nothing special here...

* fixed wrong location for requests.json

We don't want to clutter people's config folder, hence we should use the
cache folder instead...

Co-authored-by: 0neGal <mail@0negal.com>

2 files changed, 123 insertions, 52 deletions

diff --git a/src/requests.js b/src/requests.js
new file mode 100644
index 0000000..06c5577
--- /dev/null
+++ b/src/requests.js
@@ -0,0 +1,77 @@
+const { app } = require("electron");
+const path = require("path");
+const fs = require("fs");
+const { https } = require("follow-redirects");
+
+
+// all requests results are stored in this file
+const cachePath = path.join(app.getPath("cache"), "requests.json");
+const NORTHSTAR_LATEST_RELEASE_KEY = "nsLatestRelease";
+
+
+function _saveCache(data) {
+    fs.writeFileSync(cachePath, JSON.stringify(data));
+}
+
+function _getRequestsCache() {
+    if (fs.existsSync(cachePath)) {
+        return JSON.parse(fs.readFileSync(cachePath, "utf8"));
+    } else {
+        fs.writeFileSync(cachePath, "{}");
+        return {};
+    }
+}
+
+// Returns latest Northstar version available from GitHub releases. If
+// there's no cache result for this request, or if cache exists but is
+// old, refreshes cache with new data.
+async function getLatestNsVersion() {
+    return new Promise((resolve, reject) => {
+        let cache = _getRequestsCache();
+    
+        if (cache[NORTHSTAR_LATEST_RELEASE_KEY] && (Date.now() - cache[NORTHSTAR_LATEST_RELEASE_KEY]["time"]) < 5 * 60 * 1000) {
+            console.log(`returning ${NORTHSTAR_LATEST_RELEASE_KEY} data from cache`);
+            resolve( cache[NORTHSTAR_LATEST_RELEASE_KEY]["body"]["tag_name"] );
+        } else {
+            https.get({
+                host: "api.github.com",
+                port: 443,
+                path: "/repos/R2Northstar/Northstar/releases/latest",
+                method: "GET",
+                headers: { "User-Agent": "viper" }
+            }, 
+            
+            response => {
+                response.setEncoding("utf8");
+                let responseData = "";
+
+                response.on("data", data => {
+                    responseData += data;
+                });
+
+                response.on("end", _ => {                    
+                    cache[NORTHSTAR_LATEST_RELEASE_KEY] = {
+                        "time": Date.now(),
+                        "body": JSON.parse(responseData)
+                    };
+                    _saveCache(cache);
+                    resolve( cache[NORTHSTAR_LATEST_RELEASE_KEY]["body"]["tag_name"] );
+                });
+            });
+        }
+    });
+}
+
+// Returns the download link to latest Northstar version. Should always
+// be called after getLatestNsVersion, as it refreshes cache data (if
+// needed).
+function getLatestNsVersionLink() {
+    const cache = _getRequestsCache();
+    return cache[NORTHSTAR_LATEST_RELEASE_KEY]["body"].assets[0].browser_download_url;
+}
+
+
+module.exports = {
+    getLatestNsVersion, 
+    getLatestNsVersionLink
+};
diff --git a/src/utils.js b/src/utils.js
index d2e6fe6..85db119 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -7,9 +7,9 @@ const events = new Emitter();
 
 const cli = require("./cli");
 const lang = require("./lang");
+const requests = require("./requests");
 
 const unzip = require("unzipper");
-const request = require("request");
 const exec = require("child_process").spawn;
 const { https } = require("follow-redirects");
 
@@ -69,7 +69,7 @@ function getNSVersion() {
 	}
 }
 
-function update() {
+async function update() {
 	for (let i = 0; i < settings.excludes.length; i++) {
 		let exclude = path.join(settings.gamepath + "/" + settings.excludes[i]);
 		if (fs.existsSync(exclude)) {
@@ -81,59 +81,53 @@ function update() {
 	console.log(lang("cli.update.checking"));
 	var version = getNSVersion();
 
-	request({
-		json: true,
-		headers: {"User-Agent": "Viper"},
-		url: "https://api.github.com/repos/R2Northstar/Northstar/releases/latest",
-	}, (error, response, body) => {
-		var tag = body["tag_name"];
-
-		if (version === tag) {
-			ipcMain.emit("ns-updated");
-			console.log(lang("cli.update.uptodate"), version);
-
-			winLog(lang("gui.update.uptodate"));
-			return;
-		} else {
-			if (version != "unknown") {
-				console.log(lang("cli.update.current"), version);
-			}; console.log(lang("cli.update.downloading") + ":", tag);
-
-			winLog(lang("gui.update.downloading"));
-		}
+	const latestAvailableVersion = await requests.getLatestNsVersion();
+
+	if (version === latestAvailableVersion) {
+		ipcMain.emit("ns-updated");
+		console.log(lang("cli.update.uptodate"), version);
+
+		winLog(lang("gui.update.uptodate"));
+		return;
+	} else {
+		if (version != "unknown") {
+			console.log(lang("cli.update.current"), version);
+		}; console.log(lang("cli.update.downloading") + ":", latestAvailableVersion);
+
+		winLog(lang("gui.update.downloading"));
+	}
+
+	https.get(requests.getLatestNsVersionLink(), (res) => {
+		let stream = fs.createWriteStream(settings.zip);
+		res.pipe(stream);
+
+		let received = 0;
+		res.on("data", (chunk) => {
+			received += chunk.length;
+			winLog(lang("gui.update.downloading") + " " + (received / 1024 / 1024).toFixed(1) + "mb");
+		})
 
-		https.get(body.assets[0].browser_download_url, (res) => {
-			let stream = fs.createWriteStream(settings.zip);
-			res.pipe(stream);
-
-			let received = 0;
-			res.on("data", (chunk) => {
-				received += chunk.length;
-				winLog(lang("gui.update.downloading") + " " + (received / 1024 / 1024).toFixed(1) + "mb");
-			})
-
-			stream.on("finish", () => {
-				stream.close();
-				winLog(lang("gui.update.extracting"));
-				console.log(lang("cli.update.downloaddone"));
-				fs.createReadStream(settings.zip).pipe(unzip.Extract({path: settings.gamepath}))
-				.on("finish", () => {
-					fs.writeFileSync(path.join(settings.gamepath, "ns_version.txt"), tag);
-					ipcMain.emit("getversion");
-
-					for (let i = 0; i < settings.excludes.length; i++) {
-						let exclude = path.join(settings.gamepath + "/" + settings.excludes[i]);
-						if (fs.existsSync(exclude + ".excluded")) {
-							fs.renameSync(exclude + ".excluded", exclude)
-						}
+		stream.on("finish", () => {
+			stream.close();
+			winLog(lang("gui.update.extracting"));
+			console.log(lang("cli.update.downloaddone"));
+			fs.createReadStream(settings.zip).pipe(unzip.Extract({path: settings.gamepath}))
+			.on("finish", () => {
+				fs.writeFileSync(path.join(settings.gamepath, "ns_version.txt"), latestAvailableVersion);
+				ipcMain.emit("getversion");
+
+				for (let i = 0; i < settings.excludes.length; i++) {
+					let exclude = path.join(settings.gamepath + "/" + settings.excludes[i]);
+					if (fs.existsSync(exclude + ".excluded")) {
+						fs.renameSync(exclude + ".excluded", exclude)
 					}
+				}
 
-					ipcMain.emit("ns-updated");
-					winLog(lang("gui.update.finished"));
-					console.log(lang("cli.update.finished"));
-					cli.exit();
-				});
-			})
+				ipcMain.emit("ns-updated");
+				winLog(lang("gui.update.finished"));
+				console.log(lang("cli.update.finished"));
+				cli.exit();
+			});
 		})
 	})
 }