Impl: project requirements

index.js

@@ -2,9 +2,59 @@ require("dotenv").config();
 const express = require("express");
 const cors = require("cors");
 const app = express();
+const mongoose = require("mongoose");
+const dns = require("dns");
 
 // Basic Configuration
 const port = process.env.PORT || 3000;
+const MONGODB_URI = process.env.MONGODB_URI || "";
+
+mongoose.connect(MONGODB_URI, {
+  // @ts-ignore
+  useNewUrlParser: true,
+  useUnifiedTopology: true,
+});
+
+const urlSchema = new mongoose.Schema({
+  original: {
+    type: String,
+    unique: true,
+  },
+  short: { type: Number, unique: true },
+});
+
+const Url = mongoose.model("Url", urlSchema);
+
+const counterSchema = new mongoose.Schema({
+  name: { type: String, unique: true },
+  seq: { type: Number, default: 0 },
+});
+
+const Counter = mongoose.model("Counter", counterSchema);
+
+let shortUrlsCounter = 0;
+
+Counter.findOne({ name: "shortUrl" })
+  .then((counter) => {
+    if (counter) {
+      shortUrlsCounter = counter.seq;
+      console.log(`Old counter: ${counter}`);
+    } else {
+      const shortUrlsCounterModel = new Counter({ name: "shortUrl" });
+      shortUrlsCounterModel
+        .save()
+        .then((counter) => {
+          if (counter) {
+            shortUrlsCounter = counter.seq;
+            console.log(`New counter: ${counter}`);
+          } else {
+            console.log(`Error: could not create a new counter`);
+          }
+        })
+        .catch((err) => console.log(err));
+    }
+  })
+  .catch((err) => console.log(err));
 
 app.use(cors());
 
@@ -14,9 +64,80 @@ app.get("/", function (req, res) {
   res.sendFile(process.cwd() + "/views/index.html");
 });
 
+app.use(express.urlencoded({ extended: false }));
+
 // Your first API endpoint
-app.get("/api/hello", function (req, res) {
+app.post("/api/shorturl/", (req, res) => {
-  res.json({ greeting: "hello API" });
+  const original = req.body.url;
+  try {
+    const hostname = new URL(original).hostname;
+    dns.lookup(hostname, (err, addr, family) => {
+      if (err) {
+        console.log(`Invalid url:\n${err}`);
+        res.json({ error: "Invalid URL" });
+      } else {
+        Url.findOne({ original: original })
+          .then((url) => {
+            if (url)
+              return res.json({
+                original_url: original,
+                short_url: url?.short,
+              });
+            const urlModel = new Url({
+              original: original,
+              short: shortUrlsCounter++,
+            });
+            Counter.findOneAndUpdate(
+              { name: "shortUrl" },
+              { $set: { seq: shortUrlsCounter } },
+              { new: true }
+            )
+              .then((counter) => {
+                if (counter)
+                  console.log(`${counter?.name} updated to ${counter?.seq}`);
+                else {
+                  console.log(`Could not find "shortUrl" counter in DB`);
+                  return res.sendStatus(500);
+                }
+              })
+              .catch((err) => {
+                console.log(`Error updating shortUrl counter in DB:\n${err}`);
+                return res.sendStatus(500);
+              });
+            urlModel
+              .save()
+              .then((url) => {
+                if (url)
+                  return res.json({
+                    original_url: original,
+                    short_url: url?.short,
+                  });
+                console.log(`Unlikely scenario occurred!:\n${url}`);
+                res.sendStatus(500);
+              })
+              .catch((err) => {
+                console.log(`Inserting url to DB failed!:\n${err}`);
+                res.sendStatus(500);
+              });
+          })
+          .catch((err) => {
+            console.log(`Query failed!:\n${err}`);
+            res.sendStatus(500);
+          });
+      }
+    });
+  } catch (err) {
+    res.json({ error: "Invalid URL" });
+  }
+});
+
+app.get("/api/shorturl/:shorturl", (req, res) => {
+  const shorturl = Number(req.params.shorturl);
+  Url.findOne({ short: shorturl })
+    .then((url) => res.redirect(url.original))
+    .catch((err) =>
+      res.json({ error: "No short URL found for the given input" })
+    );
 });
 
 app.listen(port, function () {