app.js

const express = require("express");
const app = express();
const bcrypt = require("bcrypt");
const path = require("path");
const { open } = require("sqlite");
const sqlite3 = require("sqlite3");

app.use(express.json());
const dbPath = path.join(__dirname, "userData.db");
let db = null;

const initializeDbAndServer = async () => {
  try {
    db = await open({
      filename: dbPath,
      driver: sqlite3.Database,
    });
    app.listen(3000, () => {
      console.log("the server is running at http://localhost:3000/");
    });
  } catch (e) {
    console.log(`DB Error: ${e.message}`);
    process.exit(1);
  }
};

initializeDbAndServer();

//Register Api
app.post("/register", async (request, response) => {
  const { username, name, password, gender, location } = request.body;
  const hashedPassword = await bcrypt.hash(password, 10);

  const selectUserQuery = `SELECT * FROM user WHERE username = '${username}';`;
  const dbUser = await db.get(selectUserQuery);

  if (dbUser === undefined) {
    let createNewUserQuery = `
            INSERT INTO
            user (username,name,password,gender,location)
            VALUES (
                '${username}',
                '${name}',
                '${hashedPassword}',
                '${gender}',
                '${location}'
            );`;
    if (password.length < 5) {
      response.status(400);
      response.send("Password is too short");
    } else {
      const newUserDetails = await db.run(createNewUserQuery);
      response.status(200);
      response.send("User created successfully");
    }
  } else {
    response.status(400);
    response.send("User already exists");
  }
});

//Login API
app.post("/login", async (request, response) => {
  const { username, password } = request.body;
  const selectUserQuery = `SELECT * FROM user WHERE username ='${username}';`;
  const dbUser = await db.get(selectUserQuery);

  if (dbUser === undefined) {
    //Invalid User
    response.status(400);
    response.send("Invalid user");
  } else {
    //Checks password
    const isPasswordMatched = await bcrypt.compare(password, dbUser.password);
    if (isPasswordMatched === true) {
      //Password Matched
      response.send("Login success!");
    } else {
      //unmatched password
      response.status(400);
      response.send("Invalid password");
    }
  }
});

//Update Password
app.put("/change-password", async (request, response) => {
  const { username, oldPassword, newPassword } = request.body;
  const selectUserQuery = `SELECT * FROM user WHERE username = '${username}';`;
  const dbUser = await db.get(selectUserQuery);
  if (dbUser === undefined) {
    response.status(400);
    response.send("User not registered");
  } else {
    const isPasswordMatched = await bcrypt.compare(
      oldPassword,
      dbUser.password
    );
    if (isPasswordMatched === true) {
      //if true make new password
      const lengthOfPassword = newPassword.length;
      if (lengthOfPassword < 5) {
        //new password length
        response.status(400);
        response.send("Password is too short");
      } else {
        const newHashedPassword = await bcrypt.hash(newPassword, 10);
        const updateNewPassQuery = `
        UPDATE user
        SET
        password = '${newHashedPassword}'
        WHERE 
        username = '${username}';`;
        await db.run(updateNewPassQuery);
        response.send("Password updated");
      }
    } else {
      response.status(400);
      response.send("Invalid current password");
    }
  }
});
module.exports = app;