app.js

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

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

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

initializeDbAndServer();

const validatePassword = (password) => {
  return password.length > 4;
};

//User Register API

app.post("/register", async (request, response) => {
  const { username, name, password, gender, location } = request.body;
  const hashedPassword = await bcrypt.hash(password, 10);
  const selectRegisterQuery = `
    select * from user where username = "${username}";`;
  const dbUser = await db.get(selectRegisterQuery);
  if (dbUser === undefined) {
    const createUserQuery = `
        insert into
        user (username, name, password, gender, location)
        values
        (
            "${username}",
            "${name}",
            "${hashedPassword}",
            "${gender}",
            "${location}");`;
    if (validatePassword(password)) {
      await db.run(createUserQuery);
      response.send("User created successfully");
    } else {
      response.status(400);
      response.send("Password is too short");
    }
  } 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) {
    response.status(400);
    response.send("Invalid user");
  } else {
    const isPasswordMatched = await bcrypt.compare(password, dbUser.password);
    if (isPasswordMatched === true) {
      response.send("Login success!");
    } else {
      response.status(400);
      response.send("Invalid password");
    }
  }
});

// Change Password API

app.put("/change-password", async (request, response) => {
  const { username, oldPassword, newPassword } = request.body;
  const selectUserQuery = `select* from user where username = "${username}";`;
  const dbUser = await db.get(selectUserQuery);
  if (dbUser === undefined) {
    response.status(400);
    response.send("Invalid user");
  } else {
    const isPasswordMatched = await bcrypt.compare(
      oldPassword,
      dbUser.password
    );
    if (isPasswordMatched === true) {
      if (validatePassword(newPassword)) {
        const hashedPassword = await bcrypt.hash(newPassword, 10);
        const updatePasswordQuery = `
            update
            user
            set
            password = "${hashedPassword}"
            where username = "${username}";`;
        const userQuery = await db.run(updatePasswordQuery);
        response.send("Password updated");
      } else {
        response.status(400);
        response.send("Password is too short");
      }
    } else {
      response.status(400);
      response.send("Invalid current password");
    }
  }
});

module.exports = app;

// Register and Login Api
// knjun kjno knj 
// lnsca