const fs = require('fs');
const bodyParser = require('body-parser');
const jsonServer = require('json-server');
const jwt = require('jsonwebtoken');

const server = jsonServer.create();

const router = jsonServer.router('./db.json');

const userdb = JSON.parse(fs.readFileSync('./users.json', 'UTF-8'));

server.use(bodyParser.urlencoded({extended: true}))
server.use(bodyParser.json())
//server.use(jsonServer.defaults());

const SECRET_KEY = '123456789';
const expiresIn = '1h';

// Create a token from a payload
function createToken(payload){
    return jwt.sign(payload, SECRET_KEY, {expiresIn});
  }

// Verify the token
function verifyToken(token){
    return  jwt.verify(token, SECRET_KEY, (err, decode) => decode !== undefined ?  decode : err);
  }

  // Check if the user exists in database
function isAuthenticated({phone, password}){
    return userdb.users.findIndex(user => user.phone === phone && user.password === password) !== -1;
  }

// check if the number already exists in database
//this function's implementation is commented out for the time being because of the token mismatch issue, this will be implemanted later on.
function isInDatabase({phone}){
  return userdb.users.findIndex(user => user.phone === phone) !== -1;
}

//create verification code for phone number
function verificationCode(){
  var val = Math.floor(1000 + Math.random() * 9000);
  //console.log(val);
  return val;
}

// function findLatestID(data){
//     theHighestQuantity = data[0]['id'];
//     //console.log(theHighestQuantity);
//     for (var i = 0; i< data.length; i++){
//       console.log(data[i]['id']);
//       if(data[i]['id'] > theHighestQuantity){
//         theHighestQuantity = data[i]['id'];
//       }
//     }
//     return theHighestQuantity;
//   //return userdb.users.reduce((max, b) => Math.max(max, b.id),userdb.users[0].id);
// }

//Function to find a specific id in users.json file
//This function is depricted for the time being, in case we plan to use it in any way
function findUserId(data, id){
  for (var i = 0; i<data.length; i++){
    if(data[i]['id'] = id){
      return i;
    }
  }
}

  server.post('/auth/login', (req, res) => {
    const {phone, password} = req.body;
    if (isAuthenticated({phone, password}) === false) {
      const status = 401;
      const message = 'Incorrect phone or password';
      res.status(status).json({status, message});
      return;
    }
    const access_token = createToken({phone, password});
    res.status(200).json({access_token});
  });

  server.post('/send-verification', (req, res)=>{
    const {phone} = req.body;
    const id = userdb.users.length + 1;
    //if(isInDatabase({phone} === false)){
        userdb.users.push({id: id, phone: phone, password: null, name: null, role: null});
        fs.writeFile('users.json', JSON.stringify(userdb),
          function(err){
            if(err) throw err;
            console.log('added to json');
          });
    //}
    // else{
    //   console.log('number exists');
    //   const status = 409;
    //   const message = 'Number already exists';
    //   res.status(status).json({status, message});
    // }
    const verification_code = verificationCode();
    res.status(200).json({verification_code});
  });

  server.post('/update-user', (req, res)=>{
    const {name, role, password, id} = req.body;
    //var i = findUserId(userdb.users, id);
    for (var i = 0; i<userdb.users.length; i++){
      if(userdb.users[i]['id'] == id){
        userdb.users[i].password = password;
        userdb.users[i].name = name;
        userdb.users[i].role = role;
      }
    }

    fs.writeFile('users.json', JSON.stringify(userdb),
          function(err){
            if(err) throw err;
            console.log('updated json');
          });

    const status = 200;
    const message = 'Profile Updated';
    res.status(status).json({status, message});
  });

  server.use(/^(?!\/auth).*$/,  (req, res, next) => {
    if (req.headers.authorization === undefined || req.headers.authorization.split(' ')[0] !== 'Bearer') {
      const status = 401;
      const message = 'Bad authorization header';
      res.status(status).json({status, message});
      return;
    }
    try {
       verifyToken(req.headers.authorization.split(' ')[1]);
       next();
    } catch (err) {
      const status = 401;
      const message = 'Error: access_token is not valid';
      res.status(status).json({status, message});
    }
  });

  server.use(router);

  server.listen(3000, () => {
    console.log('Run Auth API Server');
  })