auth-middleware.js

const { JWT_SECRET } = require("../secrets"); // use this secret!
const usersModel = require('../users/users-model')

const restricted = (req, res, next) => {
  /*
    If the user does not provide a token in the Authorization header:
    status 401
    {
      "message": "Token required"
    }

    If the provided token does not verify:
    status 401
    {
      "message": "Token invalid"
    }

    Put the decoded token in the req object, to make life easier for middlewares downstream!
  */
 const token = req.headers.authorization
 if(!token){
   res.status(401).json({
     message:"Token required"
   })
 } else {
  jwt.verify(token,JWT_SECRET,(err,decoded)=>{
    if(err){
      res.status(401).json("Token invalid" )
    }else{
      req.decodedToken = decoded
      next()
    }
  })
 }

}

const only = role_name => (req, res, next) => {
  /*
    If the user does not provide a token in the Authorization header with a role_name
    inside its payload matching the role_name passed to this function as its argument:
    status 403
    {
      "message": "This is not for you"
    }

    Pull the decoded token from the req object, to avoid verifying it again!
  */
 if (!req.decodedToken.role_name === role_name){
   res.status(403).json({
     message: "This is not for you"
   })
 }else{
   next()
 }
}


const checkUsernameExists = async (req, res, next) => {
  /*
    If the username in req.body does NOT exist in the database
    status 401
    {
      "message": "Invalid credentials"
    }
  */
 try{
  const [user] = await usersModel.findBy({username: req.body.username})
  if(!user){
    next({ status: 422, message:"Invalid credentials" })
  }else{
    req.user = user
    next()
  }
}catch(err){
  next(err)
}
}


const validateRoleName = (req, res, next) => {
  /*
    If the role_name in the body is valid, set req.role_name to be the trimmed string and proceed.

    If role_name is missing from req.body, or if after trimming it is just an empty string,
    set req.role_name to be 'student' and allow the request to proceed.

    If role_name is 'admin' after trimming the string:
    status 422
    {
      "message": "Role name can not be admin"
    }

    If role_name is over 32 characters after trimming the string:
    status 422
    {
      "message": "Role name can not be longer than 32 chars"
    }
  */
 if(!req.body.role_name || !req.body.role_name.trim()){
   req.role_name = 'student'
   next()
 } else if(req.body.role_name.trim() === 'admin') {
  next({ status: 422, message: "Role name can not be admin" })
 }else if(req.body.role_name.trim().length > 32 ) {
  next({ status: 422, message: "Role name can not be longer than 32 chars" })
 }else{
   req.role_name = req.body.role_name.trim()
   next()
 }
}

module.exports = {
  restricted,
  checkUsernameExists,
  validateRoleName,
  only,
}