const express = require('express');
const crypto = require('crypto');
const Config = require('./config.js');
const Database = require('./db_interface.js');

let router = express.Router();

router.use(express.json());

let session_entropy = {};

user_cache = {};
email_cache = {};

async function get_user_details(id) {
  console.log(`search for user with id ${id}`);
  if (!user_cache[id]) {
    let user = await Database.schemas.user.findOne({ where: { id: id } });
    if (!user) {
      return undefined;
    }
    user_cache[user.id] = {
      id: user.id,
      email: user.email,
      password_hash: user.password_hash
    };
    email_cache[user.email] = user.id;
  }
  console.log(`returning ${JSON.stringify(user_cache[id])}`);
  return user_cache[id];
}

async function get_user_details_by_email(email) {
  console.log(`search for user with email ${email}}`);
  if (!email_cache[email] || !user_cache[email_cache[email]]) {
    let user = await Database.schemas.user.findOne({ where: { email: email } });
    if (!user) {
      return undefined;
    }
    user_cache[user.id] = {
      id: user.id,
      email: user.email,
      password_hash: user.password_hash
    };
    email_cache[user.email] = user.id;
  }
  console.log(`returning ${JSON.stringify(user_cache[email_cache[email]])}`);
  return user_cache[email_cache[email]];
}

router.get("/byEmail/:email", async (req, res) => {
  if (!req.params?.email) {
    res.status(400).json({
      error: "email is a required parameter"
    });
  }
  let user = get_user_details_by_email(req.params.email);
  console.log(user);
  if (user != null) {
    res.json({
      id: user.id,
      email: user.email
    });
  }
  else {
    res.sendStatus(404);
  }
});

function hash(secret, password) {
  let pw_hash = crypto.pbkdf2Sync(password,
    secret,
    Config.config.key?.iterations || 1000,
    Config.config.key?.length || 64,
    "sha512");

  return pw_hash.toString('base64');
}

function verify(secret, password, hash) {
  let pw_hash = crypto.pbkdf2Sync(password,
    secret,
    Config.config.key?.iterations || 1000,
    Config.config.key?.length || 64,
    "sha512");

  return hash === pw_hash.toString('base64');
}

function hash_password(password) {
  return hash(Config.config.secret, password);
}

function verify_password(password, hash) {
  return verify(Config.config.secret, password, hash);
}

function get_session_token(id, token) {
  session_entropy[id] = crypto.randomBytes(Config.config.session_entropy || 32);
  return hash(session_entropy[id], token);
}

function verify_session_token(id, hash, token) {
  if (session_entropy[id]) {
    return verify(session_entropy[id], hash, token);
  }
  else {
    return false;
  }
}

async function enforce_session_login(req, res, next) {
  let userid = req.cookies?.userid;
  let session_token = req.cookies?._session;
  console.log("a", userid, session_token);
  if (!userid || !session_token) {
    res.sendStatus(401);
  }
  let user = await get_user_details(userid);
  if (!user) {
    res.sendStatus(401);
  }
  let verified_session = verify_session_token(userid, user.password_hash, session_token);
  if (!verified_session) {
    res.sendStatus(401);
  }
  return next();
}

router.post("/new", async (req, res) => {
  if (!req.body?.email || !req.body?.password) {
    res.status(400).json({
      error: "must have email and password fields"
    });
  }
  let user = await get_user_details_by_email(req.body.email);
  console.log(user);
  if (user != null) {
    res.status(403).json({
      error: `email ${req.body.email} is already in use.`
    });
  }
  else {
    let user = await Database.schemas.user.create({
      email: String(req.body.email),
      password_hash: hash_password(req.body.password)
    });

    res.json({
      id: user.id,
      email: user.email
    });
  }
});

router.post("/login", async (req, res) => {
  if (!req.body?.email || !req.body?.password) {
    res.status(400).json({
      error: "must have email and password fields"
    });
  }
  let user = await get_user_details_by_email(req.body.email);
  if (!user) {
    res.status(401).json({
      error: "incorrect email or password"
    });
  }
  let verified = verify_password(req.body.password, user.password_hash);

  if (!verified) {
    res.status(401).json({
      error: "incorrect email or password"
    });
  }

  res.cookie("userid", user.id);
  res.cookie("_session", get_session_token(user.id, user.password_hash));
  res.sendStatus(204);
});

router.get("/:id(([a-f0-9\-])+)", async (req, res) => {
  if (!req.params?.id) {
    res.status(400).json({
      error: "must have id parameter"
    });
  }
  let user = await get_user_details(req.body.id);
  console.log(user);
  if (user != null) {
    res.json({
      id: user.id,
      email: user.email
    });
  }
  else {
    res.sendStatus(404);
  }
});

router.use("/authorized", enforce_session_login);
router.get("/authorized", async (req, res) => {
  let userid = req.cookies?.userid;
  let user = get_user_details(userid);
  res.json({
    authorized: true,
    user: {
      id: user.id,
      email: user.email
    }
  });
});


module.exports = {
  router: router,
  enforce_session_login: enforce_session_login
};