const express = require('express');
const {nanoid} = require('nanoid');

const { Pool } = require('pg');
const db = new Pool({
  host: 'postgres',
  database: 'pastebin',
  user: 'pastebin',
  password: 'buginoo'
  });


// initialize app:
const app = express();
const port = 80;

db.query("CREATE TABLE IF NOT EXISTS bin (id VARCHAR PRIMARY KEY);"
      + "CREATE TABLE IF NOT EXISTS note (id VARCHAR PRIMARY KEY, text TEXT, modified TIMESTAMPTZ);"
      + "CREATE TABLE IF NOT EXISTS bin_note (bin_id VARCHAR REFERENCES bin (id), note_id VARCHAR REFERENCES note (id), PRIMARY KEY (bin_id, note_id));"
      + "CREATE TABLE IF NOT EXISTS user_ (id VARCHAR PRIMARY KEY, username TEXT, password TEXT);" // table 'user' is already taken
      );


const router = express.Router();

router.get('/', (req, res)=>{
  res.send('Feh')
  });

const load_notes_stmt =
  "SELECT n.id, n.text, n.modified FROM bin_note AS bn"
    +" JOIN note AS n"
    +" ON n.id = bn.note_id"
  +" WHERE bn.bin_id = $1";
// {bin_id}
router.post('/load-notes', (req, res)=>{
  const bin_id = req.body.bin_id;
  db.query(load_notes_stmt, [bin_id])
    .then(result => {
      res.json({status: 'ok', bin:{id:bin_id}, notes:result.rows})
      });
  // {status: 'ok', bin:{id:bin.id}, notes: bin.notes}
  });

const search_stmt = 
  "SELECT n.id, n.text, n.modified FROM note AS n"
  +" WHERE n.text LIKE '%' || $1 || '%'" // need to use string concat otherwise the `$1` is viewed as part of the string instead of a placeholder
  +" ORDER BY n.modified DESC";
// {search_term, sorting, bin_id}
router.post('/search', (req, res)=>{
  const search_term = req.body.search_term;
  db.query(search_stmt, [search_term])
    .then(result => {
      res.json({status:'ok', notes:result.rows});
      });
  // {status: 'ok', notes}
  });

const upsert_note_stmt = 
            "INSERT INTO note (id, text, modified) VALUES ($1, $2, NOW())"
          +" ON CONFLICT (id)"
          +" DO UPDATE SET text = EXCLUDED.text, modified = EXCLUDED.modified";
const upsert_bin_stmt = 
            "INSERT INTO bin (id) VALUES ($1)"
          +" ON CONFLICT (id)"
          +" DO NOTHING";
const upsert_bin_note_stmt = 
            "INSERT INTO bin_note (bin_id, note_id) VALUES ($1, $2)"
          +" ON CONFLICT (bin_id, note_id)"
          +" DO NOTHING";

// {bin_id, note_id, text}
router.post('/save', (req, res)=>{
  const {bin_id, note_id, text} = req.body;
  db.connect().then(async (client)=>{
    await client.query(upsert_note_stmt, [note_id, text]);
    await client.query(upsert_bin_stmt, [bin_id]);
    await client.query(upsert_bin_note_stmt, [bin_id, note_id]);
    // don't forget to release back into the Pool:
    client.release();
    res.json({status: 'ok'});
    });
  // {status: 'ok'}
  });

const login_check_stmt = 
          "SELECT id, password FROM user_ AS u"
        +" WHERE u.username = $1";
const register_stmt = 
          "INSERT INTO user_ (id, username, password) VALUES ($1, $2, $3)";
router.post('/login', (req, res)=>{
  const {username, password_from_client} = req.body;
  db.query(login_check_stmt, [username])
    .then(result=>{
      // if there is such a username:
      if(result.rows.length > 0){
        const row = result.rows[0];
        const id=row.id, password_from_db=row.password;
        // if the passwords match:
        if(password_from_client === password_from_db){
          res.json({success:true, user:{id, username}, session_id:nanoid()});
          }
        else{
          res.json({success: false});
          }
        }
      // if no such user exists:
      else{
        const id = nanoid();
        db.query(register_stmt, [id, username, password_from_client])
          .then(r=>{
            res.json({success: true, user:{id, username}, session_id:nanoid()});
            });
        }
      });
  });

app.use('/', express.json(), router);


// run app:
const server = app.listen(port, () => {
  console.log(`Pastebin app listening at http://localhost:${port}`)
  });




// Ruthlessly copied from [https://medium.com/@becintec/building-graceful-node-applications-in-docker-4d2cd4d5d392]:
// The signals we want to handle
// NOTE: although it is tempting, the SIGKILL signal (9) cannot be intercepted and handled
var signals = {
  'SIGHUP': 1,
  'SIGINT': 2,
  'SIGTERM': 15
};
// Do any necessary shutdown logic for our application here
const shutdown = (signal, value) => {
  console.log("shutdown!");
  server.close(() => {
    console.log(`server stopped by ${signal} with value ${value}`);
    process.exit(128 + value);
  });
};
// Create a listener for each of the signals that we want to handle
Object.keys(signals).forEach((signal) => {
  process.on(signal, () => {
    console.log(`process received a ${signal} signal`);
    shutdown(signal, signals[signal]);
  });
});