'use strict';

var oracledb = require('oracledb');

console.log('start');

watch();

var numberOfTests = 0;

var repeat = process.argv[2] || 1;
for (var i = 1; i <= repeat; ++i) {
  dbTest(i);
}

setTimeout(function() {
  dbTest('confirm');
}, 2500 * repeat);

//

function watch() {
  console.log('running');
  setTimeout(function() {
    if (numberOfTests === 0) {
      console.log('finished');
      return;
    }
    watch();
  }, 1000);
}

// DB

var sqlLock = 'SELECT * FROM hr.employees WHERE employee_id = 100 FOR UPDATE';
var sqlDelay = 'begin dbms_lock.sleep(1); end;';

function dbTest(id) {
  ++numberOfTests;
  connect(function(conn) {
    delay(conn, function() {
      lock(conn, function() {
        delay(conn, function() {
          release(conn, function() {
            --numberOfTests;
          }, id);
        }, id);
      }, id);
    }, id);
  }, id);
}

function connect(callback, id) {
  console.log(id, 'connecting');
  oracledb.getConnection({
    user: 'hr',
    password: 'hr',
    connectString: '192.168.56.101',
  }, function(err, conn) {
    if (err) {
      console.error(id + ': ' + err.message);
      throw err;
    }
    callback.call({}, conn);
  });
}

function delay(conn, callback, id) {
  console.log(id, 'try to delay');
  conn.execute(sqlDelay, {}, function(err) {
    if (err) {
      console.error(id + ': ' + err.message);
      throw err;
    }
    console.log(id, 'delayed');
    callback.call();
  })
}

function lock(conn, callback, id) {
  console.log(id, 'try to lock');
  conn.execute(sqlLock, {}, function(err) {
    if (err) {
      console.error(id + ': ' + err.message);
      throw err;
    }
    console.log(id, 'locked');
    callback.call();
  })
}

function release(conn, callback, id) {
  console.log(id, 'try to release');
  conn.release(function(err) {
    if (err) {
      console.error(id + ': ' + err.message);
      throw err;
    }
    console.log(id, 'released');
    callback.call();
  });
}