var Connection = require('tedious').Connection;
var Request = require('tedious').Request;
var TYPES = require('tedious').TYPES;
var async = require('async');

// Create connection to database
var config = {
  userName: 'sa', // update me
  password: 'your_password', // update me
  server: 'localhost',
  options: {
    database: 'SampleDB'
  }
}
var connection = new Connection(config);

// Attempt to connect and execute queries if connection goes through
connection.on('connect', function(err) {
  if (err) {
    console.log(err);
  } else {
    console.log('Connected');

    // Execute all functions in the array serially
    async.waterfall([
      function Start(callback) {
        console.log('Starting...');
        callback(null, 'Jake', 'United States');
      },
      function Insert(name, location, callback) {
        console.log("Inserting '" + name + "' into Table...");

        request = new Request(
          'INSERT INTO TestSchema.Employees (Name, Location) OUTPUT INSERTED.Id VALUES (@Name, @Location);',
          function(err, rowCount, rows) {
            if (err) {
              callback(err);
            } else {
              console.log(rowCount + ' row(s) inserted');
              callback(null, 'Nikita', 'United States');
            }
          });
        request.addParameter('Name', TYPES.NVarChar, name);
        request.addParameter('Location', TYPES.NVarChar, location);

        // Execute SQL statement
        connection.execSql(request);
      },
      function Update(name, location, callback) {
        console.log("Updating Location to '" + location + "' for '" + name + "'...");

        // Update the employee record requested
        request = new Request(
          'UPDATE TestSchema.Employees SET Location=@Location WHERE Name = @Name;',
          function(err, rowCount, rows) {
            if (err) {
              callback(err);
            } else {
              console.log(rowCount + ' row(s) updated');
              callback(null, 'Jared');
            }
          });
        request.addParameter('Name', TYPES.NVarChar, name);
        request.addParameter('Location', TYPES.NVarChar, location);

        // Execute SQL statement
        connection.execSql(request);
      },
      function Delete(name, callback) {
        console.log("Deleting '" + name + "' from Table...");

        // Delete the employee record requested
        request = new Request(
          'DELETE FROM TestSchema.Employees WHERE Name = @Name;',
          function(err, rowCount, rows) {
            if (err) {
              callback(err);
            } else {
              console.log(rowCount + ' row(s) deleted');
              callback(null);
            }
          });
        request.addParameter('Name', TYPES.NVarChar, name);

        // Execute SQL statement
        connection.execSql(request);
      },
      function Read(callback) {
        console.log('Reading rows from the Table...');

        // Read all rows from table
        request = new Request(
        'SELECT Id, Name, Location FROM TestSchema.Employees;',
        function(err, rowCount, rows) {
          if (err) {
            callback(err);
          } else {
            console.log(rowCount + ' row(s) returned');
            callback(null);
          }
        });

        // Print the rows read
        var result = ""; request.on('row', function(columns) {
          columns.forEach(function(column) {
            if (column.value === null) {
              console.log('NULL');
            } else {
              result += column.value + " ";
            }
          });
          console.log(result);
          result = "";
        });

        // Execute SQL statement
        connection.execSql(request);
      }
    ],
    function Complete(err, result) {
      if (err) {
        callback(err);
      } else {
        console.log("Done!");
      }
    })
  }
});


// Initialize the connection.
connection.connect();