manager.js

var mysql = require("mysql");
var inquirer = require("inquirer");

var connection = mysql.createConnection({
  host: "localhost",
  port: 3306,
  user: "root",
  password: "insecure",
  database: "bamazon"
});

connection.connect(function(err) {
  if (err) {
    return console.log(err);
  }
  adminMenu();
});

var adminMenu = function() {
  inquirer.prompt([
    {
      type: "list",
      message: "Please select:",
      choices: [
        "View Products for Sale",
        "View Low Inventory",
        "Add to Inventory",
        "Add New Product",
        "Exit"
      ],
      name: "choice"
    }
  ]).then(function(res) {
    switch (res.choice) {
      case ("Exit"):
        connection.end();
        return;
      case ("View Products for Sale"):
        adminQuery();
        break;
      case ("View Low Inventory"):
        adminLowInventory();
        break;
      case ("Add to Inventory"):
        adminAddInvetory();
        break;
      case ("Add New Product"):
        adminAddItem();
        break;
    }
  });

  function adminQuery() {
    console.log("Items up for sale");
    console.log("------------------");
    connection.query("SELECT * FROM products", function(err, res) {
      for (var i = 0; i < res.length; i++) {
        console.log(res[i].item_id + " | " + res[i].product_name + " |  $" + res[i].price + " | " + res[i].quantity);
        console.log("------------------");
      }
      adminMenu();
    });
  }

  var adminAddInvetory = function() {
    inquirer.prompt([
      {
        type: "input",
        message: "enter the item id of the product you would like to add into",
        name: "item"
      }, {
        type: "input",
        message: "how many do you want to add?",
        name: "quantity"
      }
    ]).then(function(argument) {
      connection.query("SELECT quantity FROM products WHERE item_id = ?", [argument.item], function(err, res) {
        var numToAdd = parseInt(argument.quantity);
        var newInventory = parseInt(res[0].quantity) + numToAdd;

        if (err) {
          return console.log(err);
        }
        connection.query("UPDATE products SET quantity = ? WHERE item_id = ?", [newInventory, argument.item]);
        console.log(argument.quantity + " units added to inventory.");
        adminMenu();
      });
    });
  };

  var adminAddItem = function() {
    var depts = [
      "Electronics",
      "Decor",
      "Fashion",
      "Furniture",
      "Luggage",
      "Office Supplies",
      "Personal Hygiene",
      "Sporting Goods",
      "Food",
      "Toys and Games",
      "Art",
      "Home Goods",
      "Footwear",
      "Automotive",
      "Seasonal",
      "Tools and Hardware",
      "Appliances",
      "Alcohol",
      "Books",
      "Movies",
      "Music",
      "Basics"
    ];
    inquirer.prompt([
      {
        type: "input",
        message: "enter the name of the item you would like to add",
        name: "name"
      }, {
        type: "list",
        message: "enter the department you would to add it to",
        choices: depts,
        name: "department"
      }, {
        type: "input",
        message: "enter the item price",
        name: "price"
      }, {
        type: "input",
        message: "enter the initial inventory quantity",
        name: "inventory"
      }
    ]).then(function(item) {
      connection.query("INSERT INTO products SET ?", {
        product_name: item.name,
        dept_name: item.department,
        price: item.price,
        quantity: item.inventory
      }, function(err, result) {
        if (err) {
          return console.log(err);
        }
        console.log("Item added to products.");
        adminQuery();
      });
    });
  };

  var adminLowInventory = function() {
    connection.query("SELECT * FROM products", function(err, res) {
      if (err) {
        return console.log(err);
      }
      console.log("Low Inventory Items");
      console.log("----------------------");
      for (var j = 0; j < res.length; j++) {
        if (res[j].quantity < 5) {
          console.log(res[j].product_name + " | Units remaining: " + res[j].quantity);
        }
      }
      adminMenu();
    });
  };
};