Parking Lot

Problem Statement

• I own a parking lot that can hold up to ‘n’ cars at any given point in time. Each slot is given a number starting at 1 increasing with increasing distance from the entry point in steps of one. I want to create an automated ticketing system that allows my customers to use my parking lot without human intervention.
• When a car enters my parking lot, I want to have a ticket issued to the driver. The ticket issuing process includes us documenting the registration number (number plate) and the colour of the car and allocating an available parking slot to the car before actually handing over a ticket to the driver (we assume that our customers are nice enough to always park in the slots allocated to them).
• The customer should be allocated a parking slot which is nearest to the entry. At the exit the customer returns the ticket with the time the car was parked in the lot, which then marks the slot they were using as being available.
• Total parking charge should be calculated as per the parking time. Charge applicable is $10 for first 2 hours and $10 for every additional hour.

Pre requisites

The source code for this project is written using Node.js. Make sure you have Node.js installed on your computer before running this application, if not please install Node.js from here.

To check if you have Node.js and NPM installed by running simple commands to see what version of each is installed:

• Test Node.js: To see if Node is installed, type node -v in Terminal. This should print the version number so you’ll see something like this v14.17.2.

• Test NPM. To see if NPM is installed, type npm -v in Terminal. This should print the version number so you’ll see something like this 6.14.13.

Note: Node installer installs both Node.js and npm on your system.

How to run?

This is a console application written in Node.js. This can be run in two modes:

1. Interactive Mode: An interactive terminal based shell where commands can be typed in to perform different actions.

2. File Mode: It accepts a filename as a parameter at the terminal and read the commands from that file.

Quick Start

Proceed to the steps below only if you've Node.js installed. If not, please refer pre requisites section.

For Interactive Mode

Open terminal and navigate (cd) to this folder and type the following commands:

1. npm install
2. npm start

For File Mode

Open terminal and type node src/index.js data/input.txt.

node src/index.js <path_to_file.txt>

Note: You can find a few sample input files inside assets/ folder : node src/index.js assets/input.txt.

List of User Commands

Users can interact with the Parking Lot service via a following simple set of commands which produce a specific output:

• create_parking_lot : create_parking_lot 6 will create a parking lot with 6 slots.

• park : park KA-01-HH-1234 will allocate the nearest slot from entry gate.

• leave : leave KA-01-HH-1234 5 will make the slot free for the car of given registration number and charge fee $10 for first 2 hours and $10 for every additional hour.

• status : status will display cars and their slot details

Slot No.  Registration No.
1         KA-01-HH-1234  
2         KA-01-HH-9999  
3         KA-01-BB-0001  
5         KA-01-HH-2701  
6         KA-01-HH-3141  

• exit: exit will quit the application and return to the console.

NOTE: Any commands which are not mentioned above will throw an error: <INPUT> is an invalid command

Modules - OOPS Approach

There are three modules defined:

processUserCommands() : It is function to driver different commands for entered by users to calls respective functions of ParkingLotService based on commands

Note : if you want to read the list of user commands, please refer List of User Commands section.

ParkingLotService(): It is the main class service which is used to initialize a parking lot. In each parking lot there is maximum number of slots and an array of slots that will be occupied by the car. It has following methods:

• createParkingLot(input) : Creates a parking lot with given input. It throws an error Minimum one slot is required to create parking slot if zero or negative number (n <= 0) is provided as an input.

• parkCar(input) : Allocates nearest slot from entry gate to the car. It can throw following errors:

  • Sorry, the parking lot has not been created : When parking lot is not initialized.

  • Sorry, parking lot is full : When parking lot has reached its maximum capacity.

  • Please provide registration number : When input not contain Car registration number

  • Car with registration number <REGISTRATION_NUMBER> is already parked : When parking the car with the same registration number in the parking lot

• leave(input) : Removes car in given slot in parking lot. It throws following errors:

  • Sorry, the parking lot has not been created : When parking lot is not initialized.

  • Please provide registration number : When input not contain Car registration number

  • Please provide parking duration : When input not contain parking duration

  • Registration number <REGISTRATION_NUMBER> is not found : When registration number entered is not found

• getParkingCharge(input) : Return a parking charge. Charge applicable is $10 for first 2 hours and $10 for every additional hour

• getParkingStatus() : Returns an array containing slot number and registration number. It throws an error Sorry, the parking lot has not been created if parking lot is empty.

• findNearestAvailableSlot() : Finds nearest free slot.

Models :

• ParkingLot()
  • new ParkingLot(MAX_PARKING_SLOTS, parkingSlots) : Constructor used to initialize a ParkingLot object containing two field: MAX_PARKING_SLOTS to define maximum of parking slots allowed and parkingSlots to define array for parking slots
• Car()
  • new Car(NUMBER) : Constructor used to initialize a car object containing one field: registration number.
• ParkingSlot()
  • new ParkingSlot(CAR, SLOT) : Constructor used to initialize a ParkingSlot object containing two field: Car model and slot.

Lint test

npm run test-lint is used to run JavaScript lint tests. It detects the coding style issues. ESLint rules are defined in .eslintrc.js file. node_modules/eslint/bin/eslint.js --fix src/ can be run to fix lint errors.

Code Coverage

To see code coverage report, run npm run test:cov.

The current code coverage for the tests are following:

Type	Percentage
Statement	100 %
Branch	100 %
Function	100 %
Lines	100 %

• Function coverage: Has each function (or subroutine) in the program been called?
• Statement coverage: Has each statement in the program been executed?
• Branch coverage: Has each branch (also called DD-path) of each control structure (such as in if and case statements) been executed?
• Line coverage: Has each executable line in the source file been executed?

NOTE: You can see the code-coverage report in terminal as well as detailed HTML report inside coverage/ folder. Go to coverage/ folder and open index.html.

Sonarqube Scan

SonarQube is an open source platform developed by SonarSource for continuous code quality inspection, to perform automatic reviews with static code analysis to detect bugs, code odors and security vulnerabilities in over 20 languages. programming.

To run sonar-scanner,you need to open terminal and navigate (cd) to this folder and type followings command :

1. docker-compose -f docker-compose.sonar.yml up -d
2. npm install
3. npm run test
4. npm run sonar

NOTE: Make sure you have installed Docker. Or if you have any issue in running SonarQube Scanner you can read the tutorial here.

Screenshots

Dependencies Used

• Chalk : A npm module used to style terminal string. Learn more here.
• Jest : A JavaScript test framework for Node.js programs. Learn more here.
• ESLint: A static code analysis tool for identifying problematic patterns found in JavaScript code. It covers both code quality and coding style issues. Learn more here.
• SonarQube Scanner: Code Security for more languages, with more rules, better detection and improved workflows. Learn more here.