Nasa Rover Monitor

Monitor and control the squad of rovers landed by NASA on a plateau in planet Mars.

An amazing adventure!

I hope you enjoy!

Test it

Clone this repository and execute above commands:

npm install
npm test

Watch it

Clone this repository and execute above commands:

npm install
npm run watch

Importing text file from string

To import text file execute app/start script passing path to file commands.

npm install
node app/start ./import-data-test.txt

Script parameters:

• [fileTxtToImport]: Path to text file to import commands.
• --utils: Print grid with rover char representation.
• --debug: Show debug infos.

It uses the text file for testing, this is located into project here.

Importing text file from stream

To import text file execute app/start-stream script passing path to file commands.

npm install
node app/start-stream ./import-data-test.txt

Script parameters:

• [fileTxtToImport]: Path to text file to import commands.
• --utils: Print grid with rover char representation.
• --debug: Show debug infos.

It uses the text file for testing, this is located into project here.

Code example

Read letters from a string:

const { Readable } = require('stream')
const { RoverApplication } = require("./index");

const roverApp = new RoverApplication();
const letters = "5 5\n1 2 N\nLMLMLMLMM\n1 2 E\nMMRMMRMRRM";

const output = roverApp.start(letters);

console.log(`Output rover monitor from string:`);
console.log(output);

Read letters from a stream:

const { Readable } = require('stream')
const { RoverApplication } = require("./index");

const roverApp = new RoverApplication();
const letters = "5 5\n1 2 N\nLMLMLMLMM\n1 2 E\nMMRMMRMRRM";

const stream = Readable.from([letters])

roverApp
    .startFromStream(stream)
    .then((outputStream) => {
        console.log(`Output rover monitor from stream:`);
        console.log(outputStream);
    })
    .catch((e) => {
        console.log(`Output rover monitor from stream:`);
        console.error(e)
    });

Solution

The plateau representation in planet Mars is coordinates by:

• Bottom left: x=0 e y=0 coordinates.
• Upper right: Is a custom one coordinates.

The rover position is the cartesian coordinates:

• x: The horizontal 2D coordinate.
• y: The vertical 2D coordinate.

The rover orientation is the cardinal orientation:

• N: The north orientation.
• S: The south orientation.
• E: The east orientation.
• W: The west orientation.

The rover commands is:

• L: Turn left 90 degrees.
• R: Turn right 90 degrees.
• M: Move forward from rover orientation.

The table below represents the solution:

Cmd/Ori	North	South	East	West
Left	West	East	North	South
Right	East	West	South	North
Move	y + 1	y - 1	x + 1	x - 1

The legends to solution graph below:

• C(X): Rover command with value in X.
• O(Y): Rover orientation with value in Y.
• P(Z): Rover position with value in Z.

Graph to command left from orientation:

graph TD;
CL(Command Left) -->|on rover in| ON(Orientation North) -->|changes rover to| OW(Orientation West);
CL(Command Left) -->|on rover in| OS(Orientation South) -->|changes rover to| OE(Orientation East);
CL(Command Left) -->|on rover in| OE(Orientation East) -->|changes rover to| OS(Orientation South);
CL(Command Left) -->|on rover in| OW(Orientation West) -->|changes rover to| ON(Orientation North);

Graph to command right from orientation:

graph TD;
CR(Command Right) -->|on rover in| ON(Orientation North) -->|changes rover to| OE(Orientation East);
CR(Command Right) -->|on rover in| OS(Orientation South) -->|changes rover to| OW(Orientation West);
CR(Command Right) -->|on rover in| OE(Orientation East) -->|changes rover to| ON(Orientation North);
CR(Command Right) -->|on rover in| OW(Orientation West) -->|changes rover to| OS(Orientation South);

Graph to command move from orientation:

graph TD;
CM(Command Move) -->|on rover in| ON(Orientation North) -->|changes rover to| PYP(Position y + 1);
CM(Command Move) -->|on rover in| OS(Orientation South) -->|changes rover to| PYM(Position y - 1);
CM(Command Move) -->|on rover in| OE(Orientation East) -->|changes rover to| PXP(Position x + 1);
CM(Command Move) -->|on rover in| OW(Orientation West) -->|changes rover to| PXM(Position x - 1);

Input

The first line of input is the upper-right coordinates of the plateau, the lower-turn coordinates are assumed to be 0,0.

The rest of the input is information pertaining to the rovers that have been deployed. Each rover has two lines of input. The first line gives the rover's position, and the second line is a series of instructions telling the rover how to explore the plateau. The position is made up of two integers and a letter separated by spaces, corresponding to the x and y co-ordinates and the rover's orientation.

Each rover will be finished sequentially, which means that the second rover won't start to move until the first one has finished moving.

Output

The output for each rover should be its final co-ordinates and heading.

Example

1. Input the upper-right plateau coordinates, x and y.
2. Input first rover coordinates and orientation.
3. Input commands to the first rover.
4. Input second rover coordinates and orientation.
5. Input commands to the second rover.

Test Input

5 5
1 2 N
LMLMLMLMM
3 3 E
MMRMMRMRRM

• Rover { x: 1, y: 2, orientation: 'N' }

 ======
|      |
|      |
|      |
| N    |
|      |
|      |
 ======

• Rover { x: 3, y: 3, orientation: 'E' }

 ======
|      |
|      |
|   E  |
|      |
|      |
|      |
 ======

Expected Output

1 3 N
5 1 E

• Rover command L on plateau: Rover { x: 1, y: 2, orientation: 'W' }
• Rover command M on plateau: Rover { x: 0, y: 2, orientation: 'W' }
• Rover command L on plateau: Rover { x: 0, y: 2, orientation: 'S' }
• Rover command M on plateau: Rover { x: 0, y: 1, orientation: 'S' }
• Rover command L on plateau: Rover { x: 0, y: 1, orientation: 'E' }
• Rover command M on plateau: Rover { x: 1, y: 1, orientation: 'E' }
• Rover command L on plateau: Rover { x: 1, y: 1, orientation: 'N' }
• Rover command M on plateau: Rover { x: 1, y: 2, orientation: 'N' }
• Rover command M on plateau: Rover { x: 1, y: 3, orientation: 'N' }
• Rover complete commands on plateau: Rover { x: 1, y: 3, orientation: 'N' }

 ======
|      |
|      |
| N    |
|      |
|      |
|      |
 ======

• Rover command M on plateau: Rover { x: 4, y: 3, orientation: 'E' }
• Rover command M on plateau: Rover { x: 5, y: 3, orientation: 'E' }
• Rover command R on plateau: Rover { x: 5, y: 3, orientation: 'S' }
• Rover command M on plateau: Rover { x: 5, y: 2, orientation: 'S' }
• Rover command M on plateau: Rover { x: 5, y: 1, orientation: 'S' }
• Rover command R on plateau: Rover { x: 5, y: 1, orientation: 'W' }
• Rover command M on plateau: Rover { x: 4, y: 1, orientation: 'W' }
• Rover command R on plateau: Rover { x: 4, y: 1, orientation: 'N' }
• Rover command R on plateau: Rover { x: 4, y: 1, orientation: 'E' }
• Rover command M on plateau: Rover { x: 5, y: 1, orientation: 'E' }
• Rover complete commands on plateau: Rover { x: 5, y: 1, orientation: 'E' }

 ======
|      |
|      |
|      |
|      |
|     E|
|      |
 ======

Dependencies

• jest: JavaScript Testing Framework with a focus on simplicity.
• prettier: An opinionated code formatter.