• The application is a simulation of a toy robot moving on a square tabletop, of dimensions 5 units x 5 units.
• There are no other obstructions on the table surface.
• The robot is free to roam around the surface of the table, but must be prevented from falling to destruction. Any movement that would result in the robot falling from the table must be prevented, however further valid movement commands must still be allowed.

Create an application that can read in commands of the following form:

PLACE X,Y,F
MOVE
LEFT
RIGHT
REPORT

• PLACE will put the toy robot on the table in position X,Y and facing NORTH, SOUTH, EAST or WEST.

• The origin (0,0) can be considered to be the SOUTH WEST most corner.

• The first valid command to the robot is a PLACE command, after that, any sequence of commands may be issued, in any order, including another PLACE command. The application should discard all commands in the sequence until a valid PLACE command has been executed.

• MOVE will move the toy robot one unit forward in the direction it is currently facing.

• LEFT and RIGHT will rotate the robot 90 degrees in the specified direction without changing the position of the robot.

• REPORT will announce the X,Y and F of the robot. This can be in any form, but standard output is sufficient.

• A robot that is not on the table can choose the ignore the MOVE, LEFT, RIGHT and REPORT commands.

• Input can be from a file, or from standard input, as the developer chooses.

• Provide test data to exercise the application.

• The application must be a command line application.

• The toy robot must not fall off the table during movement. This also includes the initial placement of the toy robot.
• Any move that would cause the robot to fall must be ignored.

PLACE 0,0,NORTH
MOVE
REPORT

Expected output:

0,1,NORTH

PLACE 0,0,NORTH
LEFT
REPORT

Expected output:

0,0,WEST

PLACE 1,2,EAST
MOVE
MOVE
LEFT
MOVE
REPORT

Expected output

3,3,NORTH

PLACE 0,0,NORTH
REPORT
DRAW

Expected output

0,0,NORTH
.....
.....
.....
.....
R....

PLACE 0,0,NORTH
REPORT
PLACE_OBJECT
DRAW

Expected output

0,0,NORTH
.....
.....
.....
O....
R....

Please provide your source code, and any test code/data you using in developing your solution.

Please engineer your solution to a standard you consider suitable for production. It is not required to provide any graphical output showing the movement of the toy robot.

Please do not put your name in any of the submitted code since this makes it harder for us to review your submission anonymously.

Add this line to your application's Gemfile:

    gem "toy-robot"

And then execute:

$ bundle

Or install it yourself as:

$ gem install toy-robot

To use the toy-robot application, either execute the script and start typing in commands; e.g.

    $ bin/app

    REPORT
    "0,0,NORTH"
    PLACE 1,2,SOUTH
    REPORT
    "1,2,SOUTH"
    MOVE
    MOVE
    RIGHT
    REPORT
    "1,0,WEST"
    EXIT

Or execute the script with the path to file that will be used as input; e.g.

    $ bin/app README.md

    "0,1,NORTH"
    "0,1,NORTH"
    "0,0,WEST"
    "3,3,NORTH"
    "0,0,NORTH"
    .....
    .....
    .....
    .....
    R....
    "0,0,NORTH"
    .....
    .....
    .....
    O....
    R....
    "0,0,NORTH"
    "1,2,SOUTH"
    "1,0,WEST"

All given User inputs should match what was specified in the Toy Robot specification; meaning its case-sensitive, ignores invalid commands, reports back to the user when asked REPORT, etc. However, it also implements a EXIT command in order escape the application/script outside of the regular terminate command Ctrl + C.

• The square tabletop, of dimensions 5 units x 5 units, assumes a Range of (0...5) not (0..5); e.g.

      (0...5).to_a  # => [0, 1, 2, 3, 4]
      (0...5).count # => 5
  
      (0..5).to_a  # => [0, 1, 2, 3, 4, 5]
      (0..5).count # => 6

  Since counting starts at 0 from the origin, it means the fifth value would be 4 not 5 (which in this case would be the sixth value and create a tabletop of 6 x 6 units, with 36 possible positions, rather than 25).

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install.

Bug reports and pull requests are welcome on GitHub at https://github.com/Sonna/toy-robot.