padurean / mad-aliens

Simulates mad aliens invading Earth and destroying cities

👽👽👽 Mad Aliens

Simulating an alien invasion using the Go programming language.

The requirements can be found here.

Prerequisites

Required

• Go

Optional

• golangci-lint
• make
• Docker

Run, Lint, Test and more

Run it using go run, passing the number of aliens:

go run ./cmd/invasion 5

or to run it interactively, step by step, also pass the -i flag:

go run ./cmd/invasion -i 12

❗ The world is read from the world.txt file and what's left of it after the invasion simulation is written to a world_after_invasion.txt file.

💡 A Makefile is also provided for convenience. Please have a look at it for all the available targets, among which:

• make run_dev
• make lint (:exclamation: requires golangci-lint to be installed)
• make test
• make coverage-report

💡 A Dockerfile is provided for running it with Docker and some convenience make targets like make build_docker_image. To run it with Docker: docker run padurean/mad-aliens 10

Code and package design

The code is structured as follows:

• cmd/invasion/ is the main package containing just the main.go file. It's code parses the CLI flag and argument, reads and parses the world from the world.txt file, creates and runs a new invasion and then writes what's left of the world to a [world_after_invasion.txt] file. When creating the invasion, it also passes an onEvent callback to it which prints any events (basically informative strings) to the console.

• internal/world package contains structs and methods related to the world (map):

  • a custom World type definition (for a map holding the cities per their names) with convenience methods like String, Read and Write (from/to file) and also a more exotic one FindGhostCities👻
  • a City struct type which holds a city name, neighbors directions per names and aliens names.
  • a Direction enum type for convenience and a more type-safe way for dealing with related, fixed values.

• internal/invasion package contains a main Invasion struct representing the invasion itself with 2 exported methods (beside String): New for constructing it and Run to run it. It also has some non-exported methods which perform specialized tasks and update the state of the world and the summary of the invasion.

For more details please have a look over the code itself. Enjoy! 👋