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sidebar_position: 6
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# Command plugins

MycroForge has a plugin system that allows you to extend the CLI with your own commands.
This section will guide you through the process of creating your own extension to the `m4g` command.
MycroForge is written in C# sharp and this is the same for plugins, so decent knowledge about `C#` & `.NET` is required.
In this tutorial we will create a command plugin that extens the `m4g` command with a `dotenv` sub command.
What this command will do is generate a `.env` file in the current directory and print a message to the console.

## Setup

To start creating command plugins for MycroFroge, make sure you've added the devdisciples package repository.
This can be done by running the following command.

```
dotnet nuget add source --name devdisciples https://git.devdisciples.com/api/packages/devdisciples/nuget/index.json
```

Run the following command to add the `MycroForge.PluginTemplate.Package`.

```
dotnet add package --source devdisciples --version 1.0.0 MycroForge.PluginTemplate.Package
```

## Initialize a plugin package

Generate a template plugin project by running the following command.

```
m4g plugin init My.Dotenv.Plugin
```

This should generate the following folder structure.

```
My.Dotenv.Plugin
 ┣ 📜HelloWorldCommand.cs
 ┣ 📜HelloWorldCommandPlugin.cs
 ┗ 📜My.Dotenv.Plugin.csproj
```

Rename the following files. Also rename the classes in these files, the easiest way in `vscode` is to right click the class name and select the `Rename symbol` action. Note that this action does not (necessarily) rename the files!

```
HelloWorldCommand.cs => DotenvCommand.cs
HelloWorldCommandPlugin.cs => DotenvCommandPlugin.cs
```

Modify `Name` property in `DotenvCommandPlugin.cs`.

```cs
// Before 
public class DotenvCommandPlugin : ICommandPlugin
{
    public string Name => "My.Plugin";

    public void RegisterServices(IServiceCollection services)   
    {
        services.AddScoped<ISubCommandOf<RootCommand>, HelloWorldCommand>();
    }
}

// After 
public class DotenvCommandPlugin : ICommandPlugin
{
    public string Name => "My.Dotenv.Plugin";

    public void RegisterServices(IServiceCollection services)   
    {
        services.AddScoped<ISubCommandOf<RootCommand>, HelloWorldCommand>();
    }
}
```

Modify `DotenvCommand.cs`.  

```cs
// Before
public class DotenvCommand : Command, ISubCommandOf<RootCommand>
{
    private readonly Argument<string> NameArgument =
        new(name: "name", description: "The name of the person to greet");

    private readonly Option<bool> AllCapsOption =
        new(aliases: ["-a", "--all-caps"], description: "Print the name in all caps");

    private readonly ProjectContext _context;

    public DotenvCommand(ProjectContext context) :
        base("hello", "An example command generated by dotnet new using the m4gp template")
    {
        _context = context;
        AddArgument(NameArgument);
        AddOption(AllCapsOption);
        this.SetHandler(ExecuteAsync, NameArgument, AllCapsOption);
    }

    private async Task ExecuteAsync(string name, bool allCaps)
    {
        name = allCaps ? name.ToUpper() : name;

        await _context.CreateFile("hello_world.txt",
            $"Hello {name}!",
            "This file was generated by your custom command!"
        );
    }
}

// After
public class DotenvCommand : Command, ISubCommandOf<RootCommand>
{
    private readonly Argument<string> VarsArgument =
        new(name: "vars", description: "Env vars to include in the .env file separated by ';'");

    private readonly Option<bool> PrintOption =
        new(aliases: ["-o", "--overwrite"], description: "Overwrite the .env file if it exists");

    private readonly ProjectContext _context;

    public DotenvCommand(ProjectContext context) :
        // dotenv = the name of the sub command that will be added to the m4g command
        base("dotenv", "Generate a .env file in the current directory")
    {
        _context = context;
        AddArgument(VarsArgument);
        AddOption(PrintOption);
        this.SetHandler(ExecuteAsync, VarsArgument, PrintOption);
    }

    private async Task ExecuteAsync(string vars, bool overwrite)
    {
        var path = Path.Join(Environment.CurrentDirectory, ".env");

        if (File.Exists(path))
        {
            if (overwrite) 
            {
                await _context.WriteFile(".env", content);
                return;
            }
            
            Console.WriteLine($"File {path} already exists, add the -o or --overwrite flag to overwrite it.");
        }

        var content = string.Join(Environment.NewLine, vars.Split(';'));
        await _context.CreateFile(".env", content);
    }
}
```

## Install the plugin

Open a terminal an make sure you're in the root directory of the plugin, i.e. the `My.Dotenv.Plugin` folder.
Run the following command to install the plugin.

```
m4g plugin install --platform <platform=linux_arm|linux_arm64|linux_x64|osx_arm64|osx_x64>
```

Make sure to choose the right platform option for your machine.
If everything went well then running `m4g` should now also show a `dotenv` command.

## Test the plugin

Try running `m4g dotenv "FIRSTNAME=JOHN;LASTNAME=JOE"`, this should generate a `.env` in the current directory with the vars you specified.

## Uninstall the plugin

Uninstall the plugin by running `m4g plugin install My.Dotenv.Plugin`.

## Resources

For examples of how the core commands are implemented, you can take a look at the commands in the [MycroForge.CLI.Commands](https://git.devdisciples.com/devdisciples/mycroforge/src/branch/main/MycroForge.CLI/Commands) namespace.

The MycroForge.CLI project uses [SystemCommand.Line](https://learn.microsoft.com/en-us/dotnet/standard/commandline/get-started-tutorial) for the CLI support, check out the Microsoft documentation for more info.