installs MSys2 or refreshes an existing installation using winget; updates pacman, and optionally executes additional bash setup commands

msys2-setup.ps1

param (
    # provide a list of addition bash setup commands to invoke
    [string] $additional = "msys2-additional-setup",
    # true teardown existing installations, false to stop if installation exists
    [switch] $refresh = $false
)

# constant defining MSys2 winget package name
[string] $package = "MSys2"
# checks to see if an installaiton already exists
[string] $check = winget list $package --source winget 
# generates a user home path, c:\msys64 is default winget installation path
[string] $user_home = "C:\msys64\home\$($env:UserName)"
# determines the padding for uniform formated progress output
[int32]  $padding = 18 + $user_home.Length # 18 is derived from potentially the widest output without the user name

# load and parse any additional bash setup commands if file it exists, otherwise skips any additional setup
[PSCustomObject[]] $bashCommands = if (Test-Path -Path $additional -PathType Leaf) {
    [string[]] $parts = @()
    [string] $command = ""
    [string] $message = ""

    Get-Content $additional | ForEach-Object {
        # ignore blank lines or comment lines
        if ([string]::IsNullOrWhiteSpace($_) -or $_.Trim().StartsWith("#")) {
            return
        }

        # parses the line "command | message"
        $parts = $_.Split('|')
        $command = $parts[0].Trim()

        # minimally validate command
        if ([string]::IsNullOrWhiteSpace($command)) {
            Write-Host "Additional setup must provide a valid bash ""Command""" -ForegroundColor Red
            exit -1
        }

        $message = $parts[1].Trim()

        # minimally validate message
        if ([string]::IsNullOrWhiteSpace($message)) {
            Write-Host "Additional setup must provide a descriptive ""Message""" -ForegroundColor Red
            exit -2
        }

        # determines the padding for uniform formated progress output 
        if ($message.Length -gt $padding) {
            $padding = $message.Length
        }

        # adds a --noconfirm flag to pacman instructions 
        if ($command.ToUpper().Contains("PACMAN") -and !$command.ToUpper().Contains("--NOCONFIRM")) {
            $command += " --noconfirm"
        }
    
        [PSCustomObject] @{
            Command = $command
            Message = $message
        }
    }
} else {
    @() # otherwise no additional setup
}

# confims the success of the previous instruction and outputs a status message, exits script if it failed
function Confirm-Success {
    Write-Host " - " -NoNewline
    if ($LASTEXITCODE -ne 0) {
        Write-Host failed: $LASTEXITCODE -ForegroundColor Red
        exit $LASTEXITCODE
    } else {
        Write-Host succeeded -ForegroundColor Blue
    }
}

# invokes and checks the success of bash command
function Invoke-BashCommand {
    param ([string] $command)
    
    # c:\msys64 is default winget installation path
    C:\msys64\usr\bin\bash -l -c $command *>$null
    Confirm-Success
}

# checks to see if MSys2 is installed
if (!$check.ToUpper().Contains("NO INSTALLED PACKAGE") ) {
    # if installed and the refresh flag is set, MSys2 is uninstalled
    if ($refresh) {
        Write-Host "Uninstalling $package".PadRight($padding) -NoNewline
        winget uninstall $package --source winget  | Out-Null
        Confirm-Success
    } else {
        # otherwise the script is exited
        Write-Host $package is already installed -ForegroundColor Yellow
        return
    }
}

# install MSys2 and confirm success
Write-Host "Installing $package".PadRight($padding) -NoNewline
winget install $package --source winget | Out-Null
Confirm-Success

# create the current users home folder and confirm success
Write-Host "Creating ""$user_home"" Folder".PadRight($padding) -NoNewline
New-Item -ItemType Directory -Path $user_home | Out-Null
Confirm-Success

# update system packages and confirm success
Write-Host "Updating $package System Packages".PadRight($padding) -NoNewline
Invoke-BashCommand "pacman -Syu --noconfirm"

# update packages and confirm success
Write-Host "Updating $package Packages".PadRight($padding) -NoNewline
Invoke-BashCommand "pacman -Su --noconfirm"

# invoke additional bash setup comands
foreach($bash in $bashCommands) {
    Write-Host $bash.Message.PadRight($padding) -NoNewline
    Invoke-BashCommand $bash.Command
}