Powershell ssh-copy-id and ssh config tab complete add-ons to the `$PROFILE`

PROFILE

<#
.SYNOPSIS
    Linux-like SSH utilities and autocomplete configuration for Windows PowerShell.
.DESCRIPTION
    Adds tab completion for 'ssh', 'scp', 'sftp', and 'ssh-copy-id' by reading your ~/.ssh/config.
    Also implements a native PowerShell wrapper function for 'ssh-copy-id'.
.USAGE
    Paste this entire script block into your PowerShell profile. 
    To open your profile, run: notepad $PROFILE
#>

using namespace System.Management.Automation

# Helper function to parse Host entries from ssh config
function Get-Hosts($configFile) {
    if (Test-Path $configFile) {
        Get-Content $configFile `
        | Select-String -Pattern "^Host " `
        | ForEach-Object { $_ -replace "(?i)^host\s+", "" } `
        | ForEach-Object { $_ -split "\s+" } `
        | Where-Object { $_ -notmatch '[*?]' } `
        | Sort-Object -Unique
    }
}

# Native Windows port of the Linux ssh-copy-id script
function ssh-copy-id {
    param(
        [Parameter(Mandatory=$true, Position=0)]
        [string]$UserAtMachine,
        
        [Parameter(Mandatory=$false)]
        [string]$KeyPath = "$env:USERPROFILE\.ssh\id_rsa.pub"
    )

    # Fall back to ed25519 if default RSA doesn't exist
    if (-not (Test-Path $KeyPath)) {
        $KeyPath = "$env:USERPROFILE\.ssh\id_ed25519.pub"
    }

    if (-not (Test-Path $KeyPath)) {
        Write-Error "ERROR: Could not find a public key file at $env:USERPROFILE\.ssh\ (checked id_rsa.pub and id_ed25519.pub)"
        return
    }

    Write-Host "Copying key $KeyPath to $UserAtMachine..." -ForegroundColor Cyan
    
    # Securely append public key to remote host
    Get-Content $KeyPath -Raw | ssh $UserAtMachine "mkdir -p ~/.ssh && chmod 700 ~/.ssh && cat >> ~/.ssh/authorized_keys && chmod 600 ~/.ssh/authorized_keys"
}

# Register the interactive Tab-Completer for all SSH commands
Register-ArgumentCompleter -CommandName ssh, scp, sftp, ssh-copy-id -Native -ScriptBlock {
    param($wordToComplete, $commandAst, $cursorPosition)
    
    $sshDir = "${Env:USERPROFILE}\.ssh"
    $hosts = @()
    
    # Parse master config
    if (Test-Path "$sshDir\config") {
        $hosts += Get-Hosts "$sshDir\config"
        
        # Traverse any external 'Include' directives
        Get-Content "$sshDir\config" `
        | Select-String -Pattern "^Include " `
        | ForEach-Object { $_ -replace "(?i)^include\s+", "" } `
        | ForEach-Object { Get-Hosts "$sshDir/$_" }
    }
    
    $hosts = $hosts | Sort-Object -Unique
    $textToComplete = $wordToComplete
    $generateCompletionText = { param($x) $x }
    
    # Retain custom username prefix if typed (e.g., admin@ho[TAB])
    if ($wordToComplete -match "^(?<user>[-\w/\\\\]+)@(?<host>[-.\w]*)$") {
        $textToComplete = $Matches["host"]
        $generateCompletionText = { param($hostname) $Matches["user"] + "@" + $hostname }
    }
    
    $hosts `
    | Where-Object { $_ -like "${textToComplete}*" } `
    | ForEach-Object { [CompletionResult]::new((&$generateCompletionText($_)), $_, [CompletionResultType]::ParameterValue, $_) }
}