HostnameColorGenerator.ps1

#!/usr/bin/pwsh

<#
This file is part of helpimnotdrowning's PwshUtils.

PwshUtils is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.

PwshUtils is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
PwshUtils. If not, see <https://www.gnu.org/licenses/>.
#>
function New-HostnameColor {
	param(
		[String] $Name = $(hostname)
		
	)
	
	# Prevent expensive spawning of another Powershell session if not needed
	if ((-not $env:nhnd_HostnameColor) -or($env:nhnd_AlwaysGenerateNewHostnameColor)) {
		# Get hash of hostname with silly roundabout method since Powershell only lets us compute hashes for files/streams
		$HostMD5Hash = Get-FileHash -Algorithm MD5 -InputStream ( [IO.MemoryStream]::new( [ byte[] ][ char[] ] $Name ) )
		
		$ColorSeed = [Int32]("0x" + $HostMD5Hash.Hash[0..7] -replace " ", "" )
		
		Write-Host $Name $HostMD5Hash.Hash $ColorSeed.toString('X')
		
		# Create a new PowerShell instance to do our "math" inside
		#	This is needed because "Get-Random -SetSeed" changes the seed for the lifetime of the session -- using a new session
		#	prevents this from affecting the main instance. The R, G, & B channels are generated with the seed derived from the
		#	hostname and saved as an RGB color.
		$env:nhnd_HostnameColor = (pwsh -NoProfile -Command {
			return '#' +
			# not used, gives lots of muddy greys; getting random for R, G & B
			# *seems* to be more random and gives nicer colors
			#(Get-Random -Minimum 0x0 -Maximum 0xFFFFFF -SetSeed $Args[0]).toString('X').PadLeft(6, '0')
			(Get-Random -Minimum 0x0 -Maximum 0xFF -SetSeed $Args[0]).toString("X").PadLeft(2, '0') +
			(Get-Random -Minimum 0x0 -Maximum 0xFF                  ).toString("X").PadLeft(2, '0') +
			(Get-Random -Minimum 0x0 -Maximum 0xFF                  ).toString("X").PadLeft(2, '0')
		} -Args $ColorSeed )
		
		# * But why the hostname? It's the only identifier I knew could be consistent from machine to machine;
		#	an IP address can change at the will of the DHCP server, a MAC address / disk|motherboard|CPU|GPU|etc serial no. can
		#	change with a hardware upgrade, but a human (or machine) defined name stays as long as the OS does (which is really all
		#	that matters).
	}
}