PowerShell ForEach hash comparison between directories - arrays

Question

I'm working on a script to compare two directories. There are two main things I want the script to show in the output--which files exist on one directory but not the other, and which files appear in both directories but have differences in them. Matching files don't need to show up.
I got some advice before on how to achieve this, but since I'm still pretty new to PS I'm having trouble executing it. What I'm trying to do is this:
I have Path #1. For each file in that path, I want to test for their existence on Path #2.
If the file exists in both paths, do a hash comparison between them. If there are differences, add the files to List A.
If the file appears in Path 1 but not Path 2, put them in List B.
This isn't as important, but would it also be possible to find files that exist in Path 2 but not Path 1? For work purposes that probably won't matter, but it will still be nice just in case.
Take the output and format it so that it can show something like: "The following files exist in Path 1 and not Path 2," and "The following files exist in both paths but have differences."
Basically, I don't just want an info dump of files to be the output and people end up having to puzzle through it. And like I said, I think the advice I received on how to do it will be good, I'm just having trouble making it work.
Here's the code I have so far:
$Source = #(Get-ChildItem -Recurse -Path \\SERVER\D$\PSTest)
foreach ($file in $Source){
If ($Target = Test-Path #(Get-ChildItem -Recurse -Path \\SERVER\D$\PSTest))
{
$HashResult = (Compare-Object -ReferenceObject $file -DifferenceObject
$Target -Property hash -PassThru).Path
}
else {
$Missing += $file
}
}
Write-Host 'These files have differences.' -ForegroundColor Green
$HashResult
Write-Host 'These files are missing from the target path.' -ForegroundColor
Green
$Missing
When I run that, I don't get any results (other than the text output). Where am I going wrong with this?

Answer 1

Made a few assumptions about the file names and their uniqueness down through the various depths of the source/target folders:
$SourceDir = "C:\\temptest";
$DestDir = "D:\\temptest";
$SourceFiles = #(Get-ChildItem -Recurse -Path $SourceDir);
$DestFiles = #(Get-ChildItem -Recurse -Path $DestDir);
$SourceFileNames = $SourceFiles | % { $_.Name };
$DestFileNames = $DestFiles | % { $_.Name };
$MissingFromDestination = #();
$MissingFromSource = #();
$DifferentFiles = #();
foreach($f in $SourceFiles) {
if (!$DestFileNames.Contains($f.Name)) {
$MissingFromDestination += $f;
} else {
$t = $DestFiles | Where { $_.Name -eq $f.Name };
if ((Get-FileHash $f.FullName).hash -ne (Get-FileHash $t.FullName).hash) {
$DifferentFiles += $f;
}
}
}
foreach($f in $DestFiles) {
if (!$SourceFileNames.Contains($f.Name)) {
$MissingFromSource += $f;
}
}
"
Missing from Destination: "
$MissingFromDestination | % { $_.FullName };
"
Missing from Source: "
$MissingFromSource | % { $_.FullName };
"
Source is Different: "
$DifferentFiles | % { $_.FullName };
This is a bit naive in its approach insofar as it is really only checking file names and ignoring subfolder tree structures. But, hopefully, it will give you enough of a leaping off point.