<#
  One-off migration: give every install folder the 4-character id suffix again.

    before:  <library>\installs\Public Scripting\
    after:   <library>\installs\Public Scripting-9ce8\      (suffix = first 4 characters of the install's Id in config.json)

  Run it after 2026-10-05-flatten-install-layout.ps1 (which produced names without a suffix).
  With the suffix, two installs may share a name without their folders colliding.

  Dry run by default. Run with pwsh.
    pwsh -File 2026-10-05-add-folder-id-suffix.ps1            # show the plan
    pwsh -File 2026-10-05-add-folder-id-suffix.ps1 -Apply

  Close CVRManager and every game from the library first. config.json is backed up next to itself,
  and progress is saved after every install, so a folder held open by Explorer only blocks that install.
#>
[CmdletBinding()]
param(
    [string]$ConfigDir = (Join-Path $env:APPDATA 'CVRManager'),
    [switch]$Apply,
    [switch]$SkipAppCheck   # only for testing against a throwaway copy
)
$ErrorActionPreference = 'Stop'

function Get-SafeFolderName([string]$name) {
    $bad = [IO.Path]::GetInvalidFileNameChars()
    $clean = -join ($name.ToCharArray() | ForEach-Object { if ($bad -contains $_) { ' ' } else { $_ } })
    while ($clean.Contains('  ')) { $clean = $clean.Replace('  ', ' ') }
    $clean = $clean.Trim().TrimEnd('.')
    if ($clean.Length -gt 60) { $clean = $clean.Substring(0, 60).TrimEnd() }
    if ($clean.Length -eq 0) { 'Install' } else { $clean }
}

$configPath = Join-Path $ConfigDir 'config.json'
if (-not (Test-Path $configPath)) { throw "No config at $configPath" }
$cfg = Get-Content $configPath -Raw | ConvertFrom-Json
$lib = if ($cfg.LibraryRoot) { $cfg.LibraryRoot } else { Join-Path $env:LOCALAPPDATA 'CVRManager' }
$installs = Join-Path $lib 'installs'

$running = @(if (-not $SkipAppCheck) { Get-Process CVRManager -ErrorAction SilentlyContinue }) + @(Get-Process ChilloutVR -ErrorAction SilentlyContinue | Where-Object { $_.Path -and $_.Path.StartsWith($installs, [StringComparison]::OrdinalIgnoreCase) })
if ($Apply -and $running.Count -gt 0) { throw "Close CVRManager and any game started from the library first (running: $(($running | ForEach-Object { $_.ProcessName + ' ' + $_.Id }) -join ', '))." }

$all = @($cfg.Installs)
$plans = @()
foreach ($i in $all) {
    $stem = "$(Get-SafeFolderName $i.Name)-$($i.Id.Substring(0, 4))"
    $want = $stem; $n = 2
    while ($true) {
        $clash = $all | Where-Object { $_ -ne $i -and $_.Folder -ieq $want }
        $existsOther = ($want -ine $i.Folder) -and (Test-Path (Join-Path $installs $want))
        if (-not $clash -and -not $existsOther) { break }
        $want = "$stem-$n"; $n++
    }
    if ($want -cne $i.Folder) { $plans += [pscustomobject]@{ Install = $i; From = $i.Folder; To = $want } }
}

"Library: $lib"
if ($plans.Count -eq 0) { 'Nothing to do: every install folder already has its suffix.'; return }
"Planned renames:"
foreach ($p in $plans) { "  - $($p.Install.Name): '$($p.From)' -> '$($p.To)'" + $(if (-not (Test-Path (Join-Path $installs $p.From))) { '   (folder missing on disk: config entry only)' } else { '' }) }
if (-not $Apply) { ''; 'Dry run only. Re-run with -Apply to make these changes.'; return }

$backup = "$configPath.bak-$(Get-Date -Format 'yyyyMMdd-HHmmss')"
Copy-Item $configPath $backup
"Config backed up to $backup"

function Save-Config { [IO.File]::WriteAllText($configPath, ($cfg | ConvertTo-Json -Depth 30), (New-Object Text.UTF8Encoding($false))) }
$failed = @()
foreach ($p in $plans) {
    $oldDir = Join-Path $installs $p.From
    $newDir = Join-Path $installs $p.To
    try {
        if (Test-Path $oldDir) {
            if ($oldDir -ieq $newDir) { $tmp = "$oldDir.renaming"; [IO.Directory]::Move($oldDir, $tmp); [IO.Directory]::Move($tmp, $newDir) }
            else { [IO.Directory]::Move($oldDir, $newDir) }
        }
        $p.Install.Folder = $p.To
        Save-Config
        "  done: $($p.Install.Name) -> $newDir"
    }
    catch [UnauthorizedAccessException], [IO.IOException] {
        $failed += $p.Install.Name
        Write-Warning "$($p.Install.Name): $($_.Exception.Message)"
        Write-Warning 'A folder of this install is probably open in Explorer or another program. Close it and run the script again.'
    }
}
if ($failed.Count -gt 0) { "Finished with problems for: $($failed -join ', '). Everything else was renamed and saved." } else { 'Config updated. Start CVRManager again.' }