<#
.SYNOPSIS
  Switch the RetroBar theme (or any other RetroBar setting) from the command line.

.DESCRIPTION
  RetroBar has no command-line options (RetroBar issue #958). It reads its settings from
  %LOCALAPPDATA%\RetroBar\settings.json when it starts. This script closes RetroBar,
  changes the values you ask for in settings.json, and starts RetroBar again.

  Published by retrobar.dev (not part of the RetroBar project). Tested on Windows
  with RetroBar 1.22.122; see https://retrobar.dev/tools/settings-builder/

.EXAMPLE
  .\Set-RetroBarTheme.ps1 -Theme 'Windows XP Blue'

.EXAMPLE
  .\Set-RetroBarTheme.ps1 -List

.EXAMPLE
  .\Set-RetroBarTheme.ps1 -Theme 'Windows 2000' -Set @{ ShowClockSeconds = $true; Edge = 1 }
#>
[CmdletBinding(DefaultParameterSetName = 'Apply')]
param(
  [Parameter(ParameterSetName = 'Apply', Position = 0)][string]$Theme,
  [Parameter(ParameterSetName = 'Apply')][hashtable]$Set = @{},
  [Parameter(ParameterSetName = 'List')][switch]$List,
  [string]$RetroBarPath
)
$ErrorActionPreference = 'Stop'
$dataDir = Join-Path $env:LOCALAPPDATA 'RetroBar'
$settingsFile = Join-Path $dataDir 'settings.json'

function Find-RetroBarExe {
  if ($RetroBarPath) { return (Resolve-Path $RetroBarPath).Path }
  $running = Get-Process RetroBar -ErrorAction SilentlyContinue | Select-Object -First 1
  if ($running -and $running.Path) { return $running.Path }
  foreach ($hive in 'HKCU', 'HKLM') {
    $key = "${hive}:\Software\Microsoft\Windows\CurrentVersion\Uninstall\{574527FE-00A4-4F85-92AD-B4B8B4077D73}_is1"
    $loc = (Get-ItemProperty $key -ErrorAction SilentlyContinue).InstallLocation
    if ($loc -and (Test-Path (Join-Path $loc 'RetroBar.exe'))) { return (Join-Path $loc 'RetroBar.exe') }
  }
  foreach ($p in "$env:LOCALAPPDATA\Programs\RetroBar\RetroBar.exe", "$env:ProgramFiles\RetroBar\RetroBar.exe") {
    if (Test-Path $p) { return $p }
  }
  throw 'RetroBar.exe not found. Start RetroBar once, or pass -RetroBarPath "C:\path\to\RetroBar.exe".'
}

function Get-Themes($exe) {
  $dirs = @((Join-Path (Split-Path $exe) 'Themes'), (Join-Path $dataDir 'Themes'))
  $names = foreach ($d in $dirs) { if (Test-Path $d) { Get-ChildItem $d -Filter *.xaml | ForEach-Object { $_.BaseName } } }
  return @('System') + @($names | Where-Object { $_ -ne 'System' } | Sort-Object -Unique)
}

$exe = Find-RetroBarExe
if ($List) { Get-Themes $exe; return }

if ($Theme) {
  $themes = Get-Themes $exe
  $match = $themes | Where-Object { $_ -ieq $Theme } | Select-Object -First 1
  if (-not $match) { throw "Unknown theme '$Theme'. Available: $($themes -join ', ')" }
  $Set['Theme'] = $match
}
if ($Set.Count -eq 0) { throw 'Nothing to change. Use -Theme and/or -Set @{ Name = value }.' }

# Stop RetroBar first: it writes settings.json itself and would overwrite our change.
# It has no command to quit from outside (asking its window to close does nothing; tested on
# Windows 11 and Server 2025/2022), so the process is ended. It is started again below, and on
# start it hides the Windows taskbar again.
Get-Process RetroBar -ErrorAction SilentlyContinue | Stop-Process -Force
Start-Sleep -Milliseconds 800

New-Item -ItemType Directory -Force -Path $dataDir | Out-Null
$json = if (Test-Path $settingsFile) { Get-Content $settingsFile -Raw | ConvertFrom-Json } else { [pscustomobject]@{} }
foreach ($k in $Set.Keys) { $json | Add-Member -NotePropertyName $k -NotePropertyValue $Set[$k] -Force }
[IO.File]::WriteAllText($settingsFile, ($json | ConvertTo-Json -Depth 8), (New-Object Text.UTF8Encoding $false))

Start-Process -FilePath $exe -WorkingDirectory (Split-Path $exe)
Write-Host ("RetroBar restarted with: " + (($Set.GetEnumerator() | ForEach-Object { "$($_.Key) = $($_.Value)" }) -join '; '))