Powershell windows theme switch automation

themeswitcher.ps1

function Delete-ScheduledTask([string] $taskName)
{
    Write-Host "Delete schedule task for $taskName"
    Unregister-ScheduledTask -TaskName $taskName -Confirm:$false
}


function DeleteIfExists-ScheduledTask([string] $taskName)
{
    $exists = Get-ScheduledTask | Where-Object {$_.TaskName -like $taskName}
    if($exists)
    {
        Delete-ScheduledTask $taskName
    }
}

[int]$lighttime = 7
[int]$nighttime = 19

$enable_light_apps = 'reg add HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize /v AppsUseLightTheme /t REG_DWORD /d 1 /f'
$enable_light_system  = 'reg add HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize /v SystemUsesLightTheme /t REG_DWORD /d 1 /f'
$enable_dark_apps = 'reg add HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize /v AppsUseLightTheme /t REG_DWORD /d 0 /f'
$enable_dark_system  = 'reg add HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize /v SystemUsesLightTheme /t REG_DWORD /d 0 /f'

[int]$hrs = Get-Date -Format HH

Write-host "Day boundaries: $lighttime - $nighttime. Current time $a "

if ($hrs -ge $lighttime -and $hrs -lt $nighttime) {
  Write-Host "Its a day time!"
  Invoke-Expression $enable_light_apps
  Invoke-Expression $enable_light_system
} else {
  Write-Host "Its a night time!"
  Invoke-Expression $enable_dark_apps
  Invoke-Expression $enable_dark_system
}


[string]$user_folder = $env:USERPROFILE
[string]$script_destination_file = "$user_folder\themeswitcher.ps1"

if ($PSScriptRoot -ne $user_folder) {
    $MyInvocation.MyCommand.ScriptContents | Out-File $script_destination_file
}

$task_name = "Theme Switcher"
$user_name = [environment]::username

$trigger = @(
    $(New-ScheduledTaskTrigger -At "$([string]$lighttime):00" -Daily),
    $(New-ScheduledTaskTrigger -At "$([string]$nighttime):00" -Daily)
    $(New-ScheduledTaskTrigger -AtLogOn -User $user_name)
)

DeleteIfExists-ScheduledTask($task_name)

$action = New-ScheduledTaskAction -Execute "PowerShell.exe" -Argument "-ExecutionPolicy Bypass -File $script_destination_file"
Register-ScheduledTask -TaskName $task_name -Action $Action -Trigger $trigger